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BGA process

Views: 1789


Ev

#55472

BGA process | 11 July, 2008

We are a small prototype small volume shop looking at getting more work that involves placing BGA's. What are the concerns or issues that we should be focusing on. We have an ABW 10 zone oven and a Mydata TP11-UFP with a SMT techniques stencil printer.

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#55474

BGA process | 11 July, 2008

BGAs are actually easy, but proper stencil design, solder paste placement and oven profiles are a must. Especially oven profiles as this is your only indication that the inner balls have reached proper temp, since you cannot visually tell. If you go micro BGA you may need to look at the "Type Size" of paste you are using.

Do not over look board design either. Proper dog-bone patterns and mask coverage will only help you. The BGA data sheets will cover this for ya.

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Ev

#55516

BGA process | 15 July, 2008

Thanks for your reply.

Ev

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#55558

BGA process | 16 July, 2008

BGA Placement is not easy as we think, Mainly you have to make sure you don't have acceessive amount of paste, try to paste your board as it covers full ball, make sure it is not short before you place any part.

If you placing the BGA by hand be carefull , once you done the placement don't assume it is perfect by part's layout on pcb, check out all four side under scope try to use torch light to see clear under BGA as your ball is sitting on paste or not.

When you pass it in oven make sure you use right temperature, never try to use low temp, use little high it is ok. Once you done if you have X-ray plz check on that or check one more time using Torch light under your part as the solder is good enough, or you can now check under Scope too as now you can make your board vertical.

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#55567

BGA process | 17 July, 2008

5 mil stencil.instead of round, use diamond aperture. RSS profile @ 215�C peak temp on balls(Sn/Pb), with a total of 3.5 minutes profile lenght.Ramp rate at 1.7�C/sec from ambient to 160�C. Consider also good cooling system on reflow. If rework process, try ERSA.

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#55574

BGA process | 17 July, 2008

6 mil 100% on pad print. No shorts.

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Ev

#55607

BGA process | 21 July, 2008

Excellent feedback, thanks again.

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