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Chris and other members of the Designer Council Forum,

Chris raises some valid points concerning IPC standards and PCB fabricator capabilities. Hole registration, and associated annular ring criteria, has always been an item of discussion between designers and PCB fabricators. Keep in mind that increased number of layers and increased board thickness DO limit the the PCB fabricator's ability to meet tight registration (annular ring) requirements.

Just over two years ago at the IPC Expo 2000 PCB Presidents Meeting, a request was made to IPC that a standardized set of process capability panels be developed and that an anonymous capability database be created. The D-36 Sub-committee was created to address this request and has completed the first phase of its efforts. The IPC-9151 document, "Printed Board Process Capability, Quality, and Relative Reliability (PCQR2) Benchmark Test Standard and Database" was just released last week. Follow this link -- http://www.pcbquality.com/ -- to the IPC PCQR2 Database 'Home' page. There you will find the following files that you can download or view on-line to gain more information on this standard and database.

1) IPC-9151, Printed Board Process Capability, Quality, and Relative Reliability (PCQR2) Benchmark Test Standard and Database, document. This is an Acrobat PDF file <IPC-9151.pdf>. Tables 5-2 through 5-10 in Section 5 provide detail on the feature types and sizes included in each of the module designs, and show the difference between 'medium' and 'high' technology.

2) IPC-PCQR2 Presentation in both PowerPoint <pcqr.ppt> and Adobe Acrobat <pcqr.pdf> formats. Slides 14 through 17 show a color-coded 'Key' to to help you see the variation within PCB supplier process capability results. This color coding feature is being added to the 'Process Capability Data' portion of both the 'example' and 'live' databases; should be posted within 2 weeks. Slide 20 lists the current Subscribers and Suppliers in the database as well as the design submissions and regions of the world represented.

3) Example Database, file <example-db.xls>. There are two sheets or tabs in this database. All 'Subscriber' facilities would have access to both sheets, the 'Process Capability Database' tab as well as the 'Industry Statistics' tab. 'Suppliers' (PCB fabricators) only have access to the 'Industry Statistics' tab. This example contains "real" data from the current pool of 25 submissions. Data is shown from three each of the 6-, 12- and 24-layer panel submittals.

4) Example Analysis Report, file <ipc-014a_x8.pdf>. This 178-page report shows all of the detailed analysis information from one submission of the IPC-014A 'high' technology, 0.125" thick, 24-layer test panel design. This is real data from supplier X8 who is also shown in the example database referenced above.

As you review the information noted above, you will see that the IPC PCQR2 Database provides a wealth of quantitative data on process capability, quality and relative reliability of your PCB suppliers. This data address not only via hole registration capability but also conductor/space formation, via hole formation and quality (as formed and after assembly simulation), impedance control capability (both single-ended and differential), solder mask registration and controlled depth drill overshoot capabilities.

As you review and digest this information, please feel free to post questions to the Designer Council forum or contact me directly off-line for one-on-one discussions.

I've done a lot of research this last year on pcb specs, and have a few question

concerning high end PCB from here and overseas.

I've noticed through hole components are no where near IPC annular ring standards

Neither are the surface mount land patterns. PGAs are using alternating oblong pads.

Here are some facts;

Let me make it plain, this is not knocking IPC in anyway, but is it time we specify and go beyond the

current limitations and expand to some current practices and make some of the specification

"Technology specific"? (This may already been in the works since I've had my head buried in work

the last year and haven't been keeping up with recent events)

I've brought up the category of "Soldered thru-holes" and "non-soldered thru-holes" and have heard

nothing but agreement there.

I've witnessed thru-holes components soldered with great quality to pads with nothing more than a .

009" AR. Granted, you couldn't remove the component, but it is a throw away board.

I just keep hearing this question coming to me over and over and I can say, is if you are comfortable

with the quality, and the components will NOT be removed then there isn't a problem, just don't specify it

being finished per IPC specifications.

Chris Robertson
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