Lead-free Solder ( continued ... )

I see it as another example of well-meaning people effecting change about that which they know not. The consequence is that a few people feel they have saved the world, and everyone else suffers. Mr. Common Sense has once again died and gone to hell.

WT

I have worked with it and have concluded that it is different, but not neccesarrily that big a deal. Some of it is much harder to work with than others and I suspect that just like the early days of circuit board automated production, we will see the manufacturers go through a learning curve with respect to how to use it properly. Lead definitely has its advantages, and I think the environmental impact is minimal for now, but what about hundreds of years from now? Who knows what those lead containing boards will be subjected to in time? It is a change that I suspect will not be reversed, so I see no reason to do anything but get used to it and happily accept any repairs that it brings me. No different from all those hundreds of LA7838s that did not have enough solder deposited on the joints. We ain't going back to manual inseertion and soldering in production lines either.

Leonard

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But you can get that sort of failure with Pb/Sn if the flow soldering is not hand redone for the large metalic heatsinky pins etc, combined with a blunt post soldering leg/pin-cropper straining the joint before it comes out of the factory.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Well meaning nothing! - many of these so called "green" initiatives are led by anarchists hoping to destroy capitalism, although they do seem to have shot themselves in the foot with this one as washing machines have a much shorter life span and the capitalists sell more washing machines.

Granted, you can. But this guy saw it as enough of a difference from what he has seen over the years with traditional lead-based solder, as to be worth commenting about. Where the problem comes about, is with the higher temps required to flow this stuff. The manufacturers dare not go up too high for fear of damaging both semiconductor components, and the board substrate ( to say nothing of their bank account from the higher energy costs associated with having to use the stuff - green? - Ha! ). This leads to them going

*just* high enough to solder those components, which leaves them well short of enough temperature to get a really good joint at high thermal inertia components like connectors and power devices. Certainly, I see a lot more bad joints now than we had become used to with lead-based solder, and by far and away, the majority are on connectors and similar that would not have been giving the same trouble a few years back. I also see a higher number than would be expected, of bad joints on fine pin-pitch LSIs, often along one side only, which I'm guessing is the side away from the solder wavefront. From the time that the techniques were first developed to production-solder these devices, the soldering has been very reliable, but not any more ...

Arfa

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I'd not realised it was a hiding to nothing play off between temperature/wave speed/heat capicity/heat transfer rate. Heatsinky components/mechanically streesed ones should still be redone by hand surely.

Interesting view of the EU bureaucrats. Anarchists. One who believes in the abolishment of law and order and or government. ;-)

--
*Life is hard; then you nap

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

Who said anything about EU beaurocrats? - They've simply passes popularist legislation on things they know absolutely nothing about!

You'd have to be blind (or never watch the news) to miss the crowds of kooks that riot every time there's a political summit, the EU beaurocrats see large crowds rioting and decide that many people must all be right - eat shit, 2 000 000 000 000 flies can't be wrong!

As long as the manufacturers can (only just) get the product to out live the warranty they're very happy. Most electronic components generate heat so the temperature cycles up/down every time its used. The expansion/contraction breaks lead free solder pretty quickly so the production lines are busier than ever turning out replacement equipment.

Trouble with that philosophy, is that the jury is still out on whether you can reliably mix leaded and non-leaded solder. Some solder manufacturers say that you can, whilst others say that you can't. A number of independant metalurgical experts are of the opinion that by mixing the two solders, the long term integrity of the joint will be compromised. There is actually no requirement in the legislation to repair equipment that was originally manufactured with leaded solder, with anything other than leaded solder. Somewhere around the shop, I have an old reel of leaded high melting point solder that I used to use for that sort of thing, but haven't in a long time. It was originally for resoldering those spring-off resistors - remember them ?

Just as an aside, after this morning's NAD, this afternoon I had a Sony home cinema - one of the DAV series - I dunno, a 300 or 500 or some such. It had the usual problem of thinking that it was in headphone mode, but instead of the common bad connector, this time, it was yet more lead-free bad joints on the power amp PCB. As well as the ones on the bottom of the connector that were causing the headphone problem, it also had cracked-around joints on just about all of the six channels' output filter chokes, a problem which you've probably all seen more than once on these, and also on the output relays. Now these are problems that have developed, as the boards are old enough that if they were original production drys, they would have showed long ago. I accept that drys also 'develop' with leaded solder on certain components that suffer high levels of thermal cycling in use, but the amount of drys on this one board, all on components that are either fairly large, or subject to mechanical vibration stress ( the relays ) rather than thermal issues, leads me to believe that there is a different failure mechanism at work here, possibly related to the lack of ductility of lead-free compared to leaded solder.

As far as the suggestion of manufacturers having to hand work bunches of components as the boards roll off the line, I can't imagine any way that this could be accomplished in a practical or cost-effective way.

Arfa

well, i do use it and i don't like the finish i get from it how ever, we do like using it on repairing old electronic boards that have high wattage R's on the board that create cracks when hot. I find in those cases you can increase the heat on the tip and force it to flow nicely which gives a good bond on those hot running components.

--
"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

Who are these experts and where are the links to the info on this? I would be curious what testing they have done and on what formulations. The vendors that have been willing to comment to me off the record say that there is no problem and that they are just political CYAing when they say to use lead free to repair lead free boards.

Leonard

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Another failure mode I've come across ove rthe years is where the component sourcing changes, but the board layout/drilling remains the same and the new comps have smaller diameter pins. The solder bridges the gap ok for a few years and then cracks, not even heat stressed, just room temp changes probably. How would the non Pb/Sn stuff fare with that situation in comparison.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Hi Leonard

I came across several on the net saying much the same thing, when I was researching an article on the stuff a couple of years back, when everyone in the business thought that it was suddenly going to be "illegal" to use leaded solder after the RoHS directive came in, and that if you did, the solder police in their green uniforms would come rushing round to arrest you before beating you up and throwing you in Eurojail for 20 years. I've cleaned up the PC since then, but have found the following link to an article written by a Dr Paul Goodman, who works for a well respected institution who provide help and advice to industry on the technicalities of this directive and associated issues. I had a number of direct conversations with Paul to make sure that I was correctly understanding comments that he had made in his document on the subject, and came to the conclusion that he knew what he was talking about. The bit that refers to mixing solder types is under the heading "REWORK"

I'm sure with a bit of time spent, other similar comments could be found again, unless there has been a serious genuine ( or politically motivated ) change of opinion by those that agreed with Paul, in the intervening couple of years. The document I have referred to is still live - I've just checked. In case that long link embedded in a news post gives any trouble, the gap either side of the word "and" is filled with an underscore.

Arfa

Most of the far-eastern manufacturers were years ahead of the RoHS deadline and a huge number failed due to faulty soldering, as it was before the deadline I used lead/tin solder - most of my monitor customers were regulars so if mixing solder types had been any less reliable than the original lead-free, I would have soon found out!

..................after less than a years use you'd be able to pull most of the components out without heating the solder!

Here's another interesting and related piece that arrived on my computer today

Arfa

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Perhaps we should offer the following service. What would it be called ? From after day one, after expiry of warranty, while fully working order, go inside any kit at owner's request and pre-emptively rework the usual suspects.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Sounds like a recipe for disaster if you ask me! If it aint broke, fix it till it is broke.

Ron(UK)