My answer depends upon the drawing call out.
It is very important to be compatible with the drawing.
If you don't state that the boards are to be built in
accordance with IPC-6012, Class ?, then it is
difficult to hold your board manufacturer to those
requirements,

If you do reference IPC-6012, or a military spec or
a company specification - you have a much simpler
task.

The boards that come to you should have been inspected
to the sample plans and requirements of those documents
and you should have been supplied with some type of
information that details what tests were done on how many
samples and what the results of those tests were.

You can then pull random samples and verify the tests that
were performed by retesting, or you could just review test
data.

In IPC-6012,page 20, 21 and 22 and 23 there are tables which
give the suggested sampling plan and CONFORMANCE TESTING
AND FREQUENCY for each lot of boards produced.

By knowing the class of product you can determine how many
(boards or coupons) to be tested for each suggested attribute to
be verified.

If you need help with the tables let me know and I will be glad to help
you off line.

HOWEVER THE MOST IMPORTANT THING IS TO DETERMINE
WHAT YOUR DRAWING OR PURCHASE ORDERSTATES. so
you know what has been imposed on the manufacturer

Susan Mansilla

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