The design is a bit of both.  I have quite a number of lines going across
the board that is riddled with vias and already 10 layers. The way I
understood something in the Combs book is that 5/5 trace/space is a more
reliable and cost effective way to go than additional layers.     To enable
2 lines between vias the 5/5 works.  However; this particular engineer
thinks 5/5 should be done as standard practice on everything.  Our
environments can get harsh and the other side of that is we want everything
to last forever.  We have 10,15 and maybe even 20 year old equipment on
some of the telescopes.


Dee Stover  [log in to unmask]
Associate Technician Design
National Optical Astronomy Observatories
www.noao.edu




At 12:59 PM 9/13/2002 -0400, you wrote:
>Is the fine line requirement because of the density of the design or the
>engineer? If you are working with ultra fine pitch BGA or CSP components
>there is no way around the 5/5 mil design. 3/3 mil is pushing producibility
>but doable, and if the need arises I know of a couple of houses who claim to
>do 2/2mil boards though they classify them as proto quantities only and
>charge an arm, leg, and first born for them;-).
>
>Jeffrey A. McGlaughlin CID
>Sr. Designer
>Battelle Memorial Institute
>Columbus Ohio
>[log in to unmask]
>
>
>
>-----Original Message-----
>From: Dee Stover [mailto:[log in to unmask]]
>Sent: Thursday, September 12, 2002 4:41 PM
>To: [log in to unmask]
>Subject: [DC] fine line traces
>
>
>I have an engineer that is trying to push me into 5/5 or even 3/3 spaces
>and traces.  I see that SOME fabricators are doing stuff at this level but
>since it isn't all that wide spread.
>
>I am looking for the pros and cons for these type of designs.
>
>Your input is appreciated.
>
>
>Dee Stover  [log in to unmask]
>Associate Technician Design
>National Optical Astronomy Observatory
>950 N Cherry Ave
>Tucson, AZ 85719
>www.noao.edu
>520-318-8489
>FAX 520-318-8303
>
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