Lead-free solder is such a PITA (rant/whinge)

[pedro]

Have a gas wall oven with two supply gas valves/solenoids in series -
safeguard against one sticking open, one presumes. Coils are
connected in parallel. These are situated on TOP of (doh!) the oven
shell - not the brightest move but placed there no doubt for service
access - tick.

Original coils were by Goyen Controls, and lasted 20 years before one
failed. By then Tyco had moved in (TYCO=TakeYourCompanyOver). Tyco
replacement lasted about 18 months,during which time the other Goyen
coil died. Ever since, the Tyco replacements (at ~$A70 each) have
lasted about 18 months.

It transpires that about the time I got the first Tyco coils, they had
transitioned the Oz factory to ROHS. Now these coils are 240VAC so
the winding wire is as fine as all getout. How is it terminated? Ah,
it is SOLDERED to 1/4" QC/Faston terminals which protrude out through
the epoxy/"thermoplastic" former. Evidently thermal cycling is
causing solder joint failures, but the necessary surgery with a Dremel
to reach the joint would - apart from compromising the overall
integrity and insulation characteristics - probably take out untold
turns of the coil itself, rendering the operation pointless.

 

[pfjw@aol.com]

On Wednesday, September 7, 2016 at 7:53:21 AM UTC-4, pedro wrote:

On Wed, 07 Sep 2016 19:48:21 +0800, pedro <me@privacy.net> wrote:

I should add that coil failure mode is open cct when hot - as in,
half-way through cooking a meal - and continuity returns when cooled
to near room temperature. Also that replacing the wall oven comes
with a penalty of having to carry out significant kitchen mods.
Grrrr!

And why it is that when we built our summer house, we went to Propane for heat, hot water & cooking. More costly than electric appliances, for sure. But we have NEVER had an issue with appliance failure - apart from two floods that finally took out the refrigerator. The house is now elevated, so that will no longer be an issue.

Peter Wieck
Melrose Park, PA

 

[pedro]

On Wed, 07 Sep 2016 19:48:21 +0800, pedro <me@privacy.net> wrote:

I should add that coil failure mode is open cct when hot - as in,
half-way through cooking a meal - and continuity returns when cooled
to near room temperature. Also that replacing the wall oven comes
with a penalty of having to carry out significant kitchen mods.
Grrrr!

 

[pedro]

On Wed, 7 Sep 2016 06:12:08 -0700 (PDT), "pfjw@aol.com" <pfjw@aol.com>
wrote:

>And why it is that when we built our summer house, we went to Propane for heat, hot water & cooking.

Grid independence, I'm sure.

We went with gas because the power system here was flakey and could go
out for hours at a time. Our gas hotplates have one 'D' cell
providing ignition, while the wall oven does require AC for the
igniter/flame-monitor/gas-control (BUT that's all able to be jury
rigged off a PC UPS in about a minute flat) so cooking during a
blackout is a non-event.

 

[Jeff Liebermann]

On Wed, 07 Sep 2016 19:48:21 +0800, pedro <me@privacy.net> wrote:

Original coils were by Goyen Controls, and lasted 20 years before one
failed.

I think you can still buy Goyen valves, solenoids, and rebuild kits:
<https://www.baghouseamerica.com/dust-collector-parts/goyen-genuine-parts/
<http://cleanairsystems.com/products/solenoid-valves-for-air-gas-and-water.html>
<http://www.uniairproducts.com/uap/goyen/goyen.shtml>
etc...


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Chris Jones]

On 07/09/2016 21:48, pedro wrote:

Have a gas wall oven with two supply gas valves/solenoids in series -
safeguard against one sticking open, one presumes. Coils are
connected in parallel. These are situated on TOP of (doh!) the oven
shell - not the brightest move but placed there no doubt for service
access - tick.

Original coils were by Goyen Controls, and lasted 20 years before one
failed. By then Tyco had moved in (TYCO=TakeYourCompanyOver). Tyco
replacement lasted about 18 months,during which time the other Goyen
coil died. Ever since, the Tyco replacements (at ~$A70 each) have
lasted about 18 months.

It transpires that about the time I got the first Tyco coils, they had
transitioned the Oz factory to ROHS. Now these coils are 240VAC so
the winding wire is as fine as all getout. How is it terminated? Ah,
it is SOLDERED to 1/4" QC/Faston terminals which protrude out through
the epoxy/"thermoplastic" former. Evidently thermal cycling is
causing solder joint failures, but the necessary surgery with a Dremel
to reach the joint would - apart from compromising the overall
integrity and insulation characteristics - probably take out untold
turns of the coil itself, rendering the operation pointless.

Can you buy the same coil type but in a 24 Volts AC version? If so, that
plus a transformer may be more reliable than the 240VAC version.

 

[pedro]

On Wed, 07 Sep 2016 19:01:28 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

On Wed, 07 Sep 2016 19:48:21 +0800, pedro <me@privacy.net> wrote:

Original coils were by Goyen Controls, and lasted 20 years before one
failed.

I think you can still buy Goyen valves, solenoids, and rebuild kits:
https://www.baghouseamerica.com/dust-collector-parts/goyen-genuine-parts/
http://cleanairsystems.com/products/solenoid-valves-for-air-gas-and-water.html
http://www.uniairproducts.com/uap/goyen/goyen.shtml

BHA didn't seem to have the coils. The other two are Pentair outlets
(Pentair is slightly majority Tyco owned) and will be selling the same
parts I currently repeat purchase (*) from Pentair/Tyco here in Oz.
These are surprisingly made locally (Sydney) as they were in the "old"
Goyen days. It's fair bet that any I source nowadays will have the
ROHS curse on them.

I did some Dremel surgery today on one of the dead coils. Despite
having differing copper resistivity figures at hand (no consequence)
and the wire diameter testing my micrometer, from known ohms of a good
coil and some spreadsheeted maths I guesstimate it is 33 or 34AWG.

Maybe Chris' suggestion is worth investigating. The surgery wasn't
enough to find the dodgy termination, but thicker winding wire *may*
get a better joint.

(*) I date-mark the parts as they go in. The one that just failed was
one day short of 18 months, on an oven that gets used about once a
week on average.

 

[pedro]

On Thu, 8 Sep 2016 18:01:33 +1000, Chris Jones
<lugnut808@spam.yahoo.com> wrote:

On 07/09/2016 21:48, pedro wrote:
Have a gas wall oven with two supply gas valves/solenoids in series -
safeguard against one sticking open, one presumes. Coils are
connected in parallel. These are situated on TOP of (doh!) the oven
shell - not the brightest move but placed there no doubt for service
access - tick.

Original coils were by Goyen Controls, and lasted 20 years before one
failed. By then Tyco had moved in (TYCO=TakeYourCompanyOver). Tyco
replacement lasted about 18 months,during which time the other Goyen
coil died. Ever since, the Tyco replacements (at ~$A70 each) have
lasted about 18 months.

It transpires that about the time I got the first Tyco coils, they had
transitioned the Oz factory to ROHS. Now these coils are 240VAC so
the winding wire is as fine as all getout. How is it terminated? Ah,
it is SOLDERED to 1/4" QC/Faston terminals which protrude out through
the epoxy/"thermoplastic" former. Evidently thermal cycling is
causing solder joint failures, but the necessary surgery with a Dremel
to reach the joint would - apart from compromising the overall
integrity and insulation characteristics - probably take out untold
turns of the coil itself, rendering the operation pointless.


Can you buy the same coil type but in a 24 Volts AC version? If so, that
plus a transformer may be more reliable than the 240VAC version.

Well the winding wire will be heavier gauge at 24VAC. Whether that
will achieve a more reliable ROHS solder bond is unsure, but it
probably couldn't be any worse.

 

It's fair bet that any I source nowadays will have the
ROHS curse on them.

Ok, I see you've done your homework. Yes, ROHS is epidemic
everywhere.

I would like to see the bureaucrats that mandated ROHS to now do a cost/benefit analysis to compare the cost in money ___and lives___ due to ROHS failures vs due to leaded solder.

m

 

tiny wire is inherently unreliable

adding a transformer and using 24V valves is a good idea.

or use 120V valves and wire the 2 in series instead of parallel?

m

 

[Ralph Mowery]

In article <6ea2tbhrvbnr7kfgiqqk0s270i46bgigss@4ax.com>, me@privacy.net
says...

(*) I date-mark the parts as they go in. The one that just failed was
one day short of 18 months, on an oven that gets used about once a
week on average.

Have you checked the voltage at the coils ? No more than you are using
that oven it seems there may be something more than just the coils going
on.

I have had very little experiance with the lead free solder, but as it
melts at a higher temperature it would seem to me that it should be
beter for the simple joints as far as the thermal cycling.

 

[Chris Jones]

On 08/09/2016 19:17, pedro wrote:

On Thu, 8 Sep 2016 18:01:33 +1000, Chris Jones
lugnut808@spam.yahoo.com> wrote:

On 07/09/2016 21:48, pedro wrote:
Have a gas wall oven with two supply gas valves/solenoids in series -
safeguard against one sticking open, one presumes. Coils are
connected in parallel. These are situated on TOP of (doh!) the oven
shell - not the brightest move but placed there no doubt for service
access - tick.

Original coils were by Goyen Controls, and lasted 20 years before one
failed. By then Tyco had moved in (TYCO=TakeYourCompanyOver). Tyco
replacement lasted about 18 months,during which time the other Goyen
coil died. Ever since, the Tyco replacements (at ~$A70 each) have
lasted about 18 months.

It transpires that about the time I got the first Tyco coils, they had
transitioned the Oz factory to ROHS. Now these coils are 240VAC so
the winding wire is as fine as all getout. How is it terminated? Ah,
it is SOLDERED to 1/4" QC/Faston terminals which protrude out through
the epoxy/"thermoplastic" former. Evidently thermal cycling is
causing solder joint failures, but the necessary surgery with a Dremel
to reach the joint would - apart from compromising the overall
integrity and insulation characteristics - probably take out untold
turns of the coil itself, rendering the operation pointless.


Can you buy the same coil type but in a 24 Volts AC version? If so, that
plus a transformer may be more reliable than the 240VAC version.

Well the winding wire will be heavier gauge at 24VAC. Whether that
will achieve a more reliable ROHS solder bond is unsure, but it
probably couldn't be any worse.

It is possible that the solder has dissolved too much of the fine wire,
making it too thin. I have had a lot of trouble soldering very fine
wire, especially with lead-free solder - the wire will get thinner as it
dissolves in the molten solder, leaving it even less robust than its
original fragile state. Leaded solder that was deliberately
pre-saturated with copper ("Savbit") was supposed to be good for
preventing that, but I found it generally unpleasant to use.

As your coils develop their faults over time, I also wonder if the
manufaturer left some fairly active flux inside the encapsulation that
might be slowly eating the wire near the solder joint when it is warm.

Perhaps you can tell whether the break is at the solder joint, by
measuring the low-frequency capacitance of each terminal of the damaged
coil with respect to everything else. I doubt that knowing where the
break happens would be much use to you, but it is something the
manufacturer should be looking into.

 

On Thu, 08 Sep 2016 17:17:11 +0800, pedro <me@privacy.net> wrote:

On Thu, 8 Sep 2016 18:01:33 +1000, Chris Jones
lugnut808@spam.yahoo.com> wrote:

On 07/09/2016 21:48, pedro wrote:
Have a gas wall oven with two supply gas valves/solenoids in series -
safeguard against one sticking open, one presumes. Coils are
connected in parallel. These are situated on TOP of (doh!) the oven
shell - not the brightest move but placed there no doubt for service
access - tick.

Original coils were by Goyen Controls, and lasted 20 years before one
failed. By then Tyco had moved in (TYCO=TakeYourCompanyOver). Tyco
replacement lasted about 18 months,during which time the other Goyen
coil died. Ever since, the Tyco replacements (at ~$A70 each) have
lasted about 18 months.

It transpires that about the time I got the first Tyco coils, they had
transitioned the Oz factory to ROHS. Now these coils are 240VAC so
the winding wire is as fine as all getout. How is it terminated? Ah,
it is SOLDERED to 1/4" QC/Faston terminals which protrude out through
the epoxy/"thermoplastic" former. Evidently thermal cycling is
causing solder joint failures, but the necessary surgery with a Dremel
to reach the joint would - apart from compromising the overall
integrity and insulation characteristics - probably take out untold
turns of the coil itself, rendering the operation pointless.


Can you buy the same coil type but in a 24 Volts AC version? If so, that
plus a transformer may be more reliable than the 240VAC version.

Well the winding wire will be heavier gauge at 24VAC. Whether that
will achieve a more reliable ROHS solder bond is unsure, but it
probably couldn't be any worse.

Can the valves be relocated to a cooler location? Or can you
substitute more robust valves made for hot location use?
Eric

 

[Jeff Liebermann]

On Thu, 08 Sep 2016 17:15:16 +0800, pedro <me@privacy.net> wrote:

It's fair bet that any I source nowadays will have the
ROHS curse on them.

Ok, I see you've done your homework. Yes, ROHS is epidemic
everywhere.

I did some Dremel surgery today on one of the dead coils. Despite
having differing copper resistivity figures at hand (no consequence)
and the wire diameter testing my micrometer, from known ohms of a good
coil and some spreadsheeted maths I guesstimate it is 33 or 34AWG.

That's rather thin and could easily fuse. According to the wire
table:
<https://en.wikipedia.org/wiki/American_wire_gauge>
#34 will fuse at 5A. What do you measure for coil DC resistance?

Maybe Chris' suggestion is worth investigating. The surgery wasn't
enough to find the dodgy termination, but thicker winding wire *may*
get a better joint.

I agree. Heavier wire may solve or delay the problem. Methinks it
would be interesting to know what temperature the solder joint is
experiencing. A thermistor or thermocouple glued to as close to the
solder connection as possible might provide some interesting numbers.
If the position of the solenoid above the oven is the problem, that
will show it. Perhaps adding a metal heat shield between the coil and
oven?

For fusing, perhaps a small value resistor or "surgistor" in series
with the coil might reduce the peak current enough to let the thin
wire survive. With an inductor, there should NOT be an inrush peak,
but I'm thinking some kind of glitch, spike, or peak might be arriving
via the 240VAC line.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Ron D.]

Totally agree with Chris. The possibility of residual flux. Add heat and it corrodes quickly.

I had issues with a manufacturer of wafer probes which I unfortunately was unable to solve. Took some SEM photos of the probes which turned black after heating at 200 C.

Solution was to boil the probes as received in baking soda and water, clean and then electroless gold plate them.

Later, the manufacturer went to 60/40 solder of the mechanical portion rather than spot welding. they used SN96 for the needles. They were unable to go back to the old process, but would solder ours with Sn96.

I also agree with the ZNR or some type of transient supression.

If you have too, I would investigate adding some sort of forced cooling.

I had buzzing issues with new 24 VAC valves (non gas) from a reputable company which was traced to dust during manufacturer. All of the valves received had to be cleaned prior to use. they were used with an Inert gas as the air medium which had no lubercation.

Poor manufacturing such as dust could be causeing a higher temperature than usual.

Corona dope might be able to be used to re-insulate a repair. Be sure to clean the flux off.

Under another note, a gas dryer at home has been operating for nearly 48 years with the same electric gas valves. As you said use is 3-4 times per week.
Preventative maintenance generally was cleaning of the ducts internal and external. Painting was done rarely.

The last failure was a cascade of events where the grease in the blower bearing transmission froze up. This cause the bearing to fail, which caused the fan blower belt to fail and the dryer drum belt to fail.

The fixes employed at this point was:
1. The set screw for the fan pulley was changed to brass tipped.
2.PM's will include looking at the transmission.
3.Special thrust washers were added to the drum tensioning pulley shaft and the fan shaft.
4. A special grease was selected for the transmission.
5. The drum light was changed to LED based.
6. A gasket was made for the outlet stream.
7. Nylon hinges (lint filter door) were replaced and painted with epoxy paint
8. Material of the lint filter door bumpers changed.
9. Always on the lookout for ignitors - I have two spares.
10. Replace a lid clip.
11. Replace the drum belt. 1st time in 50 years.

The to do list includes
1. Characterizing the ignitors. Possibly building a capacitance welder.
2. Rebuilding the lint filter.
3. Possibly adding an hour meter.
4. Add a dust ring to the timer shaft.
5. Make the sheet metal screws - machine screws

FWIW: A company does rebuild 50's style oven thermostats with ROHS compatable capillary tubes.

One issue I had was threading the capillary through the outer cavity and the oven cavity double wall. I placed the sensor in a straw which was easy to thread through the double wall and then cut the straw off.

Sorry about the "noise". Hopefully it's useful to somebody.

 

[Mike Tomlinson]

En el artículo <6ea2tbhrvbnr7kfgiqqk0s270i46bgigss@4ax.com>, pedro
<me@privacy.net> escribió:

(*) I date-mark the parts as they go in. The one that just failed was
one day short of 18 months, on an oven that gets used about once a
week on average.

You seem to have the fault identified, but just to add another
perspective - since you're getting multiple failures of the solenoid
coils, and you're /assuming/ RoHS lead-free soldering is to blame
without having (yet) found evidence, perhaps you could look at other
common factors. Is the supply voltage to the coils stable, for
instance? Loose connection causing unstable voltage/surges/sags at the
coil? Voltage too high? etc. etc.

--
(\_/)
(='.'=) systemd: the Linux version of Windows 10
(")_(")

 

[pedro]

On Thu, 8 Sep 2016 10:08:04 -0400, Ralph Mowery
<rmowery28146@earthlink.net> wrote:

Have you checked the voltage at the coils ? No more than you are using
that oven it seems there may be something more than just the coils going
on.

The line voltage is in the range 240-242, the coils are embossed 240V.

I have had very little experiance with the lead free solder, but as it
melts at a higher temperature it would seem to me that it should be
beter for the simple joints as far as the thermal cycling.

In my relatively limited lead-free solder experience (just the service
bench - where I always use leaded solder for rework)> the joints seem
to develop a dry crystalline characteristic over time when in
situations subjected to thermal cycling. IMHO it isn't a melting
point issue but an alloy characteristic.

 

[pedro]

On Thu, 08 Sep 2016 08:17:12 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

On Thu, 08 Sep 2016 17:15:16 +0800, pedro <me@privacy.net> wrote:

It's fair bet that any I source nowadays will have the
ROHS curse on them.

Ok, I see you've done your homework. Yes, ROHS is epidemic
everywhere.

I did some Dremel surgery today on one of the dead coils. Despite
having differing copper resistivity figures at hand (no consequence)
and the wire diameter testing my micrometer, from known ohms of a good
coil and some spreadsheeted maths I guesstimate it is 33 or 34AWG.

That's rather thin and could easily fuse. According to the wire
table:
https://en.wikipedia.org/wiki/American_wire_gauge
#34 will fuse at 5A. What do you measure for coil DC resistance?

Maybe Chris' suggestion is worth investigating. The surgery wasn't
enough to find the dodgy termination, but thicker winding wire *may*
get a better joint.

I agree. Heavier wire may solve or delay the problem. Methinks it
would be interesting to know what temperature the solder joint is
experiencing. A thermistor or thermocouple glued to as close to the
solder connection as possible might provide some interesting numbers.

Indeed. It would be handy to have a thermoprobe with logging on it.
Note to self: see where I can borrow one.

If the position of the solenoid above the oven is the problem, that
will show it. Perhaps adding a metal heat shield between the coil and
oven?

The dual valve mechanism is bolted to the oven. The coils (see ebay
item# 322017672259 for the ones we "consume" - but at a much better
price than he's asking ...) sit over the metal housing which encloses
the valve plunger (armature) and has a metal spacer each end for
location and ?thermal separation?. So it would be necessary to
elevate the entire incoming gas pipe/valve syhstem to relieve
conducted heat to any significant degree. And if it IS the cycling -
rather than the actual temperature reached - which causes the failures
then reducing the latter may achieve nothing.

For fusing, perhaps a small value resistor or "surgistor" in series
with the coil might reduce the peak current enough to let the thin
wire survive. With an inductor, there should NOT be an inrush peak,
but I'm thinking some kind of glitch, spike, or peak might be arriving
via the 240VAC line.

Dunno. Could do (but it'd be 18 months before I'd know if it made a
difference).

 

[pedro]

On Thu, 8 Sep 2016 18:36:23 +0100, Mike Tomlinson <mike@jasper.org.uk>
wrote:

You seem to have the fault identified, but just to add another
perspective - since you're getting multiple failures of the solenoid
coils, and you're /assuming/ RoHS lead-free soldering is to blame
without having (yet) found evidence, perhaps you could look at other
common factors.

Fair comment.

>Is the supply voltage to the coils stable, for instance? Voltage too high?

Without logging it (and I don't have access to a Dranetz any more) I
would venture that it is. Reading taken at random times show good
regulation, and nothing else in the place which is surge-prone
(electronics and incandescents) is dying at all.

Loose connection causing unstable voltage/surges/sags at the
coil?

Nope, snug as.

 

[pedro]

On Fri, 9 Sep 2016 00:48:54 +1000, Chris Jones
<lugnut808@spam.yahoo.com> wrote:

It is possible that the solder has dissolved too much of the fine wire,
making it too thin. I have had a lot of trouble soldering very fine
wire, especially with lead-free solder - the wire will get thinner as it
dissolves in the molten solder, leaving it even less robust than its
original fragile state. Leaded solder that was deliberately
pre-saturated with copper ("Savbit") was supposed to be good for
preventing that, but I found it generally unpleasant to use.

As your coils develop their faults over time, I also wonder if the
manufaturer left some fairly active flux inside the encapsulation that
might be slowly eating the wire near the solder joint when it is warm.

Really don't know. The Pentair/Tyco/Goyen engineer that I discussed
this with asked for a failed one to be returned for evaluation - so I
sent two (as I have a pile of them otherwise just gathering dust).
When I followed up a few weeks later, he had departed and his
replacement was unaware of the whole matter, and could find no record
of their return despite supplying him the RMA number.

He also declined my offer to send more, really being disinterested in
finding out the reason for the failure.

Perhaps you can tell whether the break is at the solder joint, by
measuring the low-frequency capacitance of each terminal of the damaged
coil with respect to everything else. I doubt that knowing where the
break happens would be much use to you, but it is something the
manufacturer should be looking into.

The failure mode is going open cct when hot. As they cool continuity
returns.

I have made up a test lead with pea lamps that I connect up so there
is a (6V) lamp in series with each coil. When there is a failure I
connect this into circuit and re-energise the oven. (Doesn't take
long, I'm getting pretty polished at that now!) It typically takes
about ten minutes to get back up to failure temp. Then I can see
which coil is going O/C and replace it from my stock of new spares.

To be able to test it would require a fair bit of setting up.

See above re manufacturer "interest". They sell quite a number of
these during our winters as they are used in gas wall furnaces. I
guess they are figuring that as long as they keep selling them as
replacements, why investigate.