Bottom side SMT wave vs. top side reflow yields

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Assuming all things are equal (attention to good DFM guideli... - Aug 29, 2002 by Steve Thomas

Hi Steve, On my point of view, you already answered your ... - Aug 29, 2002 by

Steve, I agree, you should expect to have better results ... - Aug 29, 2002 by Larry Bay

Steve: I agree. Let�s break it down. * I�d rather print p... - Aug 29, 2002 by davef

Thanks, guys. Hi Larry, long time no "see". Dave, 60k do... - Aug 30, 2002 by Steve Thomas

;P Have a nice weekend ... - Aug 30, 2002 by davef

Steve Thomas

#21356

Bottom side SMT wave vs. top side reflow yields | 29 August, 2002

Assuming all things are equal (attention to good DFM guidelines, well trained and capable operators, well maintained equipment, etc.), which would you expect to have the higher process yield, standard SMT/through-hole all topside, or all SMT bottom (glued and waved), all through-hole top?

I would expect that reflowing SMT parts would produce a far higher yield (as well as a much lower dpmo), especially in large, high part count boards, but I'm just guessing.......

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Dreamsniper

#21362

Bottom side SMT wave vs. top side reflow yields | 29 August, 2002

Hi Steve,

On my point of view, you already answered your own questions and I agree with your answer.

regards, Dreamsniper

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Larry Bay

#21364

Bottom side SMT wave vs. top side reflow yields | 29 August, 2002

Steve,

I agree, you should expect to have better results from double sided reflow. It is more difficult to dial in a wave solder process for SMT components than a reflow oven. Besides that - adhesive is just no fun to work with.

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davef

#21367

Bottom side SMT wave vs. top side reflow yields | 29 August, 2002

Steve: I agree. Let�s break it down. * I�d rather print paste than glue any day of the week * But I know yera �Dispenser Boy�. In that case, I�d rather dispense glue than paste. * PTH / primary and SMT / secondary is a tough process either way you go at it. If you go PTH first, it becomes tough to glue / place / cure the SMT. Alternately, glue / place / cure SMT first serves-up the potential for lots of �lost� SMT during PTH handling. * Wave soldering the secondary side SMT component is more difficult than reflow soldering those same components. * Wave soldering the secondary side SMT component exposes those components to higher temperatures than reflowing the same components. * If the solderability protection on the board [er may be some component] didn�t like to see multiple heat cycles, the latter approach is preferable.

There�s probably more, but I�m madly singing [good thing no one�s here] along with �Mamma Mia!� and can�t think.

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Steve Thomas

#21384

Bottom side SMT wave vs. top side reflow yields | 30 August, 2002

Thanks, guys. Hi Larry, long time no "see".

Dave, 60k dots out of a Camalot 2800 does not a "Dispenser Boy" make. :P

I'd print them in a heartbeat if the proximity to radial leads didn't necessitate me placing radials first. Oh, wait, I'd have to heat my stencil washer to 140F, thus turning my paste stencil epoxy to something resembling creamy peanut butter. Nevermind.

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davef

#21387

Bottom side SMT wave vs. top side reflow yields | 30 August, 2002

Have a nice weekend

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