Received from Dave at 10/26/2020 23:23 UTC:
I bought some USB cables and noticed the RoHS sticker on them and never really read much about the standard so I have a few questions. It states something about 0.1% lead is allowed but in the case of cables, does that take in the whole weight of the cable??
No, it's based only on the weight of the components that are expected to contain lead... in this case the solder used can contain only 0.1% lead.
Actually ROHS stands for "Restriction of Hazardous Substances" and it refers to a dozen or so other substances, not just lead, and the allowed percentage of each varies according to the substance involved... but we're just talking lead in this case.
Or on a circuit board, how is the math actually based for the allowable limit of lead in the solder.
It's based on the weight of the solder alone.
And last but not least, I have never ever used no lead solder. Is is a good idea to buy some for future reference in case of reworking something that followed the standard?
If you're a commercial enterprise, repairing an ROHS product with non-ROHS solder would be a be no-no. In the case of a hobbyist making things for himself and a few friends I wouldn't touch ROHS solder... not even for repair of ROHS products. In general it doesn't wet the parts nearly as well as tin-lead solder does so you're more likely to get a good joint with tin-lead... and wetability aside, during a repair you're also far less likely lift a PCB pad due to the higher temperature ROHS solder requires.
And if yes, are all no lead solders the same or do the have choices using differing amounts of the ingredients to make it?
Thanks
Dave
They're not all the same. Neither are all lead containing solders.
Jim H
