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Have any paper or data talking about "BGA Stencil design guideline for avoid bridge"?

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#81007

Have any paper or data talking about "BGA Stencil design guideline for avoid bridge"? | 6 September, 2018

Dear Experts,

Have any paper or data talking about the design guideline

for avoiding BGA solder bridge?

I desire to know the rule(guideline)that compare

difference stencil thickness and safe solder design distance

(air gap) can avoid bridge.

Thanks for your helping

James

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#81009

Have any paper or data talking about "BGA Stencil design guideline for avoid bridge"? | 6 September, 2018

I'm no expert but I think you will find the majority of discussions around BGA & good printing results focus on the PCB design and things like tented vias and pad definition. e.g https://macrofab.com/blog/bga-pad-creation-smd-nsmd/

After that, work with your stencil supplier to create a stencil that works best for your design who might suggest stepping, coatings aperture reductions etc.

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#81010

Have any paper or data talking about "BGA Stencil design guideline for avoid bridge"? | 6 September, 2018

Thank you Mr.Spoiltforchoice,

My question is not clear , let me show you a photo

Did you have any suggestion?

Thanks

James

Attachments:

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#81011

Have any paper or data talking about "BGA Stencil design guideline for avoid bridge"? | 6 September, 2018

I did a Google search => pdf "BGA Stencil design guideline for avoid bridge"

As you would expect, Google found 40,000+ results in less than a second

One of my favorites was Power Point Presentation by Greg Smith [gsmithATfctassembly.com] at FCT Assembly: "Improve SMT Assembly Yields Using Root Cause Analysis in Stencil Design" [ http://blueringstencils.com/wp-content/uploads/2017/07/Improve-Yields-Using-Root-Cause_ppt.pdf ]

I searched the SMTnet Technical Library and found the technical paper version of "Improve SMT Assembly Yields Using Root Cause Analysis in Stencil Design" [ https://smtnet.com/library/files/upload/root-cause-analysis-smt-assembly.pdf ]

If you find some interesting papers, give us a link so that we learn too.

Here is a good paper by Cookson that covers lots of the bases http://www.solderworld.net/docs/SMT-troubleshooting-guide.pdf

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#81014

Have any paper or data talking about "BGA Stencil design guideline for avoid bridge"? | 6 September, 2018

Dear davef,

All of this are takling about how to improve release solder paste, Area ratio, aspect ratio...etc, but i want to learn the "When design BGA stencil which the safe air gap between solder paste in difference stencil thickness", this can help engineer design the maximum solder volume and can avoid bridge.

if i get some papers or information, i will share to you

Thanks for your help

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#81015

Have any paper or data talking about "BGA Stencil design guideline for avoid bridge"? | 7 September, 2018

You have lost me, its a stencil, you can change the aperture size, you can change the thickness and you can change the walls of the aperture. And all of those things will be in the papers anyone can find with a google. I have no clue what safe air gap means or what your picture is trying to demonstrate. A cross sectional diagram rather than top down might make more sense perhaps?

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dwl

#81017

Have any paper or data talking about "BGA Stencil design guideline for avoid bridge"? | 7 September, 2018

Air gap on the PCB is determined the pad spacing which in turn is governed by the component. As long as the PCB designer is following the typical BGA layout best practices; i.e no open via in pad, non-solder mask defined pads, solder mask covered traces etc. you should be fine.

There really isn't a reason to over print BGA pads except in the case of very small pads when you are trying to improve paste release. This leads into the stuff about stencil thickness, area ratio, etc.

Maybe you can give us more detail about your problem, then we can tailor our responses to be more helpful to you.

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