Unusual board with BGA

Yes, you can ask for scrap boards, buy Dummy boards/parts or engineer off past runs. For this cost, I would profile, profile, profile. I would make/buy a dummy board. If you don't have one this thick, glue/ adhesive/ bolt some scrap boards together to make a thickness similar. Use a band saw to cut to size. Buy dummy BGA parts and glue to the middle of your board. You don't need copper pads - just make sure there is a hole in the middle of the board so you can measure the t-couple you put up in there. Now you're all set. It's not rocket science but it will take about 90% of your doubts away.

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Hey SWAG- Not an uncommon scenario where I'm at. But the bottom line is, as others have said: Profile, profile, profile. Here, we have dedicated profile boards for each product we build and in most cases they're EXACT representations (my library is approaching 750 at this writing). Not only will it serve you in developing the initial profile, but it'll be there for you when you want to transfer to another line, diagnose a quality problem, develop a profile for your rework machine when the line installs the BGA reversed, etc.

We insist from our customers, at the quoting stage, that we need X profile boards and in most cases we get little argument for our request for both a 1st pass and a 2nd pass profile board (and wave if needed). It costs $$ in the short term but saves $$$$ in the long run. These boards also have real parts, except when price and/or availability are an issue. Then we'd use a mechanical sample, electrical defect, or a similar (and cheaper) part. Possibly, you'll have a scrapped board (built with an inadequate profile! Ah, the irony).

If they argue with us, we do the best we can- possibly using a similar-to board (which wouldn't help to profile your rework machine), but our caveat to them is: your boards will be built with our best guess. Without a robust and thorough profiling process, that's all it is: a guess. You'll make some sound assumptions and you may be ok, but we've all had boards that gave us trouble when at first, they looked like no-brainers. They way the joint 'looks' is NOT sufficient (though the bean-counters may assume so).

Make a dedicated profile board (a solder sample will work fine), and you'll nail it. Then box it up and store it away to keep it in good shape for when it's needed again, because it will be. Guaranteed. Best of luck, and Merry Christmas.

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