JPH10190199A - Method for coating circuit board with resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent insufficient insulation due to the production of bubbles on the underside of a circuit board, when the circuit board is coated with insulating resin. SOLUTION: A through hole is formed in position in a circuit board 7 mounted with circuit parts 8. The circuit board is placed in a case with an opening formed in its top, and a nozzle is inserted into the through hole through the opening in the case. Insulating resin 11 is injected into the case from underneath the circuit board through the nozzle so that the whole or almost the whole of the circuit board is submerged in the insulating resin. The through hole as the nozzle for injecting the resin is formed almost in the center of the circuit board, and the insulating resin is injected from underneath the circuit board in the center of the circuit board. As a result, it is made possible to discharge the air under the circuit board through the gap between the circuit board and the case, thus preventing the production of bubbles without fail.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of coating a circuit board with a circuit board on which circuit components are mounted with an insulating resin.

[0002]

2. Description of the Related Art A circuit board for a device used in an environment where water, water-based chemicals, etc. are liable to adhere is disclosed, for example, in Japanese Patent Application Laid-Open No. 8-14884.
As shown in Japanese Patent Application Publication No. 5 (1993) -2005, the entire circuit board is covered with a moisture-proof insulating resin.

On the other hand, in the insulating resin coating operation, the resin is poured into the case from above the board with the circuit board placed in the case. In this case, the resin flowing on the surface of the board is Since the air flows to the bottom of the case through the gap between the case and the case, there is a problem that air does not escape from the lower side of the substrate and an air pocket is generated, so that a sufficient insulating function cannot be obtained.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent the generation of bubbles in the process of coating a circuit board with an insulating resin, and to prevent insulation failure due to the bubbles.

[0005]

According to the present invention, an insertion hole is formed at an appropriate position on a circuit board on which circuit components are mounted, and the circuit board is housed in a case having an open upper surface. A nozzle is inserted into the inside, and an insulating resin is poured into the case from below the nozzle so that the entire or substantially entire circuit board is buried.

Further, in the present invention, the insertion hole is formed substantially at the center of the circuit board.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an embodiment of the present invention will be described with reference to FIGS. 1 and 2. Reference numeral 1 denotes a bottomed resin case having an opening 2 on its upper surface. Tsuba 3
., And a plurality of mounting ribs 4... Are integrally formed at the bottom corners, and a plurality of mounting ribs 4. The fixing ribs 6 are integrally protruded.

Reference numeral 7 denotes a circuit board having a large number of circuit components 8 mounted on the surface thereof.
And fixing ribs 6..., And an insertion hole 9 is formed at least substantially at the center.

Reference numeral 10 denotes a nozzle for injecting the moisture-proof insulating resin 11 into the case 1. After the circuit board 7 is housed in the case 1, the nozzle is inserted through the opening 2 while the case 1 is placed horizontally. After the tip 12 is inserted into the lower side of the circuit board 7 through the insertion hole 9, the insulating resin 11 is injected from the tip 12.

A part of the injected insulating resin 11 is inserted into the insertion hole 9.
Overflows above the circuit board 7 so as to block the tip of the nozzle 10
After the air below the circuit board 7 spreads out from the portion 12 while being pushed out to the surroundings and is filled over the entire lower side of the circuit board 7, FIG.
As shown by, the space extends from the gap 13 between the circuit board 7 and the case 1 to the upper surface of the circuit board 7 and fills the entire inside of the case 1 to cover substantially the entire circuit board 7 and the circuit components 8.

In the above embodiment, the entire circuit component 8 is covered with the insulating resin 11. However, at least a conductive portion of the circuit component 8 such as a lead wire may be covered.

In the above embodiment, the insertion hole 9 is formed in the center of the circuit board 7 and the gap 13 is formed with the injection of the insulating resin 11.
The air is discharged from the lower side of the circuit board 7 substantially at the same time from the whole, so that no air pool is generated below the circuit board 7. However, the present invention is not limited to this.
May be perforated.

[0013]

According to the structure of the present invention, the generation of bubbles when the substrate is covered with the resin can be prevented as much as possible, and the insulation failure due to the bubbles can be prevented.

Further, according to the present invention, a hole through which a nozzle for injecting a resin is passed is formed at substantially the center of the circuit board, and an insulating resin is poured from a lower center of the circuit board to reduce air below the circuit board. It is discharged from the gap between the case and the case, and the generation of bubbles can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a side longitudinal sectional view of the same.

FIG. 3 is a side longitudinal sectional view showing the operation process.

[Explanation of symbols]

 Reference Signs List 1 case 2 opening 7 circuit board 8 circuit component 9 insertion hole 11 insulating resin

Claims (2)

[Claims] 1. An insertion hole is formed at an appropriate position on a circuit board on which circuit components are mounted, the circuit board is housed in a case having an upper surface opened, and a nozzle is inserted into the insertion hole from the opening of the case. A resin coating method for a circuit board, wherein an insulating resin is poured into the case from the lower side of the circuit board from the nozzle so that the entire or substantially entire circuit board is buried. 2. The method according to claim 1, wherein the insertion hole is formed substantially at the center of the circuit board.