I tend to lean to the answers given by Phil and Richard. There
seems to be that those areas were exposed to too much heat due to poor
connection and high voltage potential. One way to find out is to check
the resistance between the bottom of the eyelet and the strand of the
wires. It should read zero ohms. If it reads several ohms it means
that there is a poor connection between the wire and the eyelet. One of
many possibilities. From the pictures it seems that part of the wire
insulation melted down onto the junction.
Regards,
Ramon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of stephen gregory
Sent: Thursday, March 02, 2006 7:17 PM
To: [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
nformation.JPG
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
all I can say is; "D-A-A-A-N-N-G!"
-Steve Gregory-
- Bogert <[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]
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]
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]
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]>
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