[sdiy] Transition to Lead-Free Hand Soldering

Tristan tu at alphalink.com.au
Fri Aug 20 06:54:25 CEST 2021


Well, if I was going to do all SMT I would be going with RoHS solder paste and hot air reflow. If I needed 
to mount some TH components as well then it makes sense to me to keep the entire board lead-free 
rather than mixing solders on the same board. While it would be possible to sneak some leaded solder in 
there, from a long term maintenance perspective I think it is better to be consistent.

/Tristan

On Fri, Aug 20th, 2021 at 11:49 AM, cheater cheater <cheater00social at gmail.com> wrote:

> > if I started doing surface mount then it would probably make more sense to
> use lead free solder in those projects.
> 
> Why? What's the point? smt devices work perfectly well with leaded.
> 
> On Fri, Aug 20, 2021 at 3:10 AM Tristan <tu at alphalink.com.au> wrote:
> >
> > I am still using leaded solder for new projects and maintenance of older
> gear. Almost all of it is TH but if I
> > started doing surface mount then it would probably make more sense to use
> lead free solder in those
> > projects. At present I only use lead free solder for work on RoHS compliant
> gear or if required for specific
> > component compatibility.
> >
> > Lead free solder joints are known to be more brittle than leaded solder
> joints as well as being more prone
> > to developing tin whiskers. That is probably why you are seeing an increase
> in broken joints on jacks and
> > pots etc. Some lead free solder formulations have been developed in an
> attempt to get around these
> > issues but for me continuing with leaded solder is the simplest solution.
> >
> > For new designs it would be worth creating them in such a way that
> components such as connectors,
> > jacks, pots and switches are directly secured to the case or panel and do
> not place mechanical stress on
> > their solder connections to the PCB. Creating small I/O boards which
> connect to the main board via a
> > cable could also be used to help isolate the stresses.
> >
> > /Tristan
> >
> > On Fri, Aug 20th, 2021 at 10:02 AM, Kenneth Balys <kenny at beatkamp.com>
> wrote:
> >
> > > I use lead on that which is leaded. Using fancy new Pb'less solder on a
> 70's
> > > era synth seems wrong.,
> > > -------- Original message --------From: cheater cheater via Synth-diy
> > > <synth-diy at synth-diy.org> Date: 19/08/2021  19:59  (GMT-05:00) To: Mike
> > > Beauchamp <list at mikebeauchamp.com> Cc: synth-diy at synth-diy.org Subject:
> Re:
> > > [sdiy] Transition to Lead-Free Hand Soldering Honestly, go back to
> leaded.
> > > There's no good reason for you to uselead free. You're not saving the
> > > environment or anyone's health(including yours) and you're just making
> work
> > > more difficult foryourself.If your flux is sputtering, use (genuine!!!)
> > > AmTech 599 tacky flux.This is the best flux I have and it keeps for ages
> even
> > > just left onthe shelf.On Thu, Aug 19, 2021 at 9:50 PM Mike Beauchamp
> > > <list at mikebeauchamp.com> 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:>
> > > https://www.kester.com/Portals/0/Documents/Knowledge%20Base/Lead-free-
> > Handsoldering.Final_.4.19.06.pdf>>>
> > > 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.>>
> > > Mike>>>>>>>>>>>>>>>> _______________________________________________>
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