Does the product meet specified requirments...

Earl Moon
----- Original Message -----
From: Mcmaster, Michael <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, August 27, 1999 8:59 AM
Subject: Re: [TN] First Pass Yields


> Craig
>
> It depends on the definition of first pass yields.  I've heard and seen
> it defined many ways.  You can report a first pass yield through an
> imaging sequence (IL and OL) where you're looking at the amount of
> product produced with no defects (opens, shorts, etc).  At electrical
> test, I've seen it reported on a piece-by-piece basis or a lot-by-lot
> basis.  I've seen the same metrics at a Final Audit operation, also,
> measuring escapes from previous processes.  Sometimes, first-pass will
> refer to the first-time build of part.  Can you provide a clearer
> definition of "first-pass"?  Otherwise it's hard to assess if 50-75% is
> "typical".
>
>         ----------
>         From:  Craig Patterson [SMTP:[log in to unmask]]
>         Sent:  Friday, August 27, 1999 3:15 AM
>         To:  [log in to unmask]
>         Subject:  [TN] First Pass Yields
>
>         Recently our bare board manufacturer indicated that his first
> pass yields
>         from his electrical test for our six layer board (FR4, couple of
> BGA, some
>         20mil QFPs, 7" x 11") was about 70%. We were concerned that this
> may mean
>         his process is not under control. He said that 50 to 75% first
> pass yield
>         was typical in the industry. The failures were for various
> reasons from
>         opens to mask on pads.
>
>         Does anyone have an opinion regarding 75% reflecting the first
> pass yield
>         as a benchmark of the board fab industry?
>
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