Rate my soldering!


Today I built my first DIY kit as a precursor to making a Shruthi. This was my first real soldering experience so I’m looking for some feedback. It’s a mono amplifier and speaker and it works! When I first tried it, I got no sound and the IC was getting red hot very quickly (surprising how hot from just a 9v battery) - luckily I spotted that 2 legs of the IC were in the same socket! Fixed it and it worked like a charm.

Anyway, back to the point, please tell me what you think of my soldering (be honest!). I enjoyed the process and am proud it’s working, I have to say though, it wasn’t like in the videos I have seen. The tutorials I’ve watched show soldering a joint taking just a couple of seconds, in my case, I had to hold the iron on some pads for upwards of 10 seconds before the solder would melt. I have an 18w iron with a very fine tip, lead free solder. Is that normal?

A couple of times the solder also stuck to the pad with me still holding it and the iron in contact - I’m concerned that the heat is not being maintained well, again maybe it’s normal and I just need to verify it’s hot by lightly touching the solder first to see if I get smoke (that’s what I was doing by the end). I did ‘tin’ the iron.

Thanks again for all the feedback, great forum!

Lead free solder requires higher temperatures, and is often scoffed upon as being daft, since you replace one toxic substance (lead), that isn’t easily transferred to the human body(don’t eat it though) with several possibly toxic chemicals that could be easy to get into the human body. Not to say that lead-free is toxic, but it is a bit pointless, and harder to solder with.

I’d say you did a really good job on the soldering, as for the sticking to pads thing, it’s something I have experienced when there wasn’t enough heat present(usually a ground pad), but it is usually not something that happens very often…

Looks pretty good, but i was you, i would cut off the visible excess of those three pins in the back of the left side. These can cause trouble, if you solder later bigger and stacked PCBs projects.

yep your soldering looks fine, leads could be shorter and it’s probably better to use more heat and lead solder. make sure you equally touch the pad and the lead when applying heat. usually the norm is the more heat the better (as you just touch it a second thus the component doesn’t have to absorb as much as if you need to heat it up to the same temperature for 10 seconds) but there are some individuals who are proud to solder with an iron that’s cool enough to scratch your head with it while waiting for the solder to melt hehehe.

Haha! Well, I could see it getting frustrating waiting so long after a while. All the same, I’m glad to have started with a lower power iron as you have a little more time to consider what’s going on. Perhaps I’ll upgrade before the Shruthi (and Ambika!).

Interesting to hear about the lead free solder - I guess I just thought it was a safer option, maybe I was misguided. I will try some lead solder too, to see for myself what the difference is.

Next project is an astable tone generator, then Shruthi. Thanks for your comments, I’m pleased my soldering has been met with a general thumbs up.

When I’m working with wire I like to tin the bare wire first. It makes it easier to insert in the hole and it keeps the stranded copper from fraying and causing a potential short. Order a small tin of rosin flux (something like thisTwist) the wire strands to a fine point, dip it in the flux and get a small bead of solder on the iron tip.

And leaded solder FTW!

about tinning stranded wires, what i always do is pulling it back (in my direction) with the iron tip so that there’s some tension to the wire, then let it spring back (in the other direction away from me) so that all excessive solder will fly off of it. that way it’s as thin as it can be, sometimes important with small holes that weren’t supposed to hold wires!

Good tip, thanks :slight_smile:

This lead vs lead-free solder thing is confusing. On the one hand, lead solder is supposedly being phased out (presumably with good reason), but I’ve read that the fumes from lead-free solder are even worse. In fact, I’m sure I read on the Mutable wiki that the smoke from lead solder doesn’t even contain lead, it’s just eating the stuff that causes issues.

I mentioned it to my mother earlier, she was quite blasé about the whole thing and reminded me that when she was in school they used lead pencils which all the children would inevitably chew/suck! Puts things in perspective, all the same, I wouldn’t want my son eating lead solder… better get an electronics box + lock… ; )

Will an 18w iron feel a lot more capable with lead solder?

The smoke from soldering is only from the rosin core burning. Vaporizing lead requires heat waaaaaay higher than any soldering iron can produce. If you don’t plan on doing a lot of soldering, just by 1 or 2 spools of leaded solder. Should last you a long time.

Id recommend a good soldering station. The Hakko fx888D is great!

make sure you wash your hand before you eat something after soldering, or touching your lips during work. lead stays in the body afaik so it’s a good thing to avoid.
the lead free indeed has a good reason. that way you can mass produce garbage that’s supposed to be thrown away after a half year halflife anyway, before the tin whiskering eats it up. and it looks so clean and environment friendly if there is at least no lead burning on african beaches where little kids salvage the gold from the boards.

the whole lead free Rohs business is only for consumer grade rubbish, professional equipment that is supposed to function in a reliable way has lead.

Just to weight into the leaded/lead-free solder debate: I’ve always used lead-free, and never had any issues, except a few years ago, when I was soldering the main board of the MB-6582 (which has an enormous heat-disipating ground-plane).

I think at the time I had a cheap soldering-iron, and it just didn’t get hot enough.


Lead solder all the way. Lower melting point, better finish (shiny shiny…).

If you have kids or pets who might eat it then sure, use lead free. But the use of lead free solder is largely about reducing toxins when discarded electronics are processed. If you aren’t planning on chucking away your synths then you have nothing to worry about.

I can’t add too much to what’s already been said, but yeah - so far, your solder joints look great. I think 18W is pretty low power for soldering, (esp. with lead-free) so it’s no wonder you were getting frustrated. If you can swing it, I also recommend the Hakko FX-888D. I got one for Christmas and it makes life so much easier.

As stated, the lead in solder is not going into your system unless you eat it. Even then, you’d need to eat a lot of it before you feel any ill effects. Someone who eats a lot of large game fish (tuna, etc.) probably has more lead in their system than the average synth hobbyist!

Today I tried out some tin/lead solder… I am never using lead-free again. It’s SO much better!