Pin hole

Hello Sir. We also encountered the same pin-hole issue but there was around MLCC.I also looked for some information in technical report and internet, But i failed to get an answer. As you know this pin hole or blow hole is caused by the solder boiling during reflow so it is recommended to check the reflow profile again in this case. And i asked IPC about the specification of pin-hole. You also can find the specification. The pin-hole is acceptable if solder connection meets the other requirement such as fillet or coverage ... I think the attached picture is acceptable. Thanks Ju-young.Jeong

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Hi, blow holes / pin holes / holes in joints are usually a sign that there is excess moisture somewhere around the solder joint. Moisture can be in pcbs / components, so try drying them....a simple thing to do is pass a bare pcb throught your reflow oven with no paste or components on to dry it, hopefully a sufficient amount... then assemble it as normal. Put devices in a dry cabinet for a few days to dry them out. Don't bake them as this increases oxide layer on leads. If neither of these work then the moisture is probably coming from the paste reaction with the oxidation on the pcb pad/device leads....H2O is probably a by-product of the flux action. The more oxides there are on the device leads and pcb pad then the more H2O the flux reaction makes, so the more moisture there is to come out of the fillet.

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Hi , Looking at your photo....can I also see a hole in the middle of the joint on the chip component ? Maybe its not just a problem with th ejoint son diodes ? Did you also get mid chip solder balls on chips? If so, I'd almost guarantee the pcb has too much moisture in it....a quick test is as I recommended in my previous post (pass bare pcb through reflow oven then assemble it as normal and inspect, no holes = excess moisture in pcb)

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