JPH1051114A - Anisotropic conductive film and mounting method - Google Patents

Abstract

(57) Abstract: The present invention relates to an anisotropic conductive film and a mounting method suitable for surface mounting of, for example, a narrow-pitch semiconductor package. An anisotropic conductive film according to the present invention includes a tape-shaped conductive portion having conductivity, and a tape-shaped insulating portion provided with insulation and connected to the conductive portion. , A medium layer, and conductive particles dispersed and held in the medium layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates are preferably surface mount the mounted body having a lead-shaped protrusions arranged side by side, such as for example a narrow pitch QFP (Q uad F lat P ackage ) type semiconductor package To an anisotropic conductive film and a mounting method.

[0002]

2. Description of the Related Art FIG. 11 shows a connection structure of an anisotropic conductive film D between a gull-wing lead A of a QFP and an electrode pad C formed on a mounting board B. The anisotropic conductive film D has a uniform structure, and conductive particles are uniformly dispersed in the adhesive tape layer. When the thickness of the connection portion of the anisotropic conductive film D is reduced, the resistance in the thickness direction is reduced due to the contact of the conductive particles F inside. Since it is uniform, the relationship of the resistance value to the connection thickness is constant regardless of the location. Therefore, the resistance value is the same at the leading end and the trailing end of the lead A in FIG.

A gull-winged lead A
, The tip of the lead A is easy to bend due to its structure. When the bending amount of the tip of the lead A is large, as shown in FIG.
There was a problem that the lead A was connected to the adjacent electrode pad C, resulting in poor connection.

[0004]

As described above, in the prior art, if the amount of bending at the tip of the lead A is large, the lead A is connected to the adjacent electrode pad C, causing a problem of poor connection. Particularly, in the current QFP, the development is being promoted with a target of 0.3 mm pitch, so that the width of the lead A naturally becomes smaller and the lead A tends to bend more easily. , Is gaining importance.

On the other hand, in order to avoid such a problem,
If the width of the anisotropic conductive film D is reduced so that the anisotropic conductive film D does not exist at the tip of the lead A, the tip of the lead A directly contacts the adjacent electrode pad C. The present invention has been made in view of the above circumstances, and has as its object to provide an anisotropic conductive film that can solve the above-described problems.

[0006]

According to a first aspect of the present invention, there is provided an anisotropic conductive film comprising: a tape-shaped conductive portion having conductivity; and a tape-shaped insulating portion connected to the conductive portion and having an insulating property. And
The conductive portion has a medium layer and conductive particles dispersed and held in the medium layer.

According to a second aspect of the present invention, in the first aspect, the medium layer is made of a thermosetting resin or a thermoplastic resin. According to a third aspect of the present invention, in the first aspect, the conductive portion and the insulating portion are connected in the width direction.

According to a fourth aspect of the present invention, there is provided the anisotropic conductive film according to the first aspect, wherein the anisotropic conductive film has a medium layer connected along both sides in the width direction of the conductive portion. According to a fifth aspect of the present invention, in the fourth aspect, the thickness of the conductive portion is larger than the thickness of the medium layer.

According to a sixth aspect of the present invention, in the first aspect, the conductive portion and the insulating portion are supported by a conductive support tape layer. Thus, since the anisotropic conductive film according to any one of claims 1 to 6 includes the conductive portion and the insulating portion,
By sticking the insulating portion side toward the tip of the lead, normal electrical connection can be obtained even if the tip of the lead is bent during mounting.

A mounting method according to a seventh aspect of the present invention is a mounting method for mounting an electronic component having a plurality of leads arranged side by side on an electrode pad formed on a circuit board corresponding to each of the leads.
A medium layer, a tape-shaped conductive portion having conductive particles dispersed and held in the medium layer, and an anisotropic conductive film provided with a tape-shaped insulating portion having insulating properties connected to the conductive portion. A first step of attaching the plurality of leads to the corresponding electrode pads in a first step of attaching the insulating portion side to a tip end side of the leads in the first step; A second step of positioning via the anisotropic conductive film, and pressurizing and heating the lead after this second step to connect the lead to the electrode pad via the anisotropic conductive film. And a third step of connecting.

According to the mounting method of the present invention, the tip of the lead is bent by attaching the anisotropic conductive film comprising the conductive portion and the insulating portion with the insulating portion facing the tip of the lead. However, a normal electrical connection can be obtained.

[0012]

An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an anisotropic conductive film 1 of this embodiment. The anisotropic conductive film 1 has a two-layer cross-section in a band shape, and its dimensions are, for example, 20 mm in length and 1 mm in width (the same length as a flat portion of a gull-wing type lead to be connected). 0.1m thick
m. Thus, the anisotropic conductive film 1 is composed of, for example, a lower film portion 2 having a thickness of 0.05 mm and an upper film portion 3 having a thickness of 0.05 mm connected to the lower film portion 2. The lower film portion 2 is divided into two strips in a direction perpendicular to the longitudinal direction (width direction), one of which is a conductive portion 4 having a width of 0.5 mm, and the other is an insulating portion 5 having a width of 0.5 mm. . The conductive part 4 includes, for example, conductive particles 6 having a diameter of 20 to 37 μm and an adhesive tape layer 7 as a medium for dispersing and holding the conductive particles 6. The conductive particles 6 include metal particles and carbon particles. And
The former metal particles include nickel (Ni), solder,
It is a conductive plating resin ball. As the latter carbon particles, for example, carbon fibers having a diameter of 7 μm and a length of 5 to 100 μm are preferable. On the other hand, as the adhesive tape layer 7,
Either thermosetting resin (epoxy resin) or thermoplastic resin may be used. For example, as a compounding example of the conductive part 4, 60 parts of a butadiene styrene copolymer, 40 parts of a terpene phenol resin, 0.5 part of an antioxidant, 25 parts of carbon fiber,
It consists of 200 parts of toluene. On the other hand, the insulating portion 5 does not contain the conductive particles 6, and is composed of only an adhesive tape layer such as a thermosetting resin (epoxy resin). Thus, the conductive part 4 containing the conductive particles 6
Is in the order of mΩ, whereas the electrical resistance of the insulating portion 5 containing no conductive particles 6 is 10 ¹⁰
Ω order. That is, in the lower film portion 2, the electric resistance value changes discontinuously at the boundary between the conductive portion 4 and the insulating portion 5.

On the other hand, the structure of the upper film portion 3 is the same as the structure of the conductive portion 4 of the lower film portion 2, and the description is omitted. Next, a mounting method using the anisotropic conductive film 1 having the above configuration will be described.

First, as shown in FIG. 2, the anisotropic conductive film 1 is attached in a direction perpendicular to the longitudinal direction of the electrode pads 11 formed on the circuit board 10. At this time, the lower film part 2 of the anisotropic conductive film 1 contacts the electrode pad 11 and the conductive part 4
Is disposed on the main body side of the semiconductor package 12. Next, for example, a semiconductor package 12 such as a QFP
The gull-wing type outer lead 13 is positioned and mounted on the corresponding electrode pad 11 via the anisotropic conductive film 1 (see FIG. 3). Further, the outer leads 13 of the semiconductor package 12 mounted on the circuit board 10 are
Pressurize and heat at 90 ° C. for 20 seconds (see FIG. 3). As a result, the outer leads 13 are bonded to the electrode pads 11 via the adhesive tape layer 7 of the anisotropic conductive film 1. At this time, the electrical resistance value of the attached anisotropic conductive film 1 on the insulating portion 5 side (outside) is on the order of 10 ¹⁰ Ω, whereas the electrical resistance value on the conductive portion 4 side (inside) is , MΩ order.

The width of the outer leads 13 is, for example, 0.3 mm, and the pitch is 0.5 mm, which is a narrow pitch. As a result, as shown in FIG. 4, the tip of the outer lead 13 is easily bent by a small force, and the tip of the bent outer lead 13 is
It overlaps with an anisotropic conductive film 1 (on the insulating portion 5 side). However, the electric resistance value of the overlapping anisotropic conductive film 1 is
Since it is on the order of 10 ¹⁰ Ω, it is in an electrically insulated state. On the other hand, this outer lead 1
The rear end of the third electrode 3 overlaps the electrode pad 11 to be connected via the anisotropic conductive film 1 (on the conductive portion 4 side). At this time,
Since the electrical resistance value of the overlapping anisotropic conductive film 1 is on the order of mΩ, it is in an electrically conductive state. As a result, even if the tip of the outer lead 13 is bent and overlaps with the adjacent electrode pad 11 via the anisotropic conductive film 1, the semiconductor package 12 can
1 has been electrically connected normally.

FIG. 5 shows an anisotropic conductive film 21 according to another embodiment of the present invention. This anisotropic conductive film 2
1 has a two-layer cross section in a strip shape, and its dimensions are, for example, 20 mm in length and 1 mm in width (the same length as the flat portion of the gull wing type lead to be connected),
The thickness is 0.05 mm. Thus, the anisotropic conductive film 21
Is composed of a lower film portion 22 having a thickness of, for example, 0.05 mm, and an upper film portion 23 connected to the lower film portion 22. The lower film portion 22 has a diameter of, for example, 20 to 37 μm.
And an adhesive tape layer 27 such as a thermosetting resin (epoxy resin) as a medium for dispersing and holding the conductive particles 26. On the other hand, the upper film portion 23
Is divided into a strip at right angles to the longitudinal direction, and has a conductive portion 24 having a thickness of, for example, 50 μm and a width of 400 μm which forms a central portion, and a thickness of, for example, 30 μm provided on both sides of the conductive portion 24.
μm and an insulating portion 25 having a width of 300 μm.
That is, the central conductive portion 24 is approximately 20 μm thicker than the insulating portions 25 on both sides. This conductive part 24
Is the same as the structure of the lower film portion 22, and the description is omitted. On the other hand, the insulating portion 25 is composed of only an adhesive tape layer such as a thermosetting resin (epoxy resin). The electrical resistance of the conductive portion 24 containing the conductive particles 26 is on the order of mΩ, whereas
The electrical resistance value of the insulating portion 25 containing no is 10 ¹⁰ Ω
Order. That is, in the upper film portion 23, the electric resistance value changes discontinuously at the boundary between the conductive portion 24 and the insulating portion 25.

Next, a mounting method using the above-described anisotropic conductive film 21 will be described. First, the anisotropic conductive film 21 is attached in a direction perpendicular to the longitudinal direction of the electrode pad 11 formed on the circuit board 10. Next, the semiconductor package 1
The second gull wing type outer lead 13 is positioned and mounted on the corresponding electrode pad 11 via the anisotropic conductive film 21. Further, the outer leads 13 of the semiconductor package 12 mounted on the circuit board 10 are brought to a temperature of 190 ° C.
And heat for 20 seconds (see FIG. 6). As a result, the outer lead 13 becomes the adhesive tape layer 2 of the anisotropic conductive film 21.
7 is bonded to the electrode pad 11. At this time, the conductive part 24 at the center is thicker than the insulating parts 25 on both sides, but is compressed until it is flush with the insulating parts 25 by the pressure and heating by the bonding tool 14 (see FIG. 7).
At this time, the electrical resistance value of the attached anisotropic conductive film 21 on the insulating portion 25 side (center portion) is on the order of 10 ¹⁰ Ω, whereas the electrical resistance value on the conductive portion 24 side (both sides) is on the order of 10 ¹⁰ Ω. Are on the order of mΩ.

The width of the outer leads 13 is, for example, 0.3 mm and the pitch is 0.5 mm, which is a narrow pitch. As a result, as shown in FIG. 8, the tip of the outer lead 13 is easily bent by a small force, and the tip of the bent outer lead 13 is
It overlaps with an anisotropic conductive film 21 (on the insulating portion 25 side). However, the electrical resistance of the overlapped portion of the anisotropic conductive film 21, because it is 10 ¹⁰ Omega order, which is electrically insulated state. On the other hand, the rear end of the outer lead 13 whose tip is bent is connected to the electrode pad 11 to be originally connected.
It overlaps with an anisotropic conductive film 21 (on the conductive part 24 side). At this time, since the electric resistance value of the overlapping anisotropic conductive film 21 is on the order of mΩ, it is in an electrically conductive state. As a result, the tip of the outer lead 13 is bent and the anisotropic conductive film 21 is formed on the adjacent electrode pad 11.
, The semiconductor package 12 is electrically connected to the predetermined electrode pad 11 normally. Further, in this embodiment, the conductive portion 24
Is pressed by the insulating portion 25, that is, pressed from both sides during the pressurization and heating by the bonding tool 14, so that
Compressive stress is generated (see FIG. 8). On the other hand, insulating part 2
In the case of 5, a tensile stress is generated on the contrary. As a result, the compressive stress is always applied to the conductive portion 24, so that the contact state between the conductive particles 26 is stabilized. As a result, there is an advantage that the reliability of the electrical connection is improved.

The anisotropic conductive films 1 and 2 of the above embodiment
In 1, when attaching to the circuit board 10, the lower film portions 2 and 22 are attached with the side facing down, but the upper film portion 3 may be attached directly to the circuit board 10. Good.

Further, as shown in FIG. 9, even if the anisotropic conductive film 31 is composed of a conductive portion 34 and an insulating portion 35 provided in parallel with the conductive portion 34, the lead during mounting is not required. Even if the tip of the is bent and overlaps the next electrode pad,
Since that part is an insulating part without electrical conduction,
A normal electrical connection can be obtained without causing a short circuit. In this case, since the internal structures of the conductive portion 34 and the insulating portion 35 are the same as those in the above-described embodiment, the description will be omitted.

Further, as shown in FIG. 10, the anisotropic conductive film 41 comprises only an adhesive tape layer 47 as a medium made of, for example, a thermosetting resin (epoxy resin). By increasing the content density of the conductive particles 46 contained in the width direction half of the conductive portion 47,
On the other hand, the same effect as in the embodiment of FIG. 9 can be obtained even if the insulating portion 45 is formed by setting the content density of the conductive particles 6 in the other part of the adhesive tape layer 47 to zero or extremely low. . In this case, the content density of the conductive particles 6 may be continuously increased from one side end to the other side end.

Furthermore, in the above-described embodiments that although the case of QFP, for example, TCP (T ape C arrier P ackag mounted on a substrate such as a liquid crystal
The present invention can be applied to e).

Furthermore, the present invention relates to, for example, QFP, T
The present invention can also be applied to a case in which a tie bar is provided at the tip of an outer lead such as a CP at a right angle to prevent deformation.

[0024]

Since the anisotropic conductive film according to any one of the first to sixth aspects comprises a conductive portion and an insulating portion, the insulating portion is attached to the lead end when mounting on a circuit board. Even if the tip of the lead is bent during mounting and overlaps with the next electrode pad, that part is an insulating part with no electrical conduction, so there is no short circuit and normal electrical You can get a connection. As a result, for example, 0.
This can contribute to improving the reliability of mounting QFPs having a narrow pitch of 4 mm or less.

Further, when the anisotropic conductive film according to the fifth aspect is pressed during mounting, the conductive portion is sandwiched between the insulating portions on both sides, and a compressive stress is generated inside the conductive portion. As a result of the stabilization of the contact state between each other, there is a specific effect that the reliability of the electrical connection is improved.

Further, in the mounting method according to claim 7, the electronic component comprising a plurality of leads projecting in parallel is mounted on an electrode pad formed on a circuit board corresponding to the lead. A conductive portion, comprising a tape-shaped insulating portion having an insulating property connected to the conductive portion,
The first conductive part is configured such that an anisotropic conductive film composed of a medium layer and conductive particles dispersed and held in the medium layer is attached to the lead with the insulating part side facing the tip end of the lead. And a second step of positioning the lead on the corresponding electrode pad via the anisotropic conductive film adhered in the first step, and after the second step, the step of positioning the lead And the third step of connecting the lead to the electrode pad via the anisotropic conductive film by heating under pressure. During the mounting, the tip of the lead is bent and overlaps the adjacent electrode pad. Even so, since that part is an insulating part without electrical conduction, without causing a short circuit,
A normal electrical connection can be obtained. As a result, it is possible to contribute to improving the reliability of mounting a QFP having a narrow pitch of, for example, 0.4 mm or less.

[Brief description of the drawings]

FIG. 1 is a perspective view of an anisotropic conductive film according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a mounting method using an anisotropic conductive film according to one embodiment of the present invention.

FIG. 3 is an explanatory diagram of a mounting method using an anisotropic conductive film according to one embodiment of the present invention.

FIG. 4 is an explanatory diagram of a mounting method using an anisotropic conductive film according to one embodiment of the present invention.

FIG. 5 is a perspective view of an anisotropic conductive film according to another embodiment of the present invention.

FIG. 6 is an explanatory diagram of a mounting method using an anisotropic conductive film according to another embodiment of the present invention.

FIG. 7 is an explanatory diagram of a mounting method using an anisotropic conductive film according to another embodiment of the present invention.

FIG. 8 is an explanatory diagram of a mounting method using an anisotropic conductive film according to another embodiment of the present invention.

FIG. 9 is a view showing a modification of the anisotropic conductive film of the present invention.

FIG. 10 is a view showing a modified example of the anisotropic conductive film of the present invention.

FIG. 11 is an explanatory diagram of a conventional technique.

FIG. 12 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

1: anisotropic conductive film, 4: conductive part, 5: insulating part, 6: conductive particle, 7: adhesive tape layer (support tape layer).

Claims (7)

[Claims] 1. A tape-shaped conductive portion having conductivity, and a tape-shaped insulating portion connected to the conductive portion and having an insulating property, wherein the conductive portion includes a medium layer and a medium layer. Anisotropic conductive films, comprising conductive particles dispersed and held. 2. The anisotropic conductive film according to claim 1, wherein the medium layer is made of a thermosetting resin or a thermoplastic resin. 3. The anisotropic conductive film according to claim 1, wherein the conductive portion and the insulating portion are connected in the width direction. 4. The anisotropic conductive film, wherein a medium layer is connected along both sides in the width direction of the conductive portion.
The anisotropic conductive film according to the above. 5. The anisotropic conductive film according to claim 4, wherein the thickness of the conductive portion is larger than the thickness of the medium layer. 6. The conductive portion and the insulating portion are supported by a conductive support tape layer.
The anisotropic conductive film according to the above. 7. A mounting method for mounting an electronic component having a plurality of leads arranged side by side on an electrode pad formed on a circuit board corresponding to each of the leads, wherein the medium layer is dispersed and held on the medium layer. A tape-shaped conductive portion having conductive particles, and an anisotropic conductive film provided with a tape-shaped insulating portion having an insulating property connected to the conductive portion, the insulating portion side on the plurality of leads. A first step of attaching the plurality of leads to a corresponding one of the electrode pads via an anisotropic conductive film attached in the first step; A second step of positioning, and a third step of connecting the lead to the electrode pad via the anisotropic conductive film by pressurizing and heating the lead after the second step. A mounting method characterized by the following.