I do know that BGAs are not level.
I have seen a demo of a machine, A3DI, which accurately measures the height of components, amongst other things, and it was interesting to see that all BGAs had a slight tilt on them.
At the demo I could not find out how the tilt was related to the direction of passage through reflow, however it was my guess that the two are related.

If you want more info contact  Dave Hall <[log in to unmask]>

Regards
Rex


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of William Noel
Sent: 03 July 2012 12:20
To: [log in to unmask]
Subject: [TN] Coplanarity of Sensors

Hello - We are mounting light sensors on a circuit board and these sensors come in a variety of packages (BGA's, QFN's etc) I was trying to determine if there is a standard or spec that addresses the deviation from a "perfect" 90 degree angle of light addressing the sensor's active surface.  Ideally the sensor would be mounted such that direct light addressing the sensor would be at a 90 degree angle to the pcb and subsequently to the sensor itself.  Anyone have any experience or advice?  Thanks in advance.

______________________________________________________________________
This email has been scanned by the MessageLabs Email

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________