JPS5826193B2 - Printed wiring board manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a printed wiring board, and more particularly to a method improved so that the process of peeling and transferring the interface between a substrate and a metal plate by a pattern plating transfer method can be carried out easily.

Today, laminates of electrically insulating laminates and conductive metal foils are widely used in fields such as printed circuits in the electronic industry, electrical switching devices, and general decorative devices.

By the way, conventionally, when attempting to obtain a metal conductive pattern circuit in this type of printed circuit, for example, a so-called etching method has been used as one method.

In other words, this method involves applying an adhesive to a metal foil such as copper, bonding this to an electrically insulating substrate, and then forming an acid-resistant resin coating on the metal film in the desired pattern using a silk screen printing method, etc. , is a method of obtaining a patterned circuit by immersing the unnecessary portions of the copper surface, that is, the portions not covered by the acid-resistant resin coating, in an aqueous solution of ferric chloride, ammonium persulfate, etc., and dissolving them. In this method, all the chemicals used for etching are highly corrosive and harmful, and expensive equipment is required to treat the wastewater.Also, after forming a metal film on the entire surface of the substrate, it is patterned. It was inefficient because it had to be dissolved and removed, and the yield as a circuit pattern was low relative to the amount of metal film used, making it uneconomical.

In addition, a so-called electroless plating method is known as a method.

This method involves printing a pattern of ink containing a catalyst on an insulating substrate, applying electroless plating to this, and depositing metal on the printed ink to obtain a metal plating film in the desired pattern on the substrate. It is something.

However, with such electroless plating, the plating adhesion strength is poor, and it has not been possible to obtain a printed wiring board that satisfies various properties such as adhesiveness and solder heat resistance required for a printed wiring board.

Furthermore, recently, a method of manufacturing printed wiring boards using a pattern plating transfer method has been considered.

In this method, a masking surface is formed on the metal plate surface so that only a predetermined pattern part is left and the other parts are covered, and then electrolytic plating is applied to this masking surface to form a conductive metal pattern on the uncovered pattern part. A conductive metal pattern is formed, an adhesive is applied thereon to form a substrate, and the conductive metal pattern is peeled off and transferred onto this substrate.

However, in the methods disclosed so far, in actual manufacturing, if adhesive is applied to the entire surface, the substrate will also adhere to the masking surface, and only the metal pattern portion can be clearly peeled off.
Transferring is a very difficult process to implement.

Therefore, in view of the drawbacks of the conventional methods as described above, the present invention eliminates the drawbacks such as uneconomical and inefficient methods in the etching method and electroless plating method, and also improves the practical performance of the conventional pattern plating transfer method. The purpose of this invention is to make it possible to easily and reliably carry out the process of peeling off and transferring an electrically insulating substrate from a metal plate interface, which is extremely difficult when manufacturing flint wiring boards.

In addition, the present invention makes it possible to directly transfer a metal conductor circuit pattern formed by electrolytic plating onto an electrically insulating substrate to obtain a clear conductor circuit pattern, and to expand the range of resins that can be used as substrate raw materials. The purpose is to

The method of the present invention involves forming a film of an electrically insulating material (hereinafter referred to as resist) in a predetermined pattern by a printing method on the surface of a metal plate that has good removability from electrolytically plated metal, and then electrolytically plating the film to form a film of electrically insulating material (hereinafter referred to as resist). A metal circuit pattern is formed, an electrically insulating substrate or an electrically insulating film is formed directly on the surface of the circuit pattern, and then a pattern of metal conductors is formed on the electrically insulating substrate or film by peeling and transferring. In forming the resist, a silicone resin having good electrical insulation properties, mold release properties, and heat resistance, that is, silicone rubber, a silicone mold release agent, or a mixture of these and a thermosetting resin is used as the resist. be.

When manufacturing a printed wiring board by the method of the present invention, a metal plate 1 to be electrolytically plated is first prepared as shown in FIG.

The material for the metal plate 1 is preferably one from which the electrodeposited metal can be easily peeled off, such as stainless steel or titanium.

Then, a patterned resist film 2 is formed on the entire surface of the metal plate 1 by silk screen printing as shown in FIG.

This resist film 2 serves as a mask for forming a conductive metal pattern portion, which will be described later, and also as a mold release agent to facilitate peeling and transfer, which will be described later. It is necessary that the material has good properties such as good properties, excellent heat resistance, and excellent acid resistance or alkali resistance so that it does not change in quality in an electrolytic plating bath.

That is, the resist used in the method of the present invention is generally commercially available silicone RTV and LTV rubber mainly composed of polydimethylcycloxane, or a release agent, or 2 to 30 parts of these in a thermosetting resin solution, for example, etching. Examples include those mixed with phenolic resins and epoxy-melamine resin solutions used as resists and solder resists.

In order to make these resists suitable for screen printing when used, solvents, fillers, etc. may be added to adjust the viscosity and chicken tropic properties.

Then, the metal plate 1 covered with the resist film 2
The portion 1a is an unnecessary portion as a circuit pattern, and becomes a portion on which conductive metal is not electrodeposited even in the subsequent electrolytic plating process.

Next, on the resist film 2 formed above, a conductive metal pattern 3 is formed by electrolytic plating as shown in FIG.

At this time, the peripheral portion of the surface of the pattern 3, that is, the boundary portion with the resist film 2 is in a slightly raised state 3a as shown in an exaggerated diagram in FIG.

Next, a thermosetting resin solution is applied directly onto the resist film 2 and the conductive metal pattern 3 formed on the entire surface of the metal plate 1, and is cured by heating under normal pressure or pressure. After a substrate 4 is formed as shown in FIG. 4, it is peeled off and transferred to obtain a printed wiring board 5 in which a conductive metal circuit pattern 3 is formed on an insulating substrate 4 as shown in FIG.

In this case, the electrodeposited patterned conductive metal pattern 3
It is sufficient that only the resist film 2 is transferred, and there is no need for the resist film 2 to be transferred.

Therefore, it is necessary that the bonding strength between the resist film and the metal plate be greater than the bonding strength between the resist plate and the substrate.

The above-mentioned electrolytically deposited metals are metals that have high conductivity and can be electrolytically plated, such as silver, copper, chromium, iron,
Cobalt, nickel, etc. or alloys thereof are used.

Then, the surface of the electrodeposited metal, such as copper, may be further plated with a metal such as nickel to improve corrosion resistance, adhesion, and the like.

Examples of the present invention will be described in detail below.

Example l 5older Re5ist 5R-3IC3--8E
--- 90 parts (manufactured by Tamura Kaken ■) KS707 (manufactured by Shin-Etsu Chemical ■) --- 10 parts of resist was printed in a predetermined pattern on a stainless steel plate, and after air-drying for 10 minutes. Heat and cure at 120°C for 30 minutes.

After this hardening, the stainless steel plate surface is subjected to the following conditions: Copper sulfate bath composition Copper sulfate...2509/
13 Sulfuric acid ・・・759/13 Electrolytic conditions Liquid temperature 25°C Current density 8 A/d7712 Plating time 30 minutes Copper plating was performed to form a conductive pattern,
Furthermore, in order to improve the peel strength of the interface between the copper and the stainless steel plate, the following conditions are met: nickel bath composition Nickel sulfate...150 &/1
Ammonium trichloride...15 &/1 Boric acid...15971 Electrolytic conditions pH 6.0 Liquid temperature 25°C NIM Density W 10 A/d7712 Plating time 1 minute to coat the copper surface with nickel.

After treatment, a thermosetting resin solution having the following composition was placed on a stainless steel plate that was washed with water and dried.
parts (manufactured by Nisso Kasei ■) Styrene monomer: 34 parts Maleic anhydride: 5 parts Ethylene dimethyl mekuacrylate: 1
0 parts benzoyl peroxide ・・・・・・
A sheet of glass cloth (Nittobo WE116BV) is placed on top of the composition for reinforcement, and pressure is applied to impregnate the glass cloth with the resin solution and make it adhere uniformly to the pattern surface.

Then, this plate is heated and cured at 120° C. for 12 hours.

After curing, the cured substrate could be easily peeled off from the stainless steel plate, and the patterned conductive portion was clearly transferred to the resin surface, yielding a printed wiring board with an average thickness of 120 μm.

The printed wiring board thus obtained has a normal peel strength of 1.8 Ky/crfL at the interface between the copper and the board, 26
It was 1.7 Ky/cm after being immersed in solder for 20 seconds at 0°C.

Example 2 The results were also carried out when KE, 12R, TV (cured by standing overnight at room temperature) manufactured by Shin-Etsu Chemical ■ and 5H9556RTV manufactured by Toshi Silicone ■ (cured for 30 minutes at 100°C) were used as resists. Easily peeled off as in Example 1.
It could be transferred and used repeatedly.

Example 3 As a resist, Toshi silicone 5H9556R,T was used.
Using V (hardened at 100°C for 30 minutes), a resin solution with the following composition, namely Epicol #1001 (manufactured by Shell) was placed on a stainless steel plate electrolytically plated with copper and nickel in the same manner as in Example 1. ...100 parts dicyandiamide solution 4 parts (20wt%
in DMF) Benzyldimethylamide... A prepreg sheet is prepared by impregnating a glass cloth (Nittobo WE-116BV) with 0.2 parts of the composition adjusted to a viscosity of 200 cps with acetone.

Drying conditions were first at 100°C for 2 minutes and then at 160°C for 4 minutes.

Place one prepreg sheet on the pattern and
It was hot pressed at 60° C. contact pressure for 5 minutes, then at 40 Ky/crit' pressure for 1 hour, and then peeled off.

In this case as well, the pattern could be easily transferred as in Example 1, and a flexible circuit with a thickness of 110 μm was obtained.

Example 4 An adhesive made of acrylic copolymer is applied to a polyester film to a thickness of about 20 μm to prepare a film with adhesive.

Next, as a resist, use silicone ■ 5H9556R.
After screen printing a pattern on a stainless steel plate using a TV and curing it at 100°C for 30 minutes, copper and nickel were electrolytically plated in a pattern in the same manner as in Example 1, and then a film with an adhesive was placed on top of this. The pattern was peeled off and transferred from the stainless steel plate to obtain a polyester-based flexible wiring board. In this case as well, peeling was very easy.

As mentioned above, according to the method of the present invention, printed wiring boards can be manufactured more economically and efficiently than the etching method or electroless plating method, and it is also much easier to manufacture when actually manufactured using the conventional pattern plating transfer method. The process of peeling and transferring an electrically insulating substrate from the surface of a metal plate, which was previously difficult, has been made easier and more reliable, and the metal conductor pattern formed by electrolytic plating can be directly transferred onto the electrically insulating substrate to create a clear conductive circuit pattern. Moreover, it is also possible to directly pour a solvent-free resin such as an unsaturated polyester resin onto the surface of an electrolytically plated metal plate and cure it as it is to obtain a substrate. The range expands.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to FIG. 5 are schematic vertical sectional views showing the method of the present invention in the order of steps. 1...Metal plate, 2...Resist film,
3... Conductive metal pattern, 4... Substrate.

Claims (1)

[Claims] 1. A step of forming a film of an electrically insulating material made of silicone resin in a pattern on the whole surface of the metal plate, which has good peelability from the electrodeposited metal, and applying a conductive metal to the whole surface of the metal plate by electroplating. a step of forming an insulating substrate on the electrically insulating material coating and the circuit pattern formed on the whole surface side of the metal plate, and a step of forming an insulating substrate and the circuit pattern on the metal plate. A method for manufacturing a printed wiring board, comprising the steps of: and separating the film from the film.