Slightly OT: TQFP mounting

Chuck Guzis cclist at sydex.com
Fri Dec 21 15:54:16 CST 2007


If you feel this subject is too far off-topic, please respond 
privately.  OTOH, it just might help some who are trying to repair 
some of the old gear that uses SMT.

At any rate, I've got some 68-pin TQFP packages that I need to mount 
on a PCB.  I've searched the web and become throughly confused over 
recommendations.

I'd like to stay away from using a hot-air rework iron as I don't 
think I have enough skill to use it without causing some damage to 
the PCB or component. I'd like to use my temperature-controlled 
Weller soldering station as the heat source.  I'll also be using Sn-
Pb solder rather than lead-free.

Two approaches that I've seen for conventional soldering iron 
mounting involve what I'll call "flood and suck" that involves 
covering all of the leads on one side of the QFP on the PCB with 
solder and then using a solder "sucker" (such as a Soldapullt) to 
remove the excess.

The other approach uses solder wick (solder removal braid), laying 
the braid over the QFP leads and PCB and heating and applying solder 
*through* the braid to the leads.

I'm fairly confident that I could do either, but who's had real 
success with either method?

Thanks,
Chuck





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