Lead Free Solder 1

[Vladpl]

Hello All

As most of you know there is a big movement towards lead free solder. Europian Union has a law that from 1 July 2006 you will not be able to use lead solder ( military, medical, aircraft will be exempt).

My question is that there is only 7 moths till that takes effect and I am unable to find a good lead free solder to use. Is there anyone that knows where and what brand of lead free solder there are on the markets.

I was looking at a sample (can't remeber the brand) lead free solder but the problem with it is that it crackes easily. Basicaly anything I saw out there isn't good enough to use. Since I am from Australia I was unable to find it here.

 

[itsmoked]

Have you looked at the solder makers? They are
all on this problem too. They have white papers and lots of info on the subject.

http://www.kester.com/en-us/index.aspx

http://www.alphametals.com/main.asp

http://www.aimsolder.com/

site

 

[ScottyUK]

Couple of others:

Indium Corp (mainly exotic solders for hybrids)
Multicore Solders

Multicore used to have an excellent technical department. Long time since I was in manufacturing.

You will need to change your inspection criteria when you move to a (probably) tin-based solder. High tin solders are harder and have a duller surface finish than the traditional 60/40 or 60/37.5/2.5 alloys, so you can't use exactly the same assessment criteria.


----------------------------------

One day my ship will come in.
But with my luck, I'll be at the airport!

 

[zeitghost]

It is, of course, a cunning plan to make all electronics so unreliable we all go back to using the abacus.

 

[itsmoked]

Multicore! Slurped up by LocBite er.. tite.

zeitghost; Yes another pile of eco-marketing BS.

 

[melone]

Adding ~1% Silver help reduce the brittleness of Pb-Free solder.

 

[VisiGoth]

We just had a corporate mandate to not use Pb-free. We make microwave modules on hard substrates and seem to be able to go Pb-free there. But that does not address the drive behind this, which is to be able to recycle cheaply in developed countries. I have a friend who runs a business in Asia, he and his partner bought a used fax machine (these are two college kids with no money), they contact major companies in Europe and lease shipping space to Asia. They double ship through China and magically the environmentalists do not have a say so (I do not like pollution, especially human toxic thins like Pb, so I am very pro environmentalists most of the time, but they do not get a blank check support).

Anyway, their business will dissolve, but Europe may be able to more cheaply grind up their own computers and boards and cut out the middle man.

So, it is not good for everyone, but I think it is better fro society as a whole. This is a problem where engineers and chemists, and basic materials people can really help and make a diference.

Anyone out there on the fixing the problem side of the isseue?

 

[felixc]

For lead-free solder to work nicely, the fluxing and temperature profiles have to be very tightly controlled. That makes evaluations very hard to conduct and very expensive. Solder vendors, but also most of your components have to be reassessed for lead-free. Several plastics do not survive to the higher reflow temperatures. The soldering equipment may have to be updated too. Do you have your own production line or are you subcontracting?

Rejects will go up, margins will go down, good products will be forced to obsolescence, others that used to work well will start to fail because the new solder does not stand the stresses. Small places like mine may just go out of business, but high-volume cell phone and consumer products companies are rubbing their hands, as the sales of the low-cost throw-away consumer stuff will go up because of the bad reliability. What a strange world ahead of us!

 

[SteveBull]

Lead Free solders appear physically different to leaded solders.

IPC-A-610 D gives inspection critera for evaluating lead free solder

Off the top of my head you should expect to see

Duller Finish
Graininess
Fillet Lift
Fillet Cracking
Different Wetting Angles
Stress marks caused by differing contraction rates

Inspectors and operators will need to be made familiar with these differences, AOI (AVI) machines may need to be reprogrammed or recalibrated in some way

Lead free solders DO work, some large Japanense organisations have been mass manufacturing with them for years, however, they have gone through the pain already.. we've got to it now.

I am currently conducting solder trails using a range of lead-free solders, on various lead free finishes to determine which is the best for our own uses, I'd suggest taht you go down the DOE line for determining what factors are critical to you, what you need to get out of your solder, and how you will evaluate this in a scientific manner.

Get yourself a copy of the IPC standard, and you will soon have everyone working to the same standard (an increasingly internationally recognised one at that), and understanding that the cracks may actually be characteristics of the new materials.


Steve Bull
Quality and Circuit Engineer.

 

[coconutalley]

There is one major issue with lead free solder: electromigration is worst. This is when small pricky dendrites grow and short to adjacent ones of opposite polarity. Apparently, the lead is a good retarder to electromigration. Conformal coating helps too and wider trace spacings. Definitely some things to consider.

 

[electricuwe]

Coverting a desing to leadfree is a hard job, but the main issue is not to get a suitable solder (SnAgCu used in Europe), but to get all the components suitable for the higher temperature during soldering.

 

[fsmyth]

If I were an activist, I would certainly jump on this.
I personally will consider moving to lead-free solder
about the same time that lead-acid batteries are banned.
Consider the amounts of lead used in each industry.
What's next? Cadmium control? Beryllium limits?
<als>

 

[itsmoked]

fsmyth; I couldn't agree more. I think this is beyond stoopid. This then means it's fine to heave a billion pc boards into the landfill??? That's nuts! They should just establish one more waste stream. One for deceased electronics. I can't wait to hear the stories about what critical device failed when...

It can create a new reality show: As the whiskers grow.

 

[zeitghost]

Oh, they've thought of that in Euroland...

There's the wonderfully named WEE directive...

Too many penpushers with not enough to do.

But hey! all this unreliable electronics is going to keep our friends in China busy building more crap for consumers to buy...

 

[felixc]

I'm sure this was a very good reason for all the consumer products manufacturers to endorse RoHS so easily. Unfortunately none of this spoiled money will stay home, while most of the small local shops will eat their shirts redesigning low-volume products to stay alive. Shame.

 

[felixc]

Oops, I was not talking technical, I'll be damned again. Let's rewrite my last post. My bread-and-butter product has gone obsolete because of RoHS. But since the reliability might be questionable, the replacement product that I have to redesign may never exist, because the customers have to restart a whole product approval cycle. While they're at it, they may of course consider the possibility of using the cheapest off-the-shelf design available. Anyway, since it's not reliable, let's make it such that you can put in any throwaway item for the lowest possible maintenance costs. Where will the cheap off-the-shelf product come?

 

[itsmoked]

Good points felixc, I never thought about.

 

[felixc]

Here's a nice article about the perverse effects of RoHS on the industrial control world:

http://www.rtcmagazine.com/home/article.php?id=100455

Felixc

 

[zeitghost]

Yup.

You can always rely on the know nothing eurocrats to screw you up.

Never mind.

It'll all be built in China anyway...

 

[itsmoked]

It's such a bad idea it's really is amazing..