JPS62230089A - 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 more.

However, with the thick film method, (i) it is difficult to print inside the through holes, (11) the fine pattern is repeated, and (iii) the firing at high temperatures is repeated (three times in the case of double-sided boards with through holes). ), there is a risk of warping or cracking on the board; (iv) noble metal paste is used for baking in air, which increases the cost; and (V) a nitrogen atmosphere is required when baking tl paste, etc. In addition, it is difficult to control the temperature, and since it is fired at a high temperature of over 900℃, it exceeds the heat resistance temperature of the enamel layer or the transformation point of the metal core (α-γ transformation point of iron = 91O℃), which tends to cause distortion. There were problems such as:

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 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. In addition, hydrofluoric acid and sodium hydroxide melts are dangerous, even if they are scattered.

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 glaze 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.
After that, solder plating such as etching resist and anti-corrosion film is applied, and 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: Zr0z > A1ga3 > Tie, >
ZnO>MgO>PbO>CaO>BaO Acid resistance: Zr0z>Al2O,>ZnO>CaO
>Tiot>PbO>MgO> BaO resistance Na0I
I property: Zr0z) Al*03. Ti0z, ZnO
, CaO NazCO+ resistance: ZaOz ) AIzO
ff, Ti0z, ZnO>Cab.

Bad, PbO, MgO Bad and 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 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 < BtOx < 35, IQ < Si
O□<30.40<Mg+CaO+BaO<
A crystal ratio axis containing a ratio of 65% (mol %) can be used.

This enamel layer consists of a BaO-rich crystalline phase and a borosilicate glass pledge. The crystalline phase has a length of 20, crm
They are needle-shaped and are 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, etc., 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.

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

Electroless plating, electroplating, and solder plating are used in the production of printed wiring, and can be performed using conventional electroless, electric, and solder plating solutions for forming circuits on the surface of an insulating substrate.

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 l having a composition (mol %) of Ba0=5.5rO=5 was used. 2
is a metal core (Fig. 1(a)). As a roughening liquid, use 20 g/j of sodium fluoride! An aqueous solution (pH 7,8) was used. The substrate with through holes was immersed in the above roughening solution at 80°C for 50 minutes, then immersed in a PB seeding solution (pH 10, 2) containing 1 g/l of Na0ll for 2 minutes, and then subjected to the same alkaline reduction treatment. liquid (pH11,2)
After being immersed in water for 1 minute (Fig. 1(b)), a hollow plating film 3 was formed on the entire surface of the substrate by electroless copper plating (plI 12.3) using formalin as a reducing agent (Fig. 1(C)). .

A plating resist 4 is formed on this board in areas other than the circuit area (Fig. 1(d)), and electroplating 5 is performed to increase the thickness of the circuit (Fig. 1(e)), followed by electrical soldering. Plating 6 is performed (Figure 1 (r)), and finally the plating resist is removed (Figure 1 (g)), using ammonia as the main ingredient, NaCl0z as an oxidizing agent, and Nl as a pH buffering agent.
Etching solution containing 1411CO1 etc. (pH 8.2)
), a circuit was formed by removing the plating film other than the circuit portion by etching (FIG. 1(h)).

The adhesion strength of the circuit thus obtained to the substrate is 1
There was more than +r/i-.

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. Further, surface observation using a SEM (scanning electron J4 microscope) revealed that the roughened surface was a pile of spherical particles with a stiffness of 0.5 to 2 μm.

(Effects of the Invention) Until now, due to reasons such as (i) the bulge of the enamel layer peculiar to enamel substrates occurs near the through-hole portions, and (11) the through-hole presses of enamel substrates are often 11 or more. 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. Further, by employing photoresist, fine patterning is possible because microfabrication, which is difficult with rcj and film, 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.

Furthermore, by forming a solder plating layer on the copper circuit, there is no reduction in the circuit film thickness due to subsequent etching, and the copper circuit does not come into contact with the atmosphere, so there is no corrosion of the circuit. Therefore, soldering can be easily performed even after long-term storage.

[Brief explanation of drawings]

FIG. 1 is a sectional view for explaining the present invention in detail. 1. Crystallized glaze enamel layer 2. Metal core 3. Electroless plating film 4. Plating resist 5. Electroplated film 6. Solder plating film To ra^ Afternoon, (9,, ()

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. (e) a step of electroplating and further solder plating; (f) a step of removing the plating resist; and (g) a step of etching. Manufacturing method. 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