Table 6-1 in IPC-2221 will provide you with the minimum electrical clearance, use the numbers from the B1 column for internal layers for the "A" factor. The "B" factor should be defined for m table 9-1 of IPC-2222 based on design complexity and maximum dimensions. Based on fabricator requirements this should give you a distance of greater than or equal to 0.25mm [0.010"].


Jeffrey A McGlaughlin, CID
Engineering Designer
Battelle
505 King Ave
Columbus Ohio 43201-2693
Phone (614)424-7582



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of GRIVON Arnaud
Sent: Wednesday, March 04, 2009 5:38 AM
To: [log in to unmask]
Subject: [TN] PTV to Ground Clearance

Hello TechNet,

For those who are familiar with IPC-2221 and IPC-2222 standards : what are 
the recommended clearances between a PTV/PTH and an internal PCB ground 
plane?
IPC-2222 §9.1.3 'Clearance area in plane' includes a picture with an 'A+B' 
distance corresponding to the summation of the electrical clearance and the 
manufacturing tolerances, but I cannot find any numerical values.
Can somebody help?
I am primarily interested in the case of an unsupported hole without NFP in a 
ground plane.
Thanks in advance for your insights.
Best regards,

A. Grivon

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