Tony,

I'm sure all fabricators and assemblers have a minimum fabrication
requirement that is controlled by that company.  However, there is
nothing wrong with good concise communication.  You can expect to get
what you ask for, but if you don't ask for a specific minimum
requirement, you'll never know what you will get.  If you specify the
requirement, you can expect all fabricators to meet the same minimum
standards.

I recommend specifying your acceptability requirements on the print as
it relates to an industry standard (like IPC-xxxx).  This is the best
way to communicate your requirements to the fabricator.  Many of our
customers also have "customer specifications" that they use to
communicate general requirements so that the print doesn't become
cluttered with notes.  In these "customer specifications" they detail
how their requirements relate to an industry standard and also include
"unless otherwise specified on the fabrication drawing or purchase
order" clauses.  These include packaging requirements,  default
acceptability requirements (ie: IPC-6011/6012 class 2), etc.  In this
case, you should put a note on the print stating that the board or
assembly should be manufactured to meet the requirements of your
customer specification.

In all cases, the fabrication drawing should have a note describing the
acceptability requirement either by industry standard or customer
specification.

Darren Hitchcock
Merix Corporation


> ----------
> From:         arrigo.tony[SMTP:[log in to unmask]]
> Sent:         Tuesday, June 30, 1998 9:32 AM
> Subject:      PWB Procurement Recommendations
> 
> Can anyone tell me what is gained by specifying "Fabricate to
> Mil-PRF-31032 vs. IPC-xxx?"  Is a  fabrication specification even
> required when purchasing a multi-layer PWB at all?   Will all PWB
> manufactures give some minimum fabrication requirement if none is
> stated on the drawing or in the purchase order, or is it  always BUYER
> BEWARE??
> Thanks for your assistance. 
> Tony Arrigo 
> 

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