Lead free solder recommendation?


#1

Can anyone please recommend lead free solder they like? I have a temperature controlled soldering iron.

I’m doing general hobbiest soldering on PCBs, and my young son likes to help. He’d like to build Tindie blinky badges and so will be handling the bare PCB as a blinky toy, so I’d like to make it lead free. Thanks!


#2

I’ve really enjoyed using Sparkfun’s mix — it wets nicely. At one point I figured out what they were re-badging, but have forgotten it now.


#3

Using SAC305 mostly. However, this is only half of the story. Secret is in the flux. LF4300 is a good REL0 flux for example. Amtech also makes SAC 305 wire with it. However – even as it says no clean on the label, you do want to clean it if it ever goes to work in humid environment (learned it the hardway – product series recall).

When it comes to wire and good looking solder joints, you want something which splatters less (read: has less flux in it). Yet this is a compromise between splattering and wetting…

Non-water soluble no-clean fluxes are quite good. Chipquick SMD291 and AIM NC for example.

A good intro to the world of flux[es]: https://www.pillarhouse.co.uk/technology/choosing-flux-technical-article


#4

@svec I have been soldering tindie badges with my children too. I wasn’t sure whether the PCB finish was lead free so I painted with clear nail polish after assembly. Seems to work well.


#5

Painting it with clear nail polish is a great idea, thanks!


#6

I have successfully used Kester Sn96.5Ag03Cu.5 with 331 flux core in combination with Kester 2331-ZX Flux pen. The 331 Flux is water soluble so cleaning the boards at the end is very easy without using any smelly chemicals. Kester also claim the 331 flux is more effective than rosin fluxes and I have noticed it worked great for me, the best lead free soldering I ever did.

Depending on the type of soldering you’re doing you might or might not need the extra flux pen. I was doing some drag soldering on 0.1 inch spaced pins, 40 in a row so extra flux was a must to avoid getting any solder bridges while dragging the tip across the entire row of pins.