it did bring some problems with it, especially in aerospace applications where fine crystals would grow out from the soldered surface (“tin whiskers.”) sudden unexpected short circuits caused all sorts of hell.
Tin/silver/copper is the most common for lead-free solder used in mass production these days. It’s a bit of a pain to work with by hand and requires higher temperatures.
Yep. That’s why specialty applications like aerospace still use the lead stuff. But consumer devices generally don’t.
Is it used in dip soldering circuit boards?
Right, it becomes boilerplate. “Complying with prop 65” does not mean being free from things that are “known to the state of California” (meaning, the regulatory panel in Sacramento has read and accepted studies indicating them) to be harmful, or reporting that you know for a fact which and how much are present, but merely, “I posted this warning”.
As mentioned it has an odd side effect of creating a business line for warning sign troll lawyers.
Though that particular message could never truly be used, it would have to be more along the lines of “This product is certified free of those chemicals listed under [citation] as of [date] as known to the State of California to…”. But this would require very close monitoring of the entire chain of origin from raw materials to store shelf.
As mentioned in links upthread, this issue turns up even in the case of compounds that are a normal product of the process of cooking foods. You may have organically grown sun-dried coffee that you are brewing with distilled water and putting through gold mesh filters and you still are on the hook for that something in the cofee bean itself gives off acrylamides when roasted.
Dip soldering isn’t used much these days. Most things that would have been dip soldered back in the day are now wave soldered.
Wave soldering video on youtube:
A lot of surface mount stuff is made with reflow oven soldering (basically, they put a solder paste on the parts to attach them to the board then run the board through an oven, which melts the paste/solder and makes the solder connections).
You can use lead solder or lead-free solder in a wave soldering machine. It doesn’t matter much to the machine. Solder paste for reflow soldering can also be made with lead solder or lead-free solder.
The higher temperatures of the lead-free stuff can be an issue though. Some components don’t tolerate the higher soldering temperatures very well. In my own job, we’ve had to redesign stuff with different connectors due to the plastic in the connectors melting during soldering.
RoHS compliance is a big thing these days, so in my experience it’s fairly rare for folks to use lead solder for new designs.
Thanks again, I was just reading about reflow soldering.
Tin whiskers are generally caused by pure tin plating on component leads, and can occur even in assemblies using tin-lead solders.
RoHS solders are a giant step backwards for electronic assembly. They are more expensive, less forgiving, and harder to work with. Although most of the assembly issues are under control, I still see more problems (usually inadequate reflow) with SnAgCu solders than I did with SnPb.