Electrical soldering

[e44-72]

Hello

I keep having the same problem when soldering, when I first plug in the iron I clean and tin the tip but I still find that when diong the first connections using the iron after its just been pluged in the solder doesn't flow very well and tends to produce cold joints of a gray colour rather than nice shiny ones.

Its only after a few uses it gets better and flow of solder is better, why does this happen. The iron is and RS 25w iron. Any advice would be appriciated

Thanks you for reading.

 

[Sceadwian]

Lack of flux.

 

[ikalogic]

How old is the tip?
how hot is the tip?

those are the two questions i ask myself when i am in your situation

As Sceadwian said flux will help, although i am able to do neat soldering points without any drop of flux.

 

[WTP Pepper]

Make sure you are using solder with flux in it.
https://uk.rs-online.com/web/c/?sra=oss&searchTerm=flux&x=0&y=0
and this is always useful
**broken link removed**
Try to avoid lead free solder. It's pretty rubbish.

 

[ljcox]

It sounds to me that the tip is not hot enough for the purpose.

I have 3 irons.

A temperature controlled one for soldering small components to a PCB

A higher powered one for soldering switches, phone jacks etc. as I find the temp controlled one does not have enough thermal capacity to tin them properly.

And a bigger one for soldering heavy guage copper wires, tin plate, etc.

 

[DerStrom8]

It sounds to me that the tip is not hot enough for the purpose.

I actually completely disagree with this (no offense, Len). It sounds to me like the tip is too hot. When you first plug in an iron, in order to tin it properly, you need to touch solder to the tip as it's heating up. If it gets too hot, the solder will just ball up on the tip and will not flow at all. What wattage is your iron? That could also be an important part. If you're trying to use a 40 watt iron with small circuit boards, you're probably getting everything too hot. Get a 15 watt iron and apply solder slowly as it's heating up. It should flow much better. Also, I'd recommend using rosin-core solder, since it cleans the joints AND the tip as you're soldering. Great invention, if you ask me

I speak this from experience. For the longest time as a kid I didn't know why I couldn't solder--the solder would always ball up on the tip and I couldn't make any decent joints. After a few years, I was told to apply solder slowly as the iron is heating up. I did that, and I've been able to solder perfectly ever since.

Good luck!
Regards,
Der Strom

 

[Mosaic]

Last week I had 3 freshly minted BSc engineers try to wire up a 128 LED matrix. They had trouble soldering because

1) They were using lead free solder
2) They were using an iron coated copper tip rather than a pure copper tip to which they were accustomed.


Both of these factors require more control in temp & tip/joint cleanliness.

They also ramped the 40watt iron to it's max temp in order to get the joint hot enough to solder.

By the time I got involved I had to use an exacto blade and scrape a heap of oxide and solder slag off the tip while tinning as I went along. Naturally adjusting the iron to the correct temp also slowed the rate of oxidation and permitted a better tip condition.


The moral is: Clean the tip, tin the tip, keep a moist tip cleaning sponge on hand and get the temp right!

BTW, if your solder wire diameter is too small it won't do a good job of tinning the tip. I have heavier gauge 1.6m to 3mm wire on hand to always tin when I am using the 0.8mm solder wire.

 

[DerStrom8]

Last week I had 3 freshly minted BSc engineers try to wire up a 128 LED matrix. They had trouble soldering because

1) They were using lead free solder
2) They were using an iron coated copper tip rather than a pure copper tip to which they were accustomed.


Both of these factors require more control in temp & tip/joint cleanliness.

They also ramped the 40watt iron to it's max temp in order to get the joint hot enough to solder.

By the time I got involved I had to use an exacto blade and scrape a heap of oxide and solder slag off the tip while tinning as I went along. Naturally adjusting the iron to the correct temp also slowed the rate of oxidation and permitted a better tip condition.


The moral is: Clean the tip, tin the tip, keep a moist tip cleaning sponge on hand and get the temp right!

BTW, if your solder wire diameter is too small it won't do a good job of tinning the tip. I have heavier gauge 1.6m to 3mm wire on hand to always tin when I am using the 0.8mm solder wire.

I use .8mm 60/40 rosin core solder for most of my projects. 3mm is plumbing solder, and should not be used on most electronics. 1.6 is okay, but it's still quite thick.

 

[ikalogic]

morality 2.0 : Soldering is an art!

 

[audioguru]

I have used my Weller temperature-controlled soldering iron for about 44 years. It never gets too hot so its tip lasts for years. It has enough power to heat huge things when needed without getting too hot. They still make the same one today.

I have always used rosin-cored tin-lead (63%, 37%) solder.
Each solder joint takes about 1 second.

 

[DerStrom8]

I have used my Weller temperature-controlled soldering iron for about 44 years. It never gets too hot so its tip lasts for years. It has enough power to heat huge things when needed without getting too hot. They still make the same one today.

I have always used rosin-cored tin-lead (63%, 37%) solder.
Each solder joint takes about 1 second.

Weller is an amazing brand, and their temperature-controlled irons are excellent. But for a hobbyist, they're somewhat expensive. The one I have now is an $8 RadioShack special, and it works great. Each joint takes less than a second, and when finished it's shiny and nicely-shaped.

I guess my point is that it's really how the iron is used that's important. Make sure the tip stays clean and well-tinned, and you won't have a problem.

 

[Sceadwian]

ikalogic, there has to be flux, even if it's just rosin core solder.

 

[e44-72]

Thanks for the replies, i will try tinning while its heating up as derstrom 8 said as I do find it tends to all ball up on the tip in one spot.
I use solder 1mm in diameter with 2.2 percent flux and is 60/40 alloy solder.

 

[KeepItSimpleStupid]

Balling up on the tip is a sure sign of SEVERE oxidation. You have to heat, scrape and tin.

Do use a damp sponge to clean the tip and tin and wipe each power on cycle.

I was working with a guy once that was soldering sheet metal. He would literally "drip" the solder to make a joint. I turned him on to resistance soldering and he was a very happy camper.

As simple as it seems, you heat the highest thermal mass and add the led and apply the solder to the "opposite" side of the tip. i.e. the parts you are soldering. 60/40 worked very well for years, but with the possibility of a cold joint. 63/37 was essential when doing SMT components.

 

[e44-72]

Thanks for your replies. I also used to clean the tip with a small flat file, I have now heard that cleaning with an abrasive surface such as a file or sand paper damages the tip, is this true and should I clean witha wet sponge instead.

 

[DerStrom8]

Thanks for your replies. I also used to clean the tip with a small flat file, I have now heard that cleaning with an abrasive surface such as a file or sand paper damages the tip, is this true and should I clean witha wet sponge instead.

Yes, that is true. When you use an abrasive material, it actually rips pieces of the metal tip off. Once you have it cleaned once and tinned properly, you will be able to keep it clean just by wiping it on a wet sponge every now and then. Something that you must remember, though, is to only use sponges that are MADE for this purpose. Others can give off harmful fumes if burnt, and are very dangerous. Get one that is specially made for soldering applications.

 

[KeepItSimpleStupid]

I second that. There is usually an "iron cladding" on the tip. You don't want to file that away.

Since I don't do much soldering, a damp rag or paper towel works.

 

[DerStrom8]

Since I don't do much soldering, a damp rag or paper towel works.

I've heard that works, as well. It's still not the best, but it'll do the job. I've also heard of using fine steel wool, to just "dip" the tip into. Don't go trying to rub the iron with steel wool I think they make little containers for this purpose. I'll see what I can find.



[UPDATE] Found it:
View attachment 63087

 

[KJ6EAD]

How and why to solder correctly.

https://m.youtube.com/#/watch?deskt...d&feature=player_embedded&v=I_NU2ruzyc4&gl=US