We use a .040" pad, with a .110" protection ring around it and a .080"
soldermask opening.. We also add a .080" pad on the next layer as well (if
it is a signal layer) to give a consistent background.
3 per board (if there are more than 8 boards in the panel we can use 1 per
board), in the corners, .050" from board edge, .450" from panel edge.
--
George Patrick
Tektronix, Inc.
Central Engineering, M/S 39-512
P.O. Box 500
Beaverton, OR 97077-0001
Phone: 503-627-5272 Fax: 503-627-5587
-----Original Message-----
From: Scott Buscomb [mailto:[log in to unmask]]
Sent: Friday, January 26, 2001 04:58
To: [log in to unmask]
Subject: Re: [DC] DC IPC Design rules for Fiducial clearances
I am also adding an annular ring around panel fiducials to protect them
during fabrication and
assembly. This is important if the fiducials are a distance away from other
copper features
(no venting). I have seen panels with fiducials knocked off during fab or
shipping.
Most SMD assembly equipment will have a recommended fiducial in their
respective manuals. Some
prefer a diamond, some prefer round. The size is usually in the .040-.060"
range with a 2X
clearance around the feature. The association that represents the SMD
equipment manufacturers
also has a recommended fiducial.
Watch out for contrasting shades around the fiducial. A trace running to
close on an internal
layer may give the optical equipment fits when trying to locate the
fiducial.
--
Scott Buscomb, C.I.D.
Techsonic Industries Inc.
PH 770 475-3020 x1032
FX 770 475-4090
[log in to unmask]
Rich Schutz wrote:
> We use 0.060" round fiducials with a 0.140" solder mask clearance located
in
> opposite corners of the PCB. A minimum of 2 fiducials is required. The
fiducial
> should be 0.125" from any board edge or panel edge. That distance is
measured
> from the edge of the pad not the center. Use the 0.140" clearance ring
also
> for distances from all parts, and mounting holes.
>
> Charlene Dwyer <[log in to unmask]> on 01/25/2001 06:01:15 PM
>
> Please respond to "DesignerCouncil E-Mail Forum."
<[log in to unmask]>;
> Please respond to Charlene Dwyer <[log in to unmask]>
>
> To: [log in to unmask]
> cc: (bcc: Rich Schutz/perry/apscoinc)
>
> Subject: [DC] DC IPC Design rules for Fiducial clearances
>
> Hi! Does anyone know of the standards for board
> fiducials?
>
> The minimum/maximum distance they should be from the
> board edge, panel edge, and the distance they should
> be from a part? Is there different distances for
> different parts? Difference for diffent fiducial
> types(round, square, bowtie, ect)
>
> What IPC spec contains this info?
>
> -Charlene Dwyer Lee
> [log in to unmask]
> contractor at Motorola
>
>
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