Hoe kan ik de vochtadsorptie op FR4 PCB minimaliseren?

Adsorption is a chemical process that occurs on the surface and can affect surface resistivity. Since you are talking about PCB mass, it sounds like you are actually talking about moisture absorption which is diffusion into the bulk of the material.

If there are any fixing holes, it will be impossible to eliminate them completely.
I have some products where the use of this sealant is mandated (they are in ship-board aircraft). I only mention this to show there are solutions, if there is a requirement for complete sealing.
Simply covering most of the PCB with solder mask will reduce the absorption of moisture.
From a system point of view, other than the bare PCB, it would be important to avoid components that absorb moisture- which would include plastic-packaged parts, but especially polyamide (Nylon) fasteners etc. which can absorb an enormous amount of moisture (as much as 10%)- enough to cause large dimensional changes as well as mass changes.

Lees verder: Een uitgebreide gids voor FR4 thermische geleidbaarheid

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Olivier Smit

Oliver is een ervaren elektronica-ingenieur met kennis van PCB-ontwerp, analoge circuits, ingebedde systemen, en prototyping. Zijn diepgaande kennis omvat schematisch vastleggen, firmware-codering, simulatie, indeling, testen, en probleemoplossing. Oliver blinkt uit in het omzetten van projecten van concept naar massaproductie met behulp van zijn elektrische ontwerptalenten en mechanische vaardigheden.