JPS62230087A - 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, a thick film method has been used to form a circuit on a floating substrate by screen printing a metal paste and then baking it at a temperature of 500° C. or higher.

However, the J\ film formation method has the following problems: (i) It is difficult to print inside through holes, (ii) It is difficult to form fine patterns, and (iii) It requires repeated firing at high temperatures (in the case of double-sided boards with through holes, (4) There is a risk of warpage or cracks occurring on the board, (iv) Precious metal paste is used for firing in air, which increases the cost; (V) When firing m paste, etc., nitrogen It is difficult to control the atmosphere, and since the firing is performed at a high temperature of over 900°C, the heat resistance temperature of the enamel layer is exceeded, or the transformation point of the metal core is exceeded (α-γ transformation point of iron = 91θ°C), causing distortion. There were some problems, such as it being easy to use.

In order to solve these problems, a method has been proposed in which the surface of the floating substrate is plated. For example, JP-A-53-5
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 hydronic 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 a fragile layer is formed near the surface, it is difficult for the subsequently applied electroless plating film to separate from the IA along with this fragile layer and 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 solution that dissolves the amorphous phase at a higher rate than the crystalline phase to promote adhesion to the plating film, and then start the electroless plating reaction without destroying this roughened shape. A plating resist is formed after forming a plating resist, or a catalyst capable of initiating an electroless plating reaction is applied after forming a plating resist, and then electroless plating is performed on the enamel substrate. Form a circuit with a plating film with good adhesion.

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: Zr01 > AIzOs > Ti01 >
ZnO>MgO>PbO>CaO>BaO
Acid resistance: Zr0z > 81zOz > ZnO > Ca
O>Tie□>PbO>MgO>BaO NaOH resistance: Zr0z) AIzOs+Ti0z,
ZnO, CaO NazCO1 resistance: ZaOz ) A
IzOs, Ti0z+ZnO>Cab.

Bad, PbO, MgO Bad and Cab as crystalline components in crystallized glass.

When using MgO, I'bO, etc., 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). Roughening is performed with a roughening liquid that dissolves the amorphous phase at a higher rate than the 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<Btus<35.10<5iOt<3
0゜40<Mg+CaO+BaO<65 ratio (mol%
) can be used.

This enamel layer consists of a BaO-rich crystalline phase and a borosilicate glassy phase. The crystalline phase is needle-shaped with a length of 20 μm or less 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 Schemer-J (pH 6,4)"
This can be done using Nippon Kanizen Co., Ltd. (trade name), etc. The pH of the roughening liquid is 2 to 13, preferably 5 to 1O1, and 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.

The plating resist is formed by a printing method, a developing method, or the like.

A catalyst capable of starting an electroless plating reaction may be applied after forming the plating resist. In this case, the plating resist is selected from a material to which the electroless plating catalyst does not easily adhere, and the electroless plating catalyst adhering to the plating resist is removed by brushing or the like.

Electroless plating is used in the production of printed wiring, and can be performed using a common electroless plating solution for forming circuits on the surface of an insulating substrate.

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

The wax layer tends to become brittle when it comes into contact with strong acids or strong alkalis, and adhesion of the plating film cannot be obtained even if strong acids or strong alkalis are used in any of the roughening, activation, and plating steps. 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.

BzOs, 20.5iOz=15. Mg0=55.
An enamel substrate coated with a crystallized glaze enamel layer 1 having a composition (mol%) of Ba0=5.5rO=5 was used. 2
is a metal core (Fig. 1(a)). A 20 g/l aqueous solution of sodium fluoride (pH 7, 8) was used as the roughening liquid. After the through-hole substrate was immersed in the above roughening solution at 80°C for 50 minutes, Na011 was added to Ig//! including p
b Immerse in Seedinda solution (pH 10, 2) for 2 minutes, then soak in the same alkaline reduction treatment solution (pH 11, 2) for 1 minute.
After soaking for a minute (FIG. 1(b)), it was dried. On this substrate, a plating resist 3 based on novolac type epoxy was formed by screen printing (Fig. 1(c)), and electroless copper plating (pH 12, 3) 4 was performed using formalin as a reducing agent.
A circuit was formed by doing this (Fig. 1(d)).

The adhesion strength of the circuit thus obtained to the substrate is 1
It was more than kg/■-.

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 Ha, 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, reasons such as (i) the bulging of the enamel layer, which is unique to enamel substrates, occurs near the through-hole portions, and (11) the fact that the through-holes of enamel substrates are often more than one dragon. As a result, ink could not be sufficiently sucked into the through-holes, making it difficult to liberalize through-hole printing.

In contrast, in the method of the present invention, circuits can be formed simultaneously on both sides of the substrate and inside the through holes. Furthermore, by employing 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.

Furthermore, since this manufacturing method does not apply plating to anything other than the circuit area, it saves materials and processes compared to the etching method, and there is no need to apply resist over the through-holes, so it can be used in addition to film-type resists. It also becomes possible to form a resist by screen printing, making it possible to further reduce costs.

[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. Resist 4. Electroless plating film

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; (b) forming a plating resist after providing a catalyst capable of starting an electroless plating reaction, or forming a plating resist and then performing an electroless plating reaction; A method for producing an enameled wiring board, comprising: (c) applying a catalyst capable of initiating electroless plating. 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