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Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


uBGA Stencil Thickness

Ron Costa

#13257

uBGA Stencil Thickness | 16 December, 1998

I have a mixed technology board ranging from 50 mil pitch devices to 20mil Qfp's to PBGA-352 at 1.27mm, and 6 Intel uBGA-48 at 30 mil pitch. With all these different package types i'm torn between using a 4 or 5mil thick stencil. The ball dia. is 14 mil. I don't have a board to measure pad size yet. Has anyone had any experience with these packages? How about reballing these packages? Any feedback helpful! Thanks everyone! ..........Ron

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Earl Moon

#13258

Re: uBGA Stencil Thickness | 17 December, 1998

| I have a mixed technology board ranging from 50 mil pitch devices to 20mil Qfp's to PBGA-352 at 1.27mm, and 6 Intel uBGA-48 at 30 mil pitch. With all these different package types i'm torn between using a 4 or 5mil thick stencil. The ball dia. is 14 mil. I don't have a board to measure pad size yet. Has anyone had any experience with these packages? How about reballing these packages? Any feedback helpful! | Thanks everyone! ..........Ron | The fly in your ointment is the 50 mil stuff. Maybe if you converted it to finer pitch or?, you would find life easier.

Earl Moon

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anamonus

#13259

Re: uBGA Stencil Thickness | 21 December, 1998

| I have a mixed technology board ranging from 50 mil pitch devices to 20mil Qfp's to PBGA-352 at 1.27mm, and 6 Intel uBGA-48 at 30 mil pitch. With all these different package types i'm torn between using a 4 or 5mil thick stencil. The ball dia. is 14 mil. I don't have a board to measure pad size yet. Has anyone had any experience with these packages? How about reballing these packages? Any feedback helpful! | Thanks everyone! ..........Ron |

Ron;

We have tested both 0.005" and 0.006" thick stencils with various aperture sizes. In all cases, acceptable solder joints were present. Given the technology you described, we would use a 0.006" stencil.

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Earl Moon

#13260

Re: uBGA Stencil Thickness | 22 December, 1998

| | I have a mixed technology board ranging from 50 mil pitch devices to 20mil Qfp's to PBGA-352 at 1.27mm, and 6 Intel uBGA-48 at 30 mil pitch. With all these different package types i'm torn between using a 4 or 5mil thick stencil. The ball dia. is 14 mil. I don't have a board to measure pad size yet. Has anyone had any experience with these packages? How about reballing these packages? Any feedback helpful! | | Thanks everyone! ..........Ron | | | | Ron; | | We have tested both 0.005" and 0.006" thick stencils with various aperture sizes. In all cases, acceptable solder joints were present. Given the technology you described, we would use a 0.006" stencil. | | Don't hide your true identy. Who is that masked man/woman. Must be a saint at this time of year.

Please tell use the secret to using such skinny stencil thickness to be so omni-capable as to support everything from 50 down to 20 mil pitch.

I don't mean to be sarcastic. I really would like to know how to do this type thing consistently - whether you reveal your identity or not.

Most respectfully,

Earl Moon

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