Not that I am aware of, which is why I only allow RMA flux to be used when tinning stranded wire, and which is why a timed entry of the fluxed wire into the skimmed solder must be held to two to three seconds, with the insulation no more than .020" from the molten solder.
Then you follow that with a swirl in an IPA container. After the swirl, you simply drop the wire into the IPA container.
Then you bundle the wires or harnesses (if possible) with a single rubber band or clip in the middle of the bundle and send the whole bundle through a saponified DI wash.
Then you bake the bundles for 10 minutes at 105 C. to dry the stranded wires.
You don't want to just let them go with any combination of IPA or water inside the insulation. That is the key to preventing the corrosion.
This process will leave you with (possibly) some very minor flux residues, but only at the very end of the insulation. Allowing longer than 2-3 seconds during the solder immersion will drive the solder (and thus the flux) waaaay up under the insulation, where it will remain at full strength. Limiting the immersion to less than 2-3 seconds prevents the solder from driving the RMA flux more than just under the insulation. That penetration of flux up under the insulation should be limited to no more than .030".
It allows the IPA to effectively clean what little flux is under the insulation, or at least greatly reduce its action.
Following with the saponified wash allows further dilution and cleaning.
Following with a quick bake leaves you with a clean, dry, tinned stranded wire. Any RMA flux particulates left behind are harmless.
This wire tinning process has been proven to be extremely reliable for more than 65 years. I learned it from the "old masters" on the Apollo program, including my Dad, when I first started out sometime around 1969, and it was the standard, proven practice at that time.
It still is; I have never heard of a wire corroding to failure that was tinned with this specific procedure.
I believe it is still listed somewhere in IPC 7711/7721. And it can be automated, but then requires a clip jig. The wires are simply loaded on the snap jig, and then stripped, tinned, dipped in IPA, then loaded through the wash and into the oven, then pulled out of the jigs with a centered grasping action. The tinned ends prevent any damage after immersion in the solder.
Good luck with your wires.
Odin
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Carl VanWormer
Sent: Thursday, November 05, 2015 1:28 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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