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July 2000

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Subject:
From:
Brock Hunter <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 13 Jul 2000 08:18:29 -0400
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Scott,
            This is actually a common problem. We have encountered here in the distant past and our customers have reported it from several other vendors as well.  Typically it only occurs on fiducials placed near the corners of the board that are away from any other copper features. It seems
to be more prevalent when horizontal HASL equipment  is used.  The solution has been simple. Around your isolated .040 round fiducial place a donut pad that surrounds the fiducial , typical dimensions are .160 outside diameter by .130 inside diameter. Your geometry may need to be adjusted
depending on the requirements of your optics. This has been incorporated by several of our customers into their standard fiducial design, but ( should be ) easily added by your fab house.

Cheers,

Brock
--
Brock Hunter  [log in to unmask]
Engineering Mgr.
Dynamic & Proto Circuits
TEL (905) 643-9900
FAX (905) 643-9437
http://www.dapc.com



"Lefebvre, Scott" wrote:

> I have a problem with fiducials missing on our FAB's when we receive  them from the vendor.  It is random and not specific to any one  assembly.
> The boards are being HASL and this is where they are coming off during  fabrication.  The fiducial size is 0.040" circle ½ oz. Copper.  We  have other board shops that we use and I haven't had this problem.
> Getting to the Question:
> The board shop in question asked if we to increase fiducial size or  increase copper around fiducial.  I feel that this isn't the source of  the problem I don't feel that we are asking anything out of the  ordinary using 0.040" fiducial.  I would appreciate any suggestions in   this matter.
> Thank you,
>
> ADC
> Scott Lefebvre
> [log in to unmask] <mailto:[log in to unmask]>
>
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