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| Nearly torn cap on Mac SE/30, need advice |
Posted by: ymk on 2024-04-27 18:08:41
Yes, always use kapton tape on the surrounding area. Especially plastics.
I use aluminum tape, since it's rigid, conducts heat well and can be tented over plastics without touching them.
I'll go to hot air for removing ICs, but very rarely for SMD caps. |
Posted by: Addicted on 2024-08-18 11:35:28
Q: what's a good air temperature for desoldering corroded leads?
On the topic of desoldering.. it seems to me that corroded solder is much harder to liquify than fresh. I just spent my first day using a narrow-nozzle, rework-intent hot air gun. I damaged absolutely no pads, which was encouraging. But I worried the whole time that the long exposures required to get corroded 14- and 16-pin chips (SOICs) to release was going to cook the logic board.
I inched up to 307C before I was able to free some parts. Which made me nervous. Modern reflow ovens are more like 260C, right? Was it higher back in 1989, or is this the effects of corrosion, or do old boards conduct heat better than modern ones (more copper, more substrate)? |
Posted by: obsolete on 2024-08-18 11:48:40
Are you applying any liquid or paste flux to the component legs before hitting them with the hot air? The flux should help break up the corrosion and liquify the solder more easily. |
Posted by: Addicted on 2024-08-18 17:02:50
I wet them, but reading around, it seems I should pause for a bit before proceeding. I'll start wetting everything I plan to work, then going back and heating up things in the same order, to give the flux more time to act. Thanks for the tip! |
Posted by: ymk on 2024-08-18 17:07:40
The flux won't do much until it's heated. |
Posted by: dalek on 2024-08-19 01:09:15
Erm don't just reflow - use some epoxy to glue it back down (ideally heat resistant epoxy but in a pinch if you are quick with the iron, any will do).
Then use some conformal coating around the edges to give it a bit more mechanical protection. Only then apply heat and solder down the component on the pad. |
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