Electronics Assembly Manufacturing Question

Sep 19, 2005 4 Replies
V

I have a board with mixed surface mount parts and thru hole parts. Furthermore, there are smt parts on both sides of the board. I would like to have the smt stuff soldered on by the assembly house, and i can solder the few thru-hole parts on myself, so to avoid extra assembly costs.



For those of you familiar with the assembly process, how do they do it? Do they place the SMT stuff on one side first, solder it, then the other side and solder that? What do they do with all the vias and thruhole holes? Do they put some type of latex-like gum on them to prevent the smt soldering process from filling up those holes?



Reason why i ask is that it may actually take more effort to prevent the thru-hole pads from getting filled up with solder during the initial smt parts soldering, that I may as well just let them stuff the thru-hole stuff too.



Thanks, Mike



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J

What we do is

Paste the bottom; use glue for big parts.

Place bottom parts.

Reflow

Paste top

Place top parts

Reflow

Place and solder thru-hole by hand.

The thru-holes stay clear during the surfmount steps.

I think some people glue all the bottom parts and wave solder the thru-holes and the bottom parts in a wave solder machine.

Why not let them do it all?

John

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S

They can typically do this, and it can be a reasonable course of action. Talk to your assembly house and get quotes both ways.

Best regards, Spehro Pefhany

"it\'s the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
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J

I read in sci.electronics.design that John Larkin wrote (in ) about 'Electronics Assembly Manufacturing Question', on Mon, 19 Sep 2005:

It avoids questions of who is responsible when the boards don't work. That can be worth $$$$.

Regards, John Woodgate, OOO - Own Opinions Only. If everything has been designed, a god designed evolution by natural selection. http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
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V

Thanks for the replies John, John, and Spehro. I have gotten quotes to do it both ways. If i let them do the smt stuff only, it would cost $25. To do the few thru-hole parts in addition, it would then cost a total of $45. Since we're a small startup with this small initial production run, then the $20 savings is worth doing it in-house.

As long as my thru-hole pads go untouched when i get the partially assembled boards, which they are, then it's all good.

Thanks! Mike

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