JPH0635669B2 - Enamel board manufacturing method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for manufacturing an enamel substrate used in a printed wiring board.

(Prior Art) An enamel substrate is generally manufactured as follows.

Raw materials, Na ₂ O, K ₂ O, CaO, PbO, ZrO ₂ , BaO, TiO ₂ ,
_{SrO, SnO 2, B 2 O} 3, Al 2 O 3, SiO 2, MgO, NiO, ZnO, compounding such CuO,溶触, cooled, and pulverized, migration resistance, together with additives for adjusting viscosity and the like, An electrodeposition liquid is prepared by dispersing it in a solvent such as water, alcohol or toluene. Using this electrodeposition liquid, a metal core of an iron alloy such as iron, aluminum, copper, iron nickel, etc. is glazed by electrodeposition, spraying, dipping, electrostatic coating, etc., dried, and then baked at 800 to 1000 ° C. To get

Conventionally, in the production of enamel substrate, etching, roughening, and plating of a metal such as nickel that contributes to adhesion have been performed as a pretreatment of the metal core for the purpose of improving the adhesion between the enamel layer and the metal core. .

(Problems to be solved by the invention) However, recently, in enameling using a glaze such as a crystallization glaze, which has a short time from melting to solidification in the firing process, when the substrate is baked after glaze, the enamel layer is formed. There is a problem of blistering.

The reason for this is that the time from melting to solidification of the glaze layer in the substrate baking process is short, so a difference in state occurs due to the difference in heating rate between the surface of the glaze layer and the interface with the metal core. It is considered that the stress generated by this causes a part of the glaze layer to be released from the surface of the metal core and causes blistering. Also, unlike conventional amorphous glazes, the melting time of the glaze during baking of the substrate is short, so the adhesion between the enamel layer and the metal core is mainly obtained by the anchoring effect, and is generally said. It is considered that the effect of chemical bonding is small.

The present invention provides a method for producing an enamel substrate which is excellent in the adhesion between the enamel layer and the metal core.

(Means for Solving the Problems) The present invention uses a metal core on the surface of which a concave shape having an opening whose size is 1/4 to 20 times the average particle size of enameled glaze is formed. Is characterized by.

The conventionally treated surface of the metal core using sulfuric acid or hydrochloric acid is a roughened surface with numerous wrinkles. FIG. 2 is an electron micrograph of a roughened surface obtained by treating the metal core of a low carbon steel plate with sulfuric acid (magnification: 2000 times).

In this case, when a stress is applied in the direction parallel to the wrinkles, the drawing effect is reduced and the adhesion is small.

In the present invention, the surface of the metal core is 1 / of the average particle size of the enamel glaze.
A recess having an opening that is 4 to 20 times larger is formed.

The particle size of enamel glaze has a certain distribution, but the average particle size is generally 1 to several tens of μm. There are various shapes of the opening of the recess, such as circular polygon and irregular shape, but the size of the opening (regardless of the diameter of any part) is 1/4 to 2 of the average particle size of the enameled glaze.
Those within the range of 0 times are more preferably 1/2 to 10 times more effective. The size of the opening is preferably 0.5 to 40 μm.

That is, in order to prevent the projection effect from decreasing depending on the direction of the stress, a roughened surface having a hole shape, preferably a roughened surface having many ink pot-shaped holes is effective.

FIG. 1 is an electron micrograph (× 2000) of a roughened surface (treatment of a low carbon steel sheet mixed with sulfuric acid and nitric acid) according to the present invention.

The area of the portion where the above-mentioned recess is provided is preferably 50% or more of the entire surface of the metal core.

In order to perform the above-mentioned roughening, it is desirable to strongly and nonuniformly erode the metal. For example, there is a method of interrupting the chemical polishing at the initial stage. The mixed acid used for chemical polishing first erodes the weak part of the metal and deposits the metal complex salt generated at that time on the concave part formed by the erosion to change the direction of the erosion to the convex part. Polish with. That is, the desired roughened surface can be formed by a method of interrupting the chemical polishing and removing the metal complex salt at a point before the concave portion is formed and the convex portion is eroded. At this time, it may be effective to add a complexing agent to the treatment liquid so that the corroded metal can be removed cleanly.

Also, what should be noted after this is that the roughened surface formed as described above should not be destroyed when the metal for improving the adhesion is plated. Especially when displacement plating is performed, the cotton-like fine metal layer covers the metal core surface,
After glazing, voids are created at the interface between the glaze layer and the metal core, which causes voids, pin poles, etc. Desirably, electroless plating using a chemical reduction method is performed.

After that, glazing and baking are performed to obtain an enamel substrate, and circuit processing is performed by a thick film baking method, an additive method or the like to obtain a printed wiring board.

Enameled steel plate SPP (100 x 70 x
1.0mm Nippon Steel product name), first 100μm on one side
On the other hand, one is immersed in a sulfuric acid aqueous solution for removing rust and the like, and then is immersed in a mixed acid aqueous solution of sulfuric acid and nitric acid, followed by thorough washing with warm water or the like (this is called A roughening). ). On the other hand, the above mixed acid treatment was applied immediately after etching (this is called B roughening). In order to compare with these, after etching, roughening was performed using sulfuric acid, hydrochloric acid, nitric acid, sulfuric acid and then hydrochloric acid, and sulfuric acid and then nitric acid.

As the next treatment, the above treated surface is immersed for 1 minute in an electroless nickel plating solution (Nippon Kanigen brand name Blue Sumer) kept at a temperature of about 60 ° C., washed with water, and then Mg.
O, SiO ₂ , BaO, B ₂ O ₃ type crystallization glaze was glazed by electrodeposition in isopropyl alcohol. Then, after drying, 8
The substrate was baked at 60 ° C. for 10 minutes. The results are shown in Table-1. The enamel film thickness was set to about 200 μm.

(Advantages of the Invention) In the present invention, the adhesion between the enamel layer and the metal core was improved, and the blistering defect that occurred when the crystallization glaze was used could be prevented. Further, further improvement in adhesion can be expected with other glazes.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and FIG. 2 are micrographs of a metal core roughened surface.

Claims (1)

[Claims] 1. A method for producing a enamel substrate, which comprises firing a crystallized enamel glaze on a metal core and then firing the enamel glaze. By forming a recess having an opening with a mixed acid roughening solution containing sulfuric acid and nitric acid, and interrupting chemical polishing at a point following the formation of the recess and before the protrusion is eroded. Method for manufacturing enamel substrate characterized by roughening