Probably a dumb question but I am assembling an Arduino Nano and need to solder the headers.
What is the best solder and flux for this purpose. Also, what solvent is good to clean off my hands and the pcb after soldering.
Use only electronics solder (rosin cored). I'd recommend avoiding lead based solder so you don't have to scrub your hands clean every time or wear gloves, in which case you need the 4% silver lead-free solder (not the cheap stuff that's just tin/copper).
For lead solder 63/37 alloy is the correct one, not 60/40.
Never ever use plumbing solder, it is evil and will destroy all your electronics. Seriously.
PCB cleaner can be used to remove excess rosin from solder joints.
I don't understand. You said to avoid lead based solder then recommended a 60/40 led solder?
What is PCB cleaner? Alcohol or other common chemical?
60/40 isn't eutectic, thus more likely to form a dry joint as it goes through a pasty stage on cooling. Eutectics
have a single melting point, ie go from liquid straight to solid.
The hideous behaviour of tin/copper only lead-free solders is due to it not being remotely eutectic, so it goes
very pasty, and refuses to melt a second time without much higher iron setting. Lots of people erroneously
think all lead-free solder is this bad. It isn't.
I recommend lead solder - 63/37 is preferable over 60/40, though I often use 60/40 without issue. Lead solder flows better and requires lower iron temperature, so it's easier to rework without lifting traces. Metallic lead isn't particularly hazardous (solder paste, as in what's used for reflow work) since its so finely divided, I'm somewhat more careful of. People get unreasonably worked up about solid metallic lead. The bioavailability of metallic lead is negligible. Just a minimal level of basic hygiene is fine.
Yes, I have used both the silver lead-free solder and the non-silver-containing stuff (which is almost unusable) - leaded solder is still better. People don't use lead because it's poisonous, they use it because it has better physical properties.
Rosin flux from rosin core solder does not need to be removed from the board. I also have had a surprisingly hard time actually cleaning it off well. Rubbing alcohol (isopropyl alcohol / isopropanol, 91%) sort of works, but requires dilligent scrubbing with a toothbrush to get rid of all of it, and usually you don't get every bit, so it leaves unsightly outlines of white crap behind, so it looks dirtier than before you tried to clean it.
When additional flux is needed (for example, for soldering SMD parts - which is actually really easy once you learn "drag soldering") I use "no clean gel flux", the yellow stuff that comes in a syringe, dirt cheap on ebay/amazon. This also does not need to be cleaned off, but being a sticky liquid, you usually want to clean it off - but it can be wiped off easily with a paper towel wet with 91% rubbing alcohol.
Don't use 70% rubbing alcohol for cleaning circuit boards. In fact, the only thing you should do with 70% rubbing alcohol is using it as rubbing alcohol or for cleaning cuts (and for the latter, 91% is fine too).
barryjo:
I don't understand. You said to avoid lead based solder then recommended a 60/40 led solder?
I said if you use lead solder, dont use 60/40.
What is PCB cleaner? Alcohol or other common chemical?
google "pcb cleaner". Its something that cleans flux residue off pcbs. Quite what you can buy depends on where you are I suspect.
As it turns out, I am using 63/37 kester solder.
I am trying 91% alcohol and it seems to work. I can probably get some 100% at home depot??
I am also using some rosin flux .
barryjo:
As it turns out, I am using 63/37 kester solder.I am trying 91% alcohol and it seems to work. I can probably get some 100% at home depot??
I am also using some rosin flux .
We use whet ever IPA, isopropal alcohol, is available the cheapest and have for 20 years. Works fine for cleaning and the water in it won't hurt a thing.
I doubt you can get 100% IPA anymore. The hazardous material charges will be horrendous. I have a 5 gallon can of it, but have not used any in many years. Not sure there is anything in the can, now. Should check it next week. We used it to replenish the fluxer on the wave solder machine we used to have.
Paul
FYI Amazon has some 99% isopropal for sale and even one that is 99+%.
barryjo:
FYI Amazon has some 99% isopropal for sale and even one that is 99+%.
That'd be what the seller of the stuff claims... not necessarily the same as what they actually have on offer.
I use 63/37 rosin core and it works great. I also use Kester 63/37 solder paste, in a syringe, mostly for reflow (just noticed my previous supplier no longer lists Kester, only Techmet?)
For header pins I will either use the wire solder or just squeeze some paste around the pin (works well).
I clean the board with Cramolin FLUX-OFF, spray a bit on, leave for a few second followed by a light rub with a toothbrush, then another spray to remove all. Works amazingly well and a 400ml can lasts forever.
I spray my finished board with KONTAKT CHEMIE Plastik. This prevents the copper from oxidizing.
Here is a board made well over a year ago.
I do not know whether you can get these sprays wherever you are.
I also have 99.9% IPA. That is the only one I can get easily - from the local electronics supplier. It is also the cheapest IPA I can get ("cheap" used relatively). I use it mostly for cleaning my 3D printer bed. I have not yet used that for PC Board cleaning.
Willem.
MarkT:
I'd recommend avoiding lead based solder so you don't have to scrub your hands clean every time or wear gloves,
I'm going to assume that is tongue-in-cheek.
Yes, of course you should wash your hands thoroughly after handling solder. You should after lead-free solder, too, and flux and pretty much any other job.
It hardly constitutes a reason not to use leaded solder as such.
As to the lead issue. I am 78 now. When I was a kid, I helped my dad install sewer pipes under my house. The pipes were joined with packing and molten lead. I am sure during my childhood I inhaled a lot of lead fumes.
Also, I have a bad habit of biting the solder wire to pull it off the roll rather than putting down myh soldering iron and using my hands. Wash my hands after using solder, never have.
I guess I am either lucky or crazy, I don't know which. I also recall that my early dentist would give me a drop or two of mercury to play with.
barryjo:
I guess I am either lucky or crazy, I don't know which.
With all that lead exposure... possibly both.
Metallic mercury and metallic lead are both not particularly hazardous. Not too good of an idea to ingest, of course.
Mercury is fun to play with (especially if you have a bit more than just a little drop, even a small beaker of the stuff is remarkably heavy).
Paul__B:
I'm going to assume that is tongue-in-cheek.Yes, of course you should wash your hands thoroughly after handling solder. You should after lead-free solder, too, and flux and pretty much any other job.
It hardly constitutes a reason not to use leaded solder as such.
You know ordinary soap doesn't remove lead from skin effectively? Specialized hand cleaning products are available specifically for it.
barryjo:
As to the lead issue. I am 78 now. When I was a kid, I helped my dad install sewer pipes under my house. The pipes were joined with packing and molten lead. I am sure during my childhood I inhaled a lot of lead fumes.Also, I have a bad habit of biting the solder wire to pull it off the roll rather than putting down myh soldering iron and using my hands. Wash my hands after using solder, never have.
I guess I am either lucky or crazy, I don't know which. I also recall that my early dentist would give me a drop or two of mercury to play with.
And then there is the guy who got lead poisoning from continuously chewing on a piece of wire with PVC insulation. You probably get more lead from your car upholstery than from soldering.
Paul
I used 63/37 solder. I also wear exam gloves when I solder. Why not? I have the 99% rubbing alcohol from Amazon. It seems to clean better than the 91%. I have a small container with tight fitting flexible lid, like it might have been used for medicine...I dunno, somebody gave it to me. I use it for holding my board cleaning quantity of alcohol. I also use an old toothbrush. Dip, scrub, repeat.
Get a fume extractor. It's my understanding that the flux fumes are nasty. Best to avoid the issue altogether by not breathing it.
MK1888:
Get a fume extractor. It's my understanding that the flux fumes are nasty. Best to avoid the issue altogether by not breathing it.
Having never smoked, I do have to wonder what might have caused my respiratory disease. 
Enthusiastic electronic home-brewing - using solder, not Dupont connectors of course - is a major suspect.
OTOH, chronically inhaling fumes from vaporised human flesh before smoke evacuators were de rigeur in the operating theatre may be more to the point. 