Because we are talking about stranded wire soldered, I suggest to take a
look at IPC/WHMA-620 A/B,
Chapt 4 Soldered Terminations. 4.1 Material, Components and equipment,
4.1.1.2 FLUX.
During soldering, the Flux could be wicked up under the wire insulation, so
the Standard tells you which Flux activation Level could be compatible with
soldering tinned/soldered stranded wires.
So, take care also about flux wicking up along stranded wires and not only
about flux residues left on surfaces
Gabriele
-----Messaggio originale-----
Da: TechNet [mailto:[log in to unmask]] Per conto di Thierolf, Chris @ MPSG -
SPD
Inviato: giovedì 5 novembre 2015 21.47
A: [log in to unmask]
Oggetto: Re: [TN] Pierced Terminal, Flux residue
As it turns out, I am dealing with Kester 44 Rosin Flux, ROM1. Kester makes
the following statement in regards to cleaning:
"Kester 44 possesses excellent fluxing ability, the flux residue is
non-corrosive and non-conductive under normal
conditions of use. When exposed to an elevated temperature and humidity
environment (38°C, 94% RH) for
72 hours, there is no evidence of corrosion caused by the flux residue.
Throughout its many years of wide
usage, 44 Rosin Flux has produced many billions of soldered connections. In
all these billions of solder
joints, involving the most delicate and critical of electrical and
electronic components, there has never been
an authentic instance of corrosion by the flux residue under normal
conditions of use. This mild property of
the residue permits leaving the flux on the assembly for many applications."
So for soldered wire attachment to pierced terminal, the consensus is to
leave the residue alone or clean?
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Carl VanWormer
Sent: Thursday, November 05, 2015 3:26 PM
To: [log in to unmask]
Subject: Re: [TN] Pierced Terminal
I think it was actually corrosion, since the area was brown/black and was
several mm of bare copper, away from the location where the solder wicking
stopped. The stranded wires merged into the chemistry experiment blob
wither the strands broke. Also, these wires were supported by the Silicone
rubber "water barrier" provided by this "waterproof" connector, so I don't
think there was much vibration at this location.
Thanks for your comments,
Carl
Carl B. Van Wormer, P.E., AE7GD
Senior Hardware Engineer
Cipher Engineering LLC
21195 NW Evergreen Pkwy Ste 209
Hillsboro, OR 97124-7167
503-617-7447x303
[log in to unmask] http://cipherengineering.com
-----Original Message-----
From: Robert Kondner [mailto:[log in to unmask]]
Sent: Thursday, November 05, 2015 11:47 AM
To: 'TechNet E-Mail Forum' <[log in to unmask]>; Carl VanWormer
<[log in to unmask]>
Subject: RE: [TN] Pierced Terminal
Carl,
Unless you saw corrosion what you described sounds like a break due to
vibration. A bending moment is concentrated at the solder/no solder
interface where the wire goes from flexible to stiff. It is like putting a
small piece of solid wire in a pair of plyers and then wiggling the wire. It
breaks off at where the plyers are clamping.
I do not think it has anything to do with flux up the insulation.
Just my thoughts.
Bob K.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Carl VanWormer
Sent: Thursday, November 05, 2015 2:28 PM
To: [log in to unmask]
Subject: Re: [TN] Pierced Terminal
Whenever the topic of soldering wires comes up, I drone on about the time
the customer unit came back, suffering from uncured flux that had wicked up
under the wire insulation. After several months in the wet-spray
environment, the unit failed with an open circuit up inside the insulation.
When I tugged on the wire, the soldered part of the stranded wire stayed on
the connector pin and the rest of the wire pulled off, leaving a 5mm length
of copper wire strands sticking up from the good solder joint.
Is there any way to keep flux from wicking up the strands?
Thanks,
Carl
Carl B. Van Wormer, P.E., AE7GD
Senior Hardware Engineer
Cipher Engineering LLC
21195 NW Evergreen Pkwy Ste 209
Hillsboro, OR 97124-7167
503-617-7447x303
[log in to unmask] http://cipherengineering.com
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Theodore J Tontis
Sent: Thursday, November 05, 2015 10:53 AM
To: [log in to unmask]
Subject: Re: [TN] Pierced Terminal
It is not a defect but it is clearly stating something is not right which
could lead to a defect. I would say this is a process indicator and push
back on the supplier asking why there are discrepancies in the two images.
My guess is they do not have a clear or well defined process and one or two
assemblers are using a different process. A different process could include
the amount of flux used, temp of the soldering iron, tip, type of solder....
Bottom line, show your supplier what you want and ask them to review their
process for variation.
As for coating over NC flux residue, I would do environmental testing to
confirm it will not be an issue before I give it a thumps up to use the
combination of flux type and coating in production. Once it's out in the
field and there are failures the damage is already done. Just my personal
opinion.
Ted T
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Thursday, November 05, 2015 12:16 PM
To: [log in to unmask]
Subject: Re: [TN] Pierced Terminal
Yes, the coating is applied directly over the NC residue. It CAN lead to
issues; you need to do your homework to ensure the coating you are using is
compatible with the flux residues. This is usually done by working with the
flux vendors, they are quite knowledgeable in this area.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Thierolf, Chris @ MPSG -
SPD
Sent: Thursday, November 05, 2015 11:59 AM
To: [log in to unmask]
Subject: Re: [TN] Pierced Terminal
So in the case of conformal coat, this is applied over top the residue? Does
this lead to latent issues?
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ed Popielarski
Sent: Thursday, November 05, 2015 12:35 PM
To: [log in to unmask]
Subject: Re: [TN] Pierced Terminal
I agree 100%. "No clean" flux really should be called "Don't clean"! The bad
guys (ionics) don't necessarily "go away", they are well encapsulated in the
residue. Disturbing the residue is opening Pandora's box.
Ed Popielarski
Engineering Manager
970 NE 21st Ct.
Oak Harbor, Wa. 98277
Ph: 360-675-1322
Fx: 206-624-0695
Cl: 949-581-6601
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Monday, November 02, 2015 8:34 AM
To: [log in to unmask]
Subject: Re: [TN] Pierced Terminal
Hi Chris,
Sorry I was out on Friday, so I apologize for the late response. I have your
pictures posted, they are here:
http://stevezeva.homestead.com/Chris_Flux_Residue.jpg
As Guy said, I would leave it alone. I agree that an attempt to clean this
you would run the risk of wicking things up into the insulation. IMHO, it
looks fine to me.
Steve
On Thu, Oct 29, 2015 at 5:43 PM, Thierolf, Chris @ MPSG - SPD <
[log in to unmask]> wrote:
> I'm seeking some input to a solder condition that gets scrutinized in
> many directions. For the soldering of a stranded 10-12awg stranded
> wire to a pierced resistor terminal, a no clean L0 or L1 (RO/RE) flux
> is used with
> 63/37 solder. This is a single solder joint on a panel mount resistor,
> so no PCB involved. Flux residue is observed and assembly rejected by
> QC but manufacturer claims its no worry, and no clean flux. My
> observation says it presents no electrical or operational issue, not a
> violation of J-STD-001, but perhaps a visual issue per IPC-A-610, sec
> 10.6.4 "Flux residue inhibits visual inspection" if floor inspector
> claims he cannot see the solder joint clearly, which has occurred. We
> can state "clean the solder joint" (relatively speaking), but what
> really is clean in this case? Should we be forced to inspect these
> joints with 4x mag, as some are doing, or generate a simple guideline
> that allows residue up to a certain level? What is this level?
>
> I have a picture of a failed solder joint if interested, but not sure
> where to upload.
>
>
> ______________________________________
> [Disc3.png]
> Chris Thierolf
> Principal EE and Project Engineer
> L-3 Electronic Systems Segment
> SPD Electrical Systems
> 13500 Roosevelt Boulevard
> Philadelphia, PA 19116
> Phone: (215) 698-6390 Fax: (215) 677-4736
>
>
> ________________________________
> CONFIDENTIALITY NOTE: This electronic transmission, including all
>
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