Hi Wendi,

The IPC-A-600 Section 2.6.1 Haloing Unsupported Hole Acceptable − Class 1, 2, 3
Penetration of haloing does not reduce the unaffected distance from the board edge to the closest conductive pattern
by more than 50% or more than 2.5 mm [0.0984 in], whichever is less.

Russ Shepherd
Director PCB\PWB Test Programs
Microtek Laboratories
1435 Allec Street
Anaheim, CA 92805
(714) 999-1616
www.thetestlab.com

-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Wendi Boger
Sent: Friday, March 12, 2010 8:11 AM
To: [log in to unmask]
Subject: [IPC-600-6012] Edges and Crazing/Haloing

Everyone,



   I seem to remember a discussion about Haloing of edges and non plated
holes at one of our recent meetings.   The requirement for the haloing
to be less than 50% the distance to nearest conductor works assuming the
design has a reasonable space from conductor to edge.  I looked in
IPC2221 but did not find a guideline for suggested minimum distance.  We
are seeing non-plated tolling holes with surface ground rings at <10mils
hole edge to copper.  Depending on the material and hole size it's
difficult to meet the 50% rule.



   Is there a section in 2221 I can send the designers to so we can
avoid this type of issue?



Thanks,

Wendi Boger





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