Drawbacks of Rohs construction
LoopyByteloose
Posts: 12,537
I read somewhere that without the lead in the solder, tin will actually crystallize and evenually grow spikes that can short the leads on ICs.
Also, certain applications such as military use and satellites have been exempted in order to extend the useful life of their electronics.
So far, I have be using lead solder with Rohs compliant parts. Is there any reason to stop other that potential lead poisioning?
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Also, certain applications such as military use and satellites have been exempted in order to extend the useful life of their electronics.
So far, I have be using lead solder with Rohs compliant parts. Is there any reason to stop other that potential lead poisioning?
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···················· Tropically,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
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Don't visit my new website...
Every country will be RoHS eventually. Europe was just the first place to do it.
There will be some third world countries·who take much longer to implement RoHS (India and places like that).
I believe it is within our best interests to·attempt to comply with RoHS. It is one reason we (Our company listed below)·do not offer leaded solder assembly.
There are quite a few things about RoHS soldering which are not easy (as well as other complications), but the payoff, in the long run, is fewer restrictions where you sell your items. If your not selling items.....then it's just your own health and environment you are contaminating (this does include landfills).
Just my observations,
James L
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James L
Partner/Designer
Lil Brother LLC (SMT Assembly Services)
Leon
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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle
So what is 'properly constructed'? The distance between IC leads keeps getting closer with surface mounted devices as the pitch gets finer and finer.
I find lead-free electronics appears to be a bit of a sham when powered by batteries chock full of heavy metals mixed with corrosives. RoHS appears to have evolved more as a trade barrier disguised as environmental protection. It also forced a lot of smaller concerns to quit business rather than convert.
If the law makers had claimed to be protecting the production workers, it would be more believeable to me. White house paint, leaded gasoline, and automotive batteries have certainly dispersed more lead into the environment than the solder in micro-electronics. Nearly all batteries are in much closer contact with children. They play with them, try to open them, and might even suck on one.
Anyway, I am more concerned that devices are being created with a much shorter useful life due to the new metalurgy. For instance, if you live in a steel mill town, the air is very acidic. With high humidity, the tin might migrate quickly and short out an otherwise good device.
I suppose one could use Rohs solder, then coat the board with a layer of sealant to protect the tin from outside corrosive influence. But no one has mentioned that so far. It will be interest to see in European electronics have a shorter useful life than other non-Rohs productions.
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Leon
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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle
I use SAC305 alloy for lead free processes and with the right profiles for reflow and the right irons for handsoldering, you can't tell the difference visually nor electrically between it and SnPb. As Forrest mentions however, extreme cases will uncover the flaws of leadfree processes.
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~~ dRu ~~
Anyone who reads these blogs and who's used lead free solder knows that it doesn't flow as well as Eutectic solder. It also doesn't solidify in the same way (That’s why they call 63/37 solder eutectic)
All the trade journals I read warn of lead free solder balling during both SMD and Wave solder. Now I'm not in the electronic assembly industry any more but I occasionally hear friends talk of the tighter reflow profiles. Lead free solder pastes seem to be unforgiving so manufacturers have to pay far greater attention to their solder screens. Etc etc etc.
To add insult to injury, unless you are a heavy drinker or have damaged your liver, you are extremely unlikely to suffer from lead poisoning, even at 10X the maximum safe exposure level. I got malaria a couple of times (a predominantly liver disease) so while maintaining very dirty wave solder machines, I required my employer to test me. We have slack safety standards in Africa so, when I was unable to get filters for my mask, I stopped wearing a mask. My lead levels were 5X those of my two assistants (even though they did the dirty work) but a fraction of the safe blood level.
So the way I see it, Joe Public is paying for a new technology that requires the overhaul of the electronics industry but gives little benefit.
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lead free solder dose not work very well at·ALL and then I have to use 60/40
lead solder
One thing also about using· lead free solder is that you MUST keep you tip clean and that your tip is·HOT·enoght or it will not flow right ·This is a Big thing not flow right
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··Thanks for any·
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Sam
The key to my statements is "the right equipment". If one thinks they can pull out their trusty weller iron with a new 700 degree tin plated tip and solder lead free solder, they will find many issues and I see where a lot of the home soldering issues come from. (However, my weller does work for "acceptably" for TH connectors with lead-free)
However, with the right equipment (I use an Ersa I-con station for example), soldering lead free solder is truly "just another soldering method". At work we process hundreds of RoHS compliant boards every month and have no issues with solder balls, solder flow issues, crystalization problems, or having to retrain operators (other than using the other irons/flux/solder). We use Kester EM907 and R520A solder pastes for SMT and Kester SAC305-66/331 or SAC305-58/275 for manual soldering.
I second your statement about lead poisoning. I have been in electronics manufacturing for 17 years and don't know of any issues other than having to buy a stupid sign that states the prop65 warning here in CA for using lead.
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~~ dRu ~~
I suspect heavy metal poisoning is far more prevalent in foundry and welding work. With the intense heat and energy, the metals are vaporized and one breathes the fumes.
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David
There are 10 types of people in this world,...
Those that understand binary numbers, and those that don't!!!
Leon
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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle
Post Edited (Leon) : 4/23/2008 8:55:16 PM GMT
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~~ dRu ~~
But, I still have an ample supply of SnPb solder that will take some time to get through. And I do indeed notice a different feel in soldering RoHS components by hand. I have to take more care with flux and with ample heat. It isn't a big deal and I really didn't want to try to discredit the industry. I brought this up because some hobbyist might think that using Pb on RoHS components might actually damage them or be something of a taboo. I have no intention of resale and export, so such things are not as important as ease of assembly.
It seems to me, the tin whiskers are more likely to occur with the messiness of hand soldered boards done in someone's home workshop.
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Post Edited (Kramer) : 4/24/2008 1:49:15 PM GMT
That's true - but that doesn't mean they will outlast their leaded predecessors. Notice these are all consumer items that are designed to last 5-10 years. I'm willing to bet most of these won't be working 25 years from now. By comparison, all of my 25 year old Atari computers are still working!
One of the biggest issues we face with RoHS is no longer mass fabrication, but the fact that the Boe-Bot kit includes a CdS photocell. This single component keeps the whole kit from being "RoHS compliant". Many appeals have been filed by photocell manufacturers which are likely to be rejected. The alternatives to CdS cells have proven expensive and have different characteristics that will cause substantial book revisions for Parallax when we finally make the switch. For now we're delaying it as long as possible and the EU continues to buy Boe-Bots. We're still watching the CdS appeals and reviewing alternatives, but nothing has become a clear option to our current component.
Aside from this, the most common complaints in our office about RoHS relate to hand assembly of prototypes. We get far better results on the pick & place machine using a stencil than by hand. But the biggest issue has clearly been the expense. Through RoHS we've had to expense out at least $300K worth of electronic components over recent years. That's a real waste of money in my view. To make matters worse the first RoHS parts were always 5-10 cents more expensive because "they are RoHS-compliant" yet they came down quickly. Maybe it has some similarities to the Costco rice rush we can see today. I imagine our local grocery stores will quickly inflate the price for a bag of rice since the media has nicely laid the groundwork for them over the past 24 hours.
This RoHS topic makes me cranky.
Ken Gracey
Parallax, Inc.
Leon
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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle
Taiwan just outlawed mercury thermometers. You now have to buy an electronic one with either carcinogenic nickel or heavy metal batteries which is likely to be RoHS compliant because the batteries are never considered.
Of course, if you are traveling these things are all now contraband that might get you in trouble with customs. But, the batteries are forevermore.
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Post Edited (Kramer) : 4/25/2008 12:58:55 PM GMT