I was very interested to see that there are a number of people who have
the same problem as we are experiencing regarding SMD capacitors.

We have found a number of our 100 NF 50 Volt ceramic de-coupling
capacitors are going short circuit after 9 months or more. The
capacitors are not a dead short, but are pulling down the VCC line.

We are using Kemet X7R 1206 caps. The caps are connected VCC to Ground.
Once the cap or caps have been replaced the units work.

The printed circuit board is FR4 and is 1.6 mm x 15 cm x 6 cm. The
boards go through 2 soldering stages ie. one for the SMD components and
then for the conventional components.

The printed circuit board once completed is coated with a urethane
MS472N conformal coating.

I would appreciate any information or suggestions you could offer.


Thanks Very Much

John Olivier

Quality Assurance Manager

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