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What Causes Board Delamination?
Board Talk
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TranscriptPhil Welcome to Board Talk with Phil Zarrow and Jim Hall of ITM Consulting, the Assembly brothers. Coming to you today from the ITM Consulting failure analysis cave high atop Mount Rialto. Jim what's our question of the day? Jim We actually have a similar question submitted by two listeners; the first one is from D.H. We are experiencing delamination on our printed circuit boards causing scrap, is there a way to definitively determine that the delamination is being caused by moisture or some other type of defect? Is it possible to repair printed circuit assemblies with delamination? Frank from Montreal has basically the same question but notes that he is processing his boards, reflowing them, very soon after receiving them so that they're not hanging around his shop. But had basically the same question; should he bake them and so forth. Phil There are a lot of aspects that come into play here, but in our allotted five minutes let's hit on the key ones. First make sure that your fabricator is using laminates that pertains to the current specification. We've run into a number of people who are still fabricating to the IPC 1399 spec. That went out quite a few years ago. Per our good friend Gary Ferrari, Dr. Design, basically any material being used these days, particularly for lead-free, should be conforming to IPC 4101/126 or /129 and this is basically high performance material with very high T sub G and T sub D decomposition temperatures and tolerances. Make sure you're using the right material. Then once we get into your shop, you should be following IPC 1601 that covers the handling and care, and storage of circuit boards. Make sure that you've done the proper due diligence and your design of experiment for your reflow profiles or your wave solder or selective soldering profiles and certainly your hand soldering is under control. Jim, there is a way, I believe, of measuring whether you have absorbed moisture. Jim I know that some people have determined that there is moisture in the board by weighting the board first then baking it per IPC 1601. That's the nice thing about 1601, it defines specific baking time cycles which has been a question throughout the industry for a long time until that came out. I know that some people have weighed the board and then baked it and weighed it afterwards and the difference was the amount of moisture. In terms of determining whether there was moisture and whether it was causing your problem that would be one thing to do. I'm not sure if that procedure is described in 1601 but you just need a very accurate scale. In terms of repair, I imagine that the more sophisticated circuit board repair shops that repair damaged boards can repair a certain amount of delamination. Delamination is really destroying the basic structure of the board. I don't imagine that a badly delaminated board could be repaired. But it's something you can check with a professional circuit board repair service. Phil Like Circuit Technology Center and there's a number of others out there. Jim Make sure that your supplier is handling the boards properly and drying them and following the procedure so that they're not getting to you wet and that they're coming they are coming in the properly sealed packages. Most boards are coming from overseas and there is storage times depending on whether your shipping by boat or by plane but in all cases, IPC 1601 will guide you about how to seal them and you should keep them sealed until you're ready to use them. Phil Yes, been there done that; I own a delaminated t-shirt. You've been listening to Board Talk. Whatever you're doing and however you're doing it, don't solder like my brother. Jim And don't solder like my brother. |
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