Solder "pooling" / How Hot is Your Soldering Iron?

[Sir TophamHatt]

A bit two in one but I wonder if they're connected.

 

I have some, what I assume 60/40 solder although it's unbranded but nearly every time I come to use it, the solder just pools like a raindrop and the tension doesnt seem to want to break and thus connect everything.  The amount of little balls of solder I have around the place is staggering (okay, it isn't that much!).

 

I wonder if my soldering iron isn't hot enough?  I usually set it to 300-350°C.  Admittedly, it does work better the hotter the iron.

 

Any advice would be greatly appreciated.

[davknigh]

What flux are you using? Usually if the solder will form into balls the iron is hot enough but if it won’t spread then the surface is dirty or there is a lack of flux to break the surface tension.

 

Cheers,

 

David

[cliff park]

If the solder is melting, the iron is hot enough. I agree with David regarding flux. But are you heating whatever it is you are trying to solder. The iron, workpiece and solder all need to be hot. In fact a good test, and the best way to work really, is to heat up the workpiece and apply the solder to the workpiece, not the iron. Just a thought:- is the solder cored?

Edited February 24, 2022 by cliff park

[Nearholmer]

Cored solder will sometimes do this if you overheat it and burn the flux off, but I suspect either lack of cleanliness, or complete absence of flux.

[dhjgreen]

Do you get smoke when you melt the solder?

[Sir TophamHatt]

Hello all

 

Yes, a little smoke.

Most components are new wires.

Not cored solder - the sample I got with some soldering stuff was and actually worked really well.

 

Most likely not enough flux.

Does [flux] have a shelf life?  Mine will be 4+ years old.

[MarkC]

13 minutes ago, Sir TophamHatt said:

Hello all

 

Yes, a little smoke.

Most components are new wires.

Not cored solder - the sample I got with some soldering stuff was and actually worked really well.

 

Most likely not enough flux.

Does [flux] have a shelf life?  Mine will be 4+ years old.

A thought - how long ago did you get the solder? Is it possible that it's actually lead-free solder?

 

Regarding flux - if it's been kept in a closed container, it should be fine.

[Torper]

Have you been soldering in the past without this problem?  Whatever, I agree that flux/cleanliness is likely to be the problem.  Make sure the area to be soldered is clean - eg, burnish it with a glass fibre brush.  Then apply flux - I use Carrs Green label with a small brush, but other fluxes should also work well. Put on enough so that you can see it.  Then if possible cut off a small piece of solder wire (not lead free!) and put it on the place to be soldered - as Cliff indicated above, this is preferable to putting the solder on the iron and taking it to the work.  Then apply the iron to the solder and flux and all being well you sould get nice joint within a very short time.  The ideal heat of the iron depends to some extent on the melting point of your solder, which you don't know, so go in with a hot iron - my default is 450°C, in and out as quick as possible.  Incidentally, as well as the temperature of the iron you have to consider its power, or wattage - the more watts the better as that will enable the iron to retain its full heat when applied to the work.

 

DT

Edited February 24, 2022 by Torper

[AndrueC]

I have a cheap iron I bought from Amazon for £20. It claims to go up to 440c which is where I put it. I don't use flux, I just give the target area a few wipes with some abrasive paper. Then I just use some cheap solder I bought with the iron.

 

The only time I've had problems is when I haven't cleaned what I'm soldering to. Oh and when the thermostat on the cheap iron has been knocked down to a lower temperature which is all too easy to do.

Edited February 24, 2022 by AndrueC

[dasatcopthorne]

4 hours ago, Sir TophamHatt said:

Hello all

 

Yes, a little smoke.

Most components are new wires.

Not cored solder - the sample I got with some soldering stuff was and actually worked really well.

 

Most likely not enough flux.

Does [flux] have a shelf life?  Mine will be 4+ years old.

 

You say 'Not cored solder!  That's the problem.

 

If it IS cored solder, go with the answers above.

 

Good flux is this that doesn't need washing off.

 

 

Dave.

 

 

 

 

Edited February 24, 2022 by dasatcopthorne

[Sir TophamHatt]

Hold on!

 

The soldering iron is corded?

 

Maybe I have gotten confused with different types of solder...  I thought corded was sort of hollow and had flux in the middle of the solder making it flow with ease.

[cliff park]

Cored, not corded, solder does indeed have flux up the middle. It is virtually impossible to see , except in very large solder sizes, BUT if it smokes when heated it is almost certainly cored. The smoke is the flux burning off. This is why you should never apply the solder to the iron away from the workpiece, except for tinning the iron. Melting the solder away from the workpiece burns off all the flux long before it can do its job at the point of soldering. So, the sequence is:- tin the iron, heat the workpiece (this may well be component lead, wire, switch tag, PCB etc  or any combination thereof) then with iron still in place apply solder to joint. All of this assumes electrical/component type work, soldering brass kits is a little different, but not much 

[melmerby]

Always use 60/40* cored solder for electrical work.

Keep the soldering iron bit fairly hot, clean & tinned. Low temp will lead to poor/dry joints as will using an underpowered iron that cools on contact.

An oversize bit will lead to heat damage to adjacent items, you need to be clear of other components.

A wet synthetic sponge is good for a quick wipe every so often during frequent soldering.

Always apply the solder to the bit & component at the joint don't carry molten solder on the bit. (Plenty of you tube vids showing people doing just that, it is wrong and you wont get reliable joints.)

 

*Don't buy lead free for electrical work, it needs a higher temp. and is more likely to make a poor joint although it works well with a blowlamp and proper brush-on flux on copper pipes!

I speak from experience  of both.(It's also mandatory for potable water supplies.)

 

As an aside, I found Rapid, whom I had had 60/40 from on several occasions going back years, wouldn't sell me any last time I tried even when I said I was buying as a former professional electronics engineer, so I bought from e-bay.

I probably spend as much time on electronics these days as on the railway but I am making things for the railway e.g. signal decoder for Dapol signals.

Edited February 25, 2022 by melmerby

[kevinlms]

On 25/02/2022 at 05:22, Sir TophamHatt said:

Hello all

 

Yes, a little smoke.

Most components are new wires.

Not cored solder - the sample I got with some soldering stuff was and actually worked really well.

 

Most likely not enough flux.

Does [flux] have a shelf life?  Mine will be 4+ years old.

Well there's your problem. If soldering wires for electrical stuff, then you should be using solder with a cored flux, not an external flux.

Make sure the work is clean just before you bring the soldering iron up and heat the work, then when hot apply the solder with it's flux. As soon as the solder starts to flow, take away the solder and iron and job should be done.

[Lurch]

On 25/02/2022 at 21:43, melmerby said:

Don't buy lead free for electrical work, it needs a higher temp. and is more likely to make a poor joint

 

This is mostly old wives tales. I use pretty much exclusively lead free solder (both for hobbies and for manufacturing assembly) and have no trouble soldering in pretty much the same way as I used to with 60/40 leaded. The only noticeable difference is you may need to heat the object (wire/solder pad/whatever) up for a second or 2 longer than with the 60/40. The higher temp you need is only really in the order of 50°C for most solders and the temp is still well within the normal operating range of even the most basic soldering irons.

 

Usually when people say "lead free doesn't work" it means they are trying to solder in exactly the same manner as they did with 60/40.

[kevinlms]

8 minutes ago, Lurch said:

 

This is mostly old wives tales. I use pretty much exclusively lead free solder (both for hobbies and for manufacturing assembly) and have no trouble soldering in pretty much the same way as I used to with 60/40 leaded. The only noticeable difference is you may need to heat the object (wire/solder pad/whatever) up for a second or 2 longer than with the 60/40. The higher temp you need is only really in the order of 50°C for most solders and the temp is still well within the normal operating range of even the most basic soldering irons.

 

Usually when people say "lead free doesn't work" it means they are trying to solder in exactly the same manner as they did with 60/40.

I've never used 'lead free' solder, because there is nothing preventing traditional 60/40 leaded from being sold/used in Australia.

However the idea that it 'doesn't work' has to be incorrect, otherwise no one in Europe and many other places, would be able to make and sell soldered items!

[AndrueC]

4 hours ago, kevinlms said:

I've never used 'lead free' solder, because there is nothing preventing traditional 60/40 leaded from being sold/used in Australia.

However the idea that it 'doesn't work' has to be incorrect, otherwise no one in Europe and many other places, would be able to make and sell soldered items!

I've had no problems using lead-free solder. Since it's difficult to find any other kind in the UK (and presumably across the EU) and has been for over a decade it's silly to suggest that it somehow 'doesn't work'. I'm no expert and only learnt how to solder a year ago in order to build my first layout but it's been straightforward and reliable.

 

I think it's just 'old farts'(*) who can't or won't adapt and like to moan about things 'not being as good as they were in my day'.

 

(*)I'm 55 tomorrow so don't go accusing me of being a millennial or a whippersnapper  

[Sir TophamHatt]

What's the best size of solder I should get?

I think my current one is 0.8mm.

 

Does that also mean I should look at getting rid of the current solder (0.8mm 35G 60/40 rosin core tin lead roll) and flux (mercury 703.003 solder flux tin)?

Sorry no actual links as they were both bought in 2017 - no active amazon pages any more.

Edited February 27, 2022 by Sir TophamHatt

[melmerby]

1 hour ago, AndrueC said:

I've had no problems using lead-free solder. Since it's difficult to find any other kind in the UK (and presumably across the EU) and has been for over a decade it's silly to suggest that it somehow 'doesn't work'. I'm no expert and only learnt how to solder a year ago in order to build my first layout but it's been straightforward and reliable.

 

I think it's just 'old farts'(*) who can't or won't adapt and like to moan about things 'not being as good as they were in my day'.

 

(*)I'm 55 tomorrow so don't go accusing me of being a millennial or a whippersnapper  

What a lot of crap. I find that very insulting.

 

60/40 is readily available, it is not and never was banned and can still be found if you really bother to look.

It was an EU directive that recommended lead free for new use but AFAIK it wasn't mandatory.

Rapid still sell 60/40 but now only to "professionals"*, not hobbyists, so I imagine RS and Farnell are possibly the same.

 

Rapid statement:

*Please note: As of 1st March 2018 the supply of solder containing lead at a concentration above the relevant limit as set out under Article 67 (by virtue of Annex XVII) is restricted to professional use only.

Define "professional"

If you have a business account they will sell no questions asked.

 

I've just looked are Farnell and they don't have a restriction notice but there is a hazard notice: https://www.farnell.com/datasheets/2340347.pdf

 

I have both lead free and leaded solder and I also have the proper flux for lead free solder, so I'm speaking from experience not from a rose tinted glasses point of view.

Lead free does need a hotter iron as it's melting point is about 35C higher than the 60/40, so the chances of poor joint are higher.

Using the two different types the 60/40 flows into the joint better and needs less time on the joint, so lessing the risk of heat damage to adjacent items.

 

I  started soldering things in the late 1950s, so have done a fair bit in my time, especially as it was part of my job, for much of the time.

 

AFAIAC you are a whippersnapper being a whole generation younger than me.

 

 

[melmerby]

50 minutes ago, Sir TophamHatt said:

What's the best size of solder I should get?

I think my current one is 0.8mm.

 

Does that also mean I should look at getting rid of the current solder (0.8mm 35G 60/40 rosin core tin lead roll) and flux (mercury 703.003 solder flux tin)?

Sorry no actual links as they were both bought in 2017 - no active amazon pages any more.

I've got 0.7mm (22SWG) and  thicker one, 1.2mm(?). Horses for courses. Personally I'd use up the 60/40 multicore before buying anything else.

(I've also got a little bit left (a few metres) of one that is 2.2mm dia.)

Multicore solder doesn't normally have a hazardous rosin core.

What's the mercury stuff?

 

Looking at the lead free solders, the melting point varies considerably on composition. The proportion of added copper and sometimes silver to the base tin makes a lot of difference.

I've found quoted melting points from 227C to 250C, compared to 185C for 60/40

Maybe the one I've got is at the high end making it less easy to use?

[Enterprisingwestern]

 

 

You're all a load of softies, us proper plumbers can do a proper solder joint, none of my brass kits need any extra weight.

 

Mike.

[Sir TophamHatt]

2 hours ago, melmerby said:

What's the mercury stuff?

Flux?
It's like grease.

[melmerby]

1 hour ago, Sir TophamHatt said:

Flux?
It's like grease.

The one I have is like soft white grease but it doesn't have Mercury in it, or is Mercury a brand name?

[melmerby]

3 hours ago, Enterprisingwestern said:

 

 

You're all a load of softies, us proper plumbers can do a proper solder joint, none of my brass kits need any extra weight.

 

Mike.

Bin there done that (actually a 15mm copper pipe to ½" lead pipe.)

[Enterprisingwestern]

6 hours ago, melmerby said:

Bin there done that (actually a 15mm copper pipe to ½" lead pipe.)

 

Doesn't the first one hurt when you have a pound and a half of molten plumbers solder in the palm of your hand because you dropped the wiping cloth and got the solder too hot?!!

 

Mike.