I'm comfortable with soldering components to a board (mostly thru-hole stuff), but I still struggle greatly with soldering wires to parts.
What is the process for soldering a wire to a connector?
Let's take 2 examples - soldering a wire to a bridge rectifier lead (the lead is 1/4" square, pretty large), and the second example is where you need to solder a wire to a 1/8" headphone jack.
So far, I've been tinning the wire, tinning the lead on the component, then heating the lead till the solder melts, then holding the wire on the lead for a second or so with the iron in place, giving the solder on the wire a chance to flow. then remove the iron, hold in place to give the solder a chance to cool.
The 2 problems I have:
There is invariably a hole in the lead, for you to feed the wire through. Does it *really* matter? [assuming of course the wire can fit]. There doesn't seem to be a good way to push the wire through the hole and have the wire flush up against the lead to make a good solder joint. If the joint is good, I've been told there is no reason to have to have the wire in the hole.
While holding the wire waiting for it to cool, invariably the head tracks up the wire and makes my fingers hot and I can't hold it. Or, if I try to hold it with a pair of tweezers, the head deforms the insulation and it looks ugly. Perhaps the iron is too hot (I have it at 700 degrees F), but how do you hold the wire against the part while waiting for it to cool?
If someone could walk me through it, or point me a to a link online, I'd appreciate it.
OK, first thing to do is ensure both the wire and component lead are clean.
Second, if you decide to tin the lead use as little solder as possible. Tinning the wire, among other things, makes step 3 easier. Strip enough wire so the insulation won't interfere with the solder joint, but not too much.
Third, think mechanical connection. If the lead is flat bend the exposed wire into a U or hook shape. If you can use the lead hole life is easier here. Using pliers squeeze the hooked wire to the lead, don't crimp it, it just needs to have firm contact. A mechanically sound joint before soldering, when possible, makes for a better joint.
Fourth, heat your work, not the solder. Apply only enough solder to fill any gaps with a fillet.
Lastly, clean off any flux and examine your work for frosting which could mean a cold joint. The finished joint should be shiny and you should be able see the shape of the wire.
It take practice which you can do on un-serviceable components.
All good suggestions from Dan. I like to twist the lead and wire together (making a mechanical joint) and then solder them. Trim off any excess wire when you are done. Perhaps one of the finickiest tasks is soldering wires into a multi- pin connector. Then I do like to have a =91third hand=92 to hold the wire in place while I solder it. I don=92t pre tin the wires and I apply the heat to the connector pin. A =91third hand=92 is any sort of clamping device that can hold the wire at the right place. I=92ve got some alligator clips on movable joints. (sorry that=92s not a good description.) The connector is held in a vise.
When it comes to round connectors I prefer crimp. As for soldering I made a board with dummy bulkheads to hold the connector. Fair warning, dummies cost more than any standard connector I have ever come across. What I did was either use old bulkhead connectors or buy the cheapest in that size, cut the back down to the flange, remove the insert and, violin(sic), you have a dummy.
Speaking of dummies, I once soldered the three panel disconnects for a T-39A pilot's instrument panel. Each wire had been numbered and cut to length. I spent a 12 hour shift doing that. It's one of those things you don't hand off to someone else in mid job. I came back the next day and had to start all over. Why? Because some dummy decided to cut all the wires to the same length to tidy things up. My personal feelings are that's grounds for justifiable homicide.
As for real fun try repairing a solder joint in the middle of a 50 plus pin connector. It takes more time to get to it than to repair it.
If you are soldering into a plastic connector then have the connector plugged into its matching plug/socket - this helps stop the plastic from melting and if it does melt the matching socket/plug at least hold the pin in the right position until the plastic re-hardens
I have never melted a plastic insert even when doing multi pin connectors with a coax. I will say I have managed to get them too hot to hold while installing them in an aircraft, but that was back when I was learning and was poor soldering technique. The nasty part was the coax was capacitance sensitive for fuel quantity systems. Nothing quite like soldering a connector hanging from an instrument panel.
There were some Japanese connectors made with styrene insulators. They would melt in a heartbeat. Long before the pin was hot enough to solder. If they weren't plugged into a a mating connector they distorted so much that you couldn't plug them in. The importers were soon out of business. :)
I prefer to pre-tin the wires, then use a single drop of Kester RMA flux on the pin. Then you align the wire and reflow the solder. You can get perfect joints without spending all day.
I always pre-tinned before I went to crimp. I made good deals on assorted crimpers on e-bay. It doesn't mean I never solder round connectors anymore, but I do it a lot less often. It's also a lot easier rearranging or replacing wires.
Most of the connectors i used the last years i worked were machine crimped Air powered AMP, berg and several other brands were used at the plant. All i had to do was tell the workers in the wire room what I needed for the test fixtures i built or repaired. My soldering was on high pin count surface mount. Up to 244 pins wit .015" spacing.
I do it for a hobby so I am happy with hand crimping. Production is something I have managed to avoid most of my life with the exception of a small company where I made infrared radiometers.
I wire number using a Kingsley hot stamp machine which is tedious, but I can't justify a production machine.
No, I rarely use the hole since it can make it more difficult getting the wire out in some cases. It is, ofcourse, more secure to do such things and depends on the specific mechanical requirements. I would take a guess that
99.9% of the time it won't matter if the wire is properly soldered in both cases.
This can be a problem, it happens. In fact the problem is your iron is either too cool or you are holding it on too long(which could be cause of various reasons).
Solder generally melts at around 400 oF. As long as you are able to melt both solder surfaces together then they should form a pretty strong fused connection. Solder will melt at around 400 oF(Depends on specifics) but even if you use a 700 oF iron does not mean that you can get good heat transfer to enough of the solder.
Generally when I solder two things together the solder will liquify almost instantanous when I touch the iron tip to the solder. This is because the iron is hot enough and is able to transfer it's heat to the solder easily. If there is any corrosion on any of the surfaces or if the solder is on something acting as a large heat sink then it can be a problem because even though you are touching a 700 oF surface to something probably at room temperature you are dumping only so much energy into it which is being pulled away very quickly.
Temperature (difference) is analogous to voltage (difference). If you know enough about electronics you know that when you hook up a voltage source to a load and the load is too large the voltage will "sag". Similar with your iron. if you try to heat something up that has very low thermal resistance the temperature of the iron will lag. You might have noticed this when you heat something up for a long time(10's of seconds) then try to heat something up that is cold immediately after it seems to take longer. This is because even though the soldering iron may be 700 oF it may not always be that(depends on the quality of the iron).
When I do solder things such as wires to large copper plates it can be very difficult. You must make sure the surface is very clean and use flux(note that flux can burn and leave a residue that can interfe with heat transfer). Ideally you would need to preheat such surfaces but this is not always plausable. Using a very hot iron can do the job as it can dump a lot of heat very quickly to a local spot without heating up the whole device.
e.g., think of a spot welder. These are able to generate very high temperatures but only for short times. They locally heat up the surface but because of the thermal resistance of the material the heat is not able to spread out quick enough(Which is why you are able to get local heating).
With an iron it is different as you can easily burn up whatever device you are using since it is "always on". This is why low wattage irons are recommended for beginners as they tend to keep the iron on too long.
You may not be having any more difficulty than most people have. It's not always easy. It depends on exactly what you are doing and what you are trying to accomplish and what tools you are using. If you are trying to solder very thick wires then it is going to be more difficult than smaller wires. You must get the surface of whatever you are trying to solder hot enough for the solder to flow on the surface. If you are able to do this for both connections then it should be easy to fuse them.
As far as the wire insulation goes you'll probably always have that problem. Most insulation isn't made for soldering. e.g., if the wire ever got 400oF then there is a big problem. Things you can try are to use heat sink clips - not great but might be enough, larger iron - less contact time which would allow quicker bonding and hence less total heat energy transfered but much worse if you leave it on too long, heat shrink tubing - These tend to have great thermal resistance and will generally not burn up but will shrink. You can sort of use it as a secondary insulation to cover up the main insulation. You can also use it to protect the bare copper completely and it will look more profession. It can be difficult to use in some cases(tight places).
Some solder is much easier to use than other. The new "ROHS" solder is total crap for hand soldering. Soldering flux is almost a necessity and usually makes things much easier to do. Having a variable temp iron is pretty good. If your iron is too low of a wattage then invariably you just end up heating up what you are trying to solder rather than actually soldering anything. e.g., suppose your iron was 300 oF. You won't meld the solder but surely end up heating up what you are trying to solder. This is why a hotter iron works better as your more likely to melt the solder but of course you have a higher likelyhood of ruining what your soldering.
Hmm, I guess with the connectors I've been doing lately the wire 'just' fits. I'm afraid if I tin it there will be some solder 'bluge' left on the side and then I can't get it in. Perhaps I don't have the proper technique.
Properly tinned wires won't have that, you should still be able to see the strands. A neat trick for tinning is to get a soldering iron with a large diameter tip, drill a hole most of the way through on the side of the tip. It should be large enough to accept any wire gauge you are likely to use. Warm it up, fill the hole with solder and you now have a small tinning pot. (I would have said voila, but getting into stringed instruments could lead to wandering threads)
You only need enough solder to fill the space between the strands. If you get too much, just re-heat it and tap it of the edge of something to allow the excess solder to hit the workbench. Just don't get careless and let it go somewhere else. A pair of safety glasses or Goggles will help. I've soldered for 50 years, now and have tackled a lot of strange problems.
Thanks for the tips (Mike and Dan). I'll try the bench tapping next time I'm doing this sort of thing. In the past I've also tinned a long section of wire with the iron at the bottom, and wathc the solder wick up. Then snip off the bottm section of wire where the excess solder is.
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