We do no rely on soldered battery connection on boards. One antique but good
solution is to crimp an eyelet on the cable and then use a screw or
screw/nut/locking washer arrangement. You can run lots of current through
such a connection without getting local heating and or milliohm problems.
This kind of battery cable connection does not degrade with time like a
direct solderd wire. Another one is to crimp a sleeve on the strands and
then solder the assembly in feedthrough holes on the board. There are many
more solutions.
/Inge
----- Original Message -----
From: "Torsten Hagge" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, August 26, 2010 5:46 PM
Subject: [TN] AW: [TN] soldered battery wire - breaking problem
Hi Carl,
as this process is not save for automotive we have to use special plastic
strain reliefs where presoldered cables are placed in the plastic. Advantage
is a faster assembly time and a safe process at our line.
Vendor e.g. is www.provertha.com, technology is called "wire clip connection
technology".
best regards,
torsten
Dipl.Ing.(FH)Torsten Hagge
tech. projectmanager
Kristronics GmbH
Gewerbegrund 5 - 9
24955 Harrislee
Tel.: +49 461 7741 624
Fax: +49 461 7741 642
[log in to unmask]
www.kristronics.de
Gerichtsstand Flensburg, Handelsregister: HRB 1433 FL
Geschäftsführer Dipl.-Ing. oec. Thormod Ohm
Ust-Id-Nr. DE 811182059
Bankverbindung: Deutsche Bank AG Flensburg, Konto-Nr. 4216610, BLZ 21570011
IBAN: DE32 2157 0011 0421 6610 00, BIC: DEUT DE HH 215
-----Ursprüngliche Nachricht-----
Von: TechNet [mailto:[log in to unmask]] Im Auftrag von Carl VanWormer
Gesendet: Donnerstag, 26. August 2010 16:37
An: [log in to unmask]
Betreff: [TN] soldered battery wire - breaking problem
We produce a small module that is powered by a small battery in a
plastic battery holder that has the standard red & black wires, which
solder into two holes in in our PC board. After initial functional
testing, the board (with battery holder attached) is sent out for
conformal coating, then the boards are re-tested before inserting into
our plastic enclosure. The most recent run of 50 boards returned from
conformal coating with about 10 broken wires, with the break leaving
Copper colored ends visible where the strands were ripped from the
solder filled mounting hole. Since this problem is new, something in
the assembly process (or conformal coating process) must have changed.
Once the battery holder and board are assembled into the plastic case,
there is no more strain on the wires, so this is only a production and
handling problem.
In reviewing the recent wire solder joints, compared to 2 samples from
previous runs that did not exhibit this problem, I noticed that the
"bad" assemblies had been heated enough to flow solder up into the wire
strands, while the "good" assemblies had solder on the wire ends on the
back side of the board, but the solder did not flow up the strands on
the front side of the board. I'm guessing that the fused wire strands
are stiffer, and this is the cause of the breakage during handling for
the conformal coating process.
Many of us "old timers" remember the classic strain relief approach used
in the battery wires for transistor radios, where the two wires were
laced through a strain relief hole before being soldered onto the board.
Since our board has no room for the extra strain relief holes, and since
we have made hundreds of these things without problems, I'm looking for
suggestions on the best approach to solder the wires onto the board to
help eliminate the problem.
Are there any IPC standards for attaching battery holder wires?
Thanks,
Carl
Carl Van Wormer, P.E., AE7GD
Senior Hardware Engineer
Cipher Systems
1800 NW 169th Place, Suite B-100
Beaverton, OR 97006
Cipher Systems (503) 617-7447 x 5163
Direct Line (503) 425-5163
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