[sdiy] Transition to Lead-Free Hand Soldering

Mike Bryant mbryant at futurehorizons.com
Sat Aug 21 12:16:31 CEST 2021


There are a few places that do leaded SMD but they tend to be very expensive as they are focused on aerospace and military and have to have all the necessary qualifications.   

I can't imagine many other places keep a leaded line going as with the RoHS regulationss the demand wouldn't be there and you'd need to keep a complete line dedicated to leaded.


-----Original Message-----
From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of cheater cheater via Synth-diy
Sent: 21 August 2021 10:00
To: Tristan
Cc: synth-diy at synth-diy.org
Subject: Re: [sdiy] Transition to Lead-Free Hand Soldering

It depends on whether you do it yourself or want someone else to do it. I don't know how popular leaded reflow is as a service, but I cannot imagine that they would have a problem with it.

On Fri, Aug 20, 2021 at 9:30 AM Tristan <tu at alphalink.com.au> wrote:
>
> Is leaded SMT assembly still a widely available process? Apart from 
> military and certain other specialist applications pretty much all 
> commercial assembly should now be for RoHS compliant products. Legacy 
> products were given a special exemption but there are probably not too many products still being manufactured unchanged 20 years on.
>
> /Tristan
>
> On Fri, Aug 20th, 2021 at 4:47 PM, cheater cheater <cheater00social at gmail.com> wrote:
>
> > Why not use leaded solder paste?
> >
> > On Fri, Aug 20, 2021 at 6:54 AM Tristan <tu at alphalink.com.au> wrote:
> > >
> > > 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 
> > > > > > how> 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 
> > > > > > designed> 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-fre
> > e-
> > > > > 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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