If you've built these cables before in the same way using the same
materials with no issues, and the only difference here is the batch of
cable, then is probably is the cable. There is probably contamnation on
the wire under the outer insulation, and moisture that has diffused under
or through the insulation has allowed exposed copper on the shielding to
corrode wrt to the silver plating.
The reason I'd use ROL1 over ORL0 is that the ROL1 flux is more moisture
resistant than ORL0. Hygroscopic contamination is sometimes wicked up
stranded wires and causes them to corrode.
The reason I asked about voltage is that it can exacerbate insulated wire
corrosion. This may seem counter-intuitive, but when stranded wire (and
sometimes solid wire) is positively biased wrt a near-by conductor or
ground, some of the cathodic reactions that occur, such as oxygen
reduction, produce hydroxide anions, and the resultant alkaline moisture
can wick up underneath the insulation and cause corrosion where the
positive voltage no longer is protecting the wire, often several inches or
even feet away from the uninsulated end of the wire. This is very common
failure mechanism in telephone subscriber wire.
Karen Tellefsen - Electrical Testing
[log in to unmask]
908-791-3069
Steve Gregory <[log in to unmask]>
Hi Karen,
The wire is PTFE Insulated, and these wires have not had any voltage
applied.
We've been using this flux and building these cables for quite some time,
and have not seen this before. The only thing that has really changed is
with the batches of wire.
The flux complies with what is called out in 3.3 of J-STD-004. Can you
elaborate on why you would use a ROl1 over a ORL0?
Steve
-----Original Message-----
From: Karen Tellefsen [mailto:[log in to unmask]]
Sent: Tuesday, June 09, 2009 9:04 AM
To: TechNet E-Mail Forum; Steve Gregory
Subject: Re: [TN] Green Junk in Wire
I would not have used ORL0 flux on braided wire shielding, but rather ROL1.
This sort of looks like corrosion of telephone subscriber wires, i.e. the
wires inside the customer's premises between the telephone jack and the
"Network interface device."
Is there any voltage on the shieiding wrt ground or the signal wire? Is
the shielding covered with any insulation (it looks like it is bare)?
Karen Tellefsen - Electrical Testing
[log in to unmask]
908-791-3069
Steve Gregory <[log in to unmask]>
Good Morning!
We've just had something come-up that really has a few of us scratching our
heads around here.
To preface this; we have a mechanical assembly building where we put
cabinents and boxes together plus do some cable and harness assembly.
Yesterday one of engineers called me and said that they were seeing some
green stuff on some of the cables that we've built and said that I should
come and take a look at it. While I was walking over to the other building
it was thinking to myself; "I hope that somebody didn't get a hold of the
wrong flux or something...".
When I got there, I was really suprised at what I saw:
http://stevezeva.homestead.com/files/Green_Junk_1.jpg
http://stevezeva.homestead.com/files/Green_Junk_2.jpg
http://stevezeva.homestead.com/files/Green_Junk_3.jpg
http://stevezeva.homestead.com/files/Green_Junk_Close.jpg
The photos that you see come from a cable assembly that is about 3-feet
long, and we're seeing it on cable assemblies that are longer. The wire in
the assembly is a PTFE insulated single conductor shielded and jacketed
cable. The conductor and shield is silver plated OFHC copper.
The photos are taken from a section in the middle of the wire well away
from any area that soldering has been done. The shields of all the wires in
the bundle get soldered together at each end using a ORL0 wire solder and
flux. The green substance appears throughout the wires. In "Green Junk 3",
you can see how the green is with a group of the strands of the braided
shield and how it spirals around the wire.
It goes without saying that I'm contacting the wire manufacturer, and I'm
sending out a cable assembly for analysis. But have any of you ever seen
this before?
Steve
Enthone GmbH Geschäftsführer: Knut Balzer, Luc de Croo, Jürgen Dietrich Amtsgericht Düsseldorf HRB 45276
USt-Id-Nr. DE 811 205 946
This communication is for use by the intended recipient and contains information that may be privileged, confidential or copyrighted under applicable law. If you are not the intended recipient, you are hereby formally notified that any use, copying or distribution of this e-mail, in whole or in part, is strictly prohibited. Please notify the sender by return e-mail and delete this e-mail from your system. Unless explicitly and conspicuously designated as "E-Contract Intended", this e-mail does not constitute a contract offer, a contract amendment, or an acceptance of a contract offer. This e-mail does not constitute a consent to the use of sender's contact information for direct marketing purposes or for transfers of data to third parties.
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
|
