JPS62145796A - Manufacture of printed wiring 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 (Field of Industrial Application) The present invention relates to a method for manufacturing a high-density printed wiring board using electroless steel plating.

(Prior art) Typical conventional methods for manufacturing printed wiring boards include (1) tenting method, (2) soldering method, (3) partial additive method,
(4) There is a fully additive method. Fig. 2 shows an example of the tenting method, which includes b) drilling, C) catalyst treatment, electroless steel plating, d) electroplating, e) etching resist formation, f) etching, g) etching resist removal, h ) A printed wiring board is manufactured by a process of forming a solder resist. Also, in the soldering method, solder is used instead of etching resist, but step e) in Figure 2 is replaced by step e,) in Figure 3.
The steps are resist formation, e2) solder plating, and e3) resist peeling. The partial additive method is a method in which the surface circuit is formed with copper foil and the inside of the hole is formed with electroless steel plating, and its main steps are shown in FIG. This lrL includes b) etching resist formation, C) etching, etching resist peeling,
The steps are d) forming a plating resist (solder resist), e) drilling holes, and f) electroless steel plating.

Finally, the fully additive method uses a catalyst-containing substrate with adhesive and performs surface circuit and hole plating by electroless steel plating, and the process is shown in Figure 5b).
By drilling, C) forming a permanent photoresist, d) plating, and e) forming a solder resist.

(Problems to be Solved by the Invention) A common problem with the tenting method and the soldering method is that because the large circles are thickened by electroplating, the plating coverage is poor in small diameter holes due to high density. , The plating thickness of the plate is uneven. In addition, since the conductor is made of copper foil, electroless copper plating, and electrical steel plating, the circuit pattern on the plane part is thick, and when forming a circuit by etching, there is a problem of undercutting, which naturally limits the pattern density. be.

Furthermore, with the tenting method, if the pad area is small, the adhesion between the resist and the copper foil is insufficient to withstand the impact of the spraying of the etching solution, causing the resist to peel off and the etching solution to seep into the large circle. Therefore, it is difficult to cope with increasing sieve density.

In addition, in the partial additive method, if a permanent photoresist is used, deburring and smear processing in a multilayer machine cannot be performed, and if an ink resist is used, the pre-NL VC, ink bleeding and plating solution resist. There is a problem with seepage to the bottom. In addition, the cost becomes 4 because γL cannot be achieved unless a catalyst-containing substrate is used.

In addition, the Tsuruadidip method has the problem that plating is deposited on areas other than the circuit pattern (copper deposition), making it difficult to achieve high density. Furthermore, in the case of multi-layering, the number of steps increases, resulting in higher costs.

(Means for Solving the Problems) The inventors of the present invention have conducted various studies to solve the above problems. All manufacturing methods have been investigated in which only the surface circuit pattern and through-holes are electrolessly plated with copper, but the resistance of the solvent-developed dry film to the plating solution becomes a problem in this process. The dry film will peel off in an electroless steel plating solution for standard laminates. Furthermore, even if the surface copper foil is laminated after being fully oxidized, the oxidized steel will be reduced and easily peeled off from the circuit pattern and through-hole pad edge portions. Furthermore, benzotriazole treatment, which has been reported as a known example, improves adhesion but causes some peeling.

Based on the above study results, the present invention provides a method for manufacturing high-density printed wiring a having small diameter holes.

The present invention uses the following as means for improving the plating solution resistance of a solvent-developed photoresist.

(1) Before photoresist lamination, the surface of the copper foil on the substrate is roughened by spraying abrasive grains at high pressure.

(2) The surface of the substrate is immersed in an alkaline degreasing solution and/or an organic compound solution containing a triazole group.

(3) After laminating, exposing and developing the photoresist, it is further exposed to ultraviolet light and heated.

(Function) By improving the plating solution resistance of the dry filler for etching, it has become possible to plate surface circuits for a long time, which was previously impossible. As a result, the etching of the surface steel is limited to the copper foil portion, resulting in a very good etching factor. This made it easier to form a high-density fine line pattern. In addition, since the inside of the hole is all electroless and copper plated, it shows good plating coverage even in small diameter holes, and the connection reliability of the product is also good because a high-performance plating solution is used with high activity.

Embodiment FIG. 1 shows a method of manufacturing a printed wiring board according to the present invention, and the present invention will be fully explained below with reference to the drawings. The holes shown in Figure 1 b) are made using a machine.

Especially for small diameter drills, 20 to 50
The value is μm/r ev. Next, a catalyst for electroless copper plating MS-201B (manufactured by Hitachi Chemical KK) is applied to the entire hole, and the entire surface is polished. Further surface treatment is performed and a solvent-developed photoresist film is laminated. As for surface treatment, first apply 3 to 6 abrasive particles of 20 to 40 ttm
Spray onto the substrate surface with a pump pressure of kg/aII+, ? ′
Then, treat with alkaline degreasing solution HCR-201 (manufactured by Hitachi Chemical KK) or benzotriazole solution (manufactured by Wako Tsumugi KK). At this time, the effect of treatment with both solutions becomes stronger. Further, the substrate is heated to 100 to 120° C., and a resist film and Laminar GT (manufactured by Dynachem) are laminated thereon. Baking and development are performed to form a resist except for the areas that should become planar circuits, the holes, and the areas around the holes that should become pads, as shown in d). In order to make the adhesion between the resist and the substrate even worse, we used an ultraviolet exposure machine to
/Cm or more, 160℃, 90 minutes to 15 minutes.
Heat at 0°C for 50 minutes. Furthermore, electroless copper plating is performed. Electroless copper plating solution.

Normal ones such as copper ion 0. ill[14-0,2m
a7I/I, copper ion complexing agent 0.004-1 mo
Ill, reducing agent 0.01 to 0.25 mol/l, and a preparation agent necessary to adjust the pH to 11.8 to 155 are used as the basic composition. Plating deposition rate 2.2zz
m/h or more, and should be a planar circuit with high activity.

Plating is deposited on the hole and the area around the hole that will become the pad (Fig. 1e)). Furthermore, an etching resist such as solder is completely applied to the copper deposited area, and a plating resist L-Th is applied.
Perform ill mL etching. Next, the entire solder resist is printed.

Also, if you use an ultra-thin copper foil (5.8 μm) copper-clad laminate layer instead of a copper-clad laminate made of general steel foil (18, 35, 70 tim), it is possible to form a circuit by quick etching. be.

(Effects of the Invention) The method for manufacturing a printed board of the present invention described above has the following effects.

(1) Glazed laminated copper foil (e.g. 18.55°70
μm or 5.8 μm) is etched to form the circuit fy.
Compared to the conventional method in which VC electrolytic copper plating is performed on the copper foil of a copper-clad laminate and then etching is performed, the etching density is extremely high and circuits can be formed with high precision.

(2) Electroless steel plating is applied only to a thickness of about 35 μm inside the hole, so even small diameter holes with a large aspect ratio, where electrolytic copper plating would result in a thinner plating thickness,
Achieves 0% throwing power.

(3) Since the circuit on the plane part is made of copper foil of a glazed laminated board, it is possible to obtain a substrate and a strong beer even with a fine pattern, and to achieve high density.

[Brief explanation of drawings]

Figure 1 shows an example of the process according to the present invention, Figure 2 shows the conventional method of tenting, and Figure 6 shows the conventional soldering process, which is different from the tenting method. Figure 4 shows the process of the conventional partial additive method.
FIG. 5 shows Step 8 of the conventional fully additive method. Explanation of symbols

Claims (1)

[Claims] 1. Before the photoresist lamination process, the copper foil on the substrate surface is roughened by spraying abrasive grains at high pressure, the substrate surface is immersed in an alkaline degreasing solution and/or an organic compound solution containing a triazole group, and then A method for manufacturing a printed wiring board, which comprises further performing ultraviolet exposure and heating after photoresist lamination, exposure, and development.