On Thu, 16 Oct 1997, Robert Butterworth wrote:

>     HI,
>        WE HAVE AN ISSUE HERE THAT NEEDS SOME CLARIFICATION.  WE'VE BEEN
>     BUILDING FIDUCIALS FOR 4 YEARS NOW THAT HAVE NOT HAD SOLDER PASTE ON
>     THEM (NO RELIEFS IN THE PASTE MASK).  NOW OUR VENDORS, (YES THE SAME
>     ONES WHO HAVE BEEN BUILDING THE BOARDS FOR 4 YEARS), ARE SAYING THAT
>     THEY'VE ALWAYS PUT SOLDER PASTE ON THE FIDUCIALS.  THE FIDUCIALS IN
>     QUESTION ARE GLOBAL BOARD FIDUCIALS.
>        MY QUESTIONS ARE;
>     1. WON'T THE SOLDER PASTE, (PRE-REFLOW), LACK CONTRAST/REFLECTIVITY?
>     2. WHAT PURPOSE DOES SOLDER PASTE SERVE ON THE FIDUCIAL?
>
>
>                                        THANKS,
>                                                ROB
>
>
>     ROBERT BUTTERWORTH
>     CAD DESIGN ENGINEER<-----WHAT THE HELL IS THIS?
>     ADC BROADBAND COMMUNICATIONS
>     11 FAIRFIELD BLVD
>     WALLINGFORD, CT 06492
>
>     203-630-5755
>
>     [log in to unmask]
>
>##############################################################
>TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
>##############################################################
>To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
>To subscribe:   SUBSCRIBE TECHNET <your full name>
>To unsubscribe:   SIGNOFF TECHNET
>##############################################################
>Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information.
>For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311
>##############################################################
>
Robert,
  One of our customers has us put the fiducials on the paste mask layer also.
When I asked why, he said they do a half etch, (as Hal said) which allows the
alignment of the paste mask. The paste application equipment can locate the
fiducial even if its a half etch and align to the board, no paste is placed
on the board. I know this is a short answer but it works for them and me...

Scott Decker
Senior PCB Designer

AKA: PadMasterson
E-Mail: [log in to unmask]

-----------------------------------------------------------------

   ^
  ^^^    Praegitzer Design - A Division of Praegitzer Industries
 ^^^^^   7245 N.W. Evergreen Pkwy, Suite 100, Hillsboro, OR 97124
^^^^^^^  Phone #: (503) 531-2050 Ext. 1820  Fax #: (503) 531-2051
-----------------------------------------------------------------

##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information.
For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311
##############################################################