JPH02291680A - Circuit connection structure - 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] [Industrial application field] The present invention relates to a highly reliable connection structure between circuits.

[Prior Art 1] For example, liquid crystal panels are currently widely used as displays for watches, calculators, televisions, measuring instruments, etc. Recently, the display capacity of liquid crystal panels has tended to increase, and FIGS. 2 and 3 are schematic diagrams of the upper and lower conductive parts of conventional liquid crystal panels. Figure 2 shows a case in which soft metal is used to provide continuity between the upper and lower boards. A hole is made in the upper substrate, and an indium ball 6 made of soft metal is inserted into the hole to establish conduction to the lead terminal 5 of the common electrode 3.
It is in a crushed state.

In this way, when vertical conduction is achieved using indium balls, contact between the common electrode 3 and the indium pole 6 often cannot be established, and it also takes a lot of man-hours, resulting in poor productivity. The state shown in FIG. 3 is a state in which this drawback is improved and the number of steps is reduced by printing the silver paste 9 on either the upper or lower substrate.

[Problems to be Solved by the Invention] However, even in liquid crystal panels in such a state, defects in the upper and lower conductive parts are a major cause of a decrease in the yield of liquid crystal panels. This is because the drying temperature of the sealant in 7 and the silver paste in 9 are different. In addition, normally LCD panels are not manufactured as a single item, but two glass plates are pasted together, shaped as shown in Figure 4, and then a cut is made along the dashed line and broken to produce a single LCD panel. It is being manufactured. As a result, force was applied to the edges of the liquid crystal panel, causing the silver paste on the outside of the sealant to peel off, causing poor vertical continuity. Therefore, when the resin content was increased to improve the adhesion of the silver paste, it became difficult to maintain contact between the silver particles within the silver paste, resulting in poor vertical conduction. Furthermore, as the number of silver particles in the silver paste increased, the adhesion properties naturally deteriorated. Furthermore, even if the ratio is appropriate, the yield varies greatly depending on the humidity and temperature during manufacturing, the temperature during drying, etc., and it is currently extremely difficult to analyze the causes of this. Further, when silver paste is used, the diameter of the silver particles is not constant, and the diameter of large particles is generally 7 μm or more. For this reason, it has been difficult to mass-produce liquid crystal panels with a gap thickness of 5 μm. FIG. 5 shows this state. 1l is the root particle, and 12 is the adhesive resin in the silver paste.

Therefore, the present invention has been made to solve the above problems, and its purpose is to provide a circuit connection structure using a conductive agent with excellent reliability.

[Means for Solving the Problems 1] In the circuit connection structure of the present invention, the connection circuits formed facing each other are substantially connected by a conductive metal thin layer formed on the surface of an elastic insulating material. are mutually connected by an electrical connection member made of a conductive agent coated with an insulating adhesive, and the conductive agent is pressed and deformed by the opposing circuit, and the circuit and the conductive agent are in surface contact with each other. It is characterized by being electrically connected.

[Example] First, examples of conductive agents that impart conductivity to elastic insulating materials include plastic balls and plastic fibers. When using this, the plastic pole or plastic fiber should have a diameter that is, for example, the same as or twice the gap thickness of the liquid crystal panel. This is a conductive agent intended to eliminate contact failure, but
If the plastic ball or plastic fiber is larger than the gap of the liquid crystal panel, it will be more elastic even if the thickness of the gap of the liquid crystal panel changes, so the metalized conductive agent will change and come into strong and planar contact with the conductive part. This means that there will be no contact defects. This state is shown in Figure 1. In Fig. 1, 15 is a metallized plastic ball, and 16 is an adhesive. If the diameter of the plastic ball or plastic fiber exceeds twice the gap thickness of the liquid crystal panel, it will be compressed to 1/2 when the panel is assembled, making it easy for cracks to form in the metal layer, resulting in poor conductivity. It will cause a cause. Preferably, the diameter of the plastic ball is 1 mm of the gap thickness. It is about 1 to 13 times as much. ? The method for manufacturing the conductive agent used in the present invention will now be described.

To plate these insulating materials, the following electroless pretreatment process is typically used.

■) Alkaline degreasing 2) Acid neutralization 3) Sensitizing in SnCg■l solution 4) P
Activation in dCff2/solution. Sensitizing is a process in which, for example, Sn" ions are adsorbed onto the surface of an insulating material, and activating is an example.
In this process, a reaction of Sn"+Pd"-+Sn'+Pd' occurs on the surface of an insulating material, and Pd' becomes a catalyst nucleus for electroless plating. After performing the electroless plating pretreatment step, metallization can be performed by immersing the product in an electroless plating bath that has been prepared and heated according to a predetermined method.

As the electroless plating bath, Au. Ni. Cu, Ag. C
o. Although there are plating baths such as Sn that can be used as a conductive agent, Ni has the best adhesion of the plating film, and therefore electroless nickel baths are the best for metallizing insulating materials.

In addition, when metalizing the aforementioned plastic balls and plastic fibers, the plating film thickness should preferably be 200 to 4 μm. If there are less than 200 people, there may be parts of the plastic balls etc. where the plating film is not formed,
This is not practical as the resistance increases. On the other hand, if a plating film is formed with a thickness of 4 μm or more, the plating layer tends to become sharp when assembling the panel, which tends to cause poor conductivity. Furthermore, if more plating film is formed, it will become difficult to control the gap of the liquid crystal panel. In addition, if a nickel film or the like is formed on an insulating material and the resistance value is large, it is recommended to form a noble metal film with good electrical conductivity such as electroless silver plating or electroless gold plating on the surface of the nickel or the like.
The thickness of the noble metal electroless plating film is preferably 50 mm to LLim.

The thus metalized insulating material is added to the adhesive and uniformly dispersed.

As the adhesive, epoxy resin, acrylic resin, etc. were used.

The proportion of the metalized insulating material in the adhesive is 0. ]wt% to 30wt% is appropriate, and O. lwt%
If it is less than that, the resistance of the conductive part becomes large and tends to fluctuate. Moreover, if it exceeds 30 wt%, problems tend to occur in adhesive properties. In addition, the dispersion state of the gap agent is
Liquid crystal panel has a small size (at least 5 pieces/mm2 or more in the conductive part)
500 pieces/mm" is good. The upper and lower limits are determined for the same reason as above. Of course, these values differ somewhat depending on the diameter of the insulating material.

The conductive agent thus produced is applied to the upper and lower conductive parts of the liquid crystal panel by, for example, printing, and is incorporated into the liquid crystal panel.

Glass is usually used for the substrate of liquid crystal panels, but transparent TFI (Sn02, I
nt Os, etc.) may be used. In the case of a plastic film, the portion in contact with the upper and lower conductive agents is dented by the pressure applied during assembly, thereby increasing the contact area with the upper and lower conductive agents and increasing reliability.

Next, this will be explained in detail using a specific example. (Example 1) A styrene ball with a diameter of 12 μm was immersed in a chromic acid mixture for 5 minutes, filtered through a microfilter with a hole diameter of 2 μm, and thoroughly washed with water. Next, SnCA21g/12, HCf
These 'particles were separated into a mixed solution of 2' lcc/ρ, filtered and washed with water, and then dispersed in a red seamer manufactured by Kanigen Co., Ltd., which had been prepared according to a prescribed method, followed by filtration and washing with water. The sample was then allowed to stand for 6 minutes in a solution of S680 manufactured by Kanigen (45°C) prepared in a prescribed manner, filtered, and washed with water. By this, 350
0 people's Nikkenorelin plating was completed. 20wt% of this was dispersed in epoxy resin, and the gap thickness was 10μm.
When used as a conductive agent between the upper and lower sides of a liquid crystal panel, the resistance value of the upper and lower conductive parts was 8KΩ. Further, even when a predetermined accelerated test was performed, there was no change in the value.

(Example 2) A liquid crystal panel with a gap thickness of 10 μm similar to that in Example 1 was prepared by adding 10 wt % of the styrene balls metalized in Example 1 to ultraviolet curable acrylic (degreaser). The resistance value of the upper and lower conductive parts of the liquid crystal panel was 9KΩ, and this value did not change even after performing the specified acceleration test.

(Example 3) As in Example 1, a nylon ball with a diameter of 10 um was used. 25
00 people were plated with Nikkenorelin. Thereafter, 500 displacement gold plating was performed using Atomex electroless gold plating solution manufactured by Nippon Engelhard Co., Ltd. When 5 wt% of this was dispersed in epoxy resin and used as a conductive agent between the upper and lower sides of a liquid crystal panel with a gap thickness of 10 LLm, the resistance value of the upper and lower conductive parts was 6KΩ, and this value did not change even after performing a specified accelerated test. There was no. (Example 4) As in Example 2, 20
Electroless nickel plating was performed by 00 people and electroless gold plating by 600 people, and 3 wt% of the silver paste was used as an upper and lower conductive agent for a liquid crystal panel with a gap thickness of 7 μm. The resistance value of the upper and lower conductive parts was 6KΩ, and there was no change in this value even after performing a predetermined acceleration test.

(Example 5) When the styrene balls metalized in Example 4 were dispersed in an ultraviolet curable acrylic resin at 10 wt% and used as an upper and lower conductive agent for a liquid crystal panel with a gear knob thickness of 10 μm, the upper and lower conductive parts of the styrene balls were dispersed. The resistance value was 8KΩ, and this value did not change even after performing the specified acceleration test. When the conductive agent used in each of the above examples was compared with a conventional conductive agent, the conductivity defects were reduced to 1/10.

Although the above embodiments have mainly been described with respect to liquid crystal panels, it goes without saying that the present invention is also applicable to various display bodies such as electrochromic panels and electroluminescent panels. [Effects of the Invention] As described above, according to the present invention, in particular, the circuit and the conductive agent are brought into surface contact and electrically connected in a state in which the conductive agent is pressed and deformed by the circuits facing each other. The reliability of the connection part can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention. FIG. 2 to FIG. 5 are diagrams explaining the prior art. that's all Applicant: Seiko Epson Corporation

Claims (1)

[Claims] An electrical connection member comprising a conductive agent and an insulating adhesive, in which connection circuits formed facing each other are substantially covered with a conductive metal thin layer formed on the surface of an elastic insulating material. 1. A circuit connection structure characterized in that the circuits and the conductive agent are electrically connected to each other by being in surface contact with each other in a state where the conductive agent is pressed and deformed by the opposing circuits.