JPS60262490A - Coupling sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention connects conductors such as pads of electronic components such as integrated circuits (vPJHc) to a large number of conductive patterns arranged on a substrate. The present invention relates to a connection sheet suitable for various cases.

Background technology and its problems Recently, with the miniaturization of electronic devices and electronic components,
For a large number of conductive patterns formed at a narrow pitch on a wiring board, such as a flexible board or a rigid board, a large number of narrow conductive patterns such as IC bands arranged at a narrow pitch corresponding to these patterns are used. There is a need to connect electrical conductors that are spaced apart. These connections are usually made by wire bonding, in which the IC is connected to the film carrier and lead frame using gold wire, or by mounting the IC once using the TAB method, and then connecting the lead part and the electrode of the board with cream solder, or by connecting the IC to the board using cream solder. The lead part of the IC pellet was connected to the butt of the IC pellet using wire bonding.

However, wire bonding using gold wire is expensive because the wire itself is expensive, and because it cannot be connected all at once, the ζ connection work is KC421F, which leads to high costs, and the narrow pitch of many connections. As a result, reliability problems such as contact between wires, connection strength due to narrower honding portions, and short circuits between connecting portions occur, and there is a limit to the ability of skewers to improve packaging density.

In addition, as shown in Figure 1, metal particles (11 is IC
(21 bat (2a) and board (3) lead (3a)
) designed to establish continuity between
101469). According to this method of using an anisotropic adhesive, the connection can be made in a simple process and at low cost. However, the metal particles +11 do not have melting properties and may not necessarily provide an electrically stable connection. In addition, in this example, there is no guideline for selecting the particle size and adhesive layer thickness in order to successfully interpose the metal particles fil between the fine pinch patterns, and the finer the pattern, the better the metal particles (1) can be interposed. However, there is a drawback that there is a risk of leakage of 0.degree. C. between the t'' (2a) and the t'' (3a), making it impossible to conduct.

The present invention solves the above-mentioned drawbacks, and makes it possible to easily and stably electrically and mechanically connect other conductors corresponding to a large number of conductive patterns arranged at narrow pitches. This provides a connecting sheet that can be used.

Summary of the Invention The present invention relates to the connection between a plurality of conductive patterns arranged on a substrate and a plurality of conductors that are electrically connected to the conductive patterns. It comprises an adhesive layer in which metal particles are dispersed in an insulating adhesive interposed between the two to electrically and mechanically connect them. The metal particles are made of a metal that melts when the conductive pattern and the conductor are bonded by pressure and heating, and the size of the metal particles is determined by the size of the metal particle at the time of bonding between the conductive pattern and the conductor. 1. Also, the thickness of the connecting agent layer is selected to be 1/3 to 2 times the diameter of the metal particles, and the insulating adhesive is melted and flowed by this heating. This adhesive is selected from among the adhesives that can be used to easily and stably connect electrically and mechanically.

In addition, the heating temperature during the above-mentioned joining, in other words, the melting point of the metal particles is 50°C to 350°C, preferably 80°C to 260°C.
Selected as ℃. The heating temperature, that is, the melting point of the metal particles, is selected to be 50°C or higher, preferably 80°C or higher, when the wiring board is mounted on, for example, an electronic device, that is, in use, and is preferably lower than 50°C. This is to avoid deterioration in reliability, such as re-melting of the metal bonded between the conductive pattern and the conductor at an ambient temperature of less than 80°C, resulting in peeling or connection failure. Yes, 35
[Selecting F1 above 1'c, preferably below 260°C, makes it difficult to select a substrate material that can withstand heat treatment exceeding this range, and also requires complicated heating means and operations, which is disadvantageous industrially. It depends on what is happening.

Further, the particle size of the metal particles is selected to be approximately 1/2 or less of the distance between the conductive pattern and the connecting portion of the conductor to the conductive pattern, that is, the distance between adjacent conductive patterns and the distance between adjacent conductors. This is desirable, and it has been confirmed that when doing so, it is possible to reliably avoid accidents such as short-circuiting between adjacent connection parts due to metal particles.

In addition, 1. The mixing ratio of the adhesive and metal particles in the adhesive layer that is pre-formed into a sheet or that is pre-coated on the substrate is interposed between the conductive pattern and the corresponding conductor as described in E. The metal particles are selected in an amount of 0.5 to 50 parts by volume per 100 parts by volume of the agent (solid content). If it is less than 0.5, the low resistance connection may be insufficient, and if it exceeds 50 capacitance, the insulation between the metal particles other than the connection part may be incomplete, or the mechanical adhesive strength may be insufficient. This is due to the fact that ζ may occur.

In addition, the insulating adhesive used for this is an adhesive that is fluid at least under the above-mentioned pressure and heating conditions during bonding, such as a rubber-based adhesive or an ethylene-based adhesive.
A so-called photomelt type adhesive based on vinyl acetate or a hardening type adhesive using thermally crosslinkable epoxy threads can be used.

The thickness of the insulating adhesive layer is 1/1 of the diameter of the metal particles.
Select 3 to 2 times.

EXAMPLE Hereinafter, an example of the connecting sheet of the present invention will be described with reference to FIGS. 2, 3, and 4.

(4) shows an aluminum wiring board with a thickness of 200 μm whose surface has been insulated, and a predetermined pattern is formed on the surface of the wiring root (4) with a thickness of 18 μm and a line width of 50. A conductive pattern (5) of um copper foil was arranged through an adhesive layer having a thickness of 3077+11. In addition, (6) is an IC chip, and this IC chip (6) has a pad part +71,
+81, +91, (101°(11), (1
2) , (13) , (14) , (1,5) and (1
6), and these pad portions 171, +8),
(91, 1101.

(11) , (12) , (13) , (14) , (
15) and (16) are pad parts (17), (1B), (19) formed at the ends of the conductive pattern (5).
, (20), (21).

(22) , (23) , (24) , (25) and (
26) as described later, and the IC chip (
4) contributes to a predetermined circuit operation.

In addition, (27) is a hot melt type insulating adhesive (
28) A connecting sheet formed from a paint in which solder metal particles (29) are dispersed is shown. Here, use this insulating adhesive (
28) had the following composition.

Furthermore, 100 parts by weight of low melting point solder metal particles were uniformly dispersed and mixed into the insulating adhesive (28) having this composition. As the metal particles, solder metal particles (29) made of a Pb-3n alloy with an average particle size of 25 μm and having a melting point of 143° C. were used. In this way, the adhesive paint in which the low melting point solder metal particles (29) are dispersed in the insulating adhesive (28) is dried so that the thickness after drying is 20 μm, which is thinner than the diameter of the solder metal particles (29). A connected sheet 1 (27) was obtained by coating a release sheet (not shown) with a coater. Next, a method for electrically and mechanically connecting the IC chip (6) and the wiring board (4) by interposing the connecting seam L (24) will be explained. In Figure 4, (30) is 30
A 0° C. heater is shown, and a wiring board (4) and a pad portion (17) are placed on this heater (30).

(1B) , (19) , (20) , (21) , (
22), (23).

(24), (25) and (26) and IC chip (6)
Pad portions (7), (8), +91. Q(1,(
11), (12), (13).

(14) , (15) and (16) are each opposed to each other, with an anisotropic electrical connection sheet (27) interposed between them, and a pressure body (31) is vibrated at 2000 Hz by an ultrasonic vibrator. Pressure bonding was performed by applying a pressure of 2 kg/cd for 2 seconds in the direction of the arrow. This allows the IC
Low melting point solder particles (29) having a diameter larger than the thickness of the adhesive layer (28) mixed into the insulating adhesive layer (28) of the connection sheet between the chip (6) and the wiring board (4) are attached to the band portion ( 1
7) , (18) , (19) , (20) , (21
), (22).

(23), (24), (25) and (26) and the pad portion (7).

+81. (91, Ql, (11) , (12) , (
13), (14).

(15) and (16) collapse before the insulating adhesive layer, ensuring good electrical connection between the corresponding phase forces, and the adhesive in the adhesive layer becoming fluid due to heating. Therefore, most of the insulating adhesive (28) interposed between the pad portion and the corresponding band portion to which pressure is applied because they substantially protrude from facing each other is pushed out to the side. The solder particles (
29) is melted and crushed by the heat and pressure, and the pad portions are soldered to electrically connect them. In this way, when the band parts are electrically connected to each other, the conduction resistance at the connection part can be made sufficiently small, and the insulation resistance between the connection parts can be made sufficiently large. This is because the insulating adhesive (28), which has been made highly fluid by heating and pressurizing as described above, is pushed outward from between the pads and the two are well fused together by the solder metal. The insulating adhesive (28) pushed out of the connection portion wraps the conductive metal particles (29) well, and the presence of this adhesive (28) between one adjacent connection portion causes the board to (
4) and the IC chip (6) are firmly attached.

Also, glue l! The thickness of (2B) may be selected between 1/3 and 2 times the diameter of the metal particles (29). This is 1/
If it is less than 3, the amount of flowing adhesive will be insufficient and it will be difficult to obtain sufficient adhesion, and if it is more than 2 times, the metal particles (29) will flow between the patterns and come off, making it difficult to maintain sufficient conductivity. It depends on when it disappears.

As described above, according to this embodiment, the connecting seam 1- (27) according to the present invention is interposed between a plurality of conductive patterns and the corresponding conductors to be connected, and heat and pressure are applied. Due to its fluidity, much of the insulating adhesive is removed from between the conductive pattern and the conductor, which are mutually connected to each other, and the metal particles (29) are used to effectively seal the area between the band part of the conductive pattern and the pad part of the IC. After fusion bonding, the insulating adhesive pushed out of the joints of the eyes and hems wraps the conductive metal particles well, and the presence of a large amount of this adhesive between the adjacent joints causes It is mechanically and firmly fixed. In addition, in order for such a phenomenon to occur effectively and the connection resistance to be 0.1Ω or less and the insulation resistance to be 10Ω or more, preferably 109Ω, the M of the insulating adhesive during heat bonding must be .

F.1. (melt flow index) is 0,
(101 or more), preferably 0.005 or more. This M, F, 1. is ^STM, A method of 0123B or JIS.

K72] (This is the number of grams of resin that flows out from the orifice (hole) in 10 minutes when a cart of 2160 g is applied at a predetermined pressure bonding temperature using an apparatus specified in Method A of 1. The thickness of the adhesive layer is 10-300% of the spatial volume created between each connection part, preferably 30-20%.
00%, and its thickness is preferably 5 to 200 μl.

Effects of the Invention As described above, according to the connection sheet of the present invention, there is mainly an insulating adhesive layer (28) between the conductive patterns that are electrically connected to each other and the corresponding conductors. Since the metal particles are fused to have a predetermined diameter, the metal particles are reliably interposed in the electrical connection, and a low resistance connection can be reliably achieved. Therefore, there is an advantage that the present invention can be applied even when adopting a current drive mode in which current is passed through this connection portion. In addition, since the insulating adhesive is filled between each connection part, the connection parts h' and 2 are close to each other at a narrow pitch, that is, even when using areal density wiring, there is no inconsistency between the connection parts. By ensuring this, reliability is improved and wiring boards with higher commercial density and finer patterns can be realized.

[Brief explanation of the drawing]

Figure 1 is a neo diagram showing an example of the connection between conventional patterns.
Figures 3 and 4 are dotted line diagrams of an embodiment of the connecting sheet of the present invention. (7) to (16), (17) to (26) are butt parts,
(27) is a connecting sheet, (28) is an insulating adhesive, (2
9) is a solder particle. 3 2

Claims (1)

[Claims] When connecting a plurality of conductive patterns arranged on a substrate and a plurality of conductors that are electrically connected to the conductive patterns, It has an adhesive layer in which metal powder is dispersed in an insulating adhesive that electrically and mechanically connects the two, and the metal particles absorb the force between the conductive pattern and the conductor. The metal particles are made of a metal that melts during bonding by conventional heating, and the size of the metal particles is such that the size of the metal particles during the bonding is smaller than the distance between the connection portion between the conductive pattern and the conductor. and the thickness of the adhesive layer is selected to be 1/3 to 2 times the diameter of the metal particles, and the insulating adhesive is an adhesive that melts and flows when heated.