[sdiy] The case of the sticky solder pt. 2

[Sam Ecoff]

So, I did a little soldering tonight, this time at the correct  
temperature (700 degrees F). I had previous set the iron to only 350,  
so things went considerably better tonight. However, the solder is  
still misbehaving. It's still more interested to stick to the iron's  
tip than to components and pads on the board.

Ken Stone suggested in a private e-mail that the pads may have become  
dirty or oxidized, but I can't see how that could have happened as I  
keep the boards wrapped in anti-static plastic when I'm not working  
on them in a temperature and humidity controlled environment (68  
degrees F, 30-35% relative humidity). I wash them each time I finish  
soldering a few more components and use a gentle nylon brush which  
means that each board is getting scrubbed 5-6 times, which I would  
guess is enough to remove oil left by my hands. I've had these boards  
in my possession for maybe 3 months, and none of them are copper  
boards. All stuff from Tom Gamble, Ray Wilson, and Ken Stone. Have I  
missed something here which could have caused the boards to get dirty  
or oxidized? I suppose I could wear latex gloves to keep oil from my  
hands completely off the pads, but that seems a tad anal. I just  
can't figure how they would get dirty otherwise.

While I appreciate the tips on soldering technique, I know that I  
haven't changed what I'm doing, but the result has changed. I used to  
be able to go down a row of pins on an IC socket zip-zip-zip, and now  
it's 10+ minutes of work to get the solder to stay on the pads.

I just upgraded my Rat Shack iron to an entry level weller, which has  
helped the problem a bit, but the solder is still more interested to  
stick to the iron's tip than to pads and component legs. The only  
other thing that I can think that has changed since I began my  
current projects is that I used up the batch of Kester 331 that I had  
originally purchased from John Blacet while building his excellent  
kits, and I am now using a reel of 331 I purchased from Mouser. So  
here's a question... does solder go bad? Has anyone ever gotten a bad  
reel? I'm just left scratching my head here, because I'm eliminating  
variables but haven't seen much improvement yet. I guess the next  
step will be to try some of the Kester 245 I bought and see if things  
are different. I'm planning to solder up a few pots tomorrow night,  
so I'll use the 245 and then report back. If anyone has any ideas as  
to what the hell is going wrong (or what I'm doing wrong) please feel  
free to chime in.

As always, I'm grateful for all of the help and suggestions I've  
received.

Kind regards,

Sam E.
_______________________________
Sam Ecoff
Secret Society Productions
5307 S. 92nd St. Suite 105
Hales Corners, WI 53130
(414) 427-0615
www.samecoff.com