7 ms·

Use lead solder, like NASA does: easier to use, and no whisker issues. Just wash your hands afterwards

by dmitrygr 5y ago

mmastrac 5y ago
Better to solve these issues long-term. Lead's external costs in full product lifecycles are just too high.
- iancmceachern 5y ago
  Yeah, and we're not allowed to even put it in products anymore by law (RoHs, reach, etc)
- dmitrygr 5y ago
  As you read in TFA, there is no known solution, nor even a known cause for whiskers
  - mmastrac 5y ago
    No known cause or solution _yet_
    - adrian_b 5y ago
      It is extremely unlikely to ever find any solution to the tin whiskers problem, other than alloying tin with toxic elements, i.e. either lead or antimony. The reliability problem could be solved only by replacing soldering with another method of making electrical connections during PCB assembly, e.g. thermal/ultrasonic welding of copper on copper, metal deposition in vacuum etc. While replacing soldering is possible, any known alternative method would hugely increase the price for the assembly of electronic equipment. Soldering is not used because it is a good method for making electrical connections, but because it is extremely cheap, allowing many thousands of connections to be made simultaneously, during a pass of a PCB through a reflow oven, or over a soldering wave.
      - Animats 5y ago
        The reliability problem could be solved only by replacing soldering with another method of making electrical connections during PCB assembly, e.g. thermal/ultrasonic welding of copper on copper, metal deposition in vacuum etc. There's been some interest in laser welding for PCB assembly. But most modern components are not designed with the pins out where you can get at them with a laser beam. Laser welding is commonly used to weld the connections in automotive battery packs, so it does work.
        Animats 5y ago
        If you can get the parts you need in SSOP or TSSOP packaging, with the pins visible from straight down, laser brazing might work. Brazing is done at higher temperatures than soldering, but with a laser, you can apply the heat to just the area of interest, and hopefully not cook the ICs. Laser soldering already exists, and there are laser cutters, so adapting one for laser brazing ought to be possible. The advantage of brazing is that you can use many more materials, most of which don't contain either tin or lead. Low-cost aluminum brazing rod or wire might work. Working temp around 700C. This is going to take careful heat management. Worth a try for aerospace applications.
        coryrc 5y ago
        Low-temp aluminum brazing rod has cadmium.
      - hulitu 5y ago
        > The reliability problem could be solved only by replacing soldering with another method of making electrical connections during PCB assembly, e.g. thermal/ultrasonic welding of copper on copper, metal deposition in vacuum etc. The whiskers are not related to soldering. Of course there are some soldering issues which facilitate whiskers but that's about it. Tin is a normal plating material so you can find whiskets in places which were not soldered.
        adrian_b 5y ago
    - formerly_proven 5y ago
      Okay, so here's what's what. Tin whiskers have been known for ~100 years. Originally solder was just tin. Lead was added specifically in the 30s or so to avoid tin whiskers [1] though nobody knows why that works. RoHS/lead-free has been around for ~20 years and there hasn't been a definitive solution. [1] (and because Pb63Sn37 or the inexplicably more popular Pb60Sn40 are eutectic and near-eutectic, respectively, which is nice for wire dipping and related sports)
Flozzin 5y ago
I wouldn't recommend this. If you do use lead soldering, make sure you don't breathe in any fumes.
- the-dude 5y ago
  The boiling point of lead is 1749 °C (3180 °F).
  - turminal 5y ago
    That by itself does not imply fumes cannot form at lower temperatures.
    - the-dude 5y ago
      Great. If we follow this line, standing next to a roll of solder is just as dangerous. No need to fire up the iron. If lead was so easily dissolved into air, wouldn't we have had massive issues in electronics factories? I don't recall ever reading such a thing ( as opposed to painters madness for example ). Not a native speaker, probably doesn't translate too well.
      - the_jeremy 5y ago
        Mad Hatter[0] is a good example in English. [0]: https://en.wikipedia.org/wiki/Erethism https://en.wikipedia.org/wiki/Erethism
      - kadoban 5y ago
        Or you could just look at the actual material property that matters, which I believe is called vapor pressure.
      - mcguire 5y ago
        "Results showed that the mean PbB concentration of the exposed workers (6.12 +4.61 µg/dl) was significantly higher than that of the unexposed workers (4.63+3.91 µg/dl ) (z = 4.96; p = 0.001). There was a significant association between the blood lead concentrations with the exposure to lead (2 = 437.72; p = 0.001)." (https://www.researchgate.net/publication/271077842_Occupational_Lead_Exposure_of_Soldering_Workers_in_an_Electronic_Factory https://www.researchgate.net/publication/271077842_Occupatio...) "Epidemiological and experimental studies indicate that chronic exposure resulting in blood lead levels (BLL) as low as 10 µg/dL in adults are associated with impaired kidney function, high blood pressure, nervous system and neurobehavioral effects, cognitive dysfunction later in life, and subtle cognitive effects attributed to prenatal exposure. Pregnant women need to be especially concerned with reducing BLL since this can have serious impact on the developing fetus." (https://www.osha.gov/lead/health-effects https://www.osha.gov/lead/health-effects)
Steltek 5y ago
On the contrary, I am not NASA. I'm not even a consumer electronics company. I'm a hobbyist at home, soldering things at my desk or table. Lead-free is the least of my problems when building something and I don't believe "just wash your hands" is sufficient for cleaning my workspace (or kitchen table?) of possible lead contamination.
- JaggedNZ 5y ago
  Fellow hobbyist here. Actually your biggest health risk is industrial asthma from flux fumes. I know professionals who have spent a good fraction of there lives soldering with no lead poisoning issues. Lead needs to be consumed or inhaled for it to be an issue. The guy I meet who did have lead poisoning, large bore rifle shooting coach, from spending to much time at the “wrong end” of the rifle range. Lots of lead dust there.
- alar44 5y ago
  It definitely is enough. I don't know where the myth that looking at lead kills you started, but unless you are eating it or breathing it in (soldering is not hot enough to vaporize lead) there's nothing to worry about.
  - throwaway0a5e 5y ago
    >I don't know where the myth that looking at lead kills you started For a large subset of western society it's highly fashionable to give a lot of shits about health and safety. I'm not saying this is a bad thing to care about but let's be honest here, when you treat abstract concepts like a minor religious deity there's some baggage that comes with that. Let the feedback loops run their course for a decade or three and combine that with the fact that it's very easy to be scared of things you're not familiar with and you get the current situation. This is why people go crazy over a long forgotten package of asbestos shingles sitting on some shelf in the maintenance department's storeroom or think you're gonna get black lung from using an antique coal stove a couple times a year. Their belief system tells them to go crazy and they don't have the experience to know they don't need to.
adrian_b 5y ago
Besides lead, there is a second element which greatly reduces the risk of tin whiskers, when alloyed to tin: antimony. However the proposals of replacing the tin-lead alloys withe tin-antimony alloys have been rejected due to the fear that antimony is also toxic. While antimony in high doses is indeed quite toxic, it is less dangerous as a pollutant than lead, because it does not have the same tendency for very long time accumulation in animal bodies and such a strong effect on the nervous system.

Use lead solder, like NASA does: easier to use, and no whisker issues. Just wash your hands afterwards

mmastrac 5y ago

Better to solve these issues long-term. Lead's external costs in full product lifecycles are just too high.

iancmceachern 5y ago
Yeah, and we're not allowed to even put it in products anymore by law (RoHs, reach, etc)
dmitrygr 5y ago
As you read in TFA, there is no known solution, nor even a known cause for whiskers
- mmastrac 5y ago
  No known cause or solution _yet_
  - adrian_b 5y ago
    It is extremely unlikely to ever find any solution to the tin whiskers problem, other than alloying tin with toxic elements, i.e. either lead or antimony. The reliability problem could be solved only by replacing soldering with another method of making electrical connections during PCB assembly, e.g. thermal/ultrasonic welding of copper on copper, metal deposition in vacuum etc. While replacing soldering is possible, any known alternative method would hugely increase the price for the assembly of electronic equipment. Soldering is not used because it is a good method for making electrical connections, but because it is extremely cheap, allowing many thousands of connections to be made simultaneously, during a pass of a PCB through a reflow oven, or over a soldering wave.
    - Animats 5y ago
      The reliability problem could be solved only by replacing soldering with another method of making electrical connections during PCB assembly, e.g. thermal/ultrasonic welding of copper on copper, metal deposition in vacuum etc. There's been some interest in laser welding for PCB assembly. But most modern components are not designed with the pins out where you can get at them with a laser beam. Laser welding is commonly used to weld the connections in automotive battery packs, so it does work.
      - Animats 5y ago
        If you can get the parts you need in SSOP or TSSOP packaging, with the pins visible from straight down, laser brazing might work. Brazing is done at higher temperatures than soldering, but with a laser, you can apply the heat to just the area of interest, and hopefully not cook the ICs. Laser soldering already exists, and there are laser cutters, so adapting one for laser brazing ought to be possible. The advantage of brazing is that you can use many more materials, most of which don't contain either tin or lead. Low-cost aluminum brazing rod or wire might work. Working temp around 700C. This is going to take careful heat management. Worth a try for aerospace applications.
        coryrc 5y ago
        Low-temp aluminum brazing rod has cadmium.
    - hulitu 5y ago
      > The reliability problem could be solved only by replacing soldering with another method of making electrical connections during PCB assembly, e.g. thermal/ultrasonic welding of copper on copper, metal deposition in vacuum etc. The whiskers are not related to soldering. Of course there are some soldering issues which facilitate whiskers but that's about it. Tin is a normal plating material so you can find whiskets in places which were not soldered.
      - adrian_b 5y ago
  - formerly_proven 5y ago
    Okay, so here's what's what. Tin whiskers have been known for ~100 years. Originally solder was just tin. Lead was added specifically in the 30s or so to avoid tin whiskers [1] though nobody knows why that works. RoHS/lead-free has been around for ~20 years and there hasn't been a definitive solution. [1] (and because Pb63Sn37 or the inexplicably more popular Pb60Sn40 are eutectic and near-eutectic, respectively, which is nice for wire dipping and related sports)

Flozzin 5y ago

I wouldn't recommend this. If you do use lead soldering, make sure you don't breathe in any fumes.

the-dude 5y ago
The boiling point of lead is 1749 °C (3180 °F).
- turminal 5y ago
  That by itself does not imply fumes cannot form at lower temperatures.
  - the-dude 5y ago
    Great. If we follow this line, standing next to a roll of solder is just as dangerous. No need to fire up the iron. If lead was so easily dissolved into air, wouldn't we have had massive issues in electronics factories? I don't recall ever reading such a thing ( as opposed to painters madness for example ). Not a native speaker, probably doesn't translate too well.
    - the_jeremy 5y ago
      Mad Hatter[0] is a good example in English. [0]: https://en.wikipedia.org/wiki/Erethism https://en.wikipedia.org/wiki/Erethism
    - kadoban 5y ago
      Or you could just look at the actual material property that matters, which I believe is called vapor pressure.
    - mcguire 5y ago
      "Results showed that the mean PbB concentration of the exposed workers (6.12 +4.61 µg/dl) was significantly higher than that of the unexposed workers (4.63+3.91 µg/dl ) (z = 4.96; p = 0.001). There was a significant association between the blood lead concentrations with the exposure to lead (2 = 437.72; p = 0.001)." (https://www.researchgate.net/publication/271077842_Occupational_Lead_Exposure_of_Soldering_Workers_in_an_Electronic_Factory https://www.researchgate.net/publication/271077842_Occupatio...) "Epidemiological and experimental studies indicate that chronic exposure resulting in blood lead levels (BLL) as low as 10 µg/dL in adults are associated with impaired kidney function, high blood pressure, nervous system and neurobehavioral effects, cognitive dysfunction later in life, and subtle cognitive effects attributed to prenatal exposure. Pregnant women need to be especially concerned with reducing BLL since this can have serious impact on the developing fetus." (https://www.osha.gov/lead/health-effects https://www.osha.gov/lead/health-effects)

Steltek 5y ago

On the contrary, I am not NASA. I'm not even a consumer electronics company. I'm a hobbyist at home, soldering things at my desk or table. Lead-free is the least of my problems when building something and I don't believe "just wash your hands" is sufficient for cleaning my workspace (or kitchen table?) of possible lead contamination.

JaggedNZ 5y ago
Fellow hobbyist here. Actually your biggest health risk is industrial asthma from flux fumes. I know professionals who have spent a good fraction of there lives soldering with no lead poisoning issues. Lead needs to be consumed or inhaled for it to be an issue. The guy I meet who did have lead poisoning, large bore rifle shooting coach, from spending to much time at the “wrong end” of the rifle range. Lots of lead dust there.
alar44 5y ago
It definitely is enough. I don't know where the myth that looking at lead kills you started, but unless you are eating it or breathing it in (soldering is not hot enough to vaporize lead) there's nothing to worry about.
- throwaway0a5e 5y ago
  >I don't know where the myth that looking at lead kills you started For a large subset of western society it's highly fashionable to give a lot of shits about health and safety. I'm not saying this is a bad thing to care about but let's be honest here, when you treat abstract concepts like a minor religious deity there's some baggage that comes with that. Let the feedback loops run their course for a decade or three and combine that with the fact that it's very easy to be scared of things you're not familiar with and you get the current situation. This is why people go crazy over a long forgotten package of asbestos shingles sitting on some shelf in the maintenance department's storeroom or think you're gonna get black lung from using an antique coal stove a couple times a year. Their belief system tells them to go crazy and they don't have the experience to know they don't need to.

adrian_b 5y ago

Besides lead, there is a second element which greatly reduces the risk of tin whiskers, when alloyed to tin: antimony. However the proposals of replacing the tin-lead alloys withe tin-antimony alloys have been rejected due to the fear that antimony is also toxic. While antimony in high doses is indeed quite toxic, it is less dangerous as a pollutant than lead, because it does not have the same tendency for very long time accumulation in animal bodies and such a strong effect on the nervous system.