Hello, my name’s Bob Willis and welcome to Defect of the Month. Every month, I try and provide an example of a particular defect and hopefully some solutions. I’ve made over a hundred different defect videos over the years so hopefully one will solve one of your production problems.
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Now popcorning on surface mount components has been around for many years. I remember seeing it very, very early on in my career at GEC when we introduced a SMT with some small parts. If the moisture increases inside plastic components it can expand as a gas and try to escape. So quite often, you’ll see a crack in the package around the edge of the plastic moulding to PCB interface on Plastic Ball Grid Arrays (PBGA)
If you’re using some BGA packages the crack will occur in the top of a plastic package or on the bottom of a plastic and in any one of those situations, potentially it can cause you an intermittent or a complete failure of the part. If you’re doing rework and repair of a package on a board it’s good practice, particularly on high price boards with more expensive parts to bake out the board assembly before you remove any components. This is also true if you’re going to do failure analysis on that particular part. If you’re just going to take it off and throw it away, it’s perhaps less important. You also have to remember about adjacent components because they too could actually see much higher temperatures during rework and repair