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March 2006

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Subject:
From:
"David D. Hillman" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Fri, 3 Mar 2006 07:51:49 -0600
Content-Type:
text/plain
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text/plain (182 lines)
Hi Gerald! I'll cast my vote with the other TechNet comments that you are
looking at some type of flux incompatibility that resulted in arcing. The
circuit voltage may have been within the requirements but if there was
contamination between the terminals you had shorting begin due to
electrochemical migration - as the dendrites (from the contamination) grew
between the terminals and made a more conductive electrical connection you
began to have arcing. You might see if you can get both a SEM and a FTIR
analysis of the black crud and identify the elements present - that more or
may not reveal some clues on the arcing/contamination theories. Good Luck.

Dave



             - Bogert
             <[log in to unmask]>
             Sent by: TechNet                                           To
             <[log in to unmask]>         [log in to unmask]
                                                                        cc

             03/03/2006 04:17                                      Subject
             AM                        Re: [TN] Black "crud" on connector
                                       solder connections causing
                                       electrical         short-circuit -
             Please respond to         Need Help Please
              TechNet E-Mail
                   Forum
             <[log in to unmask]>
             ; Please respond
                    to
                 - Bogert
             <[log in to unmask]>






Voltage in circuit was well within connector rating and electrical
clearance distance was well within limits.
  ----- Original Message -----
  From: Crepeau, Phil (Space Technology)<mailto:[log in to unmask]>
  To: [log in to unmask]<mailto:[log in to unmask]>
  Sent: Thursday, March 02, 2006 7:29 PM
  Subject: Re: [TN] Black "crud" on connector solder connections causing
electrical short-circuit - Need Help Please


  hi,

  it looks as though there was electrical arcing across these terminals.
  was high voltage or high voltage and high altitude involved?

  phil

  -----Original Message-----
  From: TechNet [mailto:[log in to unmask]] On Behalf Of stephen gregory
  Sent: Thursday, March 02, 2006 4:17 PM
  To: [log in to unmask]<mailto:[log in to unmask]>
  Subject: Re: [TN] Black "crud" on connector solder connections causing
  electrical short-circuit - Need Help Please

  Hi All!

    I got the pictures posted now. Click on the links below:


  http://www.stevezeva.homestead.com/files/solenoid_1_photo_1_with_label_i<
http://www.stevezeva.homestead.com/files/solenoid_1_photo_1_with_label_i>
  nformation.JPG


  http://www.stevezeva.homestead.com/files/solenoid_1_photo_2_with_label_i<
http://www.stevezeva.homestead.com/files/solenoid_1_photo_2_with_label_i>
  nformation.jpg

    http://www.stevezeva.homestead.com/files/solenoid_2_photo_1.JPG<
http://www.stevezeva.homestead.com/files/solenoid_2_photo_1.JPG>

    all I can say is; "D-A-A-A-N-N-G!"

    -Steve Gregory-

  - Bogert <[log in to unmask]<mailto:[log in to unmask]>> wrote:
    March 2, 2006

  Thanks. I did realize Technet strips attachments. I tried embedding them
  directly within the e-mail. They did not lake that either so I forwared
  the attached photos to Steve.
  ----- Original Message -----
  From: Stadem, Richard D.
  To: [log in to unmask]<mailto:[log in to unmask]>
  Sent: Thursday, March 02, 2006 8:28 AM
  Subject: Re: [TN] Black "crud" on connector solder connections causing
  electrical short-circuit - Need Help Please


  Bogert,
  All attachments are stripped off on Technet postings. Perhaps Steve
  Gregory can post them on his website. Else if you can provide a link to
  a Net site...

  -----Original Message-----
  From: TechNet [mailto:[log in to unmask]] On Behalf Of Richard Kraszewski
  Sent: Wednesday, March 01, 2006 8:01 PM
  To: [log in to unmask]<mailto:[log in to unmask]>
  Subject: Re: [TN] Black "crud" on connector solder connections causing
  electrical short-circuit - Need Help Please

  I don't see any photos.

  Rich K / KEDS
  260.925.8719

  -----Original Message-----
  From: TechNet [mailto:[log in to unmask]] On Behalf Of - Bogert
  Sent: Wednesday, March 01, 2006 6:51 PM
  To: [log in to unmask]<mailto:[log in to unmask]>
  Subject: [TN] Black "crud" on connector solder connections causing
  electrical short-circuit - Need Help Please

  March 1, 2006

  Folks, the three attached photographs show some problems an OEM of ours
  is having. Specifically, he hand solders two MIL-W-16878 silver coated
  stranded wires to a MIL SPEC connector that has solder eyelets plated
  with 50 microinch of gold. Sn10 WRMAP flux cored solder is used with no
  additional flux added. The OEM has had recent rash of failures in
  fielded equipment. We do not know the cause yet. We are having the black
  residue shown sent out for analysis but no results yet.

  The solder joints do not appear to be acceptable to me. One can see
  exposed gold on the gold-plated connector contact eyelets. Appears to be
  non-wetting??? Also, appears to be excess solder since strands are not
  always visible in the joint. The OEM tins the stranded wire with
  Sn63 prior to soldering.

  Do you folks have any ideas on what the problem could be? There is
  detailed info on the photographs on the application of the product. The
  connector provides power to a solenoid that actuates a valve.

  The application is hermetic sealed by welding the connector to a metal
  housing that contains the solenoid winding. The wires connecting to the
  connector are the MIL-W-16878 silver coated stranded lead wires that
  connect from the gold plated connector pins on one end to the MIL SPEC
  magnet wires on the solenoid on the other end. The solenoid is varnished
  (DIP process, no vacuum).

  I am aware that silver plated wire in an SO2 environment can cause
  corrosion, but we use a lot of silver coated wire in other product with
  no known corrosion problems.

  The connector housing has a small vent port into which air is applied to
  do a pressure seal test. After the pressure test is completed, the vent
  hole plug is welded closed. We are checking to see if the air could have
  had moisture in it.

  Dielectric strength, insulation resistance and functional testing is
  done on the solenoid after assembly is completed and all tests passed.
  However, failures occur in the field.

  Since the flux used in the SN10 flux-cored solder is RMA, one would
  normally not expect the black residue to be due to RMA flux but I am not
  sure. We will probably know for certain after we get the test results on
  the black crud.

  Any insight you may have into into this problem would be appreciated.

  Please e-mail your response to following e-mail address:

  [log in to unmask]<mailto:[log in to unmask]>>

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