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Small apperture release from stencil

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#68175

Small apperture release from stencil | 12 February, 2013

Hello everyone,

I am curious what do you think about stencil type and apperture design for better release on small appertures. I have a PCB with bunch of BGAs with small appertures. We tried with Nikel stencil using DEK's special non stick material for better release but we are still not satisfied with the results. Please give me your recommendations.

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#68176

Small apperture release from stencil | 12 February, 2013

We have a board with a 1.0mm pitch BGA. The stencil apertures are 0.0177 inch diameter. We used an electroform stencil with good results.

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#68178

Small apperture release from stencil | 12 February, 2013

You need a good designed stencil. Contact Steve - He'll make a free article stencil to try out below is his contact info. Steve@usastencils.com 714-636-6211 Good luck!

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#68179

Small apperture release from stencil | 12 February, 2013

My appertures are 10mil diameter. Using electroformed stencil is probably be my next step. Thank you!

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CPI

#68190

Small apperture release from stencil | 13 February, 2013

what type of paste are you using?

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#68192

Small apperture release from stencil | 13 February, 2013

SAC305

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#68221

Small apperture release from stencil | 15 February, 2013

What foil thickness? Type 3 or 4 paste? Have you checked your area ratio(s)? You could overprint or drop your foil thickness by one mil to improve the ratio and paste transfer. As always you can search the fine SMTnet archives for more info.

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#68222

Small apperture release from stencil | 15 February, 2013

Hi MikeS,

I didn't post all the information, because I didn't want to mislead you. I wanted to see your way. We tried 3mil and 4 mil stencil using type 4 paste. It was hard to get the right aspect ratio and that;s why we did it on Nickel stencil - aspect ratios are different for Nickel stencil. Unfortunately it didn't completely fix my problem. I still have some appertures that don't get the right deposit. Any other thoughts?

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Pete B

#68235

Small apperture release from stencil | 18 February, 2013

What type of flux material does your solder paste have? I have seen difficulties when attempting to print small apertures with water washable and rosin types.

Do you get a good first print and then have problems or is it the same from the start?

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#68236

Small apperture release from stencil | 18 February, 2013

Why don't you try some nano-marvel-snake-potion ?

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#68238

Small apperture release from stencil | 18 February, 2013

No Pete,

problems start with very first print.

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Pete B

#68240

Small apperture release from stencil | 19 February, 2013

> No Pete, > > problems start with very first > print.

OK, So what is the flux type in your paste?

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