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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Howard Rush on November 09, 2009, 04:46:33 PM

Title: Soldering Problem
Post by: Howard Rush on November 09, 2009, 04:46:33 PM

This is actually a stunt-related question.  How would a person manually (with iron or with toaster oven) solder an LGA chip?  These things have the pads on the bottom, where you can't get access to remove solder bridges.  I have the notion to get boards made with through-plated holes centered on the pads.  I'd turn the board over and solder the thing through the holes. Would that work?

Title: Re: Soldering Problem
Post by: John Witt on November 09, 2009, 09:01:12 PM

We have some guys at work who build our boards. I will ask them for suggestions tomorrow.

John

Title: Re: Soldering Problem
Post by: Igor Burger on November 09, 2009, 09:48:34 PM

Air heat gung works  VD~

you must apply solder on all points on board before, then heat it from opposite side of the board (from distance, otherwise solder sprays from holes), and when you see all points liquid ....  ;D

but you must do LGA chip FIRST ... otherwise all other component which are already on board go away  :##

Title: Re: Soldering Problem
Post by: Dean Pappas on November 09, 2009, 10:07:23 PM

Hi Howard,
Yeah its a real pain the the you-know what.
Tell you what else is a pain, my eyes just get older and the parts just get smaller!
This is progress?
I do what Igor describes, though I often use the hot air gun from the component side.
If you are likely to do this either by hand with the hot air gun or even a pointy iron with solder paste,
then make the pads a little extra longer outside the part to facilitate heating.
The standard footprint assumes an IR reflow machine.
later,
Dean

Title: Re: Soldering Problem
Post by: Ralph Wenzel (d) on November 10, 2009, 05:40:46 AM

Maybe I'm reading this wrong, but it sounds like a job for "resistance soldering". On the chance that this is correct, see:

http://www.micromark.com/resistance-soldering-equipment.html

Title: Re: Soldering Problem
Post by: John Witt on November 10, 2009, 01:05:26 PM

Howard,

Our lead tech says this is pretty tricky, he wouldn't try it at home. There is a local outfit you could get to solder just the one component on, using reflow equipment and a precision positioning device.

Printed Circuit Assemblies
425-644-7754

ask for Sim Tang -- he may have some suggestions about how to lay out the pads, as well.

If not that, then Dean's suggestion sounds good.

I have a resistance soldering tool, but the tips have about 20VAC on them. Might not be good for the circuit.

John

Title: Re: Soldering Problem
Post by: Howard Rush on November 12, 2009, 04:31:22 PM

Thanks, folks.  That printed-circuit prototype place is close to my house.  I'll visit them.  Meanwhile, I might practice doing it myself if I can find some cheap parts and boards to do it on. 

Title: Re: Soldering Problem
Post by: Dean Pappas on November 12, 2009, 08:34:14 PM

Good approach, Howard.
take care,
  Dean