PCB Warps

Hello !

I have a problem with one of high runner, our board comes in a seal package with dessicant cant really tell you how much RH% is inside the bag, but our board does not spend a lot of time in the shelf just some days or a couple of weeks max, the storage room is a control enviroment 22oC and 55%RH or lower, as a precaution we bake the boards one hour before running the product at 100oC, after an hour we take them out on put them in a ESD shield bag with active dessicant. And if you take a board out of the bag you notice a sometimes very remarkable warp in the board, for most of the time is only slight warping.

Any ideas on how to avoid warping in the board?

thanks

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