Best lead free solder (wire)?

Bill Henning · 2013-11-06 19:22

I've been doing a bit of soldering on a lead free prototyping board... and it is painful with my 40W temperature controlled iron and the leaded solder I normally use.

It takes 3x as long before the solder will adhere to the holes! It simply refuses to adhere to the Pb-free surface until it is REALLY heated.

Does anyone know of a faster way? Or should I invest in a 100W soldering iron? (mostly joking)

Peter KG6LSE · 2013-11-06 19:39

I have done a ton of ROHS on the hakko 888 iron ........ and now the 888 is digital . .. the unit is under 90 bucks in most stores .
Also some good flux may help.

http://www.hakko.com/english/products/hakko_fx888d.html
Peter

WBA Consulting · 2013-11-06 21:38

Bill, by "lead free surface" what do you mean? There are several lead free options considered standard nowadays: Immersion Tin, Immersion Silver, SAC302 HASL, SN100 HASL, and ENIG (electroless nickel immersion gold). Does your iron melt the solder alone with ease or difficulty? Lead free plating on a PCB does not increase the temperature required to properly solder, so if your iron can melt the solder without a struggle, something else is going on. Is the prototyping board old or oxidized?

Franklin · 2013-11-06 21:41

If you are having trouble using leaded solder now you will have less luck with leadfree. I'd check your tips or get a better iron. I use leaded solder on leadfree boards to lower the melting temperature so I can desolder parts easier.

Bill Henning · 2013-11-07 06:33

Peter:

I've tried both a Weller and a soldering station similar to your hakko - same issue soldering to lead free pcb. I'll try some flux.

Andrew:

The cheap PCB's use an "unknown" pb-free process. I have zero problem melting my leaded solder, on my on tinned or gold flash pcb's its extremely easy to solder. The prototype board is not old, nor oxidized, just some no-name brand/process (it was small, and a shape I needed, so I tried it... time to make some of my own small proto pcb)

Franklin:

I have no problem soldering to non-lead free pcb's, or gold flashed lead free pcb. Too bad, I was hoping for a lead-free magic bullet

ALL:

On "good" pcb's I heat the pad for <2sec and make a nearly perfect solder joint immediately on applying solder - no beading, no problems adhering

On these "funny" pcb's I have to head the pad for >8sec to get a not so good looking joint. If I apply the solder before heating the pad for at least 8 sec, the solder just beads and does not adhere to the pads.

Both "good" and "funny" soldered with same irons, and same solder (with flux core)

Funny pcb's: new, small, unknown lead-free process

Thanks guys!

WBA Consulting · 2013-11-07 12:01

Bill, Definitely sounds like a contamination or oxidation. Liquid flux should help if that is the case. If it's a metal issue (as in low quality metal at the manufacturer), the flux may not make much of a difference.

Bill Henning · 2013-11-07 12:08

Thanks Andrew.

Wifey is picking up three more different types of solder for me during her lunch, and a 60W soldering iron. I'll be picking up some flux as well (if I can't find my stash of flux for smt).

Hopefully I will solve this issue.

If the flux etc won't help, maybe I'll call in a favor and have the metal analyzed at a lab.

WBA Consulting wrote: »

Bill, Definitely sounds like a contamination or oxidation. Liquid flux should help if that is the case. If it's a metal issue (as in low quality metal at the manufacturer), the flux may not make much of a difference.

Bill Henning · 2013-11-07 14:00

Update:

I did a number of experiments, and it seems I can solder to these lead free boards reasonably well at 400'C or higher (using my Gordak 952 rework station).

I'll try it tonight with an inexpensive 60W iron.

For what its worth, I've had zero problems soldering nice gold flash lead free boards with the 40W Weller. Had to bring out the big guns for this PCB.

jrjr. · 2013-11-08 04:22

Bill, are these raw boards when you start ?

if so, a LiGhT rub with a FiNe scotchbrite will buff them enough to break through the surface oxides.

I've used abrasive cleanser as well, but the PTH's must be flushed extremely well or you will make
more problems for yourself.

rinse,rinse,rinse and repeat.

dry thoroughly and (vacuum) bag them if you must wait to use the stock.

I suspect that most of the boards shipped from China are deficient in rinsing after processing.

Who knows what demons are left under the solder masking on cheap boards.

Stick to Pb 60/40 and call them 'Hi-Rel' boards for lab work, you will have less problems especially in reflow work.

jr

Best lead free solder (wire)?

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