Ken,
Per IPC-SM-782(A), Section 5.7.1, test via lands should be .036 to .040
(0.9-1.0mm) diameter, to decrease possibilities of test probe misses.  Land
diameters below .035 may cause problems in test, for example, the test
operator may have to pull the unit under test off the test fixture, put it
back on, and re-run the test more often that desired.  Via size may or may
not be a problem; we have used .014 (0.3mm)  diameter via with needle-point
probes with no serious problems.
I am kinda interested in what other companies are using...

Roger M. Stoops, C.I.D., PCB Designer


Spectra Precision Inc./Trimble Navigation Ltd.
5475 Kellenburger Rd.
Dayton, OH 45424-1099 USA
Ph: 937.233.8921 or 937.233.4574 ext 288
Fax: 937.233.7511



                    Ken Patel
                    <KPatel@ZAFFI        To:     [log in to unmask]
                    RE.COM>              cc:
                    Sent by:             Subject:     [TN] DFT (Design for Testability): Test via
                    TechNet              size
                    <[log in to unmask]
                    ORG>


                    09/09/00
                    02:14 AM
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Expert,
What is the preferred and minimum acceptable via size (hole and land) used
for testing? A kind of DFT question.

re,
ken patel

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