ESD Damage in Zener Diode

Sometimes we’re lucky and stumble into something like this ESD damage in a Zener diode. The diode was short circuited, but it was micro sectioned in order to determine the die thickness (not something we would normally do on a shorted diode).

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A damage site was found directly under the ball bond. The damage was determined to be a gold spike (as in ESD) that punched the junction shorting the diode.

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Severe corrosion on PCBA

Activated solder flux residues left on a PCBA can cause severe corrosion problems. The leads on the component shown below are severely corroded.

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The elemental spectrum suggests that the needle like corrosion product is lead chloride & lead bromide.

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Conclusion – avoid inadequate cleaning of PCBAs.

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