| 摘要 |
PROBLEM TO BE SOLVED: To prevent a malfunction, a runaway of a microcomputer because of a circuit short subsequent to dewing or water invasion to an electronic circuit part by applying a moisture resistant potting material to seal parts of front and rear faces of a printed wiring board and making the parts moisture-proof. SOLUTION: A gas meter called as a microcomputer meter having an electronic circuit part 1 for the purpose of security to detect an abnormality in usage of a gas and drive an isolation valve thereby stopping the gas is exemplified. A microcomputer chip 11, a control IC 12, a quartz oscillator 13 and the like are parts of a front face of a printed wiring board 2. A connecting pin 19, a lead wire unit 23 and the like are mounted to an end part of the board 2. A cover 20 for covering the board 2 is fitted to a rear face of the board and a flow rate sensor unit 21 is set to the cover 20. Moisture-proof potting is provided to the board 2 to seal the parts. A moisture-proof material is an epoxy resin, a silicon resin or the like resin. When a printed wiring is soaked in an urethane resin to obtain coating to an end face of the board 2, a circuit short can be prevented furthermore.
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