Advice requested for a small but irritating soldering issue

[lesthegrngo]

All, most of the time I am fine with soldering, I've had enough practice doing my build that in theory it shouldn't be an issue. The majority of joints are good, if not the best quality, but every now and then I get a joint, or more often series of joints that have whiskers of solder sticking out from them. I can't make this happen if I try, but when it does start happening I can't seem to stop it.  

Sometimes the whiskers can be 3 or 4 mm long, and either stick up or sidewards. The soldering iron is set to about 380 degrees, and like I mentioned most joints are good. I bought a good ceramic iron, wipe the iron tip regularly, use flux, generally solder with cored solder, and the problem can appear after doing ten good joints, then the next one in the line on the same component does its trick.

I've searched the web, and either I've invented a new problem or I don't know the correct terminology, but all the 'common soldering problems' tips pages don't discuss this.

If anyone can point to either some tutorials or reasons why this is happening I would be grateful

Cheers

Les

[RafaPolit]

I've had this happen to me as well.  I have not been able to pinpoint a specific culprit, though I have a couple of things that I blame for:

- The iron may get a little colder when exchanging heat with a large component or one that can sink a lot of heat
- I may try to "fuse" the solder when the component's leg is not warm enough
- The iron's tip get's coated by the flux or rosin and it gets charcoaled and I no longer have the tip correctly covered in solder

I blame a combination of (or all) those three things.  When that happens, I wipe the iron clean with a cloth or wipe, I re-tip the tip with solder, wait for it to heat up back nicely, and then resume soldering.

I would describe them as "mini spikes" or "uneven surface" rather than whiskers, but I know exactly what you mean.

[lesthegrngo]

Yeah, that's it - little spikes that form as you draw the iron tip away. I've tried cleaning the tip and all the rest of it, but once it forms on a particular joint, most times I end up having to mechanically remove it. The only other way is if it ends up bridging to another connector, then I use a piece of flux coated multicore and the iron to wick it away

Les

[No1sonuk]

Part of the problem is often too much solder.  The excess sticks to the iron rather than the joint.

[agrasyuk]

Happens to me as well . When it happens  I take it as a sign to clean and re-tin the iron. I do tend to clean regularly during work sessions so usually I can preempt. 

[No1sonuk]

And on the tip cleaning note.  While the "traditional" method is a damp sponge, I prefer the "metal shavings" type, as they don't cool the iron when they work.
e.g.
https://www.amazon.co.uk/Soldering-Cleaner-Solder-Cleaning-Brass/dp/B09GY5DFDW/ref=sr_1_1_sspa?crid=35XR9J9S8QXY2

[lesthegrngo]

Yes, I use one like that, only made from stainless rather than brass - does that make a difference?

Cheers

 

Les

[No1sonuk]

I don't think so.

[Scott-S6]

On 2/1/2023 at 6:03 AM, RafaPolit said:

I've had this happen to me as well.  I have not been able to pinpoint a specific culprit, though I have a couple of things that I blame for:

- The iron may get a little colder when exchanging heat with a large component or one that can sink a lot of heat
- I may try to "fuse" the solder when the component's leg is not warm enough
- The iron's tip get's coated by the flux or rosin and it gets charcoaled and I no longer have the tip correctly covered in solder

I blame a combination of (or all) those three things.  When that happens, I wipe the iron clean with a cloth or wipe, I re-tip the tip with solder, wait for it to heat up back nicely, and then resume soldering.

I would describe them as "mini spikes" or "uneven surface" rather than whiskers, but I know exactly what you mean.

This is exactly it, not enough sunk heat. The solder is returning to solid while the iron is being removed.

If the object is hot enough then the solder will remain liquid for a few seconds after removing the iron, allowing it to return to shape.

[lesthegrngo]

ok, thanks all. I'll try increasing the iron temperature and test it to see if it helps - it is a small one, deliberately to prevent me cooking stuff!

I'm curious as to why it is not mentioned in any of the troubleshooting FAQ's that I looked at on line

Cheers

Les

[No1sonuk]

If it's lead-free solder (e.g. SAC), the temperature needs to be higher.

[Bucic]

In case of any soldering problems I always recommend raising the temperature and shortening the operation. Not only because higher temperature is better*** but also because some soldering stations may not indicate the temperature correctly. The whole operation, starting from administering the solder, should take less than 5 seconds. And if the temperature is generous it's easy to achieve that***.

Each time you're troubleshooting, every single attempt should be preceeded with cleaning of the soldering iron tip. I do clean-retin-cleanagain^^^. Slightly wet sponge.
Lastly, watch with vs without flux videos.

Collin's Lab: Soldering - YouTube — https://www.youtube.com/watch?v=QKbJxytERvg

 

^^^ The soldering iron tip is to be free of solder when you attempt soldering a new connection.

Edited February 3, 2023 by Bucic