Hi Randy,

As you know, but I'll type up for the sake of the 6012 listserv, 1-10c discussed this topic ad nauseam.  We strongly believe that the true 601X requirements are for drill to image registration,  while annular ring is simply one of several ways to measure it.  Moreover, in some increasingly common cases it not even an appropriate way to measure it.
The A/B-R script is designed to assess using drill to image tolerances.  The R features are designed as electrical test antipads, and the C features have calculated lands that don't even necessarily exist on the actual product.
The concept behind the C feature lands has been used by fabricators successfully for years.  However, to be honest, probably in a "don't ask, don't tell" scenario, as no one really wants to get into coupon design verification.  IMO such rejiggering of the coupon land sizes is "representative of the product" for the first order intent of registration assessment.

Currently 6012 doesn't give a canned "get out of jail free" card.  So, if your assessing actual boards against 6012 black-and-white, you've got an AABUS issue.

Chris Mahanna
Robisan Lab

 

-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Reed, Randy
Sent: Tuesday, August 17, 2010 4:33 PM
To: [log in to unmask]
Subject: [IPC-600-6012] Non-Functional Land Registration and Annular Inspection

IPC-6012 has no guidance on the management of non-functional lands (that
I can find) concerning registration and annular ring limits.

 

The scenario causing problems is designs where the non-functional pad
size is smaller than the functional pad size.  I am not trying to debate
whether this is a good design practice.

 

What is the intent of IPC-6012?  Should boards with registration and/or
annular ring failures on non-functional lands, with the smaller pad
size, be considered non compliant?

 

Randy

 

Randy Reed, CQE

Reliability Lab

Viasystems Group Inc.

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503.992.4421-direct  l   503.545.0150-cell

 


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