JPS61235150A - Manufacture of substrate for electric circuit wiring - 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 Field of Application] The present invention is utilized for manufacturing a wiring board forming an electric circuit. In particular, the present invention relates to a method of manufacturing a wiring board that has a simple manufacturing process and has no pinholes penetrating both surfaces of the insulating layer.

〔overview〕

In a method for manufacturing printed circuit boards for electrical circuits, three adhesive layers are formed by repeating the process of forming an adhesive layer at least three times using a adhesive film coated with an adhesive on one side. The agent layer is formed in a laminated structure, and there are no pinholes penetrating both surfaces.

[Conventional technology]

A wiring board for an electric circuit having a metal layer formed on its surface is manufactured by applying an adhesive made of resin to the metal layer and curing the adhesive.

If the metal layer is formed on both sides, one side is used for wiring at ground potential, and if the metal layers on both sides are both thin metal foils, it is a flexible board, and the metal layer at ground potential is thick metal. When it is a board, it becomes a hard circuit board. In this electric circuit board in which metal layers are formed on both sides, if there is a pinhole penetrating the insulating layer, the withstand voltage on both sides becomes small.

To improve this, the insulating layer has a multilayer structure,
Even if there are pinholes that penetrate within one layer, there are known techniques to eliminate pinholes that penetrate both surfaces, but since pinholes cannot be completely eliminated, it is usually necessary to introduce a film layer. This is supported by

[Problem that the invention seeks to solve]

However, in order to form an insulating layer with a multilayer structure, it is necessary to repeat the steps of applying and curing the adhesive as many times as there are layers, which increases the number of manufacturing steps and has the disadvantage that the product is naturally expensive.

The present invention improves this and aims to provide a method that can manufacture an electric circuit board including a multilayered insulating layer with a small number of manufacturing steps.

[Means for solving problems]

The first invention of the present invention is a method of forming a multilayer insulating layer on metal foil, and by forming and transferring this insulating layer in a B-stage state on a pinhole-free RIKEN film with a smooth surface, By having two or more smooth, pinhole-free surfaces of the RIKEI film in the multilayered insulation, an insulating layer with excellent electrical insulation properties, especially translayer withstand voltage, is formed.

A second invention of the present invention is a method for manufacturing an electric circuit wiring board having a multilayer insulating layer with metal layers on both sides,
By making the insulating layer thinner per unit, the insulating layer itself can be made thinner than in conventional methods, and this can improve other functions, especially thermal conductivity.

Another feature is that if a single-sided metal foil is used as a base material, a single-sided steel-clad substrate with good dimensional stability can be produced.

The third aspect of the present invention is a method for forming a multilayer insulating layer that is strong against external forces that tear it apart, in which a substance that improves the strength of the film, such as whiskers, is mixed into one or three of the insulating layers. It is also possible to optionally combine a resin with strong film strength.

By making the RIKAY film transparent, visual inspection of the adhesive layer can be made possible.

[For production]

The adhesive film coated on one side can be produced very uniformly and in large quantities. In addition, Rikei film with adhesive applied on one side is easy to handle, and the process of transferring the adhesive layer of Rikei film is much easier than the process of uniformly applying a soft adhesive. It has the advantage that it is simple and requires less man-hours, and if the transparent film is used, the adhesive insulating layer can be easily inspected.

Therefore, according to the present invention, an electric circuit wiring board having multiple insulating layers can be manufactured at low cost with a small number of man-hours.

Since it is very difficult to create a thin insulating layer without pinholes through the B stage, it is known that a thickness of 100 μm or more is usually required from the viewpoint of reliability. As a result of extensive studies, the inventors of the present invention found that when using a solvent-based FES, pinholes occur due to evaporation shrinkage during the formation of the resin thin film when the solvent is evaporated and dried to produce a B-stage resin thin film. However, the researchers discovered that because evaporation occurs only in one direction on Rikei film, pinholes do not occur in the resin thin film on the surface that is in contact with the film. This results in
A pinhole-free insulating layer can be created using the transfer method, and repeating this three times ensures the effect.

[Example 1] Flexible epoxy resin is coated on a 60 μm thick polypropylene film (Torephan Film manufactured by Toshi Corporation) of Rikei Film to a thickness of 20 μm, and dried to bring it to the B stage state. Step 1).

Next, the epoxy resin in the B stage state obtained in the first step is laminated onto the treated surface of a 35 μm thick copper foil and cured by heating (second step).

Next, the epoxy resin obtained in the first step is laminated on the resin surface of the copper foil laminated epoxy resin obtained in the second step,
Heat and cure (third step).

Next, the epoxy resin obtained in the first step is laminated on the resin surface of the copper foil laminated epoxy resin obtained in the third step,
By heating and curing, a single-sided copper-clad flexible printed circuit board with an insulating layer of 60 μm was obtained.

[Example 2] Rikei Film's 60 μm thick polypropylene film (Honshu Paper Industries side type Alphan film) was coated with a 5 μm thick
Coat flexible polyimide resin so that
Dry this to bring it to B stage state (first step)
.

Next, the B-stage polyimide resin obtained in the first step is laminated onto the treated surface of a copper foil having a thickness of 18 μm and cured by heating (second step).

Next, the polyimide resin obtained in the first step is laminated onto the resin surface of the copper foil laminated polyimide resin obtained in the second step (third step).

Next, the resin surfaces of the copper foil laminated polyimide resin obtained in the third step are laminated together and heated to harden to form an insulating layer 1.
A single-sided flexible printed circuit board with a thickness of 0.00 μm was obtained.

[Example 3] A 60 μm thick Teflon monofluoride film (Tedra film manufactured by DuPont, USA) was coated with a 10 μm thick Rikei film.
Epoxy resin is coated to a thickness of μm, and this is dried to bring it into a B-stage state (first step).

Next, the epoxy resin in the B-stage state obtained in the first step is laminated onto the treated surface of a 35 μm thick copper foil and cured by heating (second step).

A flexible epoxy resin containing 25% potassium titanate fiber is applied to a 60 μm thick polypropylene film (Alphan Film manufactured by Honshu Paper Corporation) by Rikei Film to a thickness of 30 μm and dried to bring it to the B stage. (Third step).

Next, the epoxy resin obtained in the third step is laminated onto the resin surface of the copper foil laminated epoxy resin obtained in the second step (fourth step).

Next, the resin surface of the copper foil laminated epoxy resin obtained in the second step and the resin surface of the copper foil laminated epoxy resin obtained in the fourth step are laminated together and heated and cured to form an insulating layer of 50 μm.
A double-sided copper-clad flexible printed circuit board of m was obtained.

[Example 4] Epoxy resin is applied to a 50 μm thick polyester film (Lumirror Film manufactured by Toshi Corporation) that has been subjected to RIKEI treatment to a thickness of 15 μm and dried to bring it to the B stage state (first stage). process).

Next, the epoxy resin in the B-stage state obtained in the first step is laminated onto the treated surface of a 35 μm thick ti4 foil and cured by heating (second step).

Next, the epoxy resin obtained in the first step is laminated on the resin surface of the copper foil laminated epoxy resin obtained in the second step,
Heat and cure (third step).

Next, the epoxy resin obtained in the first step is laminated onto the resin surface of the copper foil laminated epoxy resin obtained in the third step (fourth step).

Next, the resin surface of the copper foil laminated epoxy resin obtained in the fourth step is laminated with the copper foil obtained in the first step (fifth step).

Next, the resin surface of the copper foil-laminated epoxy resin obtained in the fifth step was laminated to the treated surface of the 2H-thick aluminum plate and cured by heating to obtain an aluminum metal-based copper-clad substrate with an insulating layer of 60 μm.

[Example 5] Rikei film is coated to form a 40 μm thick polypropylene film (Torephan film manufactured by Toshishima) and dried to bring it to the B stage state (first step).

Next, the epoxy resin obtained in the first step is laminated onto the treated surface of a copper foil having a thickness of 18 μm and cured by heating (second step).

Next, a heat-resistant nylon resin with a thickness of 30 μm is coated on the 50 μm thick polyester film (east side Lumirror film) of the Rikei film and dried (third step).

Next, the nylon resin obtained in the third step is heated and bonded to the resin surface of the copper foil laminated epoxy resin obtained in the second step (fourth step).

Next, the resin surface of the copper foil laminated epoxy nylon resin obtained in the fourth step and the resin surface of the copper foil laminated epoxy resin obtained in the second step are heated and laminated together to form an insulating layer 5.
A 0 μm double-sided copper-clad flexible printed circuit board was obtained.

[Example 6] Flexible epoxy resin is coated on a 60 μm thick polypropylene film (Torephan Film manufactured by Toshi Corporation) of Rikei Film to a thickness of 15 μm and dried to bring it to the B stage state (first stage). process).

Next, the epoxy resin in the B-stage state obtained in the first step is laminated onto the treated surface of a rolled copper foil having a thickness of 35 μm and cured by heating (second step).

Next, the B-stage epoxy resin obtained in the first step is laminated onto the treated surface of a 50 μm thick iron foil (third step).

Next, the resin surface of the iron foil laminated epoxy resin obtained in the third step is bonded to the epoxy resin in the B stage state obtained in the first step (fourth step).

Next, the resin surface of the epoxy resin laminated with iron foil obtained in the fourth step is laminated with the resin surface of the epoxy resin laminated with copper foil obtained in the second step, and heated and cured to form an insulating layer of 45 μm.
A copper-clad flexible printed circuit board based on iron foil was obtained. Its cross-sectional structure is shown in the figure.

〔Test results〕

The results of tests conducted on each of the above examples are shown in the following table.

Peel strength and solvent resistance were determined by peeling off a 2.5f1 width copper foil or iron foil in a 90 degree direction.

It is shown as a value converted to

(Hereinafter, in the margin of this page) [Effects of the Invention] As explained above, according to the present invention, the number of manufacturing steps is small, and a product that is equivalent to or better than conventional products can be obtained.

[Brief explanation of drawings]

The figure is a structural sectional view of a substrate obtained by the method described in Example 6.

Claims (8)

[Claims] (1) By pasting a metal foil on the surface of the adhesive layer of a re-keying film with adhesive applied on one side, curing the adhesive and removing the re-keying film, the first hardened metal foil is The first step is to form an adhesive layer, and the surface of the cured adhesive layer produced by this first step is further coated with the surface of the adhesive layer of the adhesive film coated on one side. a second step of forming hardened first and second adhesive layers on the metal foil by laminating the metal foil, curing the adhesive, and removing the adhesive film; The surface of the cured second adhesive layer is further laminated with the surface of the adhesive layer of a rekeying film coated with an adhesive on one side, and the adhesive is cured and the rekeying film is removed. and a third step of forming hardened first, second and third adhesive layers on the metal foil. (2) The method for manufacturing an electric circuit wiring board according to claim (1), wherein each of the first, second, and third adhesive layers has a thickness of 10 μm or more and 100 μm or less. (3) The method for manufacturing an electric circuit wiring board according to claim (1), wherein the metal foil has a thickness of 9 μm or more and 200 μm or less. (4) By laminating a metal foil on the surface of the adhesive layer of a re-keying film coated with adhesive on one side, curing the adhesive and removing the re-keying film, the first hardened metal foil is The first step is to form an adhesive layer, and the surface of the cured adhesive layer produced by this first step is further coated with the surface of the adhesive layer of the adhesive film coated on one side. a second step of forming hardened first and second adhesive layers on the metal foil by laminating the metal foil, curing the adhesive, and removing the adhesive film; The surface of the adhesive layer of the adhesive film coated with adhesive on one side is pasted onto the surface of the cured second adhesive layer, and then the adhesive film is removed, and the adhesive film is removed. A method for manufacturing an electrical circuit wiring board, comprising the steps of: laminating the surface of the adhesive layer to the surface of a metal body other than the metal foil, and curing the adhesive layer. (5) The method for manufacturing an electric circuit wiring board according to claim (4), wherein the metal body is a metal foil. (6) Claim No. (4) in which the metal body is a metal substrate
A method for manufacturing an electric circuit wiring board according to 1. (7) By pasting a metal foil on the surface of the adhesive layer of the adhesive film with adhesive applied on one side, and curing the adhesive, and removing the adhesive film, the first hardened metal foil is a first step of forming an adhesive layer; and adhesion of a fibrous inorganic insulating material film coated with adhesive on one side to the surface of the cured adhesive layer produced by this first step; Paste the surfaces of the agent layers together,
a second step of forming cured first and second adhesive layers on the metal foil by curing the adhesive and removing the adhesive film; The surface of the second adhesive layer is further laminated with the surface of the adhesive layer of the adhesive film coated with adhesive on one side through the fibrous inorganic insulating material, and the adhesive is cured and and a third step of forming cured first, second and third adhesive layers on the metal foil by removing the adhesive film. (8) The method for manufacturing an electric circuit wiring board according to claim (6), wherein the fibrous inorganic insulating material is fibrous potassium titanate.