From china, with love: bad solder paste

Recently I was running out of solder paste and I’ve bought some chinese paste to try out from a (very) popular online electronics outlet. I think somewhere in the reviews or in one of the tutorials they say they actually use that paste internally so I got confident and the price was right (I guess… even though I later found the same paste on dx.com for under $5), about $14 for a jar of 50g which would last a long time. Great I thought, I’d get it in time to assemble more boards, without the insane shipping delays from china, so I ordered and got peace of mind.

A few days later I got it and I assembled a batch of boards with it and peeked through the microscope to inspect how it reflowed. Here’s what I saw:

bad_solder_paste

Holy cow! What happened? Tons of tiny balls of solder stuck in tons of solder paste residue. Not one of my best days, but certainly memorable. Continue reading