Gary,
Thank you for your response. I totally agree with your assessment. I simply wanted to point out that in today's market I suspect many commercial board fabricators either choose to ignore many of the quality conformance testing and inspection requirements or are simply not aware of them. I suspect the board level conformance requirements may even be less understood by OEMs. The costs associated with manufacturing and evaluating today's printed circuit boards continue to increase while the sell price continues to plummet. I feel strongly that even the improved yields we have experienced over the last few years with application of effective process control and management techniques cannot reduce the cost factor at the same rate the pricing structure is reducing. To remain competitive in the commercial industry, I wonder how many shops serialize the parts and coupons in accordance to IPC-6012 section 3.3.5 to provide traceability between the boards and the test strips and how many commercial panels have a complete test coupon per IPC-275. I would really be surprised to find many commercial shops that have records to support the microsectioning requirements of Table 4-3 as outlined in section 3.6.2.1 thru 3.6.2.12. Shops that ignore these requirements and therefore do not factor those costs into the bid make it very difficult for rest of us be competitive. Because few commercial OEMs actually ask for the supporting data it is rarely and issue until there is a problem with the parts. Wouldn't it be nice if everybody played on the same field.
Ed Cosper
Ed Cosper
----------
From: Gary Ferrari[SMTP:[log in to unmask]]
Sent: Saturday, January 31, 1998 6:47 PM
To: [log in to unmask]
Subject: [TN] coupons
Ed,
I share your frustrations and concerns. The IPC-D-275 is indeed a design
specification and not a manufacturing specification. It should not be listed on the
fabrication drawing as is so often seen. The manufacturing specification is the
IPC-6011/12. The design standard invokes the quality provisions for a design. The
manufacturing standard provides the information of implementation on a panel and the
quality characteristics such as voids, sampling plans, electrical test paramenters,
etc. THIS specification is what should appear on the fabrication drawing.
The designer creates board data at one-up, including coupons that reflect the design.
The fabricator then multiplies the images onto a panel and places copies of the
supplied coupons in the locations called out for in the specification.
We haven't spoken about whether your customer wishes to use coupons or destuctively
test a board on the panel. The option is his. With a little guidance form the
fabricator, as to cost etc. an educated agreement can be reached.
Regards,
Gary Ferrari
Executive Director
IPC Designers Council
860-350-9300
<Reply-to: [log in to unmask] (TechNet E-Mail <Forum.), [log in to unmask] (Ed Cosper)
<To: [log in to unmask]
<The coupon issue of IPC-D-275 has long been a issue with me <as a bare board
manufacturer. Many instances I have been in <discussions where this standard is
quoted in reference as to how <a board is manufactured. To this date, I believe the
scope of this <documents still limits this document to board design and not
<manufacturing. However, there are sections within this document <that directly
influences if not outright specify manufacturing <requirements. Such as in the case
cited in Werner Engelmaier <response regarding the placement of coupons on a panel
where <he cited the requirements of 7.3.1.
<The problem is that the board manufactures has little control over <the design of
the parts we bid on and build.
<First off, of the thousands of data sets I have received from <customers to
manufacture parts, rarely does the data come in <panel form and almost never is a
coupon design included ( <military accounts excluded ). Furthermore, most commercial
<drawings only cite the performance spec such as RB-276 or the <A-600 acceptability
guidelines.
<This leads to my comment / question. When D-275 is cited along <with say the RB-276
spec ( many prints still have this) Must the <board shop review the DESIGN to
insure it meets the D-275 <standard? And if it fails to meet the design requirements
and the <shop builds it anyway, should the board shop be held <responsible? And I'm
speaking real world here folks. Due to cost <and pricing considerations many
commercial designs are quoted <and panelized with the minimum required boarder for
<manufacturing. I would venture to say ( based on my experience) <that a vast number
of commercial designs do not allow for proper <boarder that would supports a complete
coupon and many <frequently violate the hole to pad ratio as well as conductor edge
<clearance. Many double sided designs are being process with <less than a .500
boarder total. And that is necessary just to stay <competitive. I wonder just how
many commercial manufactures <are really adhering to the "total" spec as it is
written. Frankly I <wonder how many commercial houses actually have the required
<group A test data on file as required. If I understand the specs <correctly, even
commercial board require a group A test and that <would technically require
serialization wouldn't it? I believe the <new IPC-6012 section 3.3.5 is very clear on
this. How will this <requirement affect pricing since the newer specs basically
<require commercial parts to be manufactured, tested and <inspected along the same
lines as the old Mil-P-5510. Just how <many of us are actually serializing our
commercial product and if <we are, is the customer paying for the added costs?
<Hmmmmm... I wonder..
<Just my thoughts.
<Ed Cosper
<Director Quality Assurance and Engineering.
<Graphic Electronics Inc.
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