Soldering on a PCB

[Beancounter]

The clocks on my Caponord have broken, lost the LCD display with the fuel gauge, temperature gauge and various other pieces of info. Capo owners tell me it's down to a failed capacitor shown in the image below.

Capo Capacitor.jpg (61.45 KiB) Viewed 764 times

Apparently this is quite simple to remove and replace but it does require soldering a new one in place.

This is where I need advice please - soldering, specifically on to a PCB. I've soldered wires together before with reasonable if untidy success. My soldering irons are either a cheap gas job or a cheap mains powered one, usually the gas one to be fair because it's convenient.

Happy to buy a better soldering iron if it would make the job easier. Do I need flux? Do I need quality solder?

Ta.

[MrLongbeard]

Flux will make desoldering easier, and resoldering neater, but you can get away without it.
Soldering iron, if the tip is small enough and it gets hot enough what you have should be fine.
Quality solder is always best, I'm not going to recommend any particular brand as I still use my stash of leaded solder before nanny EU said I couldn't have it anymore.

[Count Steer]

One of these might be useful too.

https://www.amazon.co.uk/Solder-Sucker- ... d_source=1

[Lutin]

You might want to have a look at this youtube video from Paul Carlson (Mr Carlson's Lab)






I suppose giving this technique a go on a scrap surface mount PCB would give you a tad more confidence.

Every PCB, these days, is populated with surface mount components and finding a scarp one shouldn't be too hard.

[Lutin]

One of these might be useful too.

https://www.amazon.co.uk/Solder-Sucker- ... d_source=1

For surface mount stuff some solder wick (and flux) would be be more useful.

[dern]

Old lead solder melts at a lower temperature I’ve found, if you can some it would make it slightly easier.

[Count Steer]

Pretty sure I've got some lead solder in my soldering kit. I'll have to have a rummage. IIRC it's not on a reel as I was given it for a project but the modern stuff was ok so I didn't use it all.

[iansoady]

It's still available on ebay. https://www.ebay.co.uk/itm/176388752045

[Count Steer]

It's still available on ebay. https://www.ebay.co.uk/itm/176388752045

Yeah, it seems the main no-no is for plumbing and it seems it's being 'phased out' generally. TBH, with a decent, temperature-adjustable soldering iron either tin/lead or lead free are OK for most jobs but for fiddly stuff on a PCB, lower temperature stuff might be pref.

[Horse]

I used to design PCBs. 20 layers, 18,000 connections, couple of thousand components (both sides) - but I know nurthing about fixing them

[Apart from that we had to design them to be fixable, otherwise the test bay people got upset]

[MrLongbeard]

Yeah, it seems the main no-no is for plumbing and it seems it's being 'phased out' generally

It's been a big no no in electronics for some time (2018 - 2019ish IIRC) thanks to RoHS, there are very specific exemptions that allow it's use when you absolutely must have low melting point stuff, but it shouldn't be available to general consumers

[Count Steer]

Yeah, it seems the main no-no is for plumbing and it seems it's being 'phased out' generally

It's been a big no no in electronics for some time (2018 - 2019ish IIRC) thanks to RoHS, there are very specific exemptions that allow it's use when you absolutely must have low melting point stuff, but it shouldn't be available to general consumers

Isn't the RoHS rule for PCB production environments? It doesn't appear to apply to home users (or lead soldier repairers ).

Mind you, my BiL (deceased) used to make lead weights for payphone handsets and that involved melting and casting the stuff in bulk...in his garage!

[MrLongbeard]

Yeah, it seems the main no-no is for plumbing and it seems it's being 'phased out' generally

It's been a big no no in electronics for some time (2018 - 2019ish IIRC) thanks to RoHS, there are very specific exemptions that allow it's use when you absolutely must have low melting point stuff, but it shouldn't be available to general consumers

Isn't the RoHS rule for PCB production environments? It doesn't appear to apply to home users (or lead soldier repairers ).

Mind you, my BiL (deceased) used to make lead weights for payphone handsets and that involved melting and casting the stuff in bulk...in his garage!

RoHS is intended for manufacturers, but the wording can be a bit woolly and hobbyists can be thought of as a grey area, it applies to EEE, which can be but into the waste stream by anyone manufacturers and home tinkers alike.
I think we're on RoHS 3 now and every time its updated that crack down on substances and uses.

[Ian]

Your main risk is the PCB tracks lifting if you heat it too much

I used a tiny 15W Antex with a tip about the size of a pencil lead for that sort of thing. As others have said lead solder melts sooner, I have some really thin lead solder (says size 10 it's like 30A fuse wire). I can send you some if you PM me your address tonight/ tomorrow but after that it'll be next weekend

You can reduce the risk by not trying to get the old leads out and just solder onto the pads. Mark the polarity before you take it out or there will be some head scratching