Soldering and overheating of circuit board


2003-10-11 4:37 pm
Yesterday I was replacing some parts on a DAC project I'm building. I was using a desoldering braid and a Hakko soldering station set to 600 degrees F. I desoldered the parts to remove them and soldered new parts in afterwards.

After I was done, I noticed that there were slight "fracture" marks around some of the solder pads.

These marks look like little fractures in the board material - they kind of look like whitish chips that fracture into the depth of the board a little bit.

Is this due to overheating? I've changed out parts for many years and never noticed this until now. The board looks like a good 4 layer fiberglass epoxy board.

The only thing I did differently that I can think of is that I cleaned the flux off the board with Q-tips and alcohol on several different occasions. Could the alcohol have dried up the board somewhat causing the cracking when heat was applied later?

I don't think the extent of the fracturing should affect the board too much since It's in a low stress environment.

The board does have a 6DJ8 tube on it, though, so I'm a bit worried that the heating/ cooling might cause the little cracks to expand and eventually form a bigger crack.

Anyone have any insight on this?