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| Reply To: | (Combined Forum of D-33a and 7-31a Subcommittees) |
| Date: | Thu, 31 Oct 2002 09:01:30 EST |
| Content-Type: | text/plain |
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Hi Constantino,
The 'aspect ratio' is the hole depth divided by the hole diameter. It is more
important for through-vias [PTVs] than blind vias, because of the larger
loads during temperature increases on the PTVs. Generally speaking, a higher
aspect ratio via is more difficult to plate with uniform and good quality
copper. For PTVs the aspect ration above which special attention was found to
be required has been 4; but with improving plating technologies this number
has been moving upwards.
Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL 32174 USA
Phone: 904-437-8747, Fax: 904-437-8737
E-mail: [log in to unmask], Website: www.engelmaier.com
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