what solder should be used ??

[jneutron]

Tin whiskers are not the reason to stay away from non lead alloys. That is a pure tin issue, and is not really an issue with the tin/silver alloys. Last I read, they were thinking it was something to do with tin oxide having lower energy level than the unbounded tin surface.

Pure tin is 232 C melt.

Tin/silver is 221 C at eutectic.

lead tin is 183 C at eutectic.

PC reliability issue:

Problems with high temp alloys stems from temperature expansion differences between the boards and the components. G-10 boards expand in the 16 ppm per C range, while various parts go from BeO and Alumina, around 6 ppm, to plastics which go up to about 100 ppm/C. Higher solidus temperatures lock the parts together at the higher temp, meaning higher room temp strain, and lower temp cycle fatigue resistance, a military requirement from 150C down to -40C.

The high temp alloys are stronger, and creep less. Tin/lead does suffer more from low cycle fatigue, like the kind you'd see on a telephone pole due to day/night cycles.

The high temp alloys force higher reflow temps, which is in itself a problem.

High temp alloys require flux which activates at the higher temps without burning.

Indium could be used, alloyed or straight up, but it doesn't play well with copper, as the copper/indium alloy is less dense, leading to Kirkendall voiding. #4 indalloy, which is 100% indium, is 157 C melt. Very soft stuff, very good for expansion mismatch control, as long as you control the layer thickness..

Lead free is being gradually embraced because of the huge amount of it that is making it to the landfills. It has caused all kinds of problems with the electronics industry. The military cannot afford to wait for those problems to be solved by industry..

Cheers, John

[mzzj]

I prefer 63/37 type with mildly activated rosin core. Easy to work with repairworks, if you do only new boards almost everything does, but take 20 years old epoxy-coated board and see what works for that.

Seems that I should change from rosin flux as it seem that I am allergic to that (quite big problem among real electronics workers)

For higher-strenght joints i use SnCu or SnAg, better than ordinary for joints that are thermally or mechanically stressed.

And then I have Alusol that solders aluminum and every other possible metal, +Arax organic acid fluxed SnAg and SnPb

(and fosfor-copper for hard-soldering copper and multi-use hard-silver solder)

[AudioWizard]

jneutron, thanks.

That was pretty thorough and informative!

[anatech]

Hi AudioWizard,
Audio has been a throw away product for years. Many products go from package to consumer to distributor (for service) to landfill (unrepaired). **** should be outlawed. Bye-bye Pioneer for one.

-Chris

[Hayden]

Being a service agent for the biggest brand names in audio and visual appliances for over 25 years we(The business)has had no problems with the standard solder from WES 60% Tin + 40% Lead.

Hayden

[anatech]

Hi Hayden,
It's not the 60/40 solder that is the problem. It's shoddy manufacturing from the volume guys and lack of service info and parts. No value and the solder in the unit ends up in landfill. Since the governments will not regulate responsible design of consumer goods (back to durable products), they will acknowledge the stuff is throw-away and mandate lead free products.

Once again the average consumer loses. I was in the same business as you. It became very clear that distributors did not want the product repaired out of warranty. With one or two year model life, how do you expect the bugs to get ironed out? Spares are becoming next to non-existant. Manuals take what, 6 months to arrive? Consumers view audio products as commodity items - like computers. No value.

So are you prepared for working in a lead free world in a couple years? Where will your return on investment come from for the new equipment? Hopefully it's just solder and shorter tip life. Your stock of parts, lead free? Do your customers see an added value to your service?

I sold my business because I could not make a good business plan with the way things have gone and are going. This does not make economic sense on any level. I am not saying you should do the same, but understand what market forces are at play here.

-Chris

[sbrads]

I work for a company that makes EU military gear mostly (except from lead-free requirements) but also some commercial, and we have a lead-free assembly area. Some of our engineers also used to work on Sony commercial gear which has been lead-free for ages, so they have experience and misgivings in its reliability. Basically, assembly sucks in comparison with lead solder, and joints on larger components won't put up with the vibration levels required by military gear in service, they fracture much sooner.

[Hayden]

Yes I know exactly what you mean some products have no spare parts available and with plasma screens when they fail its usually big time and their throw away because some of the i.c’s that fail are glued on the board and to replace the board costs as much as the unit.
We have so much work on now we stopped all customer work and focus on warranty stuff because we are over a month behind even taking on 1 company like LG and nothing else is too much work, the other repair agent in town closed because too much work and he was tired with it all
Sad