Checking soldering iron temperature

I have an old Weller PS-3D with a 24V 50W iron and #7 tip, which is only just managing to melt the lead-free solder I have.

I've tried a #8 tip, which is better but still doesn't work as well as my newer-but-cheaper uncontrolled 40W iron.

I'm wondering if I'm missing something obvious or if the Weller is broken - it heats up quickly and I can hear the clicking as the temperature control operates, it just doesn't seem man enough for 1mm Sn 99.3 Cu 0.7 solder wire.

Bearing in mind that the last time I had any hands-on with soldering was when 60/40 lead solder was still considered ok to use, can you give me any ideas about where I'm going wrong? AFAIK a #7 tip on my Weller should give 700F, which is enough, isn't it?

RogerRowland: can you give me any ideas about where I'm going wrong?

Yes. You're trying to use lead-free for hand soldering.

I use the same iron. Lead is much easier to use. Lead free works ok, but th problem seems to be gettinf the contact needed to pass the heat. It does not wet as well as lead. I have to tin/clean much more often

Thanks guys,

I'll get my hands on some different solder then - it seems like everyone's pushing the lead free stuff now ....

lead solder

http://www.ebay.com/sch/i.html?_odkw=lead+solder.&_osacat=0&_from=R40&_from=R40&_trksid=p2045573.m570.l1313.TR11.TRC1.A0.H4.Xlead+solder&_nkw=lead+solder&_sacat=0

One other tip, keep the tips you use for lead seperate for non lead. Discard any pitted or damaged tips.

Weller tips last very well i have found compared to most but a bad one can make a lot of difference.

I have had some tips which i suspect were not origionals in the past, they were awful.

Use lead-free, then you won't risk get lead poisoning. Lead doesn't wash off your skin with ordinary soaps and detergents, BTW.

lead free needs a higher temperature which means you have to clean the bit much more frequently and switch the iron off when not in use (or the oxide builds up and ruins the bit).

Its just as easy to work with if you use the right temperature and clean and tin your bit properly.

The more expensive lead-free with silver is the best, and unless you solder a crazy amount the extra cost isn't significant.

I have found lead-free solder to be much pickier about the tip temperature. Generally higher than 700F so your #7 tip will be too cold. Depending on the type, sometimes a change of 25F is too much. And so a #8 tip may not work, either.

I use old Soder Wick reels and put solder in them so I don't have to handle it so much.

Lead-free solder is Crap. Be responsible and use common sense when using lead solder.

http://www.ecnmag.com/articles/2011/12/was-lead-free-solder-worth-effort

In 2005, the U.S. Environmental Protection Agency published a report, "Solders in Electronics: A Life-Cycle Assessment Summary," in which it "...assessed the environmental life-cycle impacts of selected lead-free solders as alternatives to tin-lead solder. The analysis also provides an assessment of the recyclability and leachability of the solders" (Ref. 2). The study considers leaded and lead-free solders from ore mining and waste recycling through refining and use to disposal and recycling again. Results show mostly small differences between the environmental impact of leaded and lead-free solders. After all, tin-copper, tin-silver-copper, and bismuth-tin-silver solders all require metal-ore mining and refining, fabrication, and disposal. And lead mining would continue because 80 percent of the metal still goes into vehicle batteries. I would bet less than one percent has gone into solders.

On his Signal Consulting Web site, signal-integrity expert Howard Johnson notes:

"Replacing tin-lead with pure tin is turning out to have been a huge mistake. There are two significant differences between lead-free assembly and lead-based assembly.

"1. Lead-free assembly is not better for the environment, it is worse. The additional tin mining required to produce high-purity tin alloys, plus the mining of other precious metals required to alloy with tin in substitution for lead is a poor trade for the use of existing lead, much of which comes from recycled products. This information comes from a study conducted by the U.S. Environmental Protection Agency (EPA). The study undercuts the primary basis for RoHS.

"2. Lead-free assembly is less reliable than lead-based assembly. The E.U. environmental commission admits this point. That's why they grant exceptions for military and high-reliability applications that still use SnPb solder. (Ref. 3)

Lead won't go into aerosol form or vapor form at soldering temperatures. The smoke is just flux, which is -much- more dangerous to breath.

And in fact, lead-free soldering requires a lot more flux, and the fluxes must be more aggressive. So the end result is likely to be more occupational hazards from lead-free soldering.

MarkT: Its just as easy to work with if you use the right temperature and clean and tin your bit properly.

So, can you give me an idea of what would be the "right temperature"? I only just managed with a #8 tip, which should be ~800F (426C), and that exceeds any melting-point data I've seen for lead-free solder. It just seems strange that I have to put so much more heat into the system.

I understand the issues around health etc, but this is only a hobby, not my only hobby and certainly not my full-time job. It seems to me that using 60/40 sensibly in this situation is probably the better way to go, but I am open to other options.

I took instruction in lead-free soldering. Up to that point, I'd been using a Weller with the tips determining the temperature, same as you.

After playing with a variable temperature iron with lead-free solder, I went out and bought a new soldering iron. I found that using too high a temperature was nearly as bad as using too low a temperature, and as little as +-10F could define the sweet spot.

Unfortunately, it depends on the exact formulation of the solder. For the class, we may have been given an especially touch formulation on purpose.

If you do use lead-free, plan on using a lot of flux. You can no longer rely on just the rosin core. Get an applicator (works like a felt-tip pen or one of those paint markers where you push to feed more) and a bottle to refill it. I suggest "No Clean" flux.

I agree with all the above. Using the same iron with a no 7 tip i find the lead free solder wire sold by maplins to work well.

Its one of those with silver though so not the cheapest.

polymorph: Lead won't go into aerosol form or vapour form at soldering temperatures. The smoke is just flux, which is much more dangerous to breath.

Yeah, tell me about it!

I have never smoked (tobacco or weed) and I have respiratory disease.

It must be either flux vapour, or arguably, vaporised humans (from my Monday job). Well, to be honest, rather more exposure to the latter. :astonished:

Boardburner2: I agree with all the above. Using the same iron with a no 7 tip i find the lead free solder wire sold by maplins to work well.

Its one of those with silver though so not the cheapest.

That probably explains it, I went with the cheaper option XD

I have a soldering station with a dial and a light.

this thread makes me think there should be a simple circuit that you could slip over the end of the iron and get a temperature reading. my thermocouple sensor has a huge mass, so would not be viable. but a simple thermocouple would make sense. makes me think that one could also add mass as a load, or read watts input....... just thinking out loud.

I have a thermocouple sensor which plugs into my multimeter, bead is abot pinhead size. Cheap but meter requires a temperature function