Jack - first, it would be important that the spec clarified if the .0762mm was +/- (x/y), RTP (radial), or DTP (diameter).  Second, it is assumed that this tolerance is relative to the board datum (usually another drilled hole).  This spec does not imply any control of hole position to copper features or board edge, unless specifically stated as such.  Industry standard hole to hole positional tolerance across large PCBs is 3 mil (.0762mm) radial true position.  So take the nominal x/y position of the hole, draw a circle around that point of radius 3 mils, and the center of the hole must fall within that circle.  Note that hole true position specs normally apply to bare boards.  Boards shrink during reflow, and there have been countless arguments between PCB fabricators, OEMs, and contract manufacturers about whether or not a true position spec applies after reflow.

Morgan Viggers
Field Applications Engineer
ISU Petasys
503.675.3877

-----Original Message-----
From: Jack Olson [mailto:[log in to unmask]] 
Sent: Wednesday, August 12, 2020 1:40 PM
To: [log in to unmask]
Subject: [TN] Drilling positional tolerance (hole-to-hole)

If a spec says that PCB drilling positional tolerance is .0762 mm, doesn't that mean that the drill hole PATTERN can be off that much in relation to other features?
(like to board outline or copper pattern?) What is a safe number for hole-to-hole positional tolerance?