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Requirements for Depaneling and Rescoring Circuit Boards with BGA Components
Board Talk
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TranscriptPhil And welcome to Board Talk with Phil Zarrow and Jim Hall, The Assembly Brothers, sometimes known as Pick and Place, and who by day go as ITM Consulting. We are here to talk about assembly processes, including equipment, methodologies, material and components. Today we have a question from A.A. Are there any special requirements for depaneling and rescoring separate panel circuit boards if they contain BGA components? Then he goes on to ask, what are the safest, best methods for depaneling circuit board that have BGA components? Jim First off, Phil, I want to point out that far and away, the most common component damage by depaneling are chip components, resistors, and capacitors. They are very small. They tend to be all over the board, close to the edge, and so forth. Phil There are design guidelines, depending on the methodology that you are using, for singulation. I seem to recall people using pizza cutters. Probably not the best method, but I have to say probably the most common out there. If I recall correctly, typically, the manufacturers recommend about a 5 mm keep away from the scored area and also being careful of your orientation. Another friend of ours from one of the capacitor companies once said that he wishes he had a nickel for every cracked capacitor that he saw, thanks to pizza cutters. Jim If you are using a pizza cutter type thing, you want to support that board as close to the edge as it is going through the whirling blade. Phil Yes, support is very, very important. But to answer the question that A.A. is asking here, and I know we have discussed this type of thing before, probably the best and safest methodology out there that we are aware of is routing. Routing introduces the least amount of stress to the board therefore, it is the safest. Regardless of what components you are doing, certainly anything with C5 or C4 attachments BGAs, chip scale, things along those lines. Jim The thing with BGAs is, what is the pitch? How big is the solder joint? If you have 50 mil pitch BGAs 40 mil pitch BGAs, the balls are pretty big, and the solder joints are pretty big. They are going to be much less sensitive to fluxing bending in the depaneling operation. If you are putting down micro-BGAs with a .4 mm pitch and they are at all close to the edge, you need to be concerned about that. Those solder joints are much smaller and much less structurally strong. Phil And by the way, we have seen other methodologies that would make your hair turn gray in a moment. We have seen the karate chop method, bending and breaking in mid-air. What is another one? The paper cutter. I always go down to the office supply place to buy my PCB assembly equipment. All of these put undue stress on the circuit board and should be avoided at all costs. This has been Jim Hall and Phil Zarrow, The Assembly Brothers, speaking to you today on Board Talk. Regardless of how you are going to singulate your boards, when you go to solder them, don’t solder like my brother. Jim And don’t solder like my brother. |
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