Circuit board solder

[cmtul]

Be gentle with me. I'm trying to remove and replace two caps on a circuit board. I'm using a rework station underneath to warm it to 200c and using a weller iron at 650. I've tried several different tips. Flat and conical. Flux on the older solder. The tips new, and/or tinned. Even with fresh solder in the hopes of getting the old solder wicked up or sucked up. Any tips or tricks are greatly appreciated.

Best regards,
Chris

 

[ZipZapOuch]

Add some 60-40 solder to the solder joint (which is likely lead free tin and difficult to work with because pure tin has a very sharp melting (freezing) point. Adding the 60-40 will make it easier to work and give you more mass in the joint so, once heated, it takes longer to cool so you have more time to suck it out.

Then, to heat your newly formed melt, use a 700° or 750° tip. The goal here is like making a rare steak with a crispy outside - high heat for a quick hit. If you can't get it melted and sucked in about 5 to 7 seconds, wait for it to cool and try again. Working quickly prevents the board from getting hot and (1) melting the glue that holds the copper to the PCB, and (worse), (2) oxidizing the copper to an oxide and ruining the pad and adjacent traces.

Use a tip that makes good heat contact like a clipped cone (not a point). Transferring heat quickly is the goal. Also, clean your solder tip to keep it oxide free. I prefer a damp sponge. Wipe and spin at the same time in a single quick pass (you should hear a faint hiss of steam but not char the sponge - then you know it's wet enough without being too wet. Let the tip regain its temp by waiting 5 to 10 seconds before attempting anything.

Good luck.

 

[ahsrabrifat]

Be gentle with me. I'm trying to remove and replace two caps on a circuit board. I'm using a rework station underneath to warm it to 200c and using a weller iron at 650. I've tried several different tips. Flat and conical. Flux on the older solder. The tips new, and/or tinned. Even with fresh solder in the hopes of getting the old solder wicked up or sucked up. Any tips or tricks are greatly appreciated.

Best regards,
Chris

200°C is a good starting point, but stubborn solder may need a higher temperature. Try to increase it to 250°C-280°C.

 

[Nigel Goodwin]

200°C is a good starting point, but stubborn solder may need a higher temperature. Try to increase it to 250°C-280°C.

Both those are rather too low, I run my soldering iron at 325°C - and use leaded solder for soldering. However, as the OP seems to have one of the old crude Weller irons, he would need to buy a suitable new tip for the higher temperature.