Ofer,
I would suggest that you send your designer on a DFM course, and ask
your suppliers for design rules. From what I see of the comments on your
design, the product was designed on a wish and not a practical basis. If you
pay enough money, you can buy anything, but this product is at spacecraft
prices.
Dougal Stewart
email: [log in to unmask]
phone: +44 1896 822204
mob: +44 7984 629667
www.pwbsolutions.co.uk
----- Original Message -----
From: "Ofer Cohen" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, January 30, 2003 6:20 AM
Subject: Re: [TN] PCB00229 manufacturing issues.
> 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/>
> Announcement of Confidentiality
> This e-mail message, as well as any attached document, is confidential and
> may be privileged. It may be read, copied and used only by the addressee.
If
> you have received it in error please destroy the message and any
attachment
> and contact us immediately.
>
>
> 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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