JPS6155991A - Method of producing 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 printed wiring boards.

(Prior art) With the increasing density of printed wiring boards, planar circuits are constructed by etching copper-clad laminates. Therefore, the following method has been developed, assuming that the planar circuits have a uniform thickness and are suitable for forming fine line patterns. There is.

That is, an etching resist is formed on the foil of the catalyst-containing r) copper-clad laminate, etching is performed to form a pattern of steel foil, holes are made in the required positions of the pattern, and then the pad is removed. This is a method to create a double-sided through-hole wiring board by printing a plating resist on the other parts and applying electroless plating only on the inner wall of the hole and on the pad to ensure conduction on both sides.

In this case, when printing the plating resist, printing misalignment occurs for some reason, and due to the printing misalignment, the surface portion of the catalyst-containing substrate where the plating resist is not printed is exposed depending on the degree of the printing misalignment. If it is immersed in an electroless plating solution in this state for 11 hours, plating will be deposited on the exposed part of the catalyst-containing substrate surface where the plating resist is not printed, which is caused by the misalignment of the plating resist printing.5. .

As a result, the shape of the pad is enlarged in the direction of displacement of the plating resist printing, and the distance between adjacent patterns becomes narrower, which becomes an obstacle to increasing the density between the printed wiring boards.

(Object of the Invention) An object of the present invention is to provide a method for manufacturing a printed wiring board that enables the formation of a high-density wiring pattern.

(Structure of the invention) The present invention A. Prepare a copper-clad laminating machine containing a catalyst.

B. By appropriately performing the steps of forming and etching an etching resist, clearing, and forming a plating resist, the necessary planar circuit pattern, holes in the necessary locations, and the hole and pad portions are formed. In a printed wiring board manufacturing method that includes the steps of obtaining a substrate with a resist formed in the removed areas and immersing it in a C0 electroless steel plating solution, a catalyst is contained on the surface of a catalyst-containing laminating machine. The invention is characterized by providing a resin layer that does not contain any resin.

The present invention will be explained below with reference to drawing VC.

FIG. 1 shows a catalyst-containing copper-clad laminate, where 1 is a catalyst-containing laminate, 2 is a copper foil, and 3 is a resin layer that does not contain a catalyst.

As a resin that does not contain a catalyst, thin (for example (LO51)
Prepreg (about 1111) and adhesive on the back side of steel foil (thickness αO 05 to αQ 5 mm) are used. If this layer is too thick (for example, 100 μm or more), it may not be plated in the subsequent through-hole plating process.

As a catalyst, group Ⅰ and 1st BtI of the periodic table of elements are used.
Examples of metals belonging to F: include dichelics, compounds, fluorides, ethyl acetates, fluoroborates, nitrates, sulfates, and acetates. Particularly useful are palladium, gold, platinum, copper, palladium chloride,
Gold chloride, platinum chloride, oxidized steel or these and primary chloride
It is a combination of tin. These catalysts were used as AhCh51
(It is adsorbed onto a h-based carrier, and mixed with epoxy resin and dispersed in a face to make a laminate, and a catalyst-containing copper-clad laminate is made.

Next, as shown in Figure @2, holes 4 are drilled at predetermined locations. The hole is made by drilling, punching, etc.

Next, as shown in FIG. 5, an etching resist 5 is formed. The etching resist 5 may be formed by a silk screen method, or may be formed by using a photosensitive resin film and exposing to light.
It can also be formed by developing. Etching resist 5 is formed at locations where planar circuits are to be formed, holes, and locations where pads are to be formed around the holes.

Next, as shown in FIG. 4, etching is performed and the etching resist is removed. For etching, ferric chloride solution, ferric chloride M4 solution, ammonium persulfate solution,
A common etching solution such as an alkaline etching solution is used. After etching is performed to remove unnecessary copper other than the circuit, the etching resist is removed. The etching resist can be removed by conventional methods such as solvent removal and mechanical removal.

Next, as shown in FIG. 5, a plated resist 6 is formed.

The plating resist 6 is formed at 0.degree. C. except for the holes and the areas around the holes that are to become pads.

The plating resist can be formed by a silk screen method or by using a photosensitive resin film, exposing it to light, and developing it.

Next, as shown in FIG.
Non'tx, ys plating 7 is formed on areas where the plating resist is not formed, that is, on the inner wall of the hole and on the pad portion.

The electroless steel plating solution is, for example, steel ion a, 004 to (1
2 mol/7I, citrus ion complexing agent 0.004-1 mol/
1. Reducing agent 001~[L25 mol/l and river 11.
The basic composition used is Fl + regulator in an amount necessary to produce 8 to 155 tlC-f.

Electroless plating is formed to a thickness of about 10 to 100 μm.

The above is an example of the present invention, and the B process includes the steps of drilling → etching → forming a plating resist. In addition, the steps of etching → drilling → forming a plating resist and etching → forming a plating resist → drilling may also be performed. You can also do it.

(Effects of the Invention) FIG. 6 is a cross-sectional view of a printed wiring board obtained according to the present invention. Since the plating does not precipitate, even if the plating resist is misaligned, the shape of the pad portion will not change or the pad portion will not come close to the adjacent conductor portion, making it possible to create a highly accurate printed wiring board.

Therefore, the alignment work for the plating resist pattern can be simplified by 1 m.

[Brief explanation of drawings]

1 to 6 are cross-sectional views showing the method of the present invention. Explanation of symbols 1. Catalyst loaded # machine 2. Steel foil 5. Resin layer containing no contact W 4. Hole 5. Etching resist & Plating resist Otsu Mu′? ! Copper plating

Claims (1)

[Claims] 1. A. Preparing a catalyst-containing copper-clad laminate, B. Forming an etching resist and etching, drilling, and forming a plating resist as appropriate. Printing that includes the steps of: obtaining a board having a planar circuit pattern, holes in necessary locations, and plating resist formed in locations other than the holes and pads; C. immersion in an electroless copper plating solution; A method for manufacturing a printed wiring board, which comprises providing a resin layer that does not contain a catalyst on the surface of a catalyst-containing laminate.