Only electrically testing one board out of a lot ? ET for connectivity is
cheap once the fixture is made - and fast. And via opens are usually random
in any lot, which would indicate that testing one board doesn't say
anything about the balance of the lot. I have never heard of testing only
one board and passing the lot. If that is the case then what you are saving
is next to nothing compared to what you are risking. ET should be 100% and
not a sampling plan.

As you've heard from the other responses there are any number of ways a
hole can be faulty ..

The only "electrical" test that I know of that is or can be done on a
sampling basis is controlled impedance.

It doesn't sound to me that the design is that agressive, so there really
ought not to be any open vias coming out of a competent shop.

Valerie







Charles Caswell <[log in to unmask]>@LISTSERV.IPC.ORG> on 05/19/2003
04:23:05 PM

Please respond to "TechNet E-Mail Forum." <[log in to unmask]>;
       Please respond to Charles Caswell <[log in to unmask]>

Sent by:    TechNet <[log in to unmask]>


To:    [log in to unmask]
cc:

Subject:    Re: [TN] PCB_OPEN_VIAS_PROBLEMS


In our case I have been told that the netlist testing is only done on one
out of the lot.
Charles

-----Original Message-----
From: Fineline Circuits, Inc. [mailto:[log in to unmask]]
Sent: Monday, May 19, 2003 4:26 PM
To: [log in to unmask]
Subject: Re: [TN] PCB_OPEN_VIAS_PROBLEMS


Wesley:
Weren't these boards tested by your board supplier? Electrical testing
should have failed the boards with the open vias . The vias may have voids
due to bad drilling and deburring which may clog the hole, poor smear
removal or malfunction of the electroless copper line-trapped air or could
be plating voids. Cross section of the open vias should pinpoint the
problem.

Sona
Fineline Circuits Inc.

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