[sdiy] Transition to Lead-Free Hand Soldering
admin at bugbrand.co.uk
Thu Aug 19 23:33:57 CEST 2021
I've have always used Lead Free (apart from a small supply of leaded for
specific repairs). I guess RoHS was already in place over here & I
didn't want any unnecessary dealings with lead. I barely remember any
struggles with lead-free so am always a bit perplexed by such discussions!
I have used a Kester for where I need a water-soluble - no notes on the
type at present but likely the same. I have to say that the fumes off
this have appeared to present lung sensitivity for my assistant - she
always uses fume extraction for any soldering, but now wears a face mask
for the occasional times having to use this kester. So somewhat less
Most of the time I/we entirely use Warton Metals SAC3 FastFlow Lead Free
(22SWG) because it works so well & the fumes are no issue. It is not
'cheap' but I have been entirely happy using it - unfortunately it is
likely hard to find outside UK - not sure whether other SAC305 types may
be similar or not
The only thing I would perhaps note is that tips maybe seem to wear out
relatively quickly & can get gunked up with blackness - I only use brass
wire cleaners, not sponges. I use Metcal irons so have a fixed tip
It works well for me & I'm happy not to have to continue investigating
On 19/08/2021 20:45, Mike Beauchamp wrote:
> I've recently started transitioning into Lead-Free solder for all of
> my projects. Now that surface-mount assembly is affordable in small
> quantities, it's very easy to get boards made using lead-free finishes
> and solders but the hand-soldering is a more difficult transition.
> After a conversation with Kester on the telephone (it's amazing how
> helpful companies can be over the phone), they suggested a few
> products for me to try and I've now gone through a few rolls to give
> some opinions.
> For Water-Soluble flux, I am using Kester Part # 24-9574-6403
> which is a .031" K100LD solder with the Organic 331 Flux.
> For No-Clean solder, I am using Kester Part # 24-9574-7618
> which is a .031" K100LD solder with 3.3% Mildly Activated Rosin 275 Flux.
> K100LD is described as "a eutectic Tin/Copper alloy with controlled
> metallic dopants to control the grainstructure within the solder
> joint, and to minimize the dissolution of copper into the
> solder pot. K100LD virtually eliminates the occurrence of
> common defects such as icicling and bridging. The improved
> grainstructure also results in shinier solder joints than traditional
> lead-free alloy alternatives".
> I'm not sure what all of that means, but it's a cheaper alternative to
> SAC305 at less than half the price for a roll and seems to be designed
> with hand-soldering thru-hole components in mind.
> In use, both solders are "OK". I increased my tip temperature to those
> recommended by Kester right away, but was still noticing that the
> lead-free solder remains "goopier" and doesn't wet and flow into gaps
> nearly as fast, or sometimes at all. As I continued to increase the
> tip temperature, this did change and the solder started acting more
> like the Lead I've used for 20 years.
> I now have my Hakko 936 set to 800 degrees and things are mostly
> working, but not getting great flow on TH components that are being
> attached to the ground plane (even with thermal reliefs on the board).
> Also at this temperature both solders, especially the 275 Flux is
> spattering pretty crazy and eye protection is probably recommended.
> The flux residue from this solder has also completely gummed up my
> fume extraction tube as well, so that is also something to look out
> for and to be changing pre-filters often. I'm also noticing that
> soldering pins of cheap plastic IDC headers, it's very easy to melt
> the plastic with the 800F heat, so I don't dwell on them for long at
> all. Maybe better parts have higher heat tolerance?
> These solders work good enough to get the job done the first time, but
> if you try to rework something or correct a mistake, the solders will
> suddenly change to sticky goo so I usually just suck the solder off
> completely and start with new solder.
> Kester has a good PDF to troubleshoot lead free hand soldering issues:
> So there's definitely a compromise, but those two Kester parts are a
> good substitute for the leaded versions I was previously using (as
> suggested by Paul S. on here years ago). Next time I redesign my PCBS,
> I'm going to use a more aggressive thermal relief on ground plane
> thru-holes and I think the tip temperature should be adjusted based on
> the physical dimensions of the parts being soldered.
> I'm not sure about the long-term reliability of Lead-Free solder. In
> my repair shop, I get a lot of music gear coming in with broken
> solders on PCB-mounted jacks, pots, tube sockets, etc and I can't help
> thinking that the lead-free solder is more brittle and prone to
> failure in these applications.
> Have you converted to lead-free in your hobby as well? I'm curious to
> hear others' suggestions and experiences.
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