JPH11221694A - Mounting structure using lead-free solder and mounting method using the same - Google Patents

Abstract

[PROBLEMS] To provide L on both surfaces of an organic substrate such as a glass epoxy substrate.
Electronic parts such as SI and chip parts are soldered with Sn-Ag-Bi-based lead-free solder with desired connection strength without remarkably lowering the wetting property to improve the reliability of the connection part. An object of the present invention is to provide a mounting structure using a lead-free solder and a mounting method using the same. According to the present invention, an electronic component is composed of Sn as a main component, Bi of 0 to 65 mass%, and Ag of 0.5 to 4.0 on both surfaces of a first surface and a second surface of an organic substrate. 0
mass%, Cu and / or In in total of 0 to 3.0
It is characterized by reflow soldering with lead-free solder containing mass%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component such as an LSI or a component, which is provided with Sn-Ag- (Bi or Cu or I
n etc.) using a ternary lead-free solder
Also, the present invention relates to a mounting structure using lead-free solder configured to be connected to an organic substrate by flow soldering, and a mounting method using the same.

[0002]

2. Description of the Related Art A commonly used printed circuit board is made of glass epoxy. The heat-resistant temperature of the glass epoxy substrate is usually 220 ° C. to 235 when using a reflow furnace.
° C. The connection solder used for this is Sn-37
Mass% Pb (hereinafter Sn-37Pb) eutectic solder (melting point: 183 ° C) or solder having a composition near eutectic is used, and the melting point is around 183 ° C. Sufficient connections have been made below the heat resistant temperature. Also, reliability at high temperature is up to 15
It could be guaranteed up to 0 ° C. However, recently, in the United States, electronic component waste is left undisturbed, and lead (hereinafter, referred to as Pb) contained in the solder on the printed circuit board therein easily reacts with acid rain and elutes into groundwater, and is discharged into drinking water. It has been published that if used, it will have an adverse effect on the human body.

[0003]

Therefore, the Sn-P
Sn- as a Pb-free solder alloy replacing b-based solder
The one based on the Ag-Bi ternary system has been highlighted as a promising candidate. The reason is that, in the case of Pb-free solder, the composition has been studied by expanding to a binary system, and then Sn-3.5 mass% Ag (melting point: 221 ° C.)
Sn-5mass% Sb (melting point: 199 ° C.) has been used, but the melting point is too high as compared with Sn-37Pb, so that it is difficult to use for soldering a glass epoxy substrate. With -9 mass% Zn (melting point: 199 ° C.), the melting point is lowered, but the solder surface is liable to be oxidized remarkably.
Ag, Sn-Sb-based solder is significantly reduced compared to the solder, so that it is difficult to use, Sn-58 mass%
Bi (melting point: 138 ° C.) is difficult to use because the material itself is hard and brittle and has a problem in reliability. Sn-52
Mass% In (melting point 117 ° C.) has a problem in that the melting point of the connection portion is low because the melting point is too low as compared with Sn-37Pb. However, if it is expanded to Sn-Ag-Bi ternary system, 183 ° C higher than binary system
(Melting point of Sn-37Pb).

However, in this ternary system, the melting point is 18
When searching for a material close to 3 ° C, a perfect eutectic composition could not be obtained, and a solidus temperature lower than 183 ° C and a liquidus temperature higher than 183 ° C (solid-liquid coexistence temperature) It becomes a composition. Therefore, when connecting components by reflow soldering and then performing flow soldering, the connected components generally have a different heat capacity from the glass epoxy board, so after reflow or flow soldering, the board is cooled by natural air cooling. At times, the temperature of the component and the substrate decrease differently, resulting in a large temperature gradient in the solder at the connection. Therefore, during solidification of the solder, in the case of a solder having a wide solid-liquid coexistence temperature range, a phase having a low melting point (a hard and brittle phase containing a lot of Bi) is segregated toward a higher temperature, and solidification is completed. The connection strength of the reflow soldered parts later tends to be reduced. Therefore, when performing reflow or flow soldering after reflow soldering with a solder having a wide solid-liquid coexistence temperature range, the solder for reflow must have no liquid phase.

[0005] An object of the present invention is to solve the above problems.
Electronic components such as LSIs and chip components are provided on both sides of an organic substrate such as a glass epoxy substrate by Sn-Ag- (Bi and / or
Or, using lead-free solder (Cu or In, etc.), use lead-free solder which has been soldered with a desired connection strength without significantly lowering the wettability to improve the reliability of the connection part. To provide a mounting structure. Another object of the present invention is to provide an electronic component such as an LSI or a chip component on both surfaces of an organic substrate such as a glass epoxy substrate by using Sn-Ag- (Bi and / or (Cu or In or the like))-based lead-free. Provided is a mounting method using lead-free solder that can improve the reliability of a connection portion by soldering with a desired connection strength without significantly lowering wettability using solder. It is in.

[0006]

In order to achieve the above object, the present invention provides an electronic component comprising Sn as a main component, Bi of 0 to 65 mass%, and Ag of 0.5 to 4.0 mass.
%, Cu or / and In in total of 0-3.0 mass
A lead-free solder is used to connect the first and second surfaces of the organic substrate to each other with a lead-free solder. Further, the present invention comprises the first surface and the second surface of the organic substrate by a lead-free solder in which the solidus temperature of the lead-free solder on the first surface is equal to or higher than the liquidus temperature of the lead-free solder on the second surface. A mounting structure using lead-free solder, wherein electronic components are connected to both sides.

Further, according to the present invention, the electronic component contains Sn as a main component, Bi of 0 to 65 mass%, and Ag of 0.5 to 4.0.
0 mass%, Cu or / and In in total of 0-3.
0 mass%, and the solidus temperature of the lead-free solder on the first surface is equal to or higher than the liquidus temperature of the lead-free solder on the second surface.
A mounting structure using lead-free solder, wherein the mounting structure is configured to be connected to each of both surfaces including a surface and a second surface.

Further, according to the present invention, the electronic component contains Sn as a main component and Bi of 0 to 3% by mass or 50 to 65% by mass.
s%, Ag is 0.5 to 4.0 mass%, and Cu and / or In are connected to the first surface of the organic substrate by a lead-free solder containing a total of 0 to 3.0 mass%,
From the second surface side opposite to the first surface, the electronic component is composed mainly of Sn, Bi is 0 to 65 mass%, and Ag is 0.5 to 0.5%.
4.0 mass%, Cu and / or In are 0 to total.
A mounting structure using lead-free solder, wherein the mounting structure is connected to an organic substrate with a lead-free solder containing 3.0 mass%. Further, according to the present invention, the electronic component has Sn as a main component, Bi of 3 to 50 mass%, A
g is 0.5 to 4.0 mass%, Cu and / or I
n is connected to the first surface of the organic substrate by a lead-free solder containing a total of 0 to 3.0 mass%, and the electrodes of the mounted electronic component are arranged from the second surface side opposite to the first surface. Sn as a main component, Bi is 3 to 65 mass%, A
g is 0.5 to 4.0 mass%, Cu and / or I
a total of 0 to 3.0 mass% of n, and connected to the organic substrate by a lead-free solder having a liquidus temperature equal to or lower than a solidus temperature of the lead-free solder on the first surface. This is a mounting structure using free solder.

Further, according to the present invention, the electronic component is composed of Sn as a main component, Bi of 0 to 65 mass%, and Ag of 0.5 to 4.0 on each of the first and second surfaces of the organic substrate.
0 mass%, Cu or / and In in total of 0-3.
This is a mounting method using lead-free solder, wherein reflow soldering is performed using lead-free solder containing 0 mass%.

Further, according to the present invention, the electronic component contains Sn as a main component and Bi of 0 to 3 mass% or 50 to 65 mass%.
a reflow soldering step of performing reflow soldering on the first surface of the organic substrate with a lead-free solder containing 0.5 to 4.0 mass% of Ag, 0.5 to 4.0 mass% of Ag, and a total of 0 to 3.0 mass% of Cu, The electronic component has Sn as a main component, Bi of 0 to 65 mass%, and Ag of 0.5
~ 4.0 mass%, Cu and / or In total 0
A flow soldering step of performing flow soldering from a second surface side opposite to the first surface of the organic substrate with a lead-free solder containing up to 3.0 mass%. is there.

The present invention also provides a reflow soldering step of reflow soldering an electronic component to a first surface of an organic substrate with lead-free solder, and a method in which a liquidus temperature is set to a value corresponding to an electrode of the mounted electronic component. A flow soldering step of performing flow soldering from a second surface side opposite to the first surface of the organic substrate with a lead-free solder having a solidus temperature equal to or lower than a solidus temperature of the lead-free solder on the first surface. This is a mounting method using solder.

In the present invention, the electronic component is mainly composed of Sn, Bi is 3 to 50 mass%, and Ag is 0.5 to 4.
0 mass%, Cu or / and In in total of 0-3.
A reflow soldering step of performing reflow soldering on the first surface of the organic substrate with a lead-free solder containing 0 mass%, and for an electrode of a mounted electronic component, Sn is a main component, Bi is 3 to 65 mass%, and Ag is Ag. 0.5 to
4.0 mass%, Cu and / or In are 0 to total.
A flow in which the liquidus temperature is 3.0 mass% and the liquidus temperature is lower than the solidus temperature of the lead-free solder on the first surface by flow soldering from the second surface side opposite to the first surface of the organic substrate. A mounting method using lead-free solder, comprising a soldering step.

Further, according to the present invention, the electronic component contains Sn as a main component and Bi of 0 to 3% by mass or 50 to 65% by mass.
The first surface of the organic substrate and the second surface opposite to the first surface by a lead-free solder containing 0.5 to 4.0 mass% of Ag, 0.5 to 4.0 mass% of Ag, and a total of 0 to 3.0 mass% of Cu or / and In. A reflow soldering step of reflow soldering, and protecting the electronic component on the second surface with a cover.
i is 0 to 65 mass%, and Ag is 0.5 to 4.0 mass%.
s%, Cu or / and In in total of 0-3.0 mas
a flow soldering step of performing flow soldering from the second surface side of the organic substrate with lead-free solder containing s%.

Further, according to the present invention, the electronic component contains Sn as a main component and Bi of 0 to 3% by mass or 50 to 65% by mass.
s%, Ag is 0.5 to 4.0 mass%, and Cu or / and In are reflow soldered to the second surface of the organic substrate with a lead-free solder containing 0 to 3.0 mass% in total. Sn is the main component, and Bi is 3 to
50 mass%, Ag is 0.5 to 4.0 mass%, C
a reflow soldering step of performing reflow soldering on the first surface opposite to the second surface with a lead-free solder containing u or / and In in total of 0 to 3.0 mass%;
The electronic component on the second surface is protected by a cover, and the electrode of the mounted electronic component has Sn as a main component and Bi of 3 to 6
5 mass%, Ag is 0.5 to 4.0 mass%, Cu
And / or a flow soldering step of performing flow soldering from the second surface side of the organic substrate with a lead-free solder containing a total of 0 to 3.0 mass% of In. It is.
Further, in the present invention, the electronic component is mainly composed of Sn, Bi is 3 to 50 mass%, and Ag is 0.5 to 4.0 mass%.
%, Cu or / and In in total of 0-3.0 mass
% By reflow soldering on the second surface of the organic substrate with lead-free solder, and further, the electronic component is mainly composed of Sn, and has a Bi content of 0 to 3 mass% or 50 to 65 mass%.
s%, 0.5 to 4.0 mass% of Ag, and reflow soldering to the first surface opposite to the second surface with a lead-free solder containing Cu and / or In in total of 0 to 3.0 mass%. Attaching the electronic component to the second surface with a cover, and applying Sn to the electrodes of the mounted electronic component with Sn as a main component and a Bi of 3 to 65 mass.
%, Ag is 0.5 to 4.0 mass%, Cu or /
And In are contained in a total of 0 to 3.0 mass%, and the liquidus temperature is flow soldering from the second surface side of the organic substrate with a lead-free solder having a liquidus temperature not lower than the solidus temperature of the lead solder for reflow to the first surface. And a mounting method using lead-free solder.

In the present invention, the electronic component is mainly composed of Sn, Bi is 3 to 50 mass%, and Ag is 0.5 to 4.0.
0 mass%, Cu or / and In in total of 0-3.
A reflow soldering process of reflow soldering the first surface of the organic substrate and the second surface opposite to the first surface with a lead-free solder containing 0 mass%, and protecting and mounting the electronic components on the second surface with a cover With respect to the electrodes of the electronic component, with Sn as the main component, Bi at 3 to 65 mass%,
Lead containing 0.5 to 4.0 mass% of Ag and a total of 0 to 3.0 mass% of Cu and / or In and having a liquidus temperature equal to or higher than the solidus temperature of the reflow lead solder to the first surface. A flow soldering step of performing flow soldering from the second surface side of the organic substrate with free solder. Further, in the present invention, in the mounting method using the lead-free solder, when the second surface is reflow-soldered, the temperature of the lead-free solder on the first surface already reflow-soldered is 136.5 ° C. or less. It is characterized by. Further, the present invention is characterized in that, in the mounting method using the lead-free solder, when the flow soldering is performed from the second surface side, an inert gas is blown to a reflow soldering portion on the first surface to cool the portion.

As described above, according to the above configuration,
Electronic components such as LSIs and chip components are mounted on both sides of an organic substrate such as a glass epoxy substrate using lead-free solder that reduces environmental pollution, without significantly lowering the wettability.
Further, by making the melting point close to about 183 ° C., it is not brittle, and can be soldered with a desired connection strength without remarkable segregation to improve the reliability of the connection portion.

Further, according to the above configuration, electronic components such as LSIs and chip components are provided on both surfaces of an organic substrate such as a glass epoxy substrate by using Sn-Ag- (Bi and / or (Cu or In) to reduce environmental pollution. Using a lead-free solder of the type, soldering with a desired connection strength without remarkably lowering the wettability, further bringing the melting point close to about 183 ° C, not being brittle, and not causing significant segregation. As a result, the reliability of the connection portion can be improved.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail.

[First Embodiment] LSI according to the present invention
The first embodiment in which electronic components such as chips and chip components are mounted by reflow soldering using lead-free solder on both surfaces (first and second surfaces) of an organic substrate made of a material such as glass epoxy, This will be described with reference to FIG.

The heating temperature at the time of reflow soldering with a reflow furnace using lead-free solder for reducing environmental pollution is usually about 220 ° C. to 235 ° C. or less due to the heat resistant temperature of an organic substrate made of a material such as glass epoxy. Need to be In addition, Cu, Ni formed on the organic substrate
To improve the wettability of the electrodes, and to further reduce the melting point to about 18
It is necessary to secure a desired connection strength by approaching 3 ° C. without being brittle and without significant segregation. As shown in FIG. 1, electronic components 3 such as an LSI 3a and a chip component 3b are mounted on an organic substrate 1 by mounting lead-free solders 5a and 5b for reflow on both the first surface 1a and the second surface 1b of the organic substrate 1. In order to reflow at about 235 ° C. in the mounting of the lead-free solder 5a for each surface reflow,
The liquidus temperature of 5b needs to be approximately 215 ° C. or less. FIG. 4 shows Sn-Ag-Bi3 which is a lead-free solder.
The solidus temperature 9,11, the liquidus temperature 10, when the Bi amount is changed along the Sn-Ag, Ag-Bi binary eutectic line, which can obtain a melting point close to about 183 ° C in the primary system,
12 is shown. 9 is a lead-free solder, Sn-
3 shows a solidus temperature on a Sn-Ag binary eutectic line in an Ag-Bi ternary alloy system. 10 is a lead-free solder, S
4 shows a liquidus temperature on a Sn-Ag binary eutectic line in an n-Ag-Bi ternary alloy system. 11 shows the solidus temperature on the Ag-Bi binary eutectic line in the Sn-Ag-Bi ternary alloy system which is a lead-free solder. Numeral 12 denotes Ag-Bi in a Sn-Ag-Bi ternary alloy system which is a lead-free solder.
The liquidus temperature on the binary eutectic line is shown. According to this, Bi
When the amount is 0 mass%, both the solidus temperature and the liquidus temperature are about 221 ° C., but as conditions empirically obtained,
To reflow at 235 ° C., the liquidus temperature must be 215 ° C.
It must be less than or equal to ° C, which is not met. However, In or Cu is added to the Sn-Ag system in an amount of 0 to 3 mass.
%, The liquidus temperature can be reduced to about 215 ° C. or less while avoiding a sharp drop in the solidus temperature. But,
When the Bi content exceeds approximately 65 mass%, the hard and brittle nature of Bi adversely affects the solder material, so that the Bi content is 0 to 6%.
It was considered that a solder having a content of 5 mass% can be used as a solder for reflow.

That is, in the first embodiment, LS
Electronic components 3 such as I and chip components are formed on both surfaces (first surface 1a and second surface 1b) of the organic substrate 1 with Sn as a main component, Bi of 0 to 65 mass%, and Ag of 0.5 to 4.0. 0
mass%, Cu and / or In etc. in total of 0-3.
Reflow soldering is performed using a lead-free solder of Sn-Ag- (Bi and / or (Cu or In)) having a composition containing 0 mass%. In particular, by containing 0.5 to 4.0 mass% of Ag,
The structure is refined and the mechanical properties change, for example, S
Compared to n-58 mass% Bi, it is no longer hard and brittle, and desired reliability can be ensured at the connection portion. Here, first, reflow soldering is performed on the first surface 1a of the organic substrate 1, and then the organic substrate 1 is turned over and
The surface 1a faces down and reflow soldering is performed on the second surface 1b. In this case, when lead-free solders 5a and 5b for each surface reflow are used which have similar solid-liquid phase temperature characteristics, the electronic components mounted on the first surface 1a are relatively small like QFP-LSI or the like. If there is a heavy component, it is necessary to fix the electronic component to the organic substrate 1 using an adhesive or the like. Relatively light components such as chip components do not fall even if they are not fixed.

In the first embodiment, when reflow soldering the second surface, the lead-free solder temperature of the first surface already reflow soldered is 136.5 ° C.
It is desired that: According to the first embodiment, the reflow soldering can be performed by using a ternary lead-free solder at a temperature lower than the heat resistance temperature of the organic substrate 1 made of a material such as glass epoxy which is generally used. And Cu, Ni formed on the organic substrate 1
To improve the wettability of the electrodes, and to further reduce the melting point to about 18
By approaching 3 ° C., a desired connection strength can be secured without being brittle and without significant segregation.

(Embodiment 1-1) First, as shown in FIG.
Lead pitch: 0.5 mm, lead width: 0.2 mm, number of leads on each side: 208, dimensions 32 mm square, 1.6 mm thick, 90 mm long, 140 mm wide, and 18 μm thick copper foil on the board surface QFP-LSI 3a and a chip component 3b of dimensions 1.6 mm × 3.2 mm
n-2.8Ag-15Bi-0.5Cu (unit: mas)
s%) (solidus temperature: about 155 ° C, liquidus temperature: about 20
4 ° C.) with the solder paste 5a1 on the first surface 1a of the substrate.
At about 220 ° C. for reflow connection. Next, the same QFP-LSI 3a and chip component 3b as the first surface are also formed on the second surface 1b of the substrate 1 with the first surface 1a of the substrate 1 facing down.
2.8Ag-15Bi-0.5Cu (unit: mass)
%) (Solidus temperature: about 155 ° C, liquidus temperature: about 204
C.) using a solder paste 5b1 at about 220.degree. Composition Sn-2.8Ag-15Bi-
In the case of a 0.5 Cu (unit: mass%) solder paste, the solidus temperature is about 155 ° C., and the liquidus temperature is about 204 ° C.
Satisfies the liquidus temperature of 215 ° C. or less,
Reflow connection can be performed at about 220 ° C., which is about 10 ° C. lower than 0 ° C. At this time, QFP of the components on the first surface 1a
Only the LSI 3a was fixed to the substrate 1 with an adhesive, but even if the relatively light chip component 3b was not fixed, the component did not drop during the reflow of the second surface 1b.

As a result, both sides 1a, 1
5b and the lead of the QFP-LSI 3a is pulled in the direction of 45 ° with respect to the substrate surface by the method shown in FIGS. 5 and 6, and the maximum value of the tensile load until breakage occurs in the connection portion (this is the 45 ° peel strength and The average value of the measured values was about 6N on both sides of the substrate, indicating that sufficient strength was secured. That is, when the reflow connection is performed on the second surface 1b using the solder paste 5b1, the first
The effect on the solder paste 5a1 reflow-connected to the surface 1a was small, and a sufficient connection strength could be obtained also for the first surface 1a. FIG. 5 is a diagram showing the entire 45 ° peel test apparatus. FIG. 6 is an enlarged view showing a state where the test sample 16 is attached to the jig 15 in the 45 ° peel test apparatus. The 45 ° peel test apparatus includes a jig 15 for mounting a test sample 16 having a connection portion 19 in which an electronic component 18 is soldered to a substrate 17 at an angle of 45 °.
And a load applying mechanism 20 for applying a load by lowering the jig 15 as indicated by the arrow, a hook 14 for hooking the electronic component side of the connecting portion 19, and a load applied to the hook 14 are measured. It is constituted by the measuring means 13. In addition,
The jig 15 is adjusted so that the portion to be measured is directly below the measuring means 13. With the 45 ° peel test apparatus configured as described above, 45 ° until the breakage at the connection occurs.
The maximum value of the tensile load in the direction can be measured.

(Embodiment 1-2) First, as shown in FIG.
Lead pitch: 0.5 mm, lead width: 0.2 mm, number of leads on each side: 208, dimensions 32 mm square, 1.6 mm thick, 90 mm long, 140 mm wide, and 18 μm thick copper foil on the board surface QFP-LSI 3a and a chip component 3b of dimensions 1.6 mm × 3.2 mm
n-2.8Ag-15Bi-0.5Cu (unit: mas)
s%) (solidus temperature: about 155 ° C, liquidus temperature: about 20
4 ° C.) of the first surface 1 of the substrate 1 using the solder paste 5a1.
a was connected by reflow at about 220 ° C. Next, this substrate 1
With the first surface 1a facing down and the same QFP-LSI 3a and chip component 3b as the first surface on the second surface 1b of the substrate 1 with the composition Sn
-1Ag-57Bi (unit: mass%) (solidus temperature: about 137 ° C, liquidus temperature: about 137 ° C) was reflow soldered at about 180 ° C with a solder paste 5b2. This embodiment is characterized in that the liquidus temperature of the solder paste 5b2 is about 137 ° C. lower than the solidus temperature of the solder paste 5a1 is about 155 ° C. Thus, when the electronic component 3 is reflow-soldered to the second surface 1b of the substrate 1 with the solder paste 5b2, the reflow temperature applied to the solder paste 5a1 applied to the first surface 1a is set to a value near the solidus temperature of about 155 ° C. It is possible to
There is no need to worry about falling even with a relatively heavy object such as a QFP-LSI. Further, the 45 ° peel strength of the leads of the QFP-LSI on both sides 1a and 1b of the board 1 after connection was measured by the method shown in FIGS. 5 and 6, and the average value was obtained. It was found that high strength was secured. That is, since the liquidus temperature of the solder paste 5b2 is about 137 ° C. lower than the solidus temperature of the solder paste 5a1 is about 155 ° C., when the solder paste 5b2 is used for reflow connection on the second surface 1b, First side 1
There was almost no effect on the solder paste 5a1 reflow-connected to a as compared with Example 1-1, and sufficient connection strength was obtained not only for the second surface 1b but also for the first surface 1a.

[Second Embodiment] LSI according to the present invention
And electronic components such as chip components are reflow-soldered to the surface (first surface) of an organic substrate made of a material such as glass epoxy using lead-free solder, and the surface of the organic substrate (first surface)
A second embodiment in which an insertion component is inserted from the side and flow-soldering is performed on the back surface (second surface) using lead-free solder and mounted will be described with reference to FIG. The heating temperature for reflow soldering with a reflow furnace using lead-free solder that reduces environmental pollution is usually 2 due to the heat resistance temperature of the organic substrate made of a material such as glass epoxy.
It is necessary to be about 20 ° C. to 235 ° C. or less. FIG.
Sn-Ag which can obtain a melting point close to about 183 ° C in a Sn-Ag-Bi ternary system which is a lead-free solder,
The solidus temperatures 9 and 11 and the liquidus temperatures 10 and 12 when the Bi amount is changed along the Ag-Bi binary eutectic line are shown. According to this, when the Bi amount is 0 mass%, both the solidus temperature and the liquidus temperature are about 221 ° C., but as an empirically obtained condition, in order to reflow at about 235 ° C., The temperature must be below 215 ° C,
This is not satisfied. However, in the Sn-Ag system,
By adding 0 or 3 mass% of In or Cu, the liquidus temperature can be kept at 215 ° C. or lower while avoiding a sharp drop in the solidus temperature. However, the amount of Bi is about 65 mass%.
It is considered that the hard and brittle properties of Bi have an adverse effect on the solder material when the ratio exceeds Bi, so that the Bi content in the range of 0 to 65 mass% can be used as the reflow solder. It also improves the wettability of electrodes such as Cu and Ni formed on the organic substrate, and keeps the melting point close to about 183 ° C to ensure desired connection strength without being brittle and without significant segregation. There is a need to.

Furthermore, in the flow soldering, although the contact time of the molten solder with the organic substrate is as short as several seconds, it is necessary to protect the solder on the reflow surface already soldered. As shown in FIG. 2, each electronic component 3 such as an LSI 3a and a chip component 3b is reflow-soldered on the surface (first surface) 1a of the organic substrate 1 using a reflow lead-free solder 5c. Insertion part 4 from the first surface side of 1
And a lead-free solder 7 on the back surface (second surface) 1b.
When performing the mixed mounting in which the flow soldering is performed by using the lead-free solder 5a, first, the lead-free solder 5c for reflow to the first surface 1a is used.
In the case where reflow soldering is performed using a solder having a narrow solid-liquid coexistence temperature range, even if the reflowed solder is melted by heat applied to the substrate 1 during flow soldering, a hard and brittle phase containing a large amount of Bi is contained. Segregation is small and the connection strength of the component 3 is hardly reduced. The lead-free solder for reflow 5c satisfies this condition because Sn is the main component and Ag is 0.5 to 4.0 mass%, Cu or /
Sn-Ag- (Bi and / or (Cu or I) having a total composition of 0 to 3.0 mass%
n)) In the lead-free solder, the Bi amount is approximately 0 to 3
mass% and approximately 50 to 65 mass%. At this time, the Bi amount of the flow solder 7a is 0 to 6
It can be set to 5 mass%.

On the other hand, the solder 5 for reflow onto the first surface 1a
c, when reflow soldering is performed using a solder having a wide solid-liquid coexistence temperature range, that is, as the lead-free solder for reflow 5c to the first surface 1a, Sn is a main component, Bi is 0 to 65 mass%, and Ag is From 0.5 to 4.0 mass
%, Cu and / or In etc. in total of 0-3.0 mas
% of Sn-Ag- (Bi and / or (Cu or In)) lead-free solder having a composition containing
When the i amount is approximately 3 to 50 mass%, the Bi amount of the solder for flow is selected from the range of 3 to 65 mass%, and the solidus temperature of the lead-free solder for reflow 5c on the first surface is set to the second temperature.
By setting the surface temperature equal to or higher than the liquidus temperature of the lead-free solder for flow 7a, it is possible to prevent the reflowed solder 5c from being melted by heat applied to the substrate during flow soldering. In particular, Ag is 0.5 to 4.0 mass%.
By containing, the microstructure is reduced and the mechanical properties are changed. For example, hard and brittle properties are eliminated as compared with Sn-58 mass% Bi, and desired reliability can be secured at the connection portion. . In the second embodiment, when performing the flow soldering from the second surface side, it is preferable to cool by blowing an inert gas to the reflow soldering portion on the first surface.

As described above, according to the second embodiment, the temperature of the organic substrate 1 made of a commonly used material such as glass epoxy is set to be lower than the heat resistance temperature, and one side (first Surface) and flow soldering on one surface (second surface). In addition, C formed on the organic substrate 1 can be formed.
By improving the wettability with respect to electrodes such as u, Ni, etc., the melting point is brought close to about 183 ° C., and the desired connection strength can be secured without being brittle and without significant segregation.

Example 2-1 As shown in FIG.
Lead pitch: 0.5 mm, lead width: 0.2 mm, number of leads on each side: 208, dimensions 32 mm square, 1.6 mm thick, 90 mm long, 140 mm wide, and 18 μm thick copper foil on the board surface QFP-LSI 3a and a chip component 3b of dimensions 1.6 mm × 3.2 mm
n-2.8Ag-15Bi-0.5Cu (unit: mas)
s%) (solidus temperature: about 155 ° C, liquidus temperature: about 20
4 ° C) solder paste with a wide solid-liquid coexistence temperature range 5
A reflow connection was made at about 220 ° C. to the first surface 1a of the organic substrate 1 by c1. Next, the insertion component 4 is inserted from the first surface 1a side of the substrate 1, and Sn-1Ag-57Bi (unit: mass%) at about 150 ° C. (unit: mass%) is applied to the back surface (second surface) 1b (solidus temperature: A jet solder having a temperature of about 137 ° C. and a liquidus temperature of about 137 ° C.) was applied, and flow soldering was performed with the flow solder 7a1. As a result, the first
The 45 ° peel strength of the QFP-LSI lead on the surface 1a was measured by the method shown in FIGS. 5 and 6, and an average value was obtained. Was. That is, the flow solder 7a1
Since the liquidus temperature of about 137 ° C. is lower than the solidus temperature of about 155 ° C. of the solder paste 5c1, the second surface 1
b, the solder paste 5 reflow-connected to the first surface 1a at the time of reflow connection using the flow solder 7a1.
There is almost no effect on c1 and the first surface as well as the second surface 1b
Sufficient connection strength was also obtained for the surface 1a.

(Embodiment 2-2) As shown in FIG.
Lead pitch: 0.5 mm, lead width: 0.2 mm, number of leads on each side: 208, dimensions 32 mm square, 1.6 mm thick, 90 mm long, 140 mm wide, and 18 μm thick copper foil on the board surface QFP-LSI 3a and a chip component 3b of dimensions 1.6 mm × 3.2 mm
The substrate 1 is formed by a solder paste 5c2 having a narrow solid-liquid coexistence temperature range of n-4Ag-1Cu (unit: mass%) (solidus temperature: about 215 ° C., liquidus temperature: about 215 ° C.).
Was reflow-connected at about 230 ° C. to the first surface 1a. next,
The insert part 4 is inserted from the first surface 1a side of the substrate 1 and Sn-2.8Ag of about 215 ° C. is applied to the back surface (second surface) 1b.
A jet solder of −15 Bi-0.5 Cu (unit: mass%) (solidus temperature: about 155 ° C., liquidus temperature: about 204 ° C.) was applied, and flow soldering was performed with the flow solder 7a2. As a result, the first surface 1 of the connected substrate 1
The 45 ° peel strength of the lead of the QFP-LSI a was measured by the method shown in FIGS. 5 and 6, and an average value was obtained. As a result, it was found that both sides of the substrate were about 6N, and sufficient strength was secured. . That is, when the reflow connection is performed on the second surface 1b using the flow solder 7a2, there is almost no effect on the solder paste 5c2 reflow-connected to the first surface 1a, and the first surface 1a as well as the second surface 1b is affected. Also, sufficient connection strength could be obtained.

Embodiment 2-3 As shown in FIG. 2, first,
Lead pitch: 0.5 mm, lead width: 0.2 mm, number of leads on each side: 208, dimensions 32 mm square, 1.6 mm thick, 90 mm long, 140 mm wide, and 18 μm thick copper foil on the board surface QFP-LSI 3a and a chip component 3b of dimensions 1.6 mm × 3.2 mm
Substrate 1 is formed of solder paste 5c3 having a narrow solid-liquid coexistence temperature range of n-1Ag-57Bi (unit: mass%) (solidus temperature: about 137 ° C., liquidus temperature: about 137 ° C.).
Was connected by reflow at about 180 ° C. to the first surface 1a. next,
The insertion component 4 is inserted from the first surface 1a side of the substrate 1, and Sn-2.8Ag of about 220 ° C. is applied to the back surface (second surface) 1b.
A jet solder of −15 Bi-0.5 Cu (unit: mass%) (solidus temperature: about 155 ° C., liquidus temperature: about 204 ° C.) was applied, and flow soldering was performed with the flow solder 7a2. At this time, the liquidus temperature of about 204 ° C. of the flow solder 7a2 is significantly higher than the solidus temperature of about 137 ° C. of the solder paste 5c3, and the back surface (second surface) 1b
Sn-2.8Ag-15Bi-0.
Since 5Cu (unit: mass%) jet solder is applied,
Solder for flow 5 of the connection part after reflow of the first surface
c3 was once completely melted and then solidified. As a result, the 45 ° peel strength of the lead of the QFP-LSI on the first surface 1a of the substrate 1 after connection was measured by the method shown in FIGS. 5 and 6, and the average value was obtained. It turned out that sufficient strength was secured. That is, the liquidus temperature of the flow solder 7a2 is about 204 ° C.
When the solidus temperature of the solder paste 5c3 becomes higher than about 137 ° C. and the second surface 1b is reflow-connected using the solder 7a2 for flow, the solder 5c3 for flow is completely melted and solidified once. The first surface 1 as well as the surface 1b
As for a, a sufficient connection strength could be obtained.

[Third Embodiment] LSI according to the present invention
(First surface) and back surface (second surface) of an organic substrate made of a material such as glass epoxy for electronic components such as chips and chip components.
Reflow soldering using lead-free solder on the surface of the organic substrate, insert the insert from the front (first surface) side of the organic substrate, and perform flow soldering on the back surface (second surface) using lead-free solder and mount A second embodiment will be described with reference to FIG. The heating temperature when reflow soldering with a reflow furnace using lead-free solder that reduces environmental pollution is usually required to be about 220 ° C to 235 ° C or less due to the heat resistance temperature of an organic substrate made of a material such as glass epoxy. There is. FIG. 4 shows Sn-A which is a lead-free solder.
B along the Sn-Ag, Ag-Bi binary eutectic line, which can obtain a melting point close to 183 ° C. in the g-Bi ternary system.
The solidus temperatures 9, 11 and the liquidus temperatures 10, 12 when the i amount is changed are shown. According to this, the Bi amount is 0
When mass%, both solidus temperature and liquidus temperature are about 2
21 ° C., but empirically obtained conditions are 235
In order to reflow at ℃, the liquidus temperature must be below 215 ℃, which is not satisfied. However, by adding 0 to 3 mass% of In or Cu to the Sn-Ag system, the liquidus temperature can be reduced to 215 ° C. or lower while avoiding a sharp drop in the solidus temperature. However, when the Bi amount exceeds approximately 65 mass%, the hard and brittle nature of Bi adversely affects the solder material, so that the Bi amount is 0 to 65 ma.
It was considered that those in the range of ss% can be used as reflow solder. It also improves the wettability of electrodes such as Cu and Ni formed on the organic substrate, and keeps the melting point close to about 183 ° C to ensure desired connection strength without being brittle and without significant segregation. There is a need to. Furthermore, although the time required for the molten solder to contact the organic substrate is as short as a few seconds, it is necessary to protect the solder on the reflow surface that has already been soldered.

As shown in FIG. 3, each electronic component 3 is subjected to reflow soldering on the back surface (second surface) 1b of the organic substrate 1 using a reflow lead-free solder 5e.
The organic substrate 1 is turned over so that the surface 1a faces down, and the electronic component 3 is reflow-soldered on its surface (first surface) 1a using the lead-free reflow solder 5d. Next, the insertion component 4 is inserted from the first surface side of the organic substrate 1, and the electronic component 3 on the already mounted second surface 1b is protected by a cover so that the molten solder is not applied. Then the second
Flow soldering is performed on the surface 1b with the lead-free solder for flow 7b. On the first surface 1a and the second surface 1b, Sn is a main component, Bi is 0 to 65 mass%, and Ag is 0.5
Sn-Ag- (B) having a composition containing a total of 0 to 3.0 mass% of Cu or / and In and the like.
i and / or (Cu or In)) lead-free solder having a narrow solid-liquid coexistence temperature range (B
i amount is approximately 0 to 3 mass%, and approximately 50 to 65 m
ass%) When reflow soldering at 5d, 5e,
Even if the reflowed solders 5d and 5e are melted by the heat applied to the substrate 1 during the flow soldering of the second surface 1b, Bi
The segregation of a hard and brittle phase containing a large amount of is small, and the connection strength of components is hardly reduced. This condition is satisfied when the Bi amount is approximately 0 to 3 mass% and approximately 5 mass%.
In this case, the Bi amount of the solder for flow can be set to 0 to 65 mass%. On the other hand, a solder having a wide solid-liquid coexistence temperature range (Bi amount is approximately 3 to 65 mass%) is used for at least one of the reflow lead-free solders 5d and 5e on the first surface 1a or the second surface 1b. Reflow soldering, that is, Bi of at least one of the solders
When the amount is approximately 3 to 50 mass%, the solder Sn-Ag- (Bi and / or (C
u or In)), the Bi content is selected from the range of 3 to 65 mass%, and the solidus temperature of the reflow lead-free solder 5d or 5e having a wide solid-liquid coexistence temperature range on the first surface is determined. The temperature of the liquidus of the flow solder on the second surface 1b or higher, the heat applied to the substrate during the flow soldering allows the reflowed solder 5d, 5
e can be prevented from melting. In the third embodiment, when performing the flow soldering from the second surface side, it is preferable to cool by blowing an inert gas to the reflow soldering portion on the first surface.

As described above, according to the third embodiment, the temperature of the organic substrate 1 made of a material such as glass epoxy, which is generally used, is kept below the heat-resistant temperature, and the reflow is performed on both surfaces using the lead-free solder. It is possible to perform soldering and flow soldering on one side, and to improve wettability with respect to electrodes such as Cu and Ni formed on the organic substrate 1 and further reduce the melting point to about 183. C., it is not brittle and a desired connection strength can be secured without remarkable segregation.

(Embodiment 3-1) As shown in FIG.
Lead pitch: 0.5 mm, lead width: 0.2 mm, number of leads on each side: 208, dimensions 32 mm square, 1.6 mm thick, 90 mm long, 140 mm wide, and 18 μm thick copper foil on the board surface QFP-LSI 3a and a chip component 3b of dimensions 1.6 mm × 3.2 mm
n-2.8Ag-15Bi-0.5Cu (unit: mas)
s%) (solidus temperature: about 155 ° C, liquidus temperature: about 20
4 ° C.) with the solder paste 5e1.
b was connected by reflow at about 220 ° C. Next, this substrate 1
And the first surface 1a of the substrate 1 with the first surface 1a facing up.
The same QFP-LSI 3a and chip component 3b as the second surface
About 22% by a solder paste 5d1 having a composition Sn-2.8Ag-15Bi-0.5Cu (unit: mass%) (solidus temperature: about 155 ° C., liquidus temperature: about 204 ° C.)
Reflow soldering was performed at 0 ° C. At this time, the second surface 1b
Although only the relatively heavy QFP-LSI of the components 3 was fixed to the substrate 1 with an adhesive, the components did not drop during the reflow of the first surface 1a without fixing the relatively light chip components. Then, the insertion component 4 is inserted from the first surface side of the substrate 1, and a cover (not shown) is formed so that the molten solder does not cover the electronic component 3 on the back surface (second surface) 1 b that has already been reflow-connected. ) And protect the second surface 1b by about 15
Sn-1Ag-57Bi at 0 ° C. (unit: mass)
%) (Solidus temperature: about 137 ° C, liquidus temperature: about 137)
C.) and flow soldering was performed with the flow solder 7b1. In the case of this embodiment 3-1, the reflow solders 5d1, 5e on both surfaces 1a, 1b.
By setting the solidus temperature of about 155 ° C. to a liquidus temperature of about 137 ° C. or more of the flow solder 7b1 to the second surface 1b, the heat applied to the substrate at the time of flow soldering causes the reflowed solder 5d1, 5e1 can be prevented from melting.

As a result, the QFP-L on both sides of the board after connection
The 45 ° peel strength of the SI lead was measured by the method shown in FIGS. 5 and 6, and an average value was obtained. It was found that both sides of the substrate were about 6N, and sufficient strength was secured. That is, the liquidus temperature of the flow solder 7b1 is about 137.
℃, the solidus temperature of solder paste 5d1, 5e1 about 1
Since the temperature is lower than 55 ° C., when the reflow connection is performed on the second surface 1 b using the flow solder 7 b 1, the first surface 1 a
In addition, there was almost no effect on the solder pastes 5d1 and 5e1 reflow-connected to the second surface 1b, and sufficient connection strength was obtained not only for the second surface 1b but also for the first surface 1a.

(Embodiment 3-2) As shown in FIG.
Lead pitch: 0.5 mm, lead width: 0.2 mm, number of leads on each side: 208, dimensions 32 mm square, 1.6 mm thick, 90 mm long, 140 mm wide, and 18 μm thick copper foil on the board surface QFP-LSI 3a and a chip component 3b of dimensions 1.6 mm × 3.2 mm
The solder paste 5e2 of n-4Ag-1Cu (unit: mass%) (solidus temperature: about 215 ° C., liquidus temperature: about 215 ° C.) was reflow-connected to the second surface 1b of the substrate 1 at about 230 ° C. . Next, the substrate 1 is turned over and the first
The same QFP-LSI 3a and chip component 3b as the second surface 1b are also formed on the first surface 1a of the substrate 1 with the surface 1a facing up.
Reflow soldering was performed at about 230 ° C. with a solder paste 5d2 of 4Ag-1Cu (unit: mass%) (solidus temperature: about 215 ° C., liquidus temperature: about 215 ° C.). At this time, the relatively heavy QFP-
Only the LSI was fixed to the substrate 1 with an adhesive, but even if relatively light chip components were not fixed, the components did not drop during reflow of the first surface. Then, the insertion component 4 is inserted from the first surface side of the substrate, and the back surface (second surface) 1
(b) is protected by a cover (not shown) so that molten solder is not applied to the already reflow-connected electronic component 3, and the second surface 1 b is Sn-2.8Ag-15Bi- at about 215 ° C.
0.5 Cu (unit: mass%) (solidus temperature: about 15
5 ° C, liquidus temperature: about 204 ° C)
Flow soldering was performed with the flow solder 7b2.

In the case of this embodiment 3-2, both surfaces 1a, 1b
Solidus temperature of reflow solder 5d2, 5e2 about 2
By setting the temperature of 15 ° C. to a liquidus temperature of about 204 ° C. or more of the flow solder 7b2 to the second surface 1b, the solder 5d reflowed by the heat applied to the substrate during the flow soldering
2, 5e2 can be prevented from melting.

As a result, the QFP-L on both sides of the board after connection
The 45 ° peel strength of the SI lead was measured by the method shown in FIGS. 5 and 6, and an average value was obtained. It was found that both sides of the substrate were about 6N, and sufficient strength was secured. That is, the liquidus temperature of the flow solder 7b2 is about 204.
℃, the solidus temperature of the solder paste 5d2, 5e2 about 2
Since the temperature is lower than 15 ° C., when the reflow connection is performed on the second surface 1 b using the flow solder 7 b 2, the first surface 1 a
In addition, the solder pastes 5d2 and 5e2 reflow-connected to the second surface 1b have almost no effect, and sufficient connection strength was obtained not only for the second surface 1b but also for the first surface 1a.

(Embodiment 3-3) As shown in FIG.
Lead pitch: 0.5 mm, lead width: 0.2 mm, number of leads on each side: 208, dimensions 32 mm square, 1.6 mm thick, 90 mm long, 140 mm wide, and 18 μm thick copper foil on the board surface QFP-LSI 3a and a chip component 3b of dimensions 1.6 mm × 3.2 mm
The solder paste 5e2 of n-4Ag-1Cu (unit: mass%) (solidus temperature: 215 ° C, liquidus temperature: 215 ° C) was reflow-connected to the second surface 1b of the substrate 1 at about 230 ° C. Next, the substrate 1 is inverted, and the first surface 1a
With the same QFP as the second surface on the first surface 1a of the substrate 1
Composition of LSI 3a and chip component 3b with Sn-2.8Ag
Reflow soldering was performed at about 220 ° C. using a solder paste 5d3 of −15 Bi-0.5 Cu (unit: mass%) (solidus temperature: about 155 ° C., liquidus temperature: about 204 ° C.). At this time, the relatively heavy QF among the components on the second surface 1b
Although only the P-LSI 3a was fixed to the substrate 1 with an adhesive, even when relatively light chip components were not fixed, the components did not drop during reflow to the first surface 1a. And then
The insert component 4 is inserted from the first surface side of the substrate 1 and is protected by a cover (not shown) so that molten solder is not applied to the electronic component 3 on the rear surface (second surface) that has already been reflow-connected. Sn-1Ag-57Bi on two sides at about 150 ° C
(Unit: mass%) (solidus temperature: 137 ° C., liquidus temperature: 137 ° C.) was applied by a jet solder, and flow soldering was performed by the flow solder 7b1.

In the case of Example 3-3, the solidus temperature of the reflow solder 5d3 on the first surface 1a is about 155 ° C., and the solidus temperature of the reflow solder 5e2 on the second surface 1b is about 215 ° C. To a liquidus temperature of about 137 ° C. or more of the flow solder 7b1 to the second surface 1b so that the heat applied to the substrate during the flow soldering does not melt the reflowed solders 5d3 and 5e2. it can.
As a result, the 45 ° peel strength of the leads of the QFP-LSI on both sides of the board after connection was measured by the method shown in FIGS. 5 and 6, and an average value was obtained. It turned out that it was. That is, the liquidus temperature of the flow solder 7b1 is about 137 ° C. lower than the solidus temperature of the solder paste 5d3 of about 155 ° C. and the solder paste 5e2 of about 215 ° C. When the reflow connection is performed on the surface 1b using the flow solder 7b1, there is almost no effect on the solder pastes 5d3 and 5e2 reflow-connected to the first surface 1a and the second surface 1b. Sufficient connection strength was also obtained for the surface 1a.

As described above, according to the present invention, the first substrate of the organic substrate is formed by a lead-free solder whose solidus temperature on the first surface is higher than the liquidus temperature of the lead-free solder on the second surface. By connecting the electronic component to each of the two surfaces including the surface and the second surface, sufficient connection strength can be obtained on both surfaces.

Further, the present invention provides a reflow soldering step of reflow soldering an electronic component to a first surface of an organic substrate with lead-free solder, and a method in which a liquidus temperature is applied to an electrode of a mounted electronic component. A flow soldering step of performing flow soldering from the second surface side opposite to the first surface of the organic substrate with a lead-free solder having a solidus temperature of the solid-phase temperature of the lead-free solder on the first surface or less. Depending on the mounting method, a sufficient connection strength can be obtained on both sides.

[0045]

According to the present invention, electronic parts such as LSIs and chip parts are formed on both sides of an organic substrate such as a glass epoxy substrate by using lead-free solder for reducing environmental pollution, thereby significantly lowering the wettability. Without further melting, the melting point is about 183 ° C
, The effect of being able to improve the reliability of the connection portion by soldering with a desired connection strength without being brittle and without significant segregation. According to the present invention, on both sides of an organic substrate such as a glass epoxy substrate,
Electronic components such as LSIs and chip components can be replaced with Sn-Ag- (Bi and / or (Cu or I
n))-based lead-free solder, without remarkably lowering the wettability, and furthermore, by bringing the melting point close to about 183 ° C., without being brittle, and without causing significant segregation and having a desired connection strength. Thus, there is an effect that the reliability of the connecting portion can be improved. Further, according to the present invention, the surface mounting of an electronic component such as an LSI or a chip component on an organic substrate such as a glass epoxy substrate using a Sn-Ag-Bi-based lead-free solder, and the surface mounting or insertion component on the back surface thereof Reflow soldering and flow soldering can be performed without mounting components, displacing components during flow soldering, and reducing the strength of the connection portion.

[Brief description of the drawings]

FIG. 1 is a front view showing a hybrid mounting substrate using lead-free solder in a combination of first surface reflow and second surface reflow according to the present invention.

FIG. 2 is a front view showing a mixed mounting substrate using lead-free solder in a combination of a first surface reflow and a second surface flow according to the present invention.

FIG. 3 is a front view showing a hybrid mounting substrate using lead-free solder in a combination of first surface reflow, second surface reflow, and first surface flow according to the present invention.

FIG. 4 is a graph showing the relationship between the solid-liquid phase temperature of the Sn—Ag—Bi-based ternary alloy along the Sn—Ag and Ag—Bi binary eutectic lines according to the present invention.

FIG. 5 is a diagram showing a schematic configuration of a 45 ° peel test apparatus.

FIG. 6 is an enlarged view showing a surface mounting component mounting portion in the 45 ° peel test apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Organic substrate, 1a ... 1st surface, 1b ... 2nd surface, 3 ... Electronic components, 3a ... LSI, 3b ... Chip components, 4 ... Insert components, 5a-5e ... Lead-free solder for reflow, 7a, 7
b: Lead-free solder for flow, 9: Sn-Ag-Bi3
Solidus temperature on Sn-Ag binary eutectic line in ternary alloy system, Sn- in Sn-Ag-Bi ternary alloy system
Liquidus temperature on Ag binary eutectic line, 11 ... Sn-Ag-B
Solidus temperature on Ag-Bi binary eutectic line in i-ternary alloy system, 12 ... Ag in Sn-Ag-Bi ternary alloy system
-Liquidus temperature on Bi binary eutectic line

Claims (13)

[Claims] 1. An electronic component comprising Sn as a main component and Bi of 0
~ 65 mass%, Ag is 0.5 ~ 4.0 mass%,
A lead-free solder characterized by being connected to each of the first and second surfaces of the organic substrate by a lead-free solder containing a total of 0 to 3.0 mass% of Cu or / and In. Mounting structure. 2. The first surface and the second surface of the organic substrate formed by a lead-free solder having a solidus temperature of the lead-free solder on the first surface which is equal to or higher than a liquidus temperature of the lead-free solder on the second surface. A mounting structure using lead-free solder, wherein an electronic component is connected to each of both surfaces. 3. The electronic component according to claim 1, wherein Sn is a main component and Bi is 0.
~ 65 mass%, Ag is 0.5 ~ 4.0 mass%,
Contains a total of 0-3.0 mass% of Cu or / and In, and the solidus temperature of the lead-free solder on the first surface is:
A lead-free solder, wherein the lead-free solder having a liquidus temperature equal to or higher than the liquidus temperature of the lead-free solder on the second surface is connected to each of the first and second surfaces of the organic substrate. Mounting structure. 4. The electronic component has Sn as a main component and Bi of 0.
3% by mass or 50 to 65% by mass, Ag is 0.5 to 4.0% by mass, and Cu and / or In are connected to the first surface of the organic substrate by a lead-free solder containing a total of 0 to 3.0% by mass. Then, the electronic component is composed of Sn as a main component, Bi of 0 to 65 mass%, and Ag of 0.5 to 0.5 from the second surface side opposite to the first surface.
4.0 mass%, Cu and / or In are 0 to total.
A mounting structure using lead-free solder, wherein the mounting structure is connected to an organic substrate with a lead-free solder containing 3.0 mass%. 5. An electronic component comprising Sn as a main component and Bi as 3
~ 50 mass%, Ag is 0.5 ~ 4.0 mass%,
A lead-free solder containing a total of 0 to 3.0 mass% of Cu or / and In is connected to the first surface of the organic substrate, and the electrode of the mounted electronic component is connected to the second surface opposite to the first surface.
From the surface side, Sn is the main component and Bi is 3 to 65 mass.
%, Ag is 0.5 to 4.0 mass%, Cu or /
And In in total of 0 to 3.0 mass%, and connected to the organic substrate by a lead-free solder having a liquidus temperature equal to or lower than a solidus temperature of the lead-free solder on the first surface. Mounting structure using lead-free solder. 6. The method according to claim 6, wherein the electronic component is provided on the first surface and the second surface of the organic substrate.
On each of the two surfaces, Sn is a main component and Bi is 0
~ 65 mass%, Ag is 0.5 ~ 4.0 mass%,
A mounting method using lead-free solder, wherein reflow soldering is performed using lead-free solder containing a total of 0 to 3.0 mass% of Cu or / and In. 7. The electronic component has Sn as a main component and Bi of 0.
Reflow soldering is performed on the first surface of the organic substrate using a lead-free solder containing ３3 mass% or 50-65 mass%, Ag 0.5-4.0 mass%, and Cu and / or In in total 0-3.0 mass%. The reflow soldering process and the electronic component, with Sn as the main component and Bi of 0 to 65mas
flow soldering from the second surface side opposite to the first surface of the organic substrate by a lead-free solder containing 0.5 to 4.0 mass% of Ag, 0.5 to 4.0 mass% of Ag, and a total of 0 to 3.0 mass% of Cu or / and In. And a flow soldering step. 8. A reflow soldering step of reflow soldering an electronic component to a first surface of an organic substrate by using lead-free solder; and a step of setting a liquidus temperature to the first surface of an electrode of the mounted electronic component. A flow soldering step of performing flow soldering from the second surface side opposite to the first surface of the organic substrate with a lead-free solder having a solidus temperature or lower than the solidus temperature of the lead-free solder in the above. Implementation method. 9. An electronic component comprising Sn as a main component and Bi of 3
~ 50 mass%, Ag is 0.5 ~ 4.0 mass%,
A reflow soldering step of reflow soldering to the first surface of the organic substrate with a lead-free solder containing a total of 0 to 3.0 mass% of Cu or / and In; As components, Bi is 3-65 mass%, and Ag is 0.5-4.0.
mass%, Cu and / or In in total of 0 to 3.0
flow soldering in which the liquidus temperature is lower than the solidus temperature of the lead-free solder on the first surface and the liquidus temperature is lower than the solidus temperature of the first surface by flow soldering from the second surface side opposite to the first surface of the organic substrate. And a mounting method using a lead-free solder. 10. An electronic component containing Sn as a main component, Bi of 0 to 3 mass% or 50 to 65 mass%, Ag of 0.5 to 4.0 mass%, and Cu and / or In of 0 to 3.0 mass in total. % Reflow soldering on the first surface of the organic substrate and the second surface opposite to the first surface with lead-free solder, and the electronic component on the second surface is protected by a cover and mounted. To the electrodes of the electronic component, the main component of which is Sn,
5 mass%, Ag is 0.5 to 4.0 mass%, Cu
And / or a flow soldering step of performing flow soldering from the second surface side of the organic substrate with a lead-free solder containing a total of 0 to 3.0 mass% of In. . 11. An electronic component comprising Sn as a main component, Bi of 0 to 3 mass% or 50 to 65 mass%, Ag of 0.5 to 4.0 mass%, and Cu and / or In of 0 to 3.0 mass in total. %, And reflow soldering to the second surface of the organic substrate with lead-free solder, and further, the electronic component is mainly composed of Sn and has a Bi content of 3 to 50 mass.
%, Ag is 0.5 to 4.0 mass%, Cu or /
And a reflow soldering step of reflow soldering the first surface opposite to the second surface with a lead-free solder containing a total of 0 to 3.0 mass% of In and In; protecting the electronic component on the second surface with a cover; For the electrodes of the mounted electronic component, Sn is the main component and Bi is 3 to 6
5 mass%, Ag is 0.5 to 4.0 mass%, Cu
And / or a flow soldering step of performing flow soldering from the second surface side of the organic substrate with a lead-free solder containing a total of 0 to 3.0 mass% of In. . 12. An electronic component comprising Sn as a main component, Bi of 3 to 50 mass%, and Ag of 0.5 to 4.0 mass.
%, Cu or / and In in total of 0-3.0 mass
%, And reflow soldering to the second surface of the organic substrate using lead-free solder containing more than 10% by weight, and further, the electronic component is composed mainly of Sn and contains 0 to 3% by mass of Bi or 50 to 65% by mass.
s%, Ag is 0.5 to 4.0 mass%, and Cu or / and In are reflow soldered to the first surface opposite to the second surface by a lead-free solder containing 0 to 3.0 mass% in total. Attaching the electronic component to the second surface with a cover, and using Sn as a main component and Bi of 3 to 6 with respect to the electrodes of the mounted electronic component.
5 mass%, Ag is 0.5 to 4.0 mass%, Cu
And / or a total of 0 to 3.0 mass% of In, and the liquidus temperature is higher than the solidus temperature of the reflow lead-free solder to the first surface by a lead-free solder from the second surface side of the organic substrate. A mounting method using lead-free solder, comprising: a flow soldering step of performing flow soldering. 13. An electronic component comprising Sn as a main component, Bi of 3 to 50 mass%, and Ag of 0.5 to 4.0 mass.
%, Cu or / and In in total of 0-3.0 mass
% Reflow soldering on the first surface of the organic substrate and the second surface opposite to the first surface with a lead-free solder containing, and an electronic component on the second surface protected by a cover and mounted. To the electrodes of the manufactured electronic component, the main component of which is Sn and the Bi
5 mass%, Ag is 0.5 to 4.0 mass%, Cu
And / or a total of 0 to 3.0 mass% of In, and the liquidus temperature is higher than the solidus temperature of the reflow lead-free solder to the first surface by a lead-free solder from the second surface side of the organic substrate. A mounting method using lead-free solder, comprising: a flow soldering step of performing flow soldering.