Mike,

You refer to a " Beep Test " in your note to Michael.   Can you share more
information on this method.

Victor,

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Mcmaster, Michael
Sent: Wednesday, December 31, 2003 1:49 PM
To: [log in to unmask]
Subject: Re: [TN] Annular ring


First of all, using a microsection to validate annular ring is very suspect.
Unless they are doing a horizontal grind, you are looking at such a small
part of the hole/pad.  Even if you see adequate annular ring, that only
applies to what you see and misregistration out of the plane of the cross
section may exhibit insufficient annular ring.  A "beep test" registration
system is much better.

I understand what the supplier is saying about how the coupon can be worse
than the image but we've all been dealing with that forever.  Waiving the
requirements doesn't seem justified.  If they have to use cross sections,
can they move the coupon closer to the image?

If you are really in a pinch, you could allow the manufacturer to grow the
pads in the coupon by the amount necessary to reflect the difference between
the image and coupon location.  This is just a simple matter of
extrapolating how bad the coupon can be but still have the image meet spec.


Mike McMaster
RF Product Engineer
Merix Corporation
503-992-4263



> ----------
> From:         Bruce D Stilmack[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;[log in to unmask]
> Sent:         Tuesday, December 30, 2003 6:06 AM
> To:   [log in to unmask]
> Subject:      [TN] Annular ring
>
> I have a PCB manufacturer requesting a waiver for the MIL SPEC
> requirement of a 2 mil annular ring.  Their position is that the
> coupons are from the edge of the laminate where the registration is
> worse.  The assumption is that the ring will be larger in the PCB
> itself.  I am leery to grant a waiver to allow this deviation, but
> would like to know how the community feels about this.
>
> Bruce Stilmack
> GDLS-TO Manufacturing Engineer
> (850) 574-4773
> [log in to unmask]
>
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