JPS6182497A - Manufacture of printed circuit board - 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 method for manufacturing a printed wiring board that can easily obtain a fine pattern.

(Prior Art) The line width and line spacing of printed wiring boards are becoming increasingly narrower as LSIs become more highly integrated. However, in conventional manufacturing methods, for example, when forming a pattern by etching a copper-clad laminate, the processing limit is 100 .mu.m, and wire widths less than this are likely to cause wire breakage and spotting.

This is caused by dents and scratches on the steel foil surface that occur during the production of steel-clad laminates.Furthermore, when the line width and line spacing are about 50 μm, minute irregularities and scratches on the surface of the copper-clad laminate occur. Due to the undulations, the accuracy of the line width becomes a problem.

In addition, since steel foil is usually thick at 18 to 35 μm, 100 μm
The following etching becomes extremely difficult. Etching for inner layer circuits becomes easier if a copper foil of 5 to 9 μm is used, but
In the surface layer part, since the plating inside the through holes is added, the total copper thickness is 30 to 40 .mu.m, and etching of 100 .mu.m or less is extremely difficult. From such a thing,
Instead of the etching method, the additive method, which forms circuits from the necessary parts, is suitable for forming fine patterns, but at present the substrate surface has a large degree of roughness, and the steel sagging phenomenon, in which chips are deposited in unnecessary places, is a problem. However, it is not possible to form finer patterns than the subtract method.

Therefore, a semi-additive method is suitable for creating fine patterns, in which the necessary areas are plated using a copper-clad laminate using 5-9 μm copper foil as a base, and then the thin copper foil on the base is quickly etched. . However, even in this method, the defects and characteristics of the copper-clad laminate itself, as described above,
It is difficult to form fine patterns of 80 μm or less.

(Object of the Invention) An object of the present invention is to provide a method for manufacturing a printed wiring board that allows a fine pattern to be easily obtained.

(Structure of the Invention) The present invention provides a plating resist on one side of a copper foil, performs corrosion-resistant metal plating and copper plating in a copper etching solution, forms a circuit pattern, removes the plating resist, and processes the circuit pattern. After superimposing prepreg on the surface and applying heat and pressure,
A thermoplastic film coated with an adhesive is applied by heating and pressurizing both sides, and after drilling holes, copper plating is performed without heating, and a corrosion-resistant metal plating is formed in a copper etching solution, and the thermoplastic film is peeled off. After that, the copper is etched.

In order to overcome the limitations based on the characteristics and defects of the copper-clad FFI board used in the prior art, the present invention uses copper foil as the paste material for forming the circuit pattern. The copper foil used may be a copper foil plated on a stainless steel plate or the like so that it can be peeled off, or it may be a copper foil that has already been scratched or a rolled copper foil. ! As shown in Figure 1, on one side of this copper foil 1,
A resist pattern 2t- is formed by laminating, baking, developing, etc. a photoresist. Next, after plating a corrosion-resistant metal 3 such as gold, nickel, or solder in a copper etching solution by electroless plating or electroplating,
Perform steel milling 4. After removing the resist 2, the surface of the copper 4 is bonded.

Next, as shown in FIG. 2, the foil 1 having the circuit pattern 5 formed in this way is used as the surface layer, and the pattern is placed inside together with the circuit board 6 for interlayer positioning, and laminated and bonded via the Gripreg 7. A thermoplastic film 9 is applied to the substrate surface by heating and applying pressure. And, due to hole leakage, through hole 8
When the film 9 is formed and heated in a dryer, the film 9 shrinks and retreats from the hole wall. As a result, the parts of the film that have collapsed on the inner wall of the hole shrink and can be removed from the copper end, and the copper layer 12, which will become a butt part of an appropriate size, can be exposed. As thermoplastic films, those with relatively low melting points such as polyethylene, vinyl chloride, polypropylene, and nylon coated with adhesives such as acrylic and chloroprene can be used.

Next, after electroless copper plating 10 is performed as shown in FIG. 4, electrolytic copper plating may be further provided as required. Then, after applying corrosion-resistant gold plating, nickel plating, solder plating, etc. to the steel etching solution, the thermoplastic film is peeled off, leaving a surface pattern that requires padding, etc. around the hole. Then process the copper foil.

When the copper foil serving as the paste is removed by etching, the pre-formed circuit is exposed in the form of being embedded in the board. In order to use such a process, the prepreg 7 and the inner layer circuit board 60 substrate contain a compound that has catalytic properties for electroless steel plating. When using non-catalytic laminates and prepregs, double layers of adhesive-coated thermoplastic film are immersed in a solution containing a compound that acts as a catalyst for electroless plating, and then dried. After one sheet of the above film is peeled off, electroless steel plating is performed.

Example 1 A printed wiring board was manufactured by the following steps.

1) After polishing the stainless steel (SUS430-BA) surface with Scotch Ply 7448, the entire surface was plated with sulfuric acid steel to a thickness of 308° C. Next, a photoresist was laminated with a roll laminator. After applying a positive mask and irradiating it with ultraviolet rays, a developer was sprayed and developed. Next, gold plating is applied to a thickness of 1 #m, and sulfuric acid steel plating is applied to a thickness of 3 m.
0μm was performed. After immersing in a resist stripping solution and stripping off the resist, a black copper oxide treatment was performed, and then the patterned copper foil was peeled off from the stainless steel plate.

2) Inner layer Ii (catalyst-containing steel laminate was used; product name: MCL-E-168 manufactured by Hitachi Chemical Co., Ltd.) prepared by etching this copper foil in advance and catalyst-containing prepreg (product name GEA manufactured by Hitachi Chemical Co., Ltd.) -168N) in a multilayer mold that can be positioned using positioning pins, and
Heat under pressure at 70°C and 40kg/cd for 2 hours.

3) A polyethylene film coated with an adhesive (Hitalex 5500X-9, manufactured by Hitachi Chemical) was heated under pressure at 160° C. for 5 minutes at 20 kg/aIP on the thus laminated nine substrates. After drilling the holes, heat at 125℃, 2
Heat treated for 5 minutes, electroless copper plated to a thickness of 25 μm and non-under plated to a thickness of 4 μm.

4) After peeling off the polyethylene film, copper was etched with an alkaline etchant to produce a desired multilayer printed wiring board.

Example 2 A printed wiring board was manufactured by the following steps.

1) Perform the same process as in section (1) of Example 1.

2) Copper foil with catalyst-free copper clad laminate (MC)
L-E-67, Hitachi Chemical Co., Ltd., 11) and a prepreg containing no catalyst (GEA-67N1 Hitachi Chemical Co., Ltd. #Rito) were set in a multilayer mold, and heated at 170°C for 2 hours to produce 40 kg.
Pressure and heating were carried out under the conditions of /-.

3) Two adhesive-coated polyethylene films (Shitalex S-500X-9, manufactured by Hitachi Chemical) were attached to the thus laminated substrates, and heated at 160°C for 5 minutes at 20kg.
The mixture was heated under pressure under the conditions of /alF. Then, drill a hole, 1
After processing at 25°C for 30 minutes, a solution having catalytic properties for electroless steel plating (H3-101B) was added.

Hitachi Chemical Co., Ltd. (trade name) for 10 minutes at room temperature, washed with water for 3 minutes, and dried at 80° C. for 20 minutes.

4) After peeling off one sheet of the above polyethylene film, apply electroless copper plating to a thickness of 1 μm, and apply electrical steel plating to a thickness of 25 μm.
, gold plating is applied to a thickness of 1 μm.

5) Perform the same etching as in 4) of Example 1 to produce a desired multilayer printed wiring board.

(Effects of the Invention) As explained above, the method for manufacturing a printed wiring board of the present invention achieves the following advantages.

1) Since the pattern is formed on a copper foil with no scratches on the surface, it is possible to easily obtain a fine pattern with a line width and line spacing of 100 μm or less.

2) By forming fine patterns in advance and then laminating them, inspection can be performed before lamination, improving yield.

3) A conductor is formed by plating between precisely formed resist grooves, and this conductor is embedded in resin and completely preserved, so there is no side etch and the line width accuracy is extremely high.

4) Since an inexpensive thermoplastic film coated with an adhesive is used as the through-hole plated resist, and the process is shorter than that using a photosensitive resist, a low-cost printing arrangement is possible.
J board can be manufactured.

[Brief explanation of the drawing]

1 to 4 are sectional views for explaining the present invention in detail. Explanation of symbols 1 Copper foil 2 Resist pattern 3
Corrosion-resistant metal 4 Copper 5 Circuit pattern 6 Inner 1 circuit, board 7 Prepreg 8 Through hole 9 Thermoplastic film
10 Through-hole steel plating layer 11 Heat-resistant metal plating layer 12 Copper layer serving as pad portion Fig. 1 Fig. 2

Claims (1)

[Claims] 1. A plating resist is provided on one side of the copper foil, a corrosion-resistant metal plating is applied to a copper etching solution, and further copper plating is applied to form a circuit pattern.The plating resist is removed, and the circuit pattern is formed. After superposing the prepreg on the surface and applying heat and pressure, a thermoplastic film is placed on both sides by heat and pressure, a hole is made, the thermoplastic film is heated to shrink and recede from the hole wall, and then copper plating is performed. A method for producing a printed wiring board, further comprising forming a corrosion-resistant metal plating in a copper etching solution, peeling off the thermoplastic film, and then etching the copper.