JPS62230088A - 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 an enameled wiring board.

(Prior Art) Conventionally, circuit formation on enamel substrates has been carried out using a thick film method in which a metal paste is screen printed and then baked at a temperature of 500° C. or higher.

However, with the thick film method, (i) it is difficult to create a 3+1 mark inside the through hole, (ii) it is difficult to create a fine pattern, and (iii) firing is repeated at high temperatures (three times in the case of double-sided boards with through holes). ), there is a risk of warping or cranking on the board; (iv) noble metal paste is used for firing in air, which increases the cost; and (v) 11. When firing paste, etc., a nitrogen atmosphere is required. In addition, it is difficult to control the temperature, and since it is fired at a high temperature exceeding 900°C, it exceeds the heat resistance temperature of the enamel layer or the transformation point of the metal core (α-γ transformation point of iron: 910°C), which causes distortion. There were some problems, such as it being easy to use.

In order to solve these problems, CartL has been proposed, in which the surface of the enamel substrate is plated. For example, JP-A-53
The methods disclosed in Japanese Patent Laid-open No. 5438 and Japanese Patent Application Laid-Open No. 60-195078 roughen the surface of the enamel substrate 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 a brittle layer is formed near the surface, the electroless plating film applied afterwards peels off along with this brittle layer, making it difficult to obtain stable adhesion. Furthermore, handling of hydronic acid and sodium hydroxide melt 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 axial 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. By applying a suitable catalyst and performing electroless plating, a plated film with good adhesion is formed on the enamel substrate. After this, a plating resist is formed on areas other than the circuit area and electroplating is performed to increase the film thickness of the circuit in a short time.
Finally, the plating resist is removed and 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: ZrO2>A120a>Ti01>
ZnO>MgO>PbO>CaO>BaO
Acid resistance: ZrO2>A1.03>ZnO>Ca
O>Tie,>PbO>MgO>BaO Na0II resistance: Zr0z) AIzOi, Ti0g
, ZnO, CaO NazCO3 resistance: ZaOt )
AIzOs, Ti0t, ZnO> CaO+Bad, I
'bO, MgO BaO, CaO 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 of the crystalline phases 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 < Bz (h < 35.10 < Si
A crystallization axis containing the ratio (mol %) of O□<30.40<Mg+CaO+BaO<55 can be used.

This enamel layer consists of a BaO-rich crystalline phase 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 pH of the roughening liquid is 2 to 13, preferably 5 to IO1, and more preferably 6 to 9.

The catalyst capable of starting the electroless plating reaction is preferably a common catalyst used in a correction process for forming a circuit on an insulating substrate surface by electroless plating, particularly an alkaline or neutral PB-based catalyst.

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

Electroless plating and electroplating are absolutely 8 in the manufacturing of printed wiring!
This can be done using a conventional electroless or electroplating solution for forming circuits on the substrate surface.

Example This will be explained with reference to FIG.

BzO3□20.5iOz=15. MgO□55',
An enamel substrate coated with a crystallized axial enamel layer l having a composition (mol %) of Ba0=5.5rO=5 was used.

2 is a metal core (FIG. 1(a)). A 20 g/ll aqueous solution of sodium fluoride (pH 7, 8) was used as the roughening liquid. After immersing the enamel substrate with through holes in the roughening solution at 80°C for 50 minutes, 1 g/l of Na0II was added!
It was immersed for 2 minutes in the pb seedinda solution (pit 10.2) containing the same alkaline reduction treatment 1f(p).
[11,2) for 1 minute (Fig. 1(b)), and then electroless copper plating using formalin as a reducing agent (pH 12,3).
) was used to form a copper plating film 4 on the entire surface of the substrate (see Figure 1 (C)).
)). A plating resist is formed on this board other than the circuit area (Fig. 1(d)), the thickness of the circuit is increased by electroplating (Fig. 1(e)), and finally the plating resist is removed. Fig. 1(r)), ammonia is the main ingredient and NaCl0. , pTI5
A circuit was formed by removing the plating film other than the circuit portion by etching with an etching solution (pH 8.2) containing NIIallCOs or the like as a buffer agent (FIG. 1(g)).

The adhesion strength of the circuit thus obtained to the substrate is l
There were more than k+r/-.

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 IIa, 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, through-holes have been made due to the following reasons: (i) the swell of the enamel layer peculiar to enamel substrates occurs near the through-hole portions, and (11) the through-hole size of enamel substrates is often larger than lf1. The ink could not be sucked in sufficiently, making it difficult to use through-hole printing freely. 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. 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.

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.

Further, since the film thickness of the circuit is increased using electroplating, the circuit can be formed in a short time.

[Brief explanation of drawings]

FIG. 1 is a sectional view for explaining the present invention in detail. 1. Crystallized axial enamel layer 2. Metal core 3. Electroless plating film 4. Plating resist 5. Electroplated 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; 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) on an electroless plating film. A method for producing an enamel wiring board, comprising the following steps: (e) electroplating; (f) removing the plating resist; and (g) etching. 2. 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