The length of the tinned portion simply determines where the flex point
is on the wire. You want that flex point to have an anchor or tiedown
nearby. If the wire is only 3" long and one end terminates in a solder
sleeve with the other end potted, the vibration would need to be
extremely strong to cause it to fail.
If you performed the tinning process using a no-clean or RMA-type flux
rather than an organic flux, it should be alright.
Many times people make the mistake of using an organic flux when tinning
wires. This flux is driven up inside of the insulation during the
tinning, and cannot be washed out. The result, particularly with power
and ground wires, is the strands breaking from corrosion.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bloomquist, Ken
Sent: Tuesday, June 07, 2005 8:00 AM
To: [log in to unmask]
Subject: Re: [TN] Solder Wicking
Hi Ramon,
Several answers to your questions :-)
The wire will be cable tied to other wires not just hanging in
the air.
The unit that the wires are in will be exposed to vibration.
It is not close to the board or staked. The wire is 3" long and
terminates to another wire using a solder sleeve.
I agree that tinned wire is stiff but I don't know that I'd call it
brittle. The reason we are so concerned about this is that the wires are
coming out of a potted module that has a long lead time and is quite
expensive. Like I said previously, the wire will be formed once and tied
in with additional wires.
I like Werner's idea better but then I'm the manufacturing guy and not
the quality person ;-)
Thanks,
KennyB
-----Original Message-----
From: Dehoyos, Ramon [mailto:[log in to unmask]]
Sent: Tuesday, June 07, 2005 5:46 AM
To: TechNet E-Mail Forum; Bloomquist, Ken
Subject: RE: [TN] Solder Wicking
Importance: High
Hi Ken:
Several questions have to be answered:
Is the wire up in the air?
Is it going to be exposed to vibrations?
Is it closed to the board and staked?
Tinned wire is stiff and brittle. If wire is expensive and the
first two questions are answered negative and the last positive I would
use the wire. ( in the final application )
Regards,
Ramon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Bloomquist, Ken
Sent: Monday, June 06, 2005 5:15 PM
To: [log in to unmask]
Subject: [TN] Solder Wicking
We need a little help interpreting IPC-A-610 and thought this austere
group would be the place to go.
We have some wires that were tinned WAY up under the insulation. While
this is not a desirable situation we want to know if they are usable.
IPC-A-610 says "Acceptable: Solder wicks up wire provided the solder
does not extend to a portion of the wire that is required to remain
flexible."
In our application the wire will be bent once during assembly and then
the unit buttoned up and no more flexing will happen.
Does the statement "to remain flexible" mean in the final application or
during assembly?
Thanks in advance for all your wisdom!
KennyB
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