JPH0282541A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To enable bonding of wire material with good bondability to an inner section of a lead consisting of copper material even at a low temperature which can avoid fusion of a solder coating by using an aluminum material as a material to form a wire. CONSTITUTION:A silicon semiconductor pellet 12, a plurality of leads 9 arranged around the pellet, a wire 13 whose both ends are bonded to each bonding and 12a of the pellet and an inner section 9a of each lead 9 for bridging, and a package 14 for resin sealing are provided. A group of leads 9 are formed by using a copper material and a wire 13 is formed by using an aluminum material. One end of the wire is bonded to an electrode of the pellet through ball bonding. The other end is bonded to a base material surface which consists of copper material in an inner section of each lead.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a technology for manufacturing semiconductor devices, and in particular to an electrical wiring technology for extracting an electronic circuit built into a semiconductor pellet to the outside, such as a resin-sealed package. The present invention relates to a device that is effective for use in manufacturing bipolar semiconductor integrated circuit devices.

[Conventional technology]

In general, a semiconductor device equipped with a resin-sealed package includes a semiconductor pellet, a plurality of leads arranged around the semiconductor pellet, and both ends attached to the bonding pad of the semiconductor pellet and the inner part of each lead. It includes wires that are bonded and bridged, a semiconductor pellet, a part of the lead, and a package that seals the wire with resin, and the material for forming the lead group is an iron-based material or a copper-based material. Gold (Au) wire is used as the material for forming the wire.

As a semiconductor device that secures electrical connection between a semiconductor pellet and a lead frame while saving consumption of gold and silver, a device has been proposed in which a copper-based material is used for forming the lead group and the wire.

On the other hand, in a semiconductor device equipped with a resin-sealed package, in order to improve connectivity when mounting the semiconductor device on a printed wiring board, a solder coating is applied to the leads after molding the resin-sealed package. In the outer part of
It is applied by any suitable means such as plating or solder dipping.

However, if a wet process such as solder plating or solder dip treatment is performed after molding a resin-sealed package, the moisture resistance of the resin-sealed package will be reduced, and the time required to complete the product will be reduced. will be prolonged.

Therefore, it is conceivable to form a solder film on the outer part of the lead group in advance (thereby omitting the soldering process after package molding).

An example of a technique in which copper-based materials are used as materials for forming the lead group and the wire is JP-A-62-165335.

Further, as an example that describes copper wire bonding technology, there is JP-A-58-169918.

[Problem to be solved by the invention]

However, in the technology in which a wire material made of a copper material is bonded to a lead made of a copper material and a solder film is pre-formed on the outer part, the wire made of a copper material is Bondability to the base material surface of the lead made of the material - In order to bond well, it is necessary to heat the lead group to 250°C or more.
On the other hand, since the melting temperature of the solder film is 180°C,
The inventor of the present invention has revealed that there is a problem in that wire bonding with good bondability cannot be ensured.

An object of the present invention is to bond a wire material to the inner part of a lead made of a copper-based material with good bondability even under low temperature conditions where melting of the solder film can be avoided. The purpose of the present invention is to provide a manufacturing technology for semiconductor devices that can perform the following steps.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

An overview of typical inventions disclosed in this application is as follows.

That is, a semiconductor pellet, a plurality of leads arranged around the semiconductor pellet, a wire whose both ends are bonded and bridged to the bonding pad of the semiconductor pellet and the inner part of each lead, and the semiconductor pellet. , a semiconductor device comprising a part of the leads and a package in which the wires are sealed with resin, wherein the lead group is formed using a copper-based material, and the wires are formed using an aluminum-based material. , one end of this wire is bonded to the bonding pad of the semiconductor pellet by pole bonding, and the other end is bonded to the surface of the base material made of the copper-based material in the inner part of each lead,
It is configured to bridge between the semiconductor pellet and the lead.

[Effect]

According to the above-mentioned means, an aluminum-based material is used as a material for forming the wire, and since this aluminum has a lower melting temperature than a copper-based material, it is possible to avoid melting of the solder film, for example. Even under such low temperature conditions, a wire material can be bonded to the inner part of a lead made of a copper-based material with good bondability.

〔Example〕

FIG. 1 is a partially cutaway front view showing a semiconductor device equipped with a resin-sealed package which is an embodiment of the present invention;
1 to 11 are explanatory diagrams showing a method for manufacturing a semiconductor device according to an embodiment of the present invention.

In this embodiment, a semiconductor integrated circuit device (hereinafter, IC
It is configured as an IC (hereinafter sometimes referred to as MSP-IC or simply tC) equipped with a resin-sealed mini-square package. This resin-sealed MSPiC includes a silicon semiconductor pellet (hereinafter referred to as pellet) 12, a plurality of glue portions 9 arranged around the pellet, each bonding pad 12a of the pellet, and an inner layer of each lead 9. A wire 13 whose both ends are bonded and bridged to the portion 9a, and a package 14 which seals these with resin.
The lead 9 group is formed using a copper-based material, and the wire 13 is formed using an aluminum-based material. One end of this wire is bonded to the electrode of the pellet by pole bonding, and the other end is bonded to the surface of the base material made of the copper-based material in the inner part of each lead.

This MSP-IC is manufactured by the following manufacturing method.

Hereinafter, this resin-sealed MSP-
A method for manufacturing an IC will be explained. With this explanation, the MS
The details of the configuration of the P-IC will also be revealed.

In this example, resin-sealed MSP-I according to the present invention
In the manufacturing method of C, the multiple lead frame 1 shown in FIG. 2 is used. This multiple lead frame
is integrally formed using a thin plate made of a copper-based material (m or an alloy thereof) by a suitable means such as punching press working or etching process. The copper-based material forming this multi-lead frame may be a precipitation-hardened copper-based material, such as 0.05 to 0.15% zirconium (
Precipitation hardening copper-based materials containing Zr) (the rest is 1id), precipitation hardening materials containing about 0.50 to 0.60% zirconium, and about 0.20 to 0.30% chromium (Cr) A hardened copper-based material is used. Precipitation-hardened copper-based materials have high electrical conductivity, high tensile strength, and excellent mechanical connectivity to metals such as aluminum, copper, gold, etc., resulting in wires in which these metals are used. Bondability during bonding
becomes extremely good.

In this multi-lead frame 1, a plurality of unit lead frames 2 are arranged in a row in the lateral direction.

The unit lead frame 2 includes a pair of outer frames 3 each having a positioning hole 3a, and both outer frames 3 are arranged parallel to each other at a predetermined interval and extend in series. A pair of section frames 4 are disposed parallel to each other between both outer frames 3.3 and integrally constructed between adjacent unit lead frames 2.2. Unit lead frame 2 inside the square frame
is configured.

In each unit lead frame 2, a dam hanging member 5 is arranged approximately at right angles and integrally protrudes from the connecting portion of the outer frame 3 and the section par 4. The dam member 6 is arranged to have a substantially square frame shape and is integrally suspended. Tab suspension leads 7 are arranged at both ends of each dam member 6 on the section frame 4 side, and integrally protrude in an approximately 45-degree direction, and the tip of each tab suspension lead 7 has a substantially square flat plate shape. A tab 8 formed in the dam member 6 is disposed approximately concentrically with the frame shape of the dam member 6 group and is integrally suspended. The dam member 6 has a plurality of leads 9 arranged at equal intervals in the longitudinal direction and parallel to each other.
It is integrally provided so as to protrude orthogonally to the dam member 6,
The inner end of each lead 9 is disposed such that its tip is close to the tab 8 and surrounds it, thereby forming an inner portion 9a. On the other hand, the ends of the outer extension portions of each lead 9 are separated from the outer frame 3 and the section frame 4 to form outer portions 9b. The portion between adjacent leads 9 and 9 in the dam member 6 substantially constitutes a dam 6a that blocks the flow of resin during package molding, which will be described later.

In this embodiment, a solder plating film 10 as a solder film is applied to the outer portion 9b of the group of leads 9 in the multiple lead frame 1 by an appropriate means such as electrolytic plating. This solder plating film 10 is
It is formed to completely cover the surface of the lead 9 from the outer tip to a position closer to the inside than the dam member 6. The reason why the solder plating film 10 is formed on the surface of the lead 9 to a position closer to the inner side of the dam member 6 is to absorb the misalignment between the lead frame and the mold during the molding process of the resin-sealed package, which will be described later. It's about giving yourself some leeway.

Further, it is desirable that the step of applying the solder plating film is set to be performed after the step of punching out the multi-lead frame 1. This is because by carrying out the solder plating treatment after the blanking and punching steps, the solder plating film 10 can also be formed on the cut surface generated by punching the outer portion 9b.

As a material for forming the solder plating film 10, a solder material having a relatively high melting point, for example, about 180° C. is used. this is,
This is to prevent the solder plating film 10 formed on the outer part of the lead group from being melted by the heating when the lead frame is heated in the wire bonding process as described later. As a solder material having such a melting point, for example, tin (Sn
) 75-95% - lead (Pb) 25-5%.

Incidentally, in this embodiment, the inner part 9 of the lead 9 group
Not only is no solder plating film formed on a, but also no silver (Ag) plating film, which is normally formed to improve bondability, is formed. Therefore, in the inner portion 9a of the lead 9 group, the surface of the copper-based material forming the base material of the multiple lead frame is exposed.

Further, the tab 8 is lowered toward the back surface by about the thickness of the semiconductor pellet than the surface of the group of leads 9 (so-called tab lowering) before or after the solder plating film forming process.

The multiple lead frame according to the above structure is subjected to pellet bonding work for each unit lead frame 2, and then,
Wire bonding operations are performed which will produce an assembly such as that shown in FIGS. 3 and 4. These bonding operations are sequentially performed for each unit lead frame 2 by pitch-feeding the multiple lead frames in the lateral direction.

First, by pellet bonding, a pellet 12 serving as a semiconductor integrated circuit structure into which a bipolar integrated circuit element (not shown) has been fabricated in the previous step is attached to the approximately central portion on the tab 8 of each unit lead frame 2. The bonding layer 11 is formed using a suitable material such as silver paste or the like and fixed thereto. Silver paste is composed of an epoxy resin adhesive, a curing accelerator, and a solvent mixed with silver powder.
The bonding layer 11 is formed by pressing the pellet against the silver paste applied on the lead frame and curing it at an appropriate temperature.

A wire made of an aluminum material, which will be described later, is formed between the bonding pad L2a of the pellet 12 fixedly bonded to the tab 8 and the inner part 9a of each lead 9 in the unit lead frame 2. 13 is bonded and bridged at both ends by using a wire bonding device as shown in FIGS. 5 to 7. As a result, the integrated circuit built into the pellet 12 is connected to the bonding pads 12a1 wires 131. It is electrically drawn out via the inner part 9a and outer part 9b of the lead 9.

Here, the wire bonding work will be explained.

The wire bonding apparatus 20 shown in FIG. 5 bridges the wire 13 between the electrode pad 12a of the pellet 12 and each lead 9 of each unit lead frame 2. It is configured to electrically connect with. This wire bonding device 20 is equipped with a feeder 21.
1 is configured to hold a multiple lead frame 1 slidably in the longitudinal direction and to feed unit lead frames 2 step by step at a pitch. A heat block 22 is installed in the feeder 21 so as to heat each unit lead frame 2 .

An XY child table 3 is installed outside the bonding stage in the feeder 21 so as to be movable in the XY force directions, and a bonding head 24 is mounted on the XY child table 3. A bonding arm 25 is supported by the bonding head 24 with its base end rotatably supported by a shaft, and this arm 25 has a cam mechanism (not shown) so as to vertically move a capillary 26 fixed to the tip of the bonding arm 25. It is configured to be driven by

Further, the bonding head 24 is equipped with an ultrasonic oscillator (not shown) that causes the capillary 26 to vibrate ultrasonically through the bonding arm 25.

A pair of clamper arms 27.2 are installed on the upper side of the bonding arm 25 to be actuated by suitable means (not shown) such as an electromagnetic plunger mechanism, and each end of the arms 27.28 is arranged directly above the capillary 26 and constitutes a clamper 29. A wire material (described later) that is paid out from a reel (not shown) is inserted through the clamper 29 via a guide 30, and the wire material is further inserted into the capillary 26.

A discharge electrode 31 is installed near the capillary 26 and is independent of the movement of the capillary 26. The upper end of the discharge electrode 31 is rotatably supported, so that its tip is located below the capillary 26. It is configured to be moved between a position directly below the tip of the wire material and a position to the side of the capillary 26 (retracted position). Further, a power supply circuit 32 is connected between the electrode 31 and the clamper 29, so that a discharge arc is generated between the discharge electrode 31 and the wire material.

As shown in FIG. 6, this wire bonding apparatus 20 includes a tube 33 for forming a force atmosphere by supplying gas around the ball generated at the tip of the wire material. The tube 3LL serving as this gas supply means is attached to the discharge electrode 31 with the opening of the tube facing below the capillary 26. A gas supply source 34 for supplying a reducing gas 35, such as a mixed gas of nitrogen gas and hydrogen gas, is connected to the tube 33.

On the other hand, a reducing gas supply device 41 is installed at the bottom of the feeder 21 as a means for supplying a reducing gas (hereinafter referred to as lead frame oxidation prevention gas) 40 for preventing oxidation of the multiple lead frames. This supply device 41 is equipped with an air outlet 42. A plurality of air outlets 42 are provided on the upper surface of the feeder 21 so as to gently blow out the lead frame oxidation prevention gas 40 around the multiple lead frames 1.
is connected to a gas supply path 43. The gas supply path 43 is connected to a gas supply unit 44, and the gas supply unit 44 is configured to constantly supply a reducing gas, for example, a mixed gas consisting of nitrogen gas and hydrogen gas at a preset flow rate. has been done.

A cover 45 is placed on the feeder 21.
The cover 45 is equipped to cover almost the entirety of the multiple lead frame 1 to which it is fed, and this cover 45 is provided with an anti-oxidant gas 40 supplied around the multiple lead frame 1.
is made to stagnate around the multiple lead frame 1 as much as possible. A window hole 46 is disposed in the cover 45 at a position directly below the capillary 26 to serve as a bonding stage, and is opened in a substantially square shape large enough to perform wire bonding. A lead frame presser 47 formed in a substantially square frame shape is fitted into the window hole 46 so as to be able to move up and down. It is configured to move up and down in conjunction with the intermittent feeding operation of the feeder 21. That is, the presser 47 is configured to prevent the lead frame from moving by pressing the unit lead frame 2 from above when wire bonding is performed.

Next, a wire bonding method using the wire bonding apparatus according to the above configuration will be explained.

Here, in this example, a wire material (hereinafter referred to as wire material) formed using an aluminum-based material is used as a material for configuring the wire 13 that electrically connects the bonding pad of the pellet and the lead. 38 is used, and the wire material is thick enough to ensure bonding strength (and prevent bonding damage) when bonding to the bonding pad (electrode) 12a of the pellet 12 and the inner part 9a of the lead 9. It is designed to have an optimal material composition and Vickers hardness in order to achieve this.

That is, as shown in FIG. 8, the wire of this example has a Vickers hardness (HV) of the ball during pole bonding.
is selected to be within the range of 35 to 45.

Figure 9 shows the hardness of the aluminum ball part and the peeling rate (%) between the bonding wire and the aluminum pad.
) and the bonding damage occurrence rate (%) at which cracks occur in the silicon dioxide layer under the aluminum pad.

As is clear from Fig. 9, considering that the acceptable value for the occurrence rate of bonding defects is approximately 10%,
When the Vickers hardness is about 30 or less, the rate of peeling (indicated by
) has a Vickers hardness of approximately 50 or higher. In particular, the optimum range is a Vickers hardness of about 50 or higher. In particular, a range of Vickers hardness of 35 to 45 is selected as the optimum range.

Further, FIG. 8 is a diagram showing the results of many experiments conducted under the same conditions in order to obtain the composition of the material for the wire that can obtain the Vickers hardness in the optimum range.

In FIG. 8, the vertical axis shows Vickers hardness, and the horizontal axis shows the composition of each material.

The Vickers hardness of each material is, for example, aluminum (A
1) is shown as 28. Also, “0.5
%NL-AIJ indicates a wire made of A1 containing 0.5% by weight of Ni.

There are various material compositions for wires that fall within this optimum hardness range, but examples of aluminum alloy wire compositions that allow for the best pole bonding include:
1.0% by weight of nickel and 0.5% by weight of manganese (M
n) containing 1.0% by weight of nickel and 1.
0% by weight of manganese, 0.5% by weight of nickel and 1.0% by weight of manganese,
1.7% by weight of magnesium (Mg) and 0.3-0.5
containing % nickel and 0.3% iron by weight, 2
Examples include those containing 1% by weight of nickel and 2.0% by weight of silicon (Si).

One of the characteristics of the wire of this example is that it contains nickel, and by including nickel in the wire, the corrosion resistance of the wire whose main component is aluminum can be significantly improved. The wire has aluminum as its main component, and contains at least 0.03% by weight, more preferably 0.03% by weight or more.
．． A material containing 0.075% by weight or more of nickel is used.

Therefore, by containing an appropriate amount of nickel in a wire whose main component is aluminum, it is possible to obtain a wire that has good corrosion resistance and is convenient for bonding.

The reason why corrosion resistance can be improved by including nickel in aluminum wire is as follows. 6 In high-temperature high-temperature tests such as MLL883B, which is a typical corrosion resistance test method, hydrogen with a moisture content of 1 (,0) Atomic hydrogen H becomes atomic hydrogen H. Since atomic hydrogen H is small, it enters the container into the grain boundaries of aluminum. When the atomic hydrogen H reacts with each other and becomes gaseous hydrogen H2, the volume expands and pushes the grain boundaries. Corrosion progresses from this expanded grain boundary.On the other hand, in aluminum wires containing nickel, the bonding reaction of atomic hydrogen H is promoted by the catalytic action of nickel contained within the aluminum grains. As a result, atomic hydrogen H does not invade the grain boundaries of aluminum, and gaseous hydrogen H does not enter the grain boundaries of aluminum.
It becomes 2.

N1 mainly contributes to improving corrosion resistance, and Mg, Mn, and SI mainly contribute to adjusting hardness. Also,
Nt does not reduce the hardness adjustment effect of Mg and the like, and conversely, Mg and the like do not interfere with the improvement of corrosion resistance caused by Ni. Furthermore, Nt and Mg, and Mn and St stably exist simultaneously in aluminum, and do not impair the mechanical or electrical properties of the wire.

When the unit lead frame 2 that has been pellet-bonded with Ag paste in the previous process related to the above configuration is pitch-fed to the bonding stage in the feeder 21 and stopped intermittently, the lead frame presser 47 is lowered within the window hole 46. By this, the unit lead frame 2
is pressed down by the presser 47. Then XY
The child table 3 is moved as appropriate.

On the other hand, in the capillary 26, the discharge electrode 31 is brought close to the lower end of the wire material 38, and the power supply circuit 3
2 is closed, a ball 39 is melted and formed at the tip of the wire material 38.

At this time, since the wire material 38 is an aluminum material having a predetermined composition as described above, the hardness of the ball 39 is appropriate.

Further, a reducing gas 35 is supplied from the tube 33, and a reducing gas atmosphere is maintained between the wire material 38 and the electrode 31. This makes it possible to form a ball with high sphericity and appropriate ball hardness.

Subsequently, the capillary 26 is lowered by the bonding head 24 via the bonding arm 25, and the ball 39 formed at the tip of the wire material 38 is attached to the first bonding pad 12a on the pellet 12. pad (hereinafter referred to as
Unless otherwise specified, it is simply referred to as a pad. ). At this time, since the capillary 26 is energized by ultrasonic vibration and the pellet 12 is heated by the heat block 22, the ball 39 is ultrasonically thermocompressed onto the pad 12a of the pellet 12.

The ball 39 is made of a predetermined aluminum material as described above, and is prevented from becoming hard by being formed in a reducing gas atmosphere, so that it can be bonded with good bondability. will be done.

By the way, when aluminum is used as a constituent material of the bonding wire, since aluminum is easily oxidized and relatively hard, bondability in the first bonding is reduced. That is, if an oxide film is formed on the surface of the aluminum wire material during melting, the melting will be uneven and the shape of the ball will be inappropriate. Further, when an oxide film is formed on the surface of the ball, the metal bonding property with the bonding pad is reduced. Therefore, by supplying a reducing gas during ball formation, oxidation of the balls can be prevented. Even when aluminum is used as the constituent material of the bonding wire, good bondability is achieved.

That is, the ball 39 of the wire material 38 is exposed to the reducing gas 3.
5, no oxide film is formed on the aluminum surface during melting. the result,
Since the tip of the aluminum wire material 38 is melted internally and over the entire surface, a uniform surface tension is generated and a ball 39 with high sphericity is formed.

In this way, the ball 39 has high sphericity without forming an oxide film and maintains appropriate hardness, so it has good bondability even when wire material made of aluminum material is used for 3 days. - will be bonded onto the pad of the pellet 12.

After the first bonding portion 13a is formed by the ball 39, the capillary 26 is moved relative to the XY child table 3 and the bonding head 24 in a three-dimensional manner along a trajectory described later. First, a wire material 38 is attached to the tip of the lead (hereinafter referred to simply as lead unless otherwise specified) to be second bonded.
The middle part of is pressed. At this time, since the capillary 26 is energized by ultrasonic vibration and the lead is heated by the heat block 22, the insertion part of the wire material 38 is ultrasonically thermocompressed onto the inner part 9a of the lead 9. Thus, when the second bonding portion 13b is formed, the heating of the lead 9 is performed at a temperature that does not melt the solder plating film 10 deposited on the outer portion 9b of the lead, for example, 180° C. or lower. It is set as follows. Therefore, even if the leads 9 are heated, the solder plating film 1.0 will not be peeled off. On the other hand, even if the base temperature is relatively low, the wire material 38
The aluminum-based material used as a metal is relatively soft even at low temperatures and is softer than other metals (in this case, copper-based materials).
Moreover, since the ultrasonic energy is assisted at the same time as the thermocompression bonding, the intermediate portion of the wire material 3B can be mechanically connected to the inner portion 9b of the lead 9 with sufficient bonding strength. Become.

During the first and second bonding operations, the reducing gas 40 for preventing oxidation of the lead frame is constantly blown out from the outlet 42 provided on the upper surface of the feeder 21, so that the multiple lead frame 1 is exposed to the reducing gas. Being immersed in the atmosphere. At this time, since the reducing gas atmosphere is covered by the cover 45 placed over the feeder 21, the reducing gas 40 effectively surrounds the multiple lead frame 1 and the pellets 12.

Therefore, oxidation of the lead frame etc. is reliably prevented.

By the way, when a copper-based lead frame is used as the multiple lead frame 1, copper is easily oxidized and a thick oxide film is formed on the bonding surface, resulting in a decrease in bondability in the second bonding. That is, when an oxide film is formed, the metal bondability with the wire material 38 made of an aluminum-based material decreases, resulting in a decrease in bondability.

However, in this embodiment, the top of the feeder 21 is covered with a cover 45, and the multiple lead frame 1 is surrounded by a reducing gas atmosphere supplied into the cover, so that the copper is easily oxidized. Even if an aluminum-based lead frame is used, an oxide film will not be formed on its surface, and as a result, the wire material 38 made of an aluminum-based material can be bonded onto the inner part 9a of the lead 9 with good bondability. will be done.

When the second bonding portion 13b is formed, the clamper 2
9 grips the wire material 3, and the clamper 29 is moved together with the capillary 26 relatively away from the second bonding section. Due to this separation movement, the wire material 38
is torn off from the second bonding part. As a result, the wire 13 is bridged between the bonding pad of the pellet 12 and the lead.

After that, the wire material 38 that has completed the second bonding work is
When the grip of the clamper 29 is released and the capillary 26 is slightly raised, the tip of the wire material 38 is relatively protruded by the length required to form the ball 39 (so-called tail-extrusion operation). )
.

Thereafter, by repeating the above operation, the wire 13 is successively bridged between the remaining bonding pads and the inner portions of the respective leads.

Thereafter, when the wire bonding work for one unit lead frame 2 is completed, the presser 47 is raised, and the multiple lead frame 1 is placed in one pitch so that the next unit lead frame 2 is positioned at the bonding arm. Sent. Thereafter, the wire bonding work is sequentially performed for each unit lead frame 2.

Incidentally, in this embodiment, since the non-directional capillary 26 is used as the bonding tool, even if the bridge directions of the wires 13 intersect, the lead frame and the bonding arm are not relatively connected. No need to rotate. Therefore, the structure of the wire bonding device can be simplified.

For the multiple lead frames that have been pelleted and wire bonded in this way, a group of pancages that are resin-sealed for each unit lead frame is formed using a transfer 1 molding apparatus as shown in FIG. 10. Unit lead frame groups are simultaneously molded.

The transfer molding apparatus 50 shown in FIG. 10 includes a pair of upper mold 51 and lower mold 52 that are clamped together by a cylinder device or the like (not shown). There is an upper mold cavity recess 53a on the mating surface of
A plurality of sets of the lower mold cavity recess 53b and the lower mold cavity recess 53b are recessed so as to cooperate with each other to form the cavity 53.

A bot 54 is provided on the mating surface of the upper mold 51,
A plunger 55, which is moved back and forth by a cylinder device (not shown), is inserted into the bot 54 with a tablet made of resin as a molding material, and can feed resin (hereinafter referred to as resin) made by melting the tablet. It looks like this. On the mating surface of the lower die 52, the cull 56 is attached to the bottom 54.
A plurality of runners 57 are radially arranged and recessed so as to be connected to the bots 54, respectively. The other end of each runner 57 is connected to the lower cavity recess 53b, and a gate is formed at the connection portion so that resin can be injected into the cavity 53. Further, on the mating surface of the lower die 52, a recess 59 is formed in a rectangular shape slightly larger than the outer shape of the multiple lead frame 1, and has a constant depth approximately equal to the thickness thereof, so that the recess 59 can escape the thickness of the lead frame. It is embedded in.

When transfer molding a resin-sealed package using the multi-lead frame 1 having the above structure, the upper mold 51
Each cavity 53 in the lower die 52 corresponds to a space between a pair of dams 6a, 6a in each unit lead frame 2, respectively.

During transfer molding, the multiple lead frame 1 having the above-mentioned structure is inserted into the relief recess 5 recessed in the lower mold 52.
9, pellets in each unit lead frame 2) 12
are arranged and set so as to be accommodated in each cavity 53, respectively.

Subsequently, the upper mold 51 and the lower mold 52 are clamped, and the bot 5
4 to the resin 6 as a molding material by the plunger 55.
0 is fed into each cavity 53 through the runner 57 and gate 58 and press-fitted therein.

After injection, the resin is thermally cured to form a resin-sealed package 1.
0 is molded, the upper mold 51 and the lower mold 52 are opened, and the group of packages 10 is released by an ejector pin (not shown). In this way, the 11th
As shown in the figure, the multi-lead frame 1 on which the packages 14 have been molded is removed from the transfer molding apparatus 5o.

Then, the pellet 12, the inner portion 9a of the lead 9, and the wire 13 are sealed with resin inside the resin-molded package 14 in this manner. In this state, the pellet 12 held by the wire 13 is fixed by the resin-sealed package 14. Further, as will be described later, since the copper-based lead frame without plating exhibits extremely good adhesion to the resin of the package, the inner portion 9a of each lead 9 can be integrated with the package 14 very effectively.

In the lead cutting and forming process, the outer frame 3 and dam 6a of the multi-lead frame l are sequentially cut off for each unit lead frame by a lead cutting device (not shown). ), the outer portion 9b of the lead 9 is bent downward.

Resin-sealed MSP/IC7 manufactured as above
0 is mounted on a printed wiring board as shown in FIGS. 12 and 13.

In FIGS. 12 and 13, printed wiring board 7
1, a plurality of lands 72 are arranged to correspond to each lead 9 in a resin-sealed MSP-IC 70 to be mounted, and are formed into a substantially rectangular thin plate shape using a solder material, The outer portions 9b of the leads 9 of the IC 70 are aligned and in contact with the lands 72, and the outer portions 9b of the respective leads 9 and the lands 72 are sharpened by a solder mound layer 7 formed by flow soldering.
3, electrically and mechanically connected.

At this time, since the solder plating film 10 has been previously applied to the entire outer portion 9b of the lead, the solder material on the land 72 is effectively sucked up, and the solder layer 73 is formed very properly. Become.

By the way, the MSP-IC according to the above configuration is subjected to an environmental test inspection before being shipped. Environmental tests include burn-in tests, high-temperature high-temperature bias tests, pressure hookah tests, and temperature cycle/thermal shock tests. In particular, the high temperature, high temperature bias test, and the pressure hooker test are performed at accelerated temperatures, humidity, and bias in order to test moisture resistance (corrosion of aluminum wiring).

Further, as described above, when MSPiC is mounted on a printed wiring board or the like, a high temperature condition may occur due to solder dip or flow soldering process.

If high temperature and high humidity conditions are applied to 1c equipped with a resin-sealed package during such environmental testing or mounting, moisture will enter from the boundary between the package 14 and the group of leads 9, and this moisture will corrode the wires. Sometimes. However, in the MSP/IC 70 according to this embodiment, since the wires 1-3 made of a predetermined aluminum-based material are used, corrosion of the wires is prevented. In other words, even if moisture were to reach the wire, the wire itself would be prevented from being corroded by the moisture because the wire is made of an aluminum-based material that has corrosion resistance as described above. .

By the way, when a copper-based material is used for the lead frame, the surface of the inner part of the copper-based lead frame is sometimes subjected to silver plating treatment to prevent oxidation and improve bondability.

However, in an IC that uses a copper-based lead frame with a silver-plated film on the inner part, when the above-mentioned thermal stress is applied, the package deteriorates due to the difference in thermal expansion coefficient between the package and the lead frame. The inventor of the present invention has revealed that there is a problem in that peeling occurs at the interface between the lead and the inner part of the lead, resulting in a decrease in moisture resistance. This is thought to be due to the following reasons. Since the silver plating film is formed from a collection of fine particles, relative movement tends to occur between these fine particles and the resin of the package due to the effect of thermal stress. Peeling occurs at the interface between the product and the package.

However, in this embodiment, a copper lead frame is used as the multi-lead frame 1, but since the surface of the inner part 9a is not plated, the above-mentioned thermal stress is applied and the copper lead frame is not plated. It has been confirmed through experiments that no peeling occurs between the interface between the inner portion 9a of each lead 9 and the package 14 even in the case where the lead 9 is removed.

This is thought to be due to the following reasons. That is,
In a lead frame with no plating on the inner part, the material surface of the lead frame and the resin of the package are directly bonded to each other, so even if thermal stress is applied, the bonding point at the interface between the two is relatively This is because the thermal stress is absorbed by the strain generated inside the lead frame and the pan cage.

According to the embodiment described above, the following effects can be obtained.

(1) The lead group is formed using a copper-based material, and the bonding wire is formed using an aluminum-based material, and one end of this wire is bonded to a bonding pad of a semiconductor pellet by pole bonding, By bonding the other end to the surface of the base material made of the copper-based material in the inner part of each lead to create a bridge between the semiconductor pellet and the lead, the melting temperature of aluminum is lower than that of the copper-based material. Therefore, for example, a wire material can be bonded to the inner part of a lead made of a copper-based material with good bondability even under low temperature conditions where melting of the solder film can be avoided. .

(2) The corrosion resistance of the bonding wire can be improved by using an aluminum material containing nickel and having a Vickers hardness of 35 to 45 in the ball portion as the wire material. At the same time, it ensures sufficient bonding strength of the wire,
In addition, excessive crushing and damage to the bonding pad can be prevented, and reliability can be improved.

(3) By using an aluminum-based material whose main component is aluminum for the bonding wire, the cost can be significantly reduced compared to gold wire.

(4) By using a wire material whose main component is aluminum, pole bonding of the bonding wire can be performed stably and easily, making use of the low cost, which is one of the advantages of aluminum wire. becomes possible.

(5) The pole hardness described in (2) above facilitates the processing of wires containing aluminum as a main component.

(6) By using a wire material made of aluminum-based material that has corrosion resistance, even if moisture reaches the bonding wire, the wire itself is corrosion resistant, so the wire will not be corroded by moisture. can be prevented.

(7) By using a copper-based lead frame and aluminum-based bonding wire, the bonding strength and bondability of the second bonding part, which is the connection between the wire and the lead, can be increased, improving product quality and reliability. It is possible to improve performance and reduce costs.

(8) By using a copper lead frame with no plating on the inner part as the lead frame, it is possible to prevent peeling at the interface between the inner part of each lead and the package. It is possible to prevent a decline in sexual performance.

(9) By applying a solder film to the outer portion of the lead group in advance, it is possible to omit the solder film formation process after the package is formed, which prevents deterioration of the moisture resistance performance of the package. , it is possible to shorten the time it takes to complete a product.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, the material compositions of the copper-based material of the lead group and the aluminum-based material of the wire are not limited to those described above, and various other compositions may be used.

Furthermore, the specific configurations of the wire bonding device, transfer molding device, etc. are not limited to those of the embodiments described above.

Further, the process of applying a solder film to the leads may be performed by a solder dip process after the lead cutting and forming process.

The above explanation will mainly focus on the field of application of the invention made by the present inventor, which is the resin-sealed MSPi.
Although the case where the present invention is applied to C is described, the present invention is not limited thereto, and can be applied to general semiconductor devices such as ICs that include a group of bonding wires in a resin-sealed package.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

The lead group is formed using a copper-based material, and the bonding wire is formed using an aluminum-based material. One end of this wire is bonded to a bonding pad of a semiconductor pellet by pole bonding, and the other end is bonded to a bonding pad of a semiconductor pellet. By bonding to the surface of the base material made of the copper-based material in the inner part of each lead to create a bridge between the semiconductor pellet and the lead, aluminum has a lower melting temperature than the copper-based material. ,
For example, a wire material can be bonded to the inner part of a lead made of a copper-based material with good bondability even under such low temperature conditions that melting of the solder film can be avoided.

[Brief explanation of the drawing]

Figure 1 shows a resin-sealed MSP-I which is an embodiment of the present invention.
A partially cutaway front view showing C, and FIGS. 2 to 11 are MSP-I which is an embodiment of the present invention.
Fig. 2 is a partially omitted plan view showing the multi-lead frame used therein, Fig. 3 is a partially omitted enlarged partial plan view showing the bullet and after wire bonding, and Fig. Figure 4 is a front sectional view taken along line IV-IV in Figure 3;
Figure 6 is a partially cutaway front view showing the wire bonding device, Figure 6 is a partially cutaway enlarged front view showing the vicinity of the discharge wire, Figure 7 is an enlarged front sectional view showing the upper part of the feeder, and Figure 8. and Fig. 9 is a diagram for explaining its function, Fig. 10 is a vertical sectional view showing the molding process of a resin-sealed package, and Fig. 11 is a multi-lead frame after molding a resin-sealed package. 12 is a partially omitted partially cutaway perspective view showing the mounted state of this resin-sealed MSP-IC, and FIG. 13 is a partially omitted enlarged vertical sectional view thereof. 1...Multiple lead frame, 2...Unit lead frame, 3...Outer frame, 4...Section frame, 5...
Dam hanging member, 6... Dam member, 6a... Dam, 7
...Tab suspension lead, 8...Tab, 9...Lead, 9a...Inner part, 9b...Outer part, 10...
・Solder plating film, 11... bonding layer, 12
... Pellet, 13 ... Bonding wire, 13
a... 1st (ball) bonding, 131)...
・Second bonding part, 14...Resin sealed package, 20...Wire bond ink device, 21...Feeder, 22...Heat block, 23...XY child table 24...Bonding Head, 25... Bonding arm, 26... Capillary (bonding tool), 27.28... Clamper arm, 29
... Clamper, 30 ... Guide, 31 ... Discharge electrode, 32 ... Power supply circuit, 33 ... Tube (gas supply means), 34 ... Gas supply source, 35 ... Reducibility Gas, 38... Aluminum wire material, 39...
Ball, 40... Reducing gas for preventing lead frame oxidation, 41... Reducing gas supply device, 42... Air outlet, 43... Supply path, 44... Gas supply unit, 4
5... Cover 46... Window hole, 47... Lead frame presser, 50... Transfer molding device, 5
1... Upper mold, 52... Lower mold, 53... Cavity 54... Pot, 55... Plunger, 56...
... Cal, 57... Runner, 58... Gate, 59
...Lead frame escape recess, 60...Resin (resin, molding material), 70...Resin-sealed MSP-IC (
semiconductor device), 71... printed wiring board, 72...
・Land, 73...Solder mound layer.

Claims (1)

[Claims] 1. A semiconductor pellet, a plurality of leads disposed around the semiconductor pellet, and a bonding pad of the semiconductor pellet and an inner portion of each lead having both ends bonded and bridged. a semiconductor pellet, a part of the lead, and a package for sealing the wire with resin, the lead group being formed using a copper-based material, and the wire is formed using an aluminum-based material, and one end of this wire is bonded to the bonding pad of the semiconductor pellet by pole bonding, and the other end is bonded to the copper-based material in the inner part of each lead. A semiconductor device characterized by being bonded to the surface of a base material made of a material. 2. The semiconductor device according to claim 1, wherein a solder coating is applied to an outer portion of the lead group before molding the package. 3. The semiconductor device according to claim 1, wherein the lead side end portion of the wire is bonded using ultrasonic energy. 4. A semiconductor pellet, a plurality of leads arranged around the semiconductor pellet, a wire whose both ends are bonded and bridged to the bonding pad of the semiconductor pellet and the inner part of each lead, and the semiconductor pellet. , a method for manufacturing a semiconductor device comprising a part of the lead and a package for resin-sealing the wire, the semiconductor device being formed using a copper-based material, and having a solder coating applied to an outer part of each lead. a step of preparing a lead frame, a step of bonding the semiconductor pellet to a tab in the lead frame, and a step of bonding the semiconductor pellet to the tab of the lead frame; By pole bonding and bonding the other end to the surface of the base material made of the copper material in the inner part of each lead, the wire is bonded between the bonding pad of the semiconductor pellet and the inner part of each lead. A method for manufacturing a semiconductor device, comprising a wire bonding step for bridging, and a step for molding a package in which the semiconductor pellet, a part of the lead, and the wire are sealed with resin. 5. The method of manufacturing a semiconductor device according to claim 4, wherein in the wire bonding step, the heating temperature of the lead frame is set to be lower than the melting point of the solder film.