Cause: The feedback from the customer of Volkswagen; use SM15 to protect the circuit board, which was used well before. Recently customer found SM15 circuit defective, just one road of SM15.
LEIDITECH’S ANALYSIS IS AS BELOW:
SM15 SOT-23 15V, TWO ROAD, ONE-WAY
SM15 PACKAGE IS AS BELOW
SM15 internal diagram:
Thru X-ray vision SM15, we cannot see any damage, picture as below:
Analysis diagram of SM15 is as below picture:
SM15 have two roads, the analysis show that the electric of one road is normal, the breakdown voltage is 17v, and this road is not damaged.
The electricity for the other road is not normal, the breakdown voltage is 7V. Analysis shows that this road is damaged.
SM15 is magnified to 1000 times, as below picture:
Then we can see the damage mark in the SM15 PIN
Leiditech’s analysis result:
The customer find that one road of SM15 is broken when combine the whole car, which meet the analysis result from Leiditech.
The reason is there’s one road is damaged. The breakdown voltage of SM15 is down to 7V not 17V.
It has been a long time since the customer begin to use SM15.One piece is broken this time, it means SM15 was surly attracted by the surging. Sm15 has already provide a protect function for the IC. Also, this caused only small damage and itself has anti-ESD ability.
The customer should analyse where the surge voltage exists and how to do with surge voltage in the production period.
Especially in the dry autumn, production machine will cause too much static electricity when working. Customer should release ESD.
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