JPS624769A - Method for laminating planar conductor board - Google Patents

Abstract

PURPOSE:To laminate planar conductor boards to each other without causing uneveness in bonding, irrespective of the curing time of an adhesive, by applying a principal ingredient of a two-pack adhesive to the adherend surface of one board, applying the hardener thereof to the adherend surface of the other board and bonding them to each other when desired. CONSTITUTION:In laminating two planar conductor boards to each other, a principal ingredient of a two-pack adhesive is applied to the adhered surface of one board and the hardener thereof is applied to the adherend surface of the other board. When desired, both boards are bonded to each other. The preferred blending ratio of the principal ingredient to the hardener is a value corresponding to the ratio of the coating thickness of the principal ingredient to that of the hardener on the boards. When the principal ingredient and the hardener in the optimum coating thickness are brought into contact with each other, they are gradually cured by diffusion from the contact surface to form an adhesive layer.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for bonding substrates having planar conductor portions such as printed circuits.

(Prior art and its problems) Conventionally, when bonding planar conductors using a two-component high viscosity adhesive, the main ingredient and curing agent are mixed just before bonding, and the mixture is mixed before curing begins. The method employed was to quickly apply the adhesive to the adhesive surface of one substrate or the adhesive surfaces of both substrates and then bond them together.

However, when bonding substrates to each other in large quantities and continuously, the conventional method is very time-consuming and inefficient. Once mixed, the two-component adhesive begins to harden immediately, so the timing of mixing must be determined while carefully adjusting and monitoring the work flow. Furthermore, since a large amount of adhesive is used, a considerable amount of space and labor is required to mix the main agent and curing agent. Furthermore, a considerable amount of the mixed adhesive is wasted because it hardens without actually being used for bonding, and cleaning of mixing equipment and tools that have a large amount of hardened adhesive adheres to the adhesive. It takes a lot of effort to dispose of it. In addition, when applying the mixed adhesive to the surface to be bonded, use a blade coater or roller coater to spread it from one side of the surface to the other, so when applying to a large surface, it is necessary to apply the adhesive at the beginning and end of the coating. The degree of curing of the adhesive differs at the time of application, and when the adhesive is applied many times, the degree of curing of the adhesive also differs between the beginning and the end, which tends to cause uneven adhesion effects.

Furthermore, in order to obtain a thin and uniform adhesive layer, if a two-component adhesive is mixed and then applied thinly to one substrate and then attached to another substrate, the adhesive layer will contain small and large air bubbles. This results in a decrease in adhesive strength.

(Objective of the Invention) The present invention solves the above-mentioned problems, and uses a two-component adhesive to bond planar conductors together quickly and without being affected by the adhesive's effective time. This provides a method of bonding without causing unevenness.

(Means for Achieving the Object of the Invention) That is, in the case of bonding two planar conductive substrates together, the present invention includes adding a main ingredient of a two-component adhesive to the adherend of one substrate and a curing agent in advance. is applied to the surface of the other substrate to be bonded, and when the time comes to bond, one planar substrate surface coated with the main agent and the other planar substrate surface coated with the curing agent. This is a method for bonding planar conductive substrates together, characterized by bringing them into close contact with each other.

Planar conductive substrates in the present invention include not only truly planar substrates but also gently curved substrates that interlock with each other.

Two-component adhesives generally exhibit their adhesive effect when the base agent and curing agent are mixed in an appropriate ratio. It is best to apply it to the adhesive surface. That is, it is preferable to set the most preferable compounding ratio of the main ingredient and curing agent specific to the two-component adhesive used as the ratio of the coating thicknesses of the main ingredient and the curing agent to each substrate. When the base agent and curing agent applied at the optimum mixing ratio are brought into contact with each other, they gradually harden by diffusion from the contact surface, forming an adhesive layer.

The two-component adhesive used may have any compounding ratio, but one having a compounding ratio of 1:1 is particularly preferred.

The method for uniformly applying an appropriate amount of the base agent or curing agent to each substrate is not particularly limited, but it is preferable to use a screen printing method. A cloth (called a screen) woven from nylon, Tetron, stainless steel, etc. is stretched over a frame and pulled and fixed on all sides to form a plate of the same size as that required for coating.The base agent or hardening agent is then poured into the plate. This is a coating method in which a spatula-shaped rubber plate called a squeegee presses and slides the inner surface of the fabric to force it through a screen and onto the surface to be adhered placed under the plate. Using this method, it is possible to adjust the coating amount of the base resin or hardener thinly and uniformly by adjusting the size of the mesh of the screen and the thickness of the emulsion applied to the plate, and the base resin and hardener can be applied to the screen respectively. Since the coating state has gaps due to the mesh, the adhesive enters into the gaps between each other during bonding, increasing the contact area between the base agent and the curing agent, making it difficult for uneven adhesion to occur.

Furthermore, in order to obtain a particularly thin adhesive substrate, it is necessary to apply a thin layer of the main agent to one substrate and a hardening agent to the other substrate by screen printing, and then bond them together by bringing them into contact, or compare each side. There is a method that involves applying a thick layer of adhesive and applying pressure when bonding to squeeze out the excess adhesive from the outside of the substrate. Preferably, pressure is applied to such an extent that the thickness of the adhesive layer finally obtained is smaller than the thickness of the base layer or the curing agent layer. By doing so, not only will the final adhesive layer become thinner, but it will also accelerate the curing reaction, making it less likely that uneven adhesive strength will occur.

Embodiments of the present invention are listed below, but the present invention is not limited thereto.

(Example) An insulating varnish for overcoat (WI-640, manufactured by Hitachi Chemical Co., Ltd.) was applied to a printed circuit board in which copper foil was pasted on a glass epoxy substrate, and then dried and cured. In order to bond these printed circuit boards so that their overcoats match, first apply the main ingredient of a two-component adhesive (5G-EPOEP-007 manufactured by Cemedine Co., Ltd.) onto the overcoat surface of one of the printed circuit boards. Applied by screen printing. However, in screen printing,
The screen is a 300 mesh made by Tetron, and the squeegee is made of urethane with a hardness of 60" and set at an angle of 75'.
Coating was performed at a speed of L4.5c+a/sec. 1
When coating was performed on 00 substrates, the base material that had passed through the mesh of the screen was coated on all 100 substrates to an average thickness of 30 μm.

Further, when the curing agent was applied in the same manner as the main agent, the coating thickness of the curing agent was 25 μm on all 100 sheets.

After coating, the main agent and curing agent are heated at 60°C for 30 minutes to remove air bubbles.
Heated for 0 minutes.

The pair of substrates made in this way are stacked together,
They were placed one after another in a press-type heating machine, heated at 2.0 Kg/cd, and then heated to 100° C. and left for 40 minutes. As a result, part of the adhesive was pushed out, and 100 laminates of planar conductors having a uniform adhesive layer with a thickness of 50 μm were obtained. No air bubbles that would cause uneven adhesion were found in the adhesive layer.

(Comparative example) Insulating varnish (Hitachi Chemical KK!!
! Enemy! -640) was applied, dried and cured at 150°C for 30 minutes.

Next, a two-component engineered poxy adhesive (5G manufactured by Cemedine Co., Ltd.)
-EPOEP-007) and a curing agent were mixed.

In particular, because the viscosity of the curing agent was high, a large amount of air bubbles were mixed into the mixture of the base resin and the curing agent. Therefore, we heated it at 60℃ to increase the viscosity and defoaming by partially raising the temperature, but defoaming did not start within 10 to 20 minutes, and after 30 minutes, it started to harden and the viscosity began to increase. . Therefore, 60
After heating for 20 minutes at ℃, using a Tetron 300 mesh screen and a urethane hardness 60' squeegee set at an angle of 756, both of the above glass epoxy substrates were bonded at a speed of 4.5 al/sec. 100 sheets each were coated on the planned surfaces. It took about 3 hours to coat a total of 200 sheets, but after 1 hour and 30 minutes after the coating started, the viscosity became high (perhaps due to curing), and the film thickness became uneven, and in the end, the average was 27μ steel. However, the coating thickness, especially in the second half, was so uneven that it was visible to the naked eye.Also, the adhesive on the screen used had hardened and could not be cleaned even with acetone, etc., making it impossible to reuse. became.

The pair of substrates made in this way are stacked together,
20Kg/ci 100 by press heating machine one after another
Heated at ℃ for 40 minutes.

As a result, the thickness of the first coated substrate was about 50 μm±20 μm as the adhesive was pushed out, but the overall color of the 100 sets was 75 μm±45 μm and ugly. There were also blisters caused by air bubbles everywhere.

(Effects of the Invention) In the present invention, the main agent and curing agent do not come into contact with each other until the substrates are bonded together, so the entire bonding process is not dominated by the curing time of the already mixed adhesive, unlike in the past. Therefore, a flexible work process can be established. In addition, since the base resin and curing agent are applied separately, the amount of air bubbles mixed in is much smaller than when they are mixed, and unlike when they are mixed, curing does not start even if heated for defoaming. Therefore, it is easy to apply the adhesive layer uniformly and thinly, and there is no need to worry about the conventional method where the pre-mixed adhesive hardens and becomes unusable before it is actually used for bonding. There is no

Claims (1)

[Claims] When bonding two planar conductive substrates together, the main agent of a two-component adhesive is applied in advance to the surface to be bonded of one substrate, and the curing agent is applied to the surface to be bonded of the other substrate. A method for bonding planar conductor substrates together, which is characterized in that each substrate is brought into close contact with each other at a desired time.