Solder - lead free or not?

[alan_m]

One problem is that the component industry also had to change in the way they 'tinned' component leads. They now use other alloys that are more compatible with lead free solders. It's not just a simple matter of the military/medical industry continuing to use traditional 60/40 tin/lead type solders as reliability can depend on the mix of metals at the solder joint. If a component is effectively single source and the main market is consumer then they may not provide a component ideally suited for lead solder.

[alan_m]

It doesn't matter what temperature you set your iron to or which solder you use if the joint is larger than your iron can cope with. Not so much the joint but the effective heat sink it's attached to be it either a large area of copper or a tag connected to a metal chassis.

It's one reason I have more that one soldering iron, a low wattage one for general small component work up to a 100W+ gun where the heating tip is a piece of thick copper wire.

It helps if you can reflux an old joint either by adding new solder with a flux core or by adding a paste or liquid flux before/during heating.

As long as the water is treated and/or a protective scale has built up on the inside of the pipe it's not that big a risk as some may claim. There may be still lot of UK homes where the underground pipe between the road and their house is still lead.

Flint in the USA had a major lead poisoning water problem when they stopped treating the water with inhibitors (they had a change in suppliers)

It became (more of) a problem when some lead free solders were used especially when the pitch between component legs or balls became so small. A conductive whisker can grow and short out two joins <0.5mm apart.

[alan_m]

My Spanish built Vaxhaul had the worst electrical problems. It wasn't so much the electronics but some of the spade type connectors behind the dash. The plastic used for the connectors was so soft that when the spade was pushed into the mating half the plastic failed to hold the mating half firmly and it pushed out of the back of the connector. The spade bit was only just making contact with the mating half and With vibration eventually the connection failed :(

When something fails in an aeroplane it could fall out of the sky.

When something fails in the car the most likely thing to happen is it stops.

Just because lead solder CAN be used in certain applications it doesn't mean that all the electronics are using lead free solder. There are other ways of mitigating a risk of failure such as double or triple redundancy.

[jon]

I have retained several 4lb reels of 20swg and 16swg Ersin Multicore lead solder from the sixties. 15W and 25W soldering irons should be sufficient to do most electrical connections.

[Clive Arthur]

<snip>

That's been a real bonus for those involved in high-temperature electronics, usually up to 180'C ambient but more with self-heating. Normal SnPb melts at a little over 180'C and weakens considerably before this.

Before lead-free, chips with SnPb tinning had to be re-tinned with a series of solder baths.

[Theo]

Yes, and it's still freely available.

Generally the deal is that automated production lines use lead free, because once you're setting such a thing up it's just a tweak to the temperature profile to go for lead free, and all your components are anyway.

For rework and hobbyist hand soldering, leaded is easier to work with. It's perfectly fine to hand solder through hole stuff using lead free, but it's slightly more annoying to use for SMD rework.

Because so little is repaired or hand soldered these days, the amount of lead escaping into the environment (eg in those countries where they burn scrap electronics in the street for the metals) is massively reduced, which is the name of the game. The percentage that have been reworked with leaded solder is minute.

For stuff like aerospace, they have proper disposal channels so the risk of them being burnt on a rubbish dump is small.

Theo

[whisky-dave]

we at university have been asked (again) to look into using lead-free and rosin free solder. Tried a few years ago and the lead-free was difficult to work with especailly for unskilled students. So we are going to try again just asked a supllier (Rap) to send us some samples of each so we can do a proper test.

But so far (last year) this is my prefered lead free nearly twice the price of leaded though.

I find the iron needs to be about 20C hotter and it takes a little longer to melt, and the joint doesn't have that mottled effect from previous lead free solders I've used.

[whisky-dave]

Well there's a clue ;-)

Maybe it's like thalidomide in that it doesn't really affect the person taking it :-D

[whisky-dave]

Last time I checked it was still OK to use leaded in educational environments, which didn't exactly make sense but it did save us from having to convert over.

[SteveW]

Finding that the power was cut in the third lane of a very busy motorway, with the hard-shoulder closed for roadworks, persuaded me that lead should still be used in car soldering!

[Ralph Mowery]

Much of the time it is not the wattage, but the size of the tip in relationship to the work. I use an iron of over 50 watts to solder SMD electronics. The tip is very small and I set the temperature to around

300 deg. The older small irons depend on the ambient air to control the temperature but the modern irons control heat by adjusting the power going to the iron.

I change tip sizes depending on the components I am soldering.

[Commander Kinsey]

Yip, inconvenience is not necessary when we had a perfectly good alternative. They recycle the lead anyway don't they? They certainly take the gold off circuit boards.

[Commander Kinsey]

Or wrecks something expensive. Engines can get very upset when timing goes wrong.

Yes, lets make three of something just to avoid lead, ffs.

[Commander Kinsey]

It's doing it on small areas too, and it didn't with lead solder. And it's an 80W iron.

Par for the course with treehuggers.

"and Legionella bacteria"

How does it grow? It's not alive.

[Commander Kinsey]

Can you not buy lead solder in the USA? It's available in the UK, let me know if you want a shipment!

[Ralph Mowery]

Yes we can buy tin/lead solder in the US.

[Fredxx]

Quite. I find it astonishing there is a correlation of lead in petrol and violent crime. Some people are in denial there might be an issue with lead in the environment with waste lead and other heavy metals leeching into water supplies.

I expect Clackmannan water is supplied by bore holes and of course Forthside landfill is close by.

[Commander Kinsey]

I thought when you said "I have retained several 4lb reels of 20swg and 16swg Ersin Multicore lead solder from the sixties" you meant because you couldn't get it anymore.

I bet you can't buy it in treehugging California.