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[Koen]

Hello,

I would like to pot a PCB including RF inductors and capacitors. The potting compound has an Er of 4.6, similar to FR4. It impacts the capacitance of the RF components and I would like to shield these with a bubble of air to reduce these changes. Would you have an idea of the necessary shielding space needed around 0402 components ? Would a few millimeters left, right and above be enough or is much more volume needed ?

Thank you !

[admin]

3mm would be more than enough for 0402s.

The fields on capacitors are pretty tightly bound so I wouldn't expect a huge change in capacitance. Inductors won't be affected unless you are near their self resonant frequency.

I would say 0.5mm surrounding the components would be more than sufficient

[Koen]

Thank you for your answer ! I will try to surround the components by a thin layer of air and report of the results as I had a terrible time finding literature about this problem.