JPS62230086A - Manufacture of enamelled 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 crawling wiring board.

(Prior Art) Conventionally, circuits have been formed on a floating substrate using a thick film method in which a metal paste is screen printed and baked at a temperature of 21,500° C. or higher.

However, with the thick film method, (11) printing inside through-holes is difficult; (11) fine patterns are difficult;
(iii) Repeated firing at high temperatures (three times in the case of double-sided boards with through holes) may cause warping or cranking on the board; (1v) Precious metal paste is used for firing in air; Higher costs (V
) When firing silver paste, etc., it is difficult to control the nitrogen atmosphere and firing at a high temperature exceeding 900°C exceeds the heat resistance temperature of the enamel layer or the transformation point of the metal core (α-γ transformation of iron). point: 910° C.), so there were problems such as distortion easily occurring.

In order to solve these problems, a method of plating the surface of a floating substrate has been proposed.
438 and Japanese Patent Application Laid-Open No. 60-195078, the surface of the floating substrate is roughened by treatment with hydrofluoric acid in the former and with a sodium hydroxide melt in the latter.

(Problem to be solved by the invention) When hydrofluoric acid or sodium hydroxide melt is used, the corrosive power is too strong, so the crystalline phase and amorphous phase on the surface of the enamel substrate are dissolved without distinction, and the unevenness of the roughened surface is In addition to being difficult to control, since the llf1g layer is formed near the surface, the non-1lit deplating film applied afterwards peels off together with this brittle layer, making it difficult to obtain stable adhesion. Furthermore, handling of hydrofluoric acid and molten sodium hydroxide is dangerous.

The present invention provides a method for manufacturing an enameled wiring board with excellent adhesion of an electroless plated film.

(Means for Solving the Problems) The present invention uses an enamel substrate in which a metal core is covered with a crystallized glazed enamel layer consisting of a crystalline phase and an amorphous phase.
Roughen the surface with a roughening liquid that melts the amorphous phase faster than the crystalline phase to promote adhesion to the plating film, and then start the electroless plating reaction without destroying this roughened shape. By applying a suitable catalyst and performing electroless plating, a plated film with good adhesion is formed on the enamel substrate. Further, after forming an etching resist, etching is performed to form a circuit.

The roughening liquid used in the present invention is a neutral or nearly neutral aqueous solution, and has different solubility in phases of different compositions of crystallized glass.

In general, the water resistance, acid resistance, and alkali resistance of oxides are as follows [Glass Optics by Sei Naruse (1968)
Kyoritsu Publishing].

Water resistance: Zr0t > AllOs > Tie, >
ZnO>MgO>PbO>CaO>BaO Acid resistance: Zr0z>AI,Os>ZnO>CaO
>TiO2>PbO>MgO> BaO N resistance
aOH property: Zr0z) AIzOz+Ti0t, Z
nO, CaO resistance NazC (1+ property: Za□z) A
Ito! lTi0g, ZnO> CaO+Bad, Pb
O, MgO Rag, Cab as crystalline components in crystallized glass.

When MgO, PbO, etc. are used, the crystalline phase is easily dissolved in both strong acids and strong alkalis. By strongly dissolving the amorphous phase with a neutral or near-neutral aqueous solution and performing a treatment that leaves the crystalline phase, a roughened surface is formed that increases adhesion with the plating film that will be applied afterwards. I can do it.

Crystallized glass consists of a crystalline phase and an amorphous phase, but the crystalline phase may consist of several types of phases (compositions), and in the present invention, at least one phase of the crystalline phase is Roughening is performed with a roughening solution that has a higher rate of dissolving the amorphous phase. As a result, at least one crystalline phase remains on the roughened surface,
A roughened surface can be formed so as to increase adhesion to a plating film applied thereafter.

In the present invention, for example, boron, silicon, magnesium,
Barium 15 < Rhoz < 35.10 < 5t
(h<30.40<Mg+CaO+BaO<
A crystallization axis containing a proportion (mol %) of 65% can be used.

This enamel layer consists of a crystalline phase containing a large amount of BaO and a borosilicate glassy phase. The crystalline phase has a needle shape of 20 μm or less in length and is dispersed in countless numbers in the amorphous matrix.

For roughening, for example, sodium fluoride, potassium fluoride,
Fluoride salt aqueous solution such as ammonium fluoride, fluoroboric acid, ammonium tetrafluoroborate, electroless nickel plating solution "Blue Schumer J (pH 6,4) (
This can be done using Nippon Kanizen Co., Ltd. (trade name), etc. The p of the roughening liquid is 2 to 13, preferably 5 to 10, more preferably 6 to 9.

As a catalyst capable of starting an electroless plating reaction, a usual catalyst used as a pretreatment for forming a circuit on an insulating substrate surface by electroless plating, particularly an alkaline or neutral PB-based catalyst is preferable.

Electroless plating can also be performed in the production of printed wiring using a normal electroless plating solution for forming circuits on the surface of an insulating substrate.

The etching resist is formed by a printing method, a developing method, etc., and the etching liquid is a liquid that does not corrode the enamel layer.

In the present invention, the crawling layer can be roughened, activated, and
It is important to perform plating and etching.

The wax layer tends to become brittle when it comes into contact with strong acids or strong alkalis, and the adhesion of the plating film cannot be obtained even if strong acids or strong alkalis are used in any of the roughening, activation, or plating steps. Furthermore, even if only the etching solution is a strong acid or strong alkali, the interface between the plating film under the etching resist and the enamel layer will be eroded from the sides by the etching solution. These problems can be solved by adjusting the pH of all treatment liquids to 2 to 13.

Example This will be explained with reference to FIG.

BzOt□20.5iOz=15. Mg0=55.
For the crystal ratio axis of the composition (mol %) of Ba0=5.5rO=5, an enamel substrate coated with the enamel layer 1 was used. 2
is a metal core (Fig. 1(a)). As the roughening solution, an aqueous solution of 1-20 g of sodium fluoride (pH 7, 8) was used. After the substrate with through holes was immersed in the roughening solution at 80°C for 50 minutes, NaOH was added to Ig/1. Immerse for 2 minutes in the pb seeding solution (pH 10, 2) containing j!, and then soak in the same alkaline reduction treatment solution (pH 11, 2).
After being immersed in water for 1 minute (Fig. 1(b)), electroless copper plating (pH 12.3) was performed using formalin as a reducing agent (
Figure 1 (C)). After forming a plating film on the entire surface of the enamel layer in this way, an etching resist 4 is formed on the part that will become the circuit. Etching solution containing NlI411CO+ etc.
After etching (FIG. 1(e)) in H8, 2), the etching resist 4 was removed (FIG. 1(f)).

The adhesion strength of the circuit thus obtained to the substrate is 1
There were more than 2/-.

On the other hand, elemental analysis of the substrate surface by XMA (X-ray microanalyzer) analysis before and after roughening revealed that the abundance ratio of Ba, which forms a crystalline phase, increased significantly after roughening. Furthermore, surface observation using a SEM (scanning electron microscope) revealed that the roughened surface was a pile of spherical particles of 0.5 to 2 μm in size.

(Effects of the invention) Until now, (i) the enamel layer unique to enamel substrates has a swell near the through-hole portion, and (11) the through-holes of porcelain substrates (in the East, there are many holes larger than one crane), etc. For these reasons, ink could not be sufficiently sucked into the through-holes, making it difficult to print through-holes freely.On the other hand, the method of the present invention allows the circuit to be printed simultaneously on both sides of the board and inside the through-holes. can be formed.Also,
By using photoresist, fine patterning is possible because microfabrication, which is difficult with thick film methods, is possible. Furthermore, since no expensive noble metal thick film paste is used, the cost of circuit formation can be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a sectional view for explaining the present invention in detail. 1. Crystallization is a thin layer 2. Metal core 3. Electroless plating film 4. Esoching resist

Claims (1)

[Claims] 1. Using an enamel substrate in which a metal core is covered with a crystallized glaze enamel layer consisting of a crystalline phase and an amorphous phase, (a) the amorphous phase is smaller than the crystalline phase; A step of roughening with a roughening solution having a high dissolution rate, (b) a step of applying a catalyst capable of starting an electroless plating reaction, (c) a step of performing electroless plating, (d) an etching process on the plating film. A method for producing an enameled wiring board, comprising the following steps: (c) forming a resist; (c) etching. 2. The method for manufacturing an enameled wiring board according to claim 1, wherein the pH of all the treatment liquids is 2 to 13. 3. The crystallized enamel layer contains boron, silicon, magnesium, and barium at 15<B_2O_3<35, 10<S
iO_2<30, 40<MgO+CaO+BaO<65
3. The method for manufacturing an enameled wiring board according to claim 1 or 2, wherein the enamel wiring board is crystallized glass containing a proportion (mol %) of