JPH07493B2 - Metallization method for crystallized glass surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a crystallized glass surface used for forming a circuit on a crystallized glass substrate, a crystallized enamel substrate, a ceramic substrate surface-coated with crystallized glass, or the like. The metallization method of.

(Prior Art) Conventionally, as a method of metallizing the surface of crystallized glass, particularly a circuit forming method, (a) a thick film method of baking a metal paste,
(B) There is a thin film method using sputtering or vapor deposition.
(C) Further, recently, a plating method using a normal electroless plating process after roughening the surface with a hydrofluoric acid or a hydroxide melt of an alkali metal has been studied.

(Problems to be Solved by the Invention) However, (a) the thick film method has drawbacks such as high conductor resistance and it is difficult to obtain a fine circuit pattern, and (b) the sputtering or vapor deposition method There were drawbacks such as difficulty in increasing the metal film thickness. (C) The plating method solves these problems, but the plating methods that have been studied so far have a too strong corrosive force against the crystallized glass of the hydrofluoric acid or alkali metal hydroxide melt. Therefore, it is difficult to control the unevenness of the roughened surface, and since the crystallized glass is weakened, it is difficult to obtain the adhesion of the plating film. In addition, it is dangerous to handle the molten liquid of hydrofluoric acid or alkali metal hydroxide.

Even if the roughness of the roughened surface can be controlled to some extent without weakening the crystallized glass, a high-concentration hydrochloric acid aqueous solution is usually used in the step of adding a catalyst that can start the next electroless plating reaction. Moreover, the crystallized glass is weakened, and even if electroless plating is performed thereafter, sufficient adhesion of the plating film cannot be obtained. Furthermore, in the case of crystallized glass containing a large amount of alkali metal oxides or alkaline earth metal oxides, it is dissolved even by an aqueous solution of a weak acid (pH 3 or less) or a weak alkali (pH 10 or more). On the other hand, when palladium which serves as a plating catalyst is dissolved in a neutral aqueous solution in the state of palladium chloride, palladium hydroxide is produced and precipitated.

The present invention provides a metallization method for forming a plating film having excellent adhesion on the surface of crystallized glass.

(Means for Solving Problems) In the present invention, after the surface of the crystallized glass is roughened with an aqueous solution containing a fluoride salt, a treatment for imparting a catalyst capable of initiating an electroless plating reaction is performed with a neutral solution. This is a metallization method for the surface of crystallized glass, which is characterized by performing non-aqueous solution and then performing electroless plating.

The roughening solution used in the present invention is a solution of a fluoride salt such as NaF or KF dissolved in water to a concentration of 5 to 50 g /, preferably 1 to 30 g /. Trace amount of acid to return neutrality of aqueous solution which shows alkaline (pH 7-8) due to hydrolysis of organic acid salt or fluoride salt that forms complex with Si such as sodium acid salt or sodium tartrate. May be added. The temperature of the roughening solution is 70 to 85 ° C, preferably 75 to 80 ° C, and the crystallized glass is immersed in this aqueous solution for about 50 minutes to crystallize the amorphous phase present in the crystallized glass. It forms a roughened surface that dissolves faster than the material phase and increases the anchor effect of the plating film. In the case of crystallized glass mainly composed of silicon oxide, boron oxide and alkaline earth metal oxide, a large amount of alkaline earth metal oxide tends to be contained in the crystalline phase.

Although crystallized glass is composed of a crystalline phase and an amorphous phase, the crystalline phase may be composed of several kinds of phases (compositions). At least one of the phases remains, and it is possible to form a roughened surface that increases the adhesion with the plating film to be applied thereafter.

In the subsequent step of applying a catalyst, a treatment in which palladium chloride is dissolved in a non-aqueous solution, preferably one having a relative dielectric constant of 30 or more, such as formamide, monomethylformamide, dimethylformamide, dimethylacetamide, methyl alcohol, and a mixture thereof. A liquid A and a treatment liquid B prepared by dissolving dimethylaminoborane (DMAB) or sodium borohydride (NaBH ₄ ) sodium hypophosphite in a non-aqueous solution similar to the above as a reducing agent for palladium are used.
The catalyst is applied by immersing the crystallized glass having the roughened surface in the order of → B. It should be noted that liquid A is allowed to contain water to the extent that palladium hydroxide does not precipitate, and liquid B does not reduce the reducing effect (that is, to the extent that palladium hydroxide does not precipitate after treatment with liquid B). The presence of water is allowed.

Further, if the next plating solution contains a reducing agent containing the solution B, the solution B may not be treated. Also,
In order to prolong the life of solutions A and B, it is preferable to use pre-dip → solution A → washing → solution B. More preferably, the pre-dip solution is the solvent of solution A and the washing solution is the same solvent as solution B. . On the other hand, since palladium is present in a solvated form, it may drop off if strongly washed with water after the non-aqueous catalyst application step, but if it is put into the plating solution without washing, it will not react with the catalyst in the plating solution. A part of it drops off, plating is deposited on other than the target object such as the plating tank, and the plating solution decomposes rapidly. In order to solve the above problems, it is advisable to immerse the crystallized glass with a roughened surface-catalyzed catalyst in water heated to the same extent as the plating solution, and then add the crystallized glass to the plating solution.

The plating solution is preferably close to neutral (pH 3 to 13).

EXAMPLE First step of metallization method of crystallized glass surface according to the present invention
As shown in the figure. The composition of the crystallized glass used here is B ₂ O ₃ =
20, SiO ₂ = 15, MgO = 55, BaO = 5, SrO = 5 (above mol%).

The surface of the crystallized glass substrate with the above composition was degreased by washing with methyl ethyl ketone (MEK), and after MEK was completely evaporated, it was immersed in pure water (80 ° C, pH 7.6) containing 12 g of NaF for 50 minutes. By doing so, the substrate surface was roughened. When the roughened surface was observed with an electron microscope (SEM), it was shown that particles having a diameter of 0.5 to 2 μm were stacked. The roughened substrate is washed with running water and then placed in a dimethylformamide (DMF) solution.
After soaking for 3 minutes, soak in DMF in which 0.5g / palladium chloride (PdCI ₂ ) is dissolved for 3 minutes, then soak in DMF for about 0.1 minutes to remove excess PdCI ₂ , and then use a reducing agent for palladium. One dimethylaminoborane (DMAB) is immersed in DMF containing 1 g / for 3 minutes. The substrate seeded in this way is immersed in pure water heated to the same temperature (70 ° C) as the electroless plating solution for about 3 minutes to remove the seeder (Pd) that may fall off in the plating solution. Finally, an electroless copper plating solution (70 ℃, pH12.3) that uses formalin as a reducing agent.
Soaked in.

When the adhesion of the plating film thus formed was examined, the crystallized glass was broken at 2.8 kg / mm ² . From this, the adhesion of the plating film is 2.8 kg / mm ² or more.

Adhesion strength is 0.2-0.5 kg / mm ² , 1-10 g /
Adhesion was 0.5 to 2.3 kg / mm ² when using the non-aqueous catalyst application process containing NaOH.

Further, when the surface of the substrate after applying the catalyst was observed by SEM, it was found that the surface of the substrate after applying the catalyst of the present invention did not change from roughening, whereas the surface of the substrate on which the catalyst was added by the other two methods was roughened. The surface was destroyed to some extent (high-concentration hydrochloric acid system: major destruction).

(Effects of the Invention) According to the present invention, a metal film by plating can be formed on the surface of crystallized glass with good adhesion. This makes it possible to form circuits by plating, facilitates through-hole wiring, which was difficult until now, reduces the sheet resistance of the conductor circuit, and does not warp the substrate or change its dimensions because it does not involve firing. In addition to improving the characteristics, the cost is expected to drop significantly.

[Brief description of drawings]

 FIG. 1 is a process drawing showing the method of the present invention.

Claims (1)

[Claims] 1. Boron, silicon, magnesium and barium are added to 15 <B ₂ O ₃ <35, 10 <SiO ₂ <30, 40 <MgO + CaO + BaO.
A step of roughening the surface of the crystallized glass, which is a crystallized glass containing <65, with a crystalline phase and an amorphous phase with (a) an aqueous solution of a fluoride salt, (b) electroless A method of metallizing a surface of a crystallized glass, which comprises: a step of applying a non-aqueous solution catalyst capable of initiating a plating reaction; and (c) a step of performing electroless plating.