JPH0220154B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a hollow printed circuit board.

As shown in Figure 1, the enameled printed circuit board is made by firing enameled enamel 2 with a thickness of about 0.13 millimeters (mm) on top of a steel plate 1, etc., and has excellent properties in terms of heat dissipation and mechanical strength. It is something that has. In particular, in order to take advantage of its heat dissipation properties, it is preferable to make the enamel enamel 2 thin. However, as shown in FIG. 2, if bubbles 3 or pinholes 4 are generated inside the enamel enamel 2, a problem arises in that the dielectric strength voltage is significantly lowered. One way to prevent this drop in dielectric strength voltage is to apply the enamel in several steps, but this not only increases the thickness and easily impairs heat dissipation, but also increases the number of steps and increases costs. easy to invite.

That is, the conventional manufacturing of hollow printed circuit boards is carried out as shown in the process example shown in FIG.

S1: Process of processing steel plates into the required size.

S2: A process in which the steel plate undergoes pretreatment such as removing burrs, degreasing, and pickling.

S3: Glass frit (enamel component)
The process of painting steel plates using electrodeposition, wet spraying, electrostatic methods, etc.

S4: Drying the painted glass frit solution.

S5: A process in which glass frit is melted at, for example, 800 to 850°C, and the enamel is baked in close contact with the steel plate.

etc. Therefore, when enameling is applied in several steps, the steps S3 to S5 in Figure 3 are repeated, which requires heating and cooling each time, which increases the work time. It is something that occurs.

The present invention was made based on the above circumstances, and
The purpose is to forcibly break down the electrical defects caused by the presence of pinholes, etc., and then electrodeposit glass frit on these areas and bake them to create a uniform enamel layer. It is an object of the present invention to provide a hollow printed circuit board having a high dielectric strength and excellent dielectric strength.

The present invention will be explained below based on an embodiment shown in FIG. In these processes, S1 to
S5 is the same as the conventional manufacturing process. Next, S6
Follow the steps below.

S6: Apply the reference voltage (for example, AC50Hz) during the dielectric strength test to the hollow printed circuit board completed in S5.
Applying a voltage of 1000 V or more causes dielectric breakdown at the electrical defect as shown in Figure 2, penetrating the enamel enamel layer and forcibly communicating the steel plate with the outside air (short circuit at dielectric breakdown). (drilling holes using electric current) process.

S7: If electrical breakdown does not occur due to voltage application (“NO”), the sample is considered to be normal. On the other hand, if dielectric breakdown occurs, the process from S8 onwards is added. , the process of determining the presence or absence of dielectric breakdown.

S8: As shown in FIG. 5A, a step of electrodepositing glass frit 5 by electrodeposition coating method to fill the defective part which is in communication with the outside air. In this step, basically the same type of glass frit as S3 is used. In addition, during electrodeposition coating, lines of electric force concentrate in areas with poor insulation, that is, electrical defects, so the glass frit 5
The filling is carried out effectively.

S9: A process in which the excess of the glass frit that was electrodeposited in the previous process is removed by washing with a solvent solution.

S10: Drying the glass frit solution.

S11: A step of melting the glass frit at, for example, 800 to 850°C and integrating it with another enamel 2 as a filled enamel 6 as shown in FIG. 5B.

In addition, in the process up to this point, S10 and
S11 is the same as S4 and S5, and the facilities can be mutually used or used together, and it is also possible to process S3 and S8 in the same facility.

In addition, in S8, the composition of the glass frit is S3.
Although it is said that it is the same type as , it is also possible to use other paints and impregnation agents as long as they can be electrically painted or sealed.

However, according to the present invention, if there is an electrical defect in the enamel layer, the hole is forcibly destroyed by electric breakdown, and the hole is integrated with the enamel filling in this part.
A uniform hollow printed circuit board with excellent electrical insulation can be manufactured.

Since the filled enamel enamel layer is enameled to target electrical defects, it is possible to prevent the thickness of the enamel layer from increasing and to maintain constant heat dissipation.

Filling electrical defects with glass frit
Since it is carried out by electrodeposition coating in which electric lines of force are concentrated, work efficiency can be improved.

It has the following effects.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view showing an example of the structure of a hollow printed circuit board, Fig. 2 is an explanatory diagram of an electrical defect, which is an enlarged view of the part indicated by the chain line in Fig. 1, and Fig. 3 is an example of the process of the conventional manufacturing method. FIG. 4 is a flowchart showing a process example for carrying out the present invention, and FIGS. 5A and 5B are explanatory views showing the state of enameling in the process example of FIG. 4. 1... Steel plate, 2... Enamel, 3...
Air bubbles, 4...pinholes, 5...glass frits, 6...filled enamel enamel.

Claims (1)

[Claims] 1. A process for producing an enamel printed circuit board, which includes the steps of electrically destroying defective parts of the enamel enamel layer, electrodepositing glass frit on the destroyed defective parts, and heating and baking the electrodeposited glass frit. Production method.