JPS6245132A - Insulating and sealing method for electronic circuit-board - Google Patents

Abstract

PURPOSE:To improve the effect of heat-dissipation of an electronic circuit-board, and to reduce trouble, damage, etc. due to a temperature rise of the electronic circuit-board by bringing the surface area of a potting or casting agent to not less than one and a half times as large as the projected area of the electronic circuit-board. CONSTITUTION:The surface area of a potting or casting agent 2 is brought to not less than one and a half times as large as the projected area of an electronic circuit-board 1. The surface areas such as one of an electronic-part loading surface in the circuit-board 1 and a casting agent 2 layer to which the back is totalized are brought to 1.9 times as large as the total of the projected areas of the electronic-part loading surface in the circuit-board 1 and the back. Accordingly, the effect of heat dissipation from heat-generating parts for an electronic circuit is improved, thus reducing trouble, damage, etc. due to heating.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to an electronic circuit board that is insulated and sealed.

In particular, the present invention relates to an insulating sealing method for an electronic circuit board in which the surface of an insulating sealing material is provided with irregularities in order to enhance the heat dissipation effect.

[Background of the invention]

Generally, electronic circuit boards on which various electronic components are mounted are coated to make them dustproof, moistureproof, and waterproof. On the other hand, with recent advances in the use of electronics in home appliances, electronic circuits are increasingly being used under high humidity conditions. Therefore, leakage current may occur in the electronic circuit due to moisture or moisture adhesion, which may cause malfunction. Conventional methods for forming this coating include spray coating, dip coating, brush coating, and the like. However, in actual electronic circuits, various types of electronic components are mounted, each having a different allowable value for leakage current that can cause malfunctions, and components and positions that are difficult to coat, making it difficult to provide complete moisture-proofing measures. Therefore, recently there has been a trend toward so-called casting, in which the entire electronic circuit board is placed in a mold and embedded in an insulating material. This method uses thermosetting or thermoplastic resin, and hardens the legs of the electronic components mounted on the circuit board in a certain mold to a thickness that completely fits both the front and back sides of the electronic circuit board. The entire board is insulated and sealed. This greatly improves the moisture-proofing effect and prevents malfunctions due to leakage current due to moisture adhesion.

However, casting has the disadvantage that it uses a large amount of polymeric material with low thermal conductivity, which significantly reduces the heat dissipation effect of heat-generating components such as transistors, and at the same time increases material costs. ing.

[Purpose of the invention]

An object of the present invention is to reduce the heat dissipation effect of a cast electronic circuit board, thereby reducing malfunctions, damage, etc. due to increased humidity of the electronic circuit board.

[Summary of the invention]

The present invention increases the surface area of a casting agent formed for the purpose of protecting electronic circuits in order to suppress the reduction in heat dissipation effect due to its low thermal conductivity. The above-mentioned casting refers to a method of forming an electronic circuit protective layer characterized by pouring a liquid casting material into a certain mold along the electronic circuit board and hardening it by polymerization, drying, etc.

As this casting agent, known ones can be used. Specific examples include acrylic resins, urethane resins, polyester resins, and epoxy resins, and these resins dissolved and diluted with organic solvents or monomers themselves can also be used. These casting agents include dyes, pigments, and thixotropic agents.

It may also contain anti-aging agents, plasticizers and fillers. Further, the electronic circuit includes an IC, a transistor, and a resistor.

This includes those equipped with electronic components such as capacitors and microcomputers.

[Embodiments of the invention]

Embodiments of the present invention are shown below according to the drawings. In FIG. 1, 1 is an electronic circuit board, 2 is a casting agent (urethane resin), and 3 is electronic parts. Of these, 3a is a microcomputer, 3b is a transistor, and 3c is a resistor. In the circuit cross section in Figure 1, the total surface area (surface area A) of the casting agent layer on the electronic component mounting surface and the back surface is 1 with respect to the total projected area (surface area B) of the electronic component mounting surface and the back surface of the circuit board. .9 times.

In FIG. 2, 4 is a filler (quartz powder) and 5 is a substrate support case (polystyrene resin). In this example, 1
The ratio of surface area A to surface area B is 1.5 times.

〔Effect of the invention〕

According to the present invention, it is possible to enhance the heat dissipation effect from heat-generating components of an electronic circuit that is insulated and sealed by casting or potting, and has the effect of reducing malfunctions, damage, etc. due to heating.

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory diagrams of an electronic circuit board subjected to a casting process according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Electronic circuit board, 2... Casting agent (potting agent), 3... Electronic components, 3a... Microcomputer, 3b... Transistor, 3C...
Resistor 4: Filler, 5: Board support case.

Claims (1)

[Claims] 1. In potting or casting an electronic circuit board, the surface area of the potting or casting agent on the front or back surface, or both, is at least 1.5 times the projected area of the electronic circuit board. A method for insulating and sealing electronic circuit boards. 2. Claim 1 which uses a material in which a potting agent or a casting agent is used as a binder and an inorganic filler is mixed therein in an amount of 10% or more by volume to the binder for the purpose of increasing the heat conduction effect. A method for insulating and sealing an electronic circuit board as described. 3. A method for insulating and sealing an electronic circuit board according to claim 1, which is used for electronic circuits such as washing machines, dryers, kitchen appliances, etc.