Lead or no lead
T Chap
Posts: 4,223
If you guys are building for the US, in cases where nobody knows or cares what board solder you use, would you use lead to possibly have a longer lasting device and avoid replacing boards? I have heard that no lead solder doesn't have a good lifespan.
Comments
This is true. When considering lead or lead-free you must consider how long the product will last. Lead-free alloys are known not to last as long (due to the crystallization of the tin).
I feel like, you should get used to doing lead-free. It is coming, and there is nothing anyone can do about it. The earlier you get accustom to the process, the better off you are. It is just a matter of time until all processes will be lead-free (RoHS).
We still do lead, but we focus on lead-free for many reasons.
Also, just as a important heath note. Lead-free is not the most healthy thing to play with, but leaded solder can poison a person, and it takes very little to do so.
If anyone is going to use leaded solder, please be careful and use a ventilator hood or similar. Lead can be very dangerous to your health.
Also, just as a business perspective. You can sell RoHS here as being more "Green", and a board that is 20 years old would be a purchase part any how, probably not going to be covered by warranty.
That is my perspective.
James L
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James L
Partner/Designer
Lil Brother SMT Assembly Services
Are you addicted to technology or Micro-controllers..... then checkout the forums at Savage Circuits. Learn to build your own Gizmos!
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24 bit LCD Breakout Board now in. $21.99 has backlight driver and touch sensitive decoder.
I do wonder about actual life span, but I do know this pertains to QFN and BGA type parts, and are fine pitch. This is one reason I shy away from those parts. If I can find a larger pitch in a QFP or TSSOP, I go that route. They could be reworked if the board fails in the future.
Solder type is a very important consideration. You should weigh it heavily.
I seriously doubt life span on the larger pitches is reduce that much. With the change of technology, most things will be far outdated before the board fails anyway.
I try to stay in a medium range that will give a small board, but still provide some room should the solder decide to grow stalagmites (that is what they look like under a microscope). I don't know the real name which they are referenced by.
James L
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James L
Partner/Designer
Lil Brother SMT Assembly Services
Are you addicted to technology or Micro-controllers..... then checkout the forums at Savage Circuits. Learn to build your own Gizmos!
Leon
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Amateur radio callsign: G1HSM
I thought that too, but couldn't find any solid evidence that solder fumes contain lead. If you have references or poison stories I would like to hear them.
Leon,
In a report from the IPC, "tin whiskers" can happen even if the profile is correct. It has a lot to do with the alloy used, and the assembly process. They state, that even if the profile is perfect, "tin whiskers" can still happen. This has to do with a "perfect" process, not just reflow. If the process is perfect there is a very good chance the whiskers will not grow. This entails open air time of the solder paste (idle time and mixing), temperature of the solder paste, and reflow profile.
The question is, who is getting a perfect process? I doubt the number is as high as one may think.
Also, only 5 or 6 stage reflow oven (and higher) can even come close to a correct profile. A batch oven can to if it has enough wattage. Vapor phase with a vapor preheat is probably the closest to perfect.
It is a real concern for anyone who is considering which solder to use.
James L
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James L
Partner/Designer
Lil Brother SMT Assembly Services
Are you addicted to technology or Micro-controllers..... then checkout the forums at Savage Circuits. Learn to build your own Gizmos!
Well, I'm not positive that lead does create fumes, but I know for certain that many flux variants are not good for the respiratory system and can cause problems. If that isn't enough for you, I guess you can breath what ever you want. I don't like to take chances. Especially since it only takes 1.3 mg of lead to poison you.
I would think with every piece of equipment that reflows, wave solders, or vapor phase reflows boards, having a venting fan, would tell all of us something.
James L
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James L
Partner/Designer
Lil Brother SMT Assembly Services
Are you addicted to technology or Micro-controllers..... then checkout the forums at Savage Circuits. Learn to build your own Gizmos!
As long as you can get by with it legally, I would continue using leaded solder. It's just easier to get good fillets and sound connections with it. If you ship to California, though, you need to include a "hazardous chemical" warning label to avoid entrapment by the legal bounty hunters. The exact wording of the label is important and can be found on numerous websites.
-Phil
I would say, you will need to decide based on the ability to support the endeavor in the future.
Also, it should be noted that California is one of the states that is already RoHS compliant. I'm not sure what steps would need to be taken since I know you are located there. I'm not sure of the legalities dealing with manufacturing with lead in Cali.
Also, the growth is pretty slow, and probably would be a decade before any failed. This is just based on my intuition, and no scientific basis for it.
Ewwwww.....Cali laws.
James L
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James L
Partner/Designer
Lil Brother SMT Assembly Services
Are you addicted to technology or Micro-controllers..... then checkout the forums at Savage Circuits. Learn to build your own Gizmos!
@James Long. I wasn't trying to say there was no danger, only that I got worried about it one day and checked it out, and couldn't find much. I currently use a fume extractor. I find it interesting that many folks used to get sick back when there was lead in gas, so there must be certain situations that produce vapor.
I have tried both lead and lead free, and find they both can work, but it can be more difficult to get nice looking joints, and proper reflow using lead free, especially if you are using a toaster oven or the like. In my experience you will have to get the oven up to 250C+ and hold it there a bit before things will flow.
www.dbicorporation.com/rc051705.pdf
It is scary at times, like PG&E with the hexavalent chromium not too many years ago.
By chemistry I have always understood that any solid, heated to a liquid state, has a chance to put off a certain amount of vapor.
I agree with you about lead-free. We typically run more lead-free than anything else, and it is more challenging.
James L
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James L
Partner/Designer
Lil Brother SMT Assembly Services
Are you addicted to technology or Micro-controllers..... then checkout the forums at Savage Circuits. Learn to build your own Gizmos!
Although very interesting reading, it should be noted the low oxygen environments do change the growth factor of tin whiskers.
It should also be noted that a PCB touched by a bare human hand will fail within 6 months in outer space(can be a matter of days). So sometimes reports about celestial items do not necessarily apply to us earth bound relatives.
James L
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James L
Partner/Designer
Lil Brother SMT Assembly Services
Are you addicted to technology or Micro-controllers..... then checkout the forums at Savage Circuits. Learn to build your own Gizmos!
It shouldn't worry you about people not buying on the basis of the warning. Like an OS giving you a security warning everytime you click a button, we see those labels on everything. I used to work at a gift shop and even the coffee mugs got them...
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Powered by enthusiasm
Fumes from handsoldering are harmful, but not because of lead vapor. As James mentioned, it takes an a larger amount of heat to vaporize lead than you can get out of a soldering iron. Here in California, we get the luxury of being audited occasionally by CAL-OSHA and we have to have our operators wear a "sniffer" during 4 hours of normal work to ensure we are not poisoning them. We just did this recently, and while using fume extractors, the results were near the same as if the person wasn't soldering (means we passed). Even at the wave soldering machine, vapors are nowhere near recordable levels due to the proper ventilation installed. During de-drossing of the wavesolder, there was recordable amounts of toxic substances but well within limits. This is low due to the ventilation and also the limits are higher because while de-drossing, the wave operator is required to wear a respirator. The lead in the dross is in powder form, so the lead particles can become airborne.
Another thing that hasn't been mentioned yet is the Material Safety Data Sheet (MSDS). Regardless of whether or not you feel something is irritating, toxic, bothersome, etc, many (if not all) states require you to comply with handling measures detailed in the MSDS. We recently did a project where we added a clear gel like potting compound over strips of 1.5 watt LEDs controlled by DMX like controllers. Even though you could not smell the gel nor did it irritate you, the MSDS called for all sorts of PPE (Personal Protection Equipment) during it's installation. See the attached picture (white block is the person's name badge cut out). And, no, the operators did not enjoy sweating in the getup. What's not seen is the large ventilation duct overhead that was also required per the MSDS. Gotta love OSHA!
Since it was a fun project, the second picture is the final install of one panel section at a university. It is basically a monochrome video art wall made up of the strips of LED bars.
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Andrew Williams
WBA Consulting
WBA-TH1M Sensirion SHT11 Module
Special Olympics Polar Bear Plunge, Mar 20, 2010
As for lead free the only trouble I have had is with bga components. Would be nice if wishers were not possible but to what I have herd I should average 10+ year without trouble.
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24 bit LCD Breakout Board now in. $21.99 has backlight driver and touch sensitive decoder.
Chris I.
www.dtsc.ca.gov/HazardousWaste/RoHS_CAvEU.cfm
yes, mostly pertains to "displays" (CRT, LCD, etc)
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Andrew Williams
WBA Consulting
WBA-TH1M Sensirion SHT11 Module
Special Olympics Polar Bear Plunge, Mar 20, 2010