JPH04180029A - Connecting structural body for circuit - Google Patents

Abstract

PURPOSE:To widen the margin of a press welding operation and to improve the reliability of connection by allowing >=2 kinds of conductive particles, such as solder particles, and particles formed by applying metal plating on a plastic nuclear material to coexist in an anisotropically conductive adhesive layer. CONSTITUTION:The solder particles 6 which are the conductive particles and the particles 7 which are formed by applying the metal plating of Ni or Au, etc., on the plastic nuclear material and are the conductive particles are made to coexist in the anisotropically conductive adhesive layer 5. The connection of the relatively high reliability at about <=200 deg.C is obtd. by the solder particles 6 and the connection of the high reliability is obtd. at a relatively high temp. of about >=180 deg.C by the particles 7 formed by applying the metal plating of the Ni or Au, etc., on the plastic nuclear material.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a highly reliable microcircuit connection structure.

(Prior art) Conventionally, connection terminals are used to face each other, such as connecting semiconductors or semiconductor components to liquid crystal panels, connecting integrated circuits to optical sensors, and connecting surface mount components to various circuit boards. Soldering or conductive paste is widely used as a connection method when the wires are lined up at a fine pitch. However, in these methods, the conductive connecting member must be formed only in the conductive circuit portion, which has caused difficulty in connecting fine circuits with increasing hole density and high definition. FIGS. 2 and 3 show an example of a conventional circuit connection structure. In FIG. 2, 21 is a TAE tape material, 22 is a copper foil pattern that is a connection circuit formed on the TAB tape that is a circuit board, 23 is a liquid crystal panel, and 24 is an IT○ that is a connection circuit on the liquid crystal panel.
25 is an anisotropic conductive adhesive layer, 2
6.27 indicates conductive particles, 26 conductive particles are the second
In the figure, numerals 27 are solder fine particles, and 27 are conductive particles substantially covered with an antistatic metal thin film layer formed on a core material made of a high molecular weight polymer.

(1llfllJ that the invention attempts to solve) However, the conventional circuit connection structure has many problems as is clear from FIGS. 2 and 3. First, the conventional circuit connection structure , an anisotropic conductive adhesive layer 25 sandwiched between a copper foil pattern 22 of a TAB tape 21 and an electrode pattern 24 on a liquid crystal panel 23.
Since the conductive particles 26 inside are solder particles, an anisotropic conductive adhesive layer is sandwiched between the TAB tape and the liquid crystal panel.
When you press the TAB tape against the LCD panel while heating it with a heater tool, the adhesive layer will harden and the TAB tape and LCD panel will be joined together. The hardening of the agent progresses and the strength in the sense of mere bonding improves, but since the solder particles, which are conductive particles, are made of eutectic metal, there is a melting point, and the solder particles melt once, so the TAB tape's strength increases. The connection reliability was reduced in terms of the reliability of the conductive connection between the copper foil pattern and the electrode pattern of the liquid crystal panel.

Furthermore, in FIG. 3, since the conductive particles are substantially covered with an antistatic metal thin film layer formed on a core material made of a polymer, the high energy side on the high temperature and high pressure side Although crimping with a crimping tool at low temperatures maintains the reliability of conductive connections compared to conductive particles using solder, crimping with crimping tools at low temperature, low voltage, and low energy sides significantly impairs the reliability of conductive connections. Ru.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve these conventional drawbacks and improve the reliability of connections between connection circuits formed oppositely.

(Means for Solving the Problems) In the circuit connection structure according to the present invention, at least one of the connection circuits formed facing each other is formed on a liquid crystal panel, and the other connection circuit is formed on a liquid crystal panel. The circuit is formed on another electronic component, and between the connecting circuits there is an anisotropically conductive adhesive layer in which conductive particles are interposed in an insulating adhesive. The conductive adhesive layer contains two or more types of solder fine particles mainly made of a lead-tin alloy, and fine particles whose conductive material is a non-low melting point metal such as Ni fine particles or particles of plastic core material plated with metal. It is characterized by being composed of conductive particles.

(Example) Examples of the present invention will be described below with reference to the drawings. 1st
The figure shows a sectional view of a main part of a circuit connection structure. 1st
In the figure, 1 is TAB tape, 2 is TA which is a circuit board.
B A conductive foil pattern as a connection circuit formed on the tape, 3
is the liquid crystal panel, and 4 is the ITO connection circuit on the liquid crystal panel.
5 is an anisotropic conductive adhesive layer, 6 is a solder fine particle among the conductive particles, and 7 is also a Ni fine particle among the conductive particles, or a particle made of metal plating on a plastic core material, etc. Indicates fine particles made of a non-low melting point metal as a conductive substance. The conductive particles are composed of two or more types of conductive particles.

Generally, solder particles are a so-called alloy and have a melting point. The melting point of fine solder particles is generally around 200°C, regardless of the alloy components. On the other hand, the curing of anisotropically conductive adhesives often occurs at temperatures above 60'C, and crimping is often carried out within the range of 170 to 190°C. As the temperature of the crimping operation and the melting point of the solder are quite close to each other, the temperature of the crimping operation may partially exceed the melting point of the solder depending on variations in the crimping operation. On the other hand, solder fine particles contain lead and tin as basic components, but because the general electrode pattern of liquid crystal panels is made of ITO, and the components of ITO are made of indium and tin oxides, ITO Indium and tin, which are free metals, have a eutectic point between lead and tin, which are component metals of solder, at temperatures below 200°C. The reliability of the conductive connection is improved because there is a metallurgically bonded portion between the ITO barrels. Furthermore, the dull foil pattern of TAB tape is generally tin-plated, and this tin plating also microscopically forms an alloy with the components of the solder particles mentioned above, improving the connection reliability with the solder particles. can. In this way, solder particles can provide a relatively reliable connection at temperatures below 200°C.

On the other hand, when the conductive particles are particles in which a plastic core material is plated with a metal such as Ni or Au. The conduction between the copper foil pattern of the TAB tape and the electrode pattern of the liquid crystal panel is not due to any kind of bonding, but simply due to contact.

Therefore, when the crimping energy is small, the conductive particles and TA
The reliability of the conductive connection with the B tape or the electrode pattern of the liquid crystal panel becomes low. On the other hand, if the pressure bonding energy is large, the conductive grains will not melt and the reliability of the conduction with the TAB tape's copper foil pattern or the LCD panel's electrode pattern will not deteriorate, and the adhesive will sufficiently harden and a conductive connection will be achieved. can be cleaned without reducing reliability. In this way, Ni or A can be added to the plastic core material.
When particles plated with metal such as U are used as conductive particles, a highly reliable connection can be obtained at a relatively high temperature of 180° C. or higher.

As explained above, particles made of a plastic core material plated with metal such as Ni or Au and conductive particles made of solder particles have different reliability at high and low temperatures. Therefore, as in the present invention, N is added to the plastic core material.
If two types of conductive particles, particles plated with metal such as i or Au and conductive particles made of solder fine particles, are mixed in one anisotropic conductive adhesive, the conditions of the crimping work will vary somewhat. However, different conductive particles contribute to maintaining reliability at high and low temperatures, making it possible to ensure reliability over a wider range. As a result, it is possible to widen the allowable limits for the conditions of the crimping operation. Thereby, connection costs can be reduced. moreover,
If the allowable limits for the conditions of the crimping operation can be widened, it is possible to diversify the peripheral structures, and this can also contribute to reducing the cost of the peripheral structures.

Furthermore, the reliability of the connection itself can be improved. As a result, the range of use of products with such a circuit connection structure can be expanded, and the cost of the circuit connection structure technology according to the present invention can be reduced by expanding the application range of the product and the range of utilization technology. It is possible to reduce the

Furthermore, by expanding the range of applications of products and the range of technologies utilized, it becomes possible to add value to products.

(Effects of the Invention) As explained above, the present invention has metal plating applied to solder fine particles mainly composed of lead-tin alloy and Ni fine particles or plastic core material in one anisotropic conductive adhesive layer. By mixing two or more types of conductive particles, such as fine particles made of non-low melting point metal as a conductive substance, the margin of the crimping operation is widened and the reliability is improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a circuit connection structure in an embodiment of the present invention. FIG. 2 Cross-sectional view of main parts of a circuit connection structure in a conventional example I TAB tape 2 Copper foil pattern 3 Liquid crystal panel 4 Electrode pattern 5 Anisotropically conductive adhesive layer 6 Solder particles 7 Metal plating on plastic core material Applied conductive particles 21 TAB tape 22 Copper foil pattern 23 Liquid crystal panel 24 Electrode pattern 25 Anisotropic conductive adhesive layer 26 Solder particles or more Applicant Seiko Epson Corporation Representative Patent Attorney Kizobe Meiki (1 person)

Claims (1)

[Claims] At least one of the connection circuits formed facing each other is formed on the liquid crystal panel, the other connection circuit is formed on another electronic component, and there is no space between the connection circuits. It has an anisotropic conductive adhesive layer in which conductive fine particles are interposed in an insulating adhesive, and the conductive particles are solder mainly composed of a lead-tin alloy in one anisotropic conductive adhesive layer. A circuit connection structure characterized by being composed of two or more types of conductive particles: fine particles and fine particles whose conductive substance is a non-low melting point metal such as Ni fine particles or particles obtained by metal plating a plastic core material. .