Good day to all,
We have designed a controversial board. A manufacturer that we called claims
that the design has a problem of long-term reliability problem. I attach the
analyzer pictures and the commentary.

The intended material is Arlon 55ST. The PCB will have 22 layers.

As being specialized in the reliability and quality aspects rather than in
the technological aspects, I would like to get some opinion as of the
influence of the design on the reliability. If possible - some guidelines on
qualitative connection between the design rules and the board reliability.

Regards
Ofer Cohen
Quality Assurance Manager
Seabridge Ltd.
3 Hanagar St., Neve-Ne'eman
POB 7242
Hod Hasharon 45241
Tel Direct: +972-9-775-1104
Tel Operator: +972-9-775-1111
Mobile +972-55-623336
Fax: +972-9-775-1100
mailto:[log in to unmask]
Website <http://www.seabridge.co.il/>
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 Manufacturing design issues.

8. , 9. , 10. , 13. , 14. , 15. , 16.
Removed - non critical issues

1
Sub-composite vias have no O/L annular ring - design has 11 mil drill with
10 mil pad.  Hole to plane spacing is only 4 mils. Manufacturing requires
that vias must have pad sizes that are 12 mils larger than the drill size.
The spacing between via pad and surrounding copper plane should be 8 mils
minimum design.
<<subviapads.gif>>

2
Blind via hole misregistration to capture pads down to 1.7 mil  a/r.
Manufacturing requires holes to be centered in innerlayer capture pads as
well as outerlayer pads.
<<viacapturepads.gif>>

3
Non-plated hole to copper spacing of 4.8 mils. Need to increase spacing to
10 mils.
<<npttocopper.gif>>

4
Plated thru hole spacing to trace of 4.4 mils on innerlayers. Manufacturing
requires spacing of 10 mils between drill hole and traces.
<<seag hole to trace.gif>>

5
Plated thru component hole misregistration down to 1.7  mil a/r
Manufacturing requires holes to be centered in the pads to prevent hole
breakout.
<<seag hole reg.gif>>

6
Thru vias have 20 mil pads with 12.5 drill.  Need to allow partial hole
breakout and allow tear dropping of pads for annular ring at pad/trace
junction.

7
Outerlayer pads smaller than drill size for 70 mil PTH size at several
locations.  Manufacturing needs pads 6 mils per side larger than drill for
annular ring.
<<no AR for 70pth.gif>>

11.
Spacing between hole and plane is down to 6.7 mils due to hole
misregistration.  Need 10 mil spacing between hole and plane.
<<holetoplane.gif>>

12.
Pad to pad spacing of 2 mils on layer 21.  Need to clip pad to 6 mil
spacing.
<<2mil spaceL21.gif>>

17.
Spacing between blind via hole to buried via hole is less than 3 mils down
to .7 mils  partly due to hole misregistration in design.  Design spacing
should be 3 mils minimum between blind via hole and buried via hole edges.
<<.7milspaceblindtoburied.gif>>

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