Hello Matt, Fiducials are visual alignment marks used by placement machines to locate the board and fine pitch components. I've seen these in the form of hashes '#' or simple 1mm dia copper pads (no hole) with a 3mm dia clearance in the solder mask. It's important that there are no other visible features within the 3mm clearance area. Thes things must be easily recognised by 'machine vision'. I usually place 2 'global' fiducials at opposite corners of the board (if it's large enough - small boards are usually loaded in multiples on a pallett, which would then have the global fiducials itself), and 2 'local' fiducials on the diagonals of the 'fine-pitch' parts. The larger boards often require 2 loading tooling holes for alignment as well, (NPTH controlled hole tolerance). There are 'cleverer' placement machines that can recognise the actual component land patterns, but not all assembly shops would have these. Talk to the assembly house, they would usually be only too glad to help you to provide them with their preferred requirements. (just a tiny part of DfM)
regards, Phil. -----Original Message----- From: Matt Daggett [mailto:[EMAIL PROTECTED]] Sent: Monday, 14 October 2002 11:59 PM To: Protel EDA Forum Subject: [PEDA] Fiducials I just sent off parts + boards for our first needed outsourced assembly and the assembly house is requesting that I... "remember to add fiducials to your design. All high precision placement machines must have visual targets as part of the design." Can someone give a brief explanation of what these are and what I need to do in Protel to satisfy their requirements. thanks, matt ����`````````````````````````````````````````````````````���� Matt Daggett MCNC - Signal Electronics Division 3021 Cornwallis Road Research Triangle Park, NC 27709 voice: 919-248-9278 fax: 919-248-1455 http://www.mcnc.org/wireless/ ���,�����������������������������������������������������,��� * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[email protected] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
