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I was wondering what effects do rough solder joints have on electrical components. Specifically, I have a hard time soldering wires to a male-male connector, as can be seen in the added photo.

Assuming little physical stress will be applied to the joints, do jagged soldering have any effects on say the electrical functionality of the components? Or are there any other implications? Thanks

enter image description here

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    \$\begingroup\$ Wet the wire and the connector with the solder first and then solder them together. It would be a much better result than this one. \$\endgroup\$ – MaNyYaCk Aug 1 '17 at 11:08
  • \$\begingroup\$ Are these cheap pinheaders from eBay? If yes, you probably can't even tin them properly. \$\endgroup\$ – Jeroen3 Aug 1 '17 at 12:08
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The jagged edges are not by themselves problems.

However, in this case they indicate bad soldering. Either the solder never properly wetted everything and didn't flow right, or you heated it too hot for too long so that the surface significantly oxidized. Your pictures also show excessive use of solder.

Go back, clean off the mess, and use just enough solder. Add fresh solder, and possibly extra flux. Make sure the solder flows nicely over everything. Make sure there is enough solder to hold everything, but not more. Once the solder flows and wets everything, remove the heat and hold both parts still until the solder hardens.

I'd probably set the iron to 650°F (345°C), or 700°F (370°C) and be sure to hold the iron there only as long as it takes. I do normal soldering where nothing is particularly large or of unusual material at 600°F. The reason I say to use a higher temperature here is due to the large pins acting as heat sinks.

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    \$\begingroup\$ A common cause of solder not wetting the surfaces is lack of flux. Most solder wires today have a flux core. You should heatup the surface and touch the solder wire to the surface; rather than first melting the solder on the iron and then applying it. \$\endgroup\$ – Tejas Kale Aug 1 '17 at 14:07
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    \$\begingroup\$ Flux pens can be extremely helpful here. \$\endgroup\$ – pjc50 Aug 1 '17 at 14:10
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I don't see this in anyone else's answers so I'll add...

As my mother always reminded me... "Keep your tip clean!"

This is a mistake often made by the inexperienced. Failure to do so will result in a build up of solder on the tip which has burnt off the flux and becomes oxidized. This residue will be deposited in your next joint making it weak.

Whenever soldering you should have, as part of your toolset, a wetted sponge which you should use frequently, even before and after every joint, to clean the tip of the soldering iron. Simply draw the tip towards you across it while rotating the iron a few times till the tip is clean and shiny again with no excess solder build up on it.

The hissing noise when you do it is also quite emotionally rewarding.

enter image description here

Note if the sponge is very wet, you may need to pause to allow the tip to regain the appropriate soldering temperature again, but with most modern irons, that does not take long. If you are doing multiple joints at once, you may get away with less frequent cleanings, but you should get into the habit of cleaning the tip frequently, and definitely if you pause for any significant duration.

BTW: There is an alternative method that uses copper coils instead of a wetted sponge which reportedly works better though I have not tried it, and have my doubts. It also just seems like a waste of a rather valuable material to me.

Also, as I mentioned elsewhere... always use heat-shrink tubing on joints like this. It adds strain-relief which will help prevent the wire from breaking at the solder interfaces and protects you from stray broken wire strands shorting to the next pin.

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  • \$\begingroup\$ Copper coils not only work better, but most importantly, they don't induce the thermal shock to the tip that a "cold" (wet) sponge does. The sizzling sound isn't a good thing. Sure, there won't be noticeable/visible harm in the short term, but in the long term, thermal variation/expansion isn't friendly to electronics/components/tools and will wear the tip out faster, weakening/slowing its ability to conduct heat. As a bonus, the copper coils don't strip away the tip's heat, requiring it to come back up to temp. \$\endgroup\$ – Coldblackice Aug 1 '17 at 18:02
  • \$\begingroup\$ @Coldblackice Actually it's the thermal shock that you want, to help remove oxidation. For example youtu.be/vIT4ra6Mo0s?t=951 \$\endgroup\$ – pipe Aug 1 '17 at 19:21
  • \$\begingroup\$ @pipe Actually, thermal shock is not what you want. See eptac.com/ask/wet-sponge-cleaning-vs-dry-brass-sponge-cleaning \$\endgroup\$ – Coldblackice Aug 1 '17 at 20:03
  • \$\begingroup\$ @pipe "...the lead-free alloys, when cleaned with a wet/moist sponge, would accelerate cracking of the plating on the soldering iron tip. This cracking allowed the tin to penetrate the tip plating, which prevented the tip from being tinned, thereby increasing oxidation on the tip, rendering the tip useless and needing to be replaced. By using a brass tip cleaner, the fluxes and excess solder were easily removed and the tip did not experience a thermal shock, providing a longer tip life. This is why many facilities today use the brass metal cleaner to clean tips" *Brass, not copper \$\endgroup\$ – Coldblackice Aug 1 '17 at 20:04
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    \$\begingroup\$ @Coldblackice How can copper not conduct away heat? \$\endgroup\$ – user207421 Aug 1 '17 at 21:42
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It's a cold solder joint. You will want to do some or all of the following:

  1. Crank up the heat on your soldering iron.
  2. Switch over to lead-based solder
  3. Swap solder tip to a bigger size
  4. clamp down the connector properly so it's not running away from you

There's actually one place where you do want cold joints - If you want to create solder bridges on a breadboard, the way to do that is by using too low temperature soldering iron which will allow you to "drag" the solder along.

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    \$\begingroup\$ lead? no, thanks. \$\endgroup\$ – pasaba por aqui Aug 1 '17 at 10:47
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    \$\begingroup\$ @pasabaporaqui: Lead issues are overrated, unless RoHS compliance is required by law. Just don't dump it in the nature, or eat it. Wash your hands and avoid getting solder in your mouth while soldering. // The fumes don't contain lead, but you should still not breath them. \$\endgroup\$ – Oskar Skog Aug 1 '17 at 12:21
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    \$\begingroup\$ Re fumes: The fumes from flux are not really great for you, so even if using non-lead solder, avoid breathing the fumes. \$\endgroup\$ – Wayne Conrad Aug 1 '17 at 17:02
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I wouldn't have a lot of confidence in these solder joints... Also, mechanical reliability will be very low, a little bit of vibration or flexing will quickly make the wires fall off.

Now, you seem to be interested in making a quick and dirty 0.1" header connected to some wires. There are several ways.

Simplest is to get some male headers with long pins on both sides, and use a pre-made wire bundle terminated with female 0.1" headers.

My favorite is to cut a piece of breadboard (the ones with pre-drilled holes and pads). Solder your male 0.1" header on it, either right angle (using the holes) or hanging off the edge (not using the holes). Then, solder the wires to it. You can run the wires through the holes or not.

The bit of protoboard acts as a handle to insert and extract the connector, and you can fasten the wire bundle to it with a ziptie, which makes it much less prone to breakage.

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As long as the electrical connection is made along the whole joint and you´re not dealing with extremly high votages or frequencies, the functionality will be normal.

But if the jagged edges come from cold solder joints, they could break eventually.

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  • \$\begingroup\$ Or they can be no good to start with. You can often pull out the wire with little resistance on a cold joint. \$\endgroup\$ – Barleyman Aug 1 '17 at 9:43
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    \$\begingroup\$ +1. I'd also ass the OP really ought to be using heat shrink tubing to cover those joints too. It not only provided a great deal of strain relief, but prevents loose or frayed wires from shorting. \$\endgroup\$ – Trevor_G Aug 1 '17 at 10:27
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    \$\begingroup\$ Eeek..sorry about the typos in my previous comment.... that's what happens when you comment at 4am half asleep.... \$\endgroup\$ – Trevor_G Aug 1 '17 at 14:56
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Soldering is a fine art you will learn with practice.

You apply heat to each part first then add some solder with a clean tip then apply the iron quickly again joining the two parts. You have to judge the timing of contacting iron to applying the solder to tin the part depending on size.

The jagged solder comes from the dross build up on the iron tip or keeping the heat on for too long.

If you can buy some tinned copper wire eg 15 AMP fuse wire, practice with making a right angle cross joints. To test them use 2 pairs of pliers and pull joint apart making a note of how easy or hard it was.

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What temperature were you making the joints at? This looks like a cold solder. Make sure your iron is at ~600F and hold the iron to the two components. It shouldn't take more than a couple of seconds. Then touch your solder wire (assuming you have flux core) to the COMPONENTS. Don't use too much solder, just a tid bit and then pull the iron away. Looking at your job I'd say you applied the solder directly to the iron and tried to sort of wipe it on? Don't do that. It's a waste of solder and much more difficult to control. The solder wire is in wire form so it's easy to point and apply to your components, not your iron.

But to answer your question.. No, in a perfect world your connection will work fine and as intended. The issue here though is the mechanical fragility of your connection. This connection looks pretty weak and I wouldn't be surprised if some bending or pulling caused a connection to break loose. So really it works, but if you intend on keeping it that way don't expect it to work very long.

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Just to round out the answers points (on solder or anywhere else) are more likely to arc at high voltages, although given the pin spacing not a problem in your case.

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Im not sure if you are dead set on soldering the wire to the pins. I agree with others that you are not applying enough heat, a larger soldering tip would help with that. The problem is that you have to also heat up your wire for a nice solder and depending on length that may be impractical. Have you considered wire-wrapping the pins instead? From your picture that seems like an ideal solution for a cleaner looking connection.

As for there being an issue in the functionality I think you might introduce a slight resistance if the wire may have gotten tugged on while soldering or perhaps a cold joint may be present. Clean connections are important in higher frequency signaling because those jagged edges may inhibit EMI interference.

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