Why not ask " Mr Whisker " himself? He has been NASA's specialist on
whiskers for many years. I mean Jay Brusse. He used to be a TN member.

Inge


On 12 June 2013 15:10, Douglas Pauls <[log in to unmask]> wrote:

> Phil,
> While this is an answer I "should" know, I don't.  Dave Hillman regularly
> attends and presents at the CALCE yearly conference on whiskers and so he
> keeps up on all of that.  At present, my esteemed colleague is bumping his
> head on rocks, kayaking upside down, on some white water in North
> Carolina.  He should be back in the office on Monday and will no doubt
> answer then.
>
> From our discussions, the general rule is still "no conformal coating
> prevents whiskers".  A thicker coating may cause the whisker to expend
> more energy punching through and yet more energy to punch through an
> adjacent coating on a lead (usually resulting in buckling), but I have yet
> to hear about some magic thickness of any kind of coating that completely
> mitigates whiskers.  But I could be wrong.
>
> Dave?
>
> Doug Pauls
>
>
>
> From:   Phil Bavaro <[log in to unmask]>
> To:     <[log in to unmask]>
> Date:   06/11/2013 02:26 PM
> Subject:        [TN] minimum thickness of Type UR Conformal coat and tin
> whiskers
> Sent by:        TechNet <[log in to unmask]>
>
>
>
> Doug et al,
>
> Is there a disagreement in the industry as to what minimum thickness of
> urethane is required in order to mitigate tin whisker concerns?
>
> I am hearing that the .003+/-.002" does not provide enough of a minimum
> thickness and that the number is as high as .004".   I can understand
> wanting the minimum being raised to .002" but higher than that would seem
> to make the process much more difficult to control.
>
> I have a potential customer asking if we measure the thickness on the
> individual component leads which is another can of worms it seems.  We
> always used flat samples to document our thicknesses.
>
> I did not get to attend this years APEX so I might have missed the latest
> data.
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