Circuit board soldering tips please

[The Other Mike]

+1 on this and essential in my view but I can't see mention of it on the wiki

[Dave Plowman (News)]

Makes things very much easier - and I have a pukka desolder set.

[John Rumm]

If it is a topfield, then the supplied parts are only rated at something like 2000h, which means they don't last long before neeing replacement. I swapped mine out for some 105 deg C 15K hour panasonic caps.

[AnthonyL]

Let me get this straight. I clean off as much of the existing solder as possible using sucker/braid, then apply a little bit of solder and let it settle, then apply some heat and remove the capacitor?

[John Williamson]

Yup.

[Dave Plowman (News)]

No - resolder first. That re-flows the original and makes it easier to work. I dunno if it's an oxide coating or what, but old solder can be difficult to melt just with an iron. This makes it easy.

[alan]

No

First resolder all joints on the capacitor leads. During manufacture the board will have been washed to get rid of the excess flux. Re-soldering the joints with a lead/tin electrical solder with integral flux will enable the solder to flow more easily when you next apply the iron to it.

Now take each capacitor in turn.

Heat up the solder on one leg and when melted at the same time from the top of board pull that side of the capacitor out (lever it out) - it will not move very far the first time. Go to the second leg and repeat. Then go back to the first leg and repeat - the second time it will move a lot more. Keep repeating until the capacitor comes out. Don't forget that you can be a bit brutal when levering the capacitor and you are not trying to save the old component.

Now clean up the holes with a solder sucker or braid. Again sometimes putting on more fresh solder beforehand helps.

[The Other Mike]

No.

Resolder first to get the existing solder to melt, otherwise you can end up heating the joint for a very extended period to get any melt of the existing. Attempting it without adding new solder is a very easy way to destroy the copper to substrate bond and lift the pad / track.

Just made joints are ok to immediately desolder without the addition of new solder / flux.

[AnthonyL]

Thanks to all for the clarification. It makes more sense now. I'll be doing it early next week and will yell if I run into problems.

[fred]

Top advice.

The only extra I'd suggest is to trim any bit of the leads showing on the solder side before walking the component out, it can mean fewer heat stress cycles so is safer and some cheap boards can have a lot of tail left uncut.