How about IPC-2222 (for rigid boards)

Table 9-4 Aspect Ratios

less than or equal to 5:1 Level A General Design Complexity - Preferred
Producibility

6:1 to 8:1 Level B Moderate Design Complexity - Standard Producibility

equal to or greater than 9:1 Level C High Design Complexity - Reduced
Producibility




 Guy Ramsey
American Competitiveness Institute
Senior Lab Technician / Instructor
610 362-1200 ext 107


-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Michael Simms
Sent: Tuesday, April 03, 2001 9:34 AM
To: [log in to unmask]
Subject: [TN] Low Aspect Via definition


Hello T'Netters,
I've not received a single reply from the last posting
of this question, so I'd like to repeat:
What document defines a low aspect via?
Is there a numerical cut-off between a low aspect via
and other vias?  Certainly, in the 6012A document, acceptable
minimum average copper thickness and absolute minimum
copper thickness are defined for typical vias and
low aspect vias. Is 3:1 a low aspect via? How about 4:1?
Or 5:1?
Any help out there?
Mike Simms
Trace Laboratories - Central

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