I need to wire something up, and I have not soldered in 15 years.
Medium wiring, 5 to 24v. Compared to the past : my soldering iron actually has a temp display and i’m using some kind of siringe instead of fat. Any Tips?
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- Heat the work, not the solder
- an iron tip with zero soldier on it creates a poor thermal bridge. Put a tiny bit of solder on the iron before you apply it to the work surface
- your iron’s heating element acts like a thermal battery. If you put it on large, cold, work, you can drain the heat below the optimal point of solder flow. Remove the iron from the work for 10 to 15 seconds to let the heating element “refill the thermal battery” before trying to solder again.
- your iron’s tip should be nearly all black with oxidation with only the tip that touches the work tinned silvery. That black oxidation is a blanket that keeps the heat in the iron and the heat can only come out of the silvery tinned tip.
Finally: Keep filling tin until it “flows around” what you’re working on. If your tin is forming a drop on the surface, it’s not bonding properly. It should spread a bit and flow nicely on the surface/wires you’re soldering.
If you’re soldering things that aren’t fresh from the store then you might want to lightly scrub the surface with something sandpapery, to ensure that it hasn’t been covered with a layer of something oily or corroded that might interfere with the solder making proper contact with it. A bit of abrasion might also make the surface rougher and more capable of clinging to solder, but I’m not super experienced, that just seems like something reasonable to me.
Definitely a good point. Soldering on an oxidised surface is hopeless, your surfaces should be shiny.
your iron’s tip should be nearly all black with oxidation
Ohh that’s something I had no idea about. I’ve always tried to clean and scrub my iron, whoops.
Removed by mod
I do have a flux pen. What temp would I set the iron at? 350-Celcius seemed to work fine.
Depends on the type of solder you have, some melt fine at 350, some need a little bit extra, I think lead free melt at higher temps. Play around with the solder you have, it’s pretty cheap and you can clean it off.
Yes, lead-free is more of a pain to work with in my experience. If the device/wire is already tinned with lead free, it can be doped with leaded solder from the iron to make it behave a little bit more nicely.
350 is good if you’re working on wires, 400 for connecting to boards (only touch the metal and touch it like it’s tissue paper, or just touch the leads since they won’t take damage), 430 for larger parts, 450 and a heat gun only if you know what you’re doing (the line between heating the board enough to attach the part and watching every other part fall off is most easily found by watching all the parts fall off). no-clean flux is a good choice for diy projects, but if something needs to last more than 20 years the flux will cause shorts.
you’re probably going to want to add flux to whatever surface you’re trying to connect, hover your iron over the spot while adding solder to your iron, then force the ball of solder over the connection. you might need to do this multiple times as wire can absorb a lot of solder. have something hold the wires in place as far from where you’re heating if you can, otherwise try to twist the exposed metal together, or twist a single strand of wire around them to keep them connected. you also can’t solder aluminum (at your skill level) so holding it together with tweesers could be an option.
can you describe the parts you’re going to connect? soldering might not be the only option.
Your last sentence nailed it. We need to know what they are trying to solder. Wire to wire… Maybe wire nuts or a bomb splice. Wire to pad or lead, that changes everything.
Don’t turn the iron up too hot.
Tin the wires first.
Flux everything. If you need to rework, add more flux. Flux boils/burns off fairly quickly, and the residue left behind is not flux.
Clean your work so you can inspect it.
If your wire insulation has a low melting temperature, 1: be quick about it, and 2: strip the wire shorter than you need, because It will creep back as you’re tinning it.
Google for “NASA Soldering Spec” for instructions and pictures of what “perfect” looks like. All of the NASA specs are free public info.Listen to this man, particularly about the flux thing. That stuff is magic.
These vintage videos from Pace offer a solid set of lessons that cover just about everything for electronic soldering.
If there’s already some old solder where you have to solder again, add a little new solder it before removing the old. Make sure that the pad is clean before you solder your new piece in place. Heat up the metal and touch the solder to it, don’t try just heating up the solder and letting it drip on.
I don’t know what you mean by “siringe instead of fat” though.
I guess you call it grease or paste, this is what I meant with fat https://www.ubuy.co.in/product/4M37F90F2-welding-grease-soldering-tips-fat-solder-paste-flux-50g
I’m a big fan of poster putty (also called Blue Tack, basically the semi sticky putty you use to hang posters) for holding small objects. Helping hands are great for certain things, but it takes time to position every object just right.
If I have a bunch of short wires to tin, for instance, i roll out a little snake of the putty and place the wires all in a row. Then I can just touch the iron to each piece as needed. It’s really handy stuff so I keep a ball in my soldering kit.
Huh. Imma try that next time. Thanks!
From my limited experience, make sure the things you want to solder are mechanically held together. And heat the pieces you want to solder, and use them to melt the tin. Never melt the tin directly on the iron.
make sure the things you want to solder are mechanically held together
I got great long term tips from others, but yea, that is my main mistake now.
I do not have 3 hands! but I pretend I do!
You can use a third hand, typically like this: https://befr.rs-online.com/web/p/soldering-accessories/1466439
for those third hand tools, put some heat shrink around the jaws of the alligator clips so they don’t scratch up the part you’re holding
A common tool that accompanies soldering irons is a stand with some alligator clips, often called a “third hand”. You can use those to hold one or both of the items you’re soldering together.
Set the temp to something suggested for the solder you’re using and practice on something else you don’t care about first.
Also consider ventilation and avoid breathing in the fumes. At least that’s what I do, I’m not a lawyer or doctor.
Yeah, do not fuck around with metal fumes
solder flows towards the heat. Just get the tip good and hot. Once the solder melts on the iron immediately it’s good to go.
Alligator clips can help hold wires in place while you’re soldering them.
have something underneath the joint that hot solder can drip onto without any problem.
If you used to solder 15 years ago then you’d want to look for leadded solder. Just follow basic precautions of some sort of fume extractor. I just use a small desk fan behind what I’m soldering that pulls it away. Yeah it does just mix it in with air in room but for hobby work it’s not going to be a big deal.
I’m also a big fan of the brass solder sponges for cleaning tips. Will clean it, the brass is softer than steel so won’t mess it up, and since you’re not using a wet sponge it doesn’t cool the tip as much
Here is a good guide:
What are you actually soldering? A wire splice? Or a wire to a pad? Wasn’t clear from your op.
Seeing as most of the soldering tips are down, I’ll list a few obvious but often neglected safety tips.
Solder in a well ventilated area and position yourself so you’re not breathing in fumes. Don’t wear loose clothes that might get in the way, and ensure any other flammable items are moved away. Make sure you know where a fire extinguisher is. You don’t have to move one nearby, but reminding yourself of where it is will make it easier to find in a panic.
Inform other people that might go through the area that you are soldering and to avoid the iron. My mom, a compulsive cleaner, reached over the space to grab a cup for the dishwasher and rested her forearm squarely on the iron (that was on it’s stand). She still has that scar 10 years later. Although in my case I had warned her, but it makes the self guilt a bit easier.
And finally - don’t solder around young children.
