Yellowish substance covering circuit board

This is a contact-less charger from an electric toothbrush.(NiCd)

What is the yellowish substance that is covering the circuit board?

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Thanks.

Reply to
Andy
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Potting Compound!!! Try poking it with hot soldering iron. The smell and/o r how easily/cleanly or what temperature it melts should help you identify if it's a polyester type, polyurethane, one-part thermoset, or something el se...

If it's soft/rubbery when you poke at it with a tool, it's likely a Silicon e based potting, however seeing the amber color in the photo suggests it is not at all Silicone type. Also, given this is a consumer item, it's more likely to be a very low cost potting. Either a thermoset (hot melt glue es sentially), or a two-part polyester resin/hardener.

Reply to
Terry

/or how easily/cleanly or what temperature it melts should help you identif y if it's a polyester type, polyurethane, one-part thermoset, or something else...

one based potting, however seeing the amber color in the photo suggests it is not at all Silicone type. Also, given this is a consumer item, it's mor e likely to be a very low cost potting. Either a thermoset (hot melt glue essentially), or a two-part polyester resin/hardener.

When touched by a 30 watt iron, it turned to opaque pieces.

In electronics, potting is a process of filling a complete electronic assem bly with a solid or gelatinous compound for resistance to shock and vibrati on, and for exclusion of moisture and corrosive agents. Thermosetting plast ics or silicone rubber gels are often used. Many sites recommend using sili cone or epoxy to protect from impact and loose wires. [1] Araldite (a brand name) potting compound has been suggested for certain automotive applicati ons[citation needed].

Since it was used in a bathroom, the potting would help with the moisture.

Unfortunately, it makes parts not reusable.

Andy

Reply to
Andy

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** IME, consumer electronics is rarely "potted" and the few that I have come across were done mainly to prevent outsiders from copying the circuitry.

Shock and vibration can be dealt with adequately by simply gluing down any bulky or heavy items on a PCB.

OTOH, not long ago the *potted* motor controller in my washing machine gave trouble. Initially the fault appeared to be mechanical, as the loud growling noise disappeared after a few minutes use.

The very common & real cause turned out triac/s that would not fire in one quadrant until they became quite warm - resulting in half wave power being fed to the main motor.

An easy and cheap to fix problem IF the module were not "potted".

.... Phil

Reply to
Phil Allison

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