Electronic – Experience with lead-free synthetic solder paste


I'm looking to start working with solder paste as I'll be making a batch of SMT boards. It seems that most people use lead-based solder paste that requires refrigeration. Vendors charge a hazardous materials fee that seems to be around $25 plus they will only ship overnight with a cold pack. So if I want just one or two syringes, the shipping can be double the product cost. Plus I have to keep it in a separate refrigerator or at least triple-bag it in my food refrigerator.

But I also see available lead-free synthetic solder paste (like Amtech's SynTECH-LF) that incurs none of the extra charges or special handling, although I'd refrigerate it anyway. I'll likely be using hot air soldering initially and then switch to stenciling and a toaster over. Does anyone have any experience with this synthetic solder paste? How difficult is it to work with?

Best Answer

I've tried both on different projects and stick with lead solder for hand soldering SMT and through hole projects. I've found lead-free solder is very difficult to obtain consistent joints. Lead free soldering is successful in consumer electronics because the soldering environment can be precisely maintained compared to hand soldering on a bench. You also don't need solder paste for SMT work. I've been successful using very thin .025 solder.