Whoa....better start checking those specs!  If the IPC-SM-782 indicates the 
.002 grid is correct, there is a problem.  In my previous post I indicated 
.010 or .020 - I was wrong - .020 is the only correct answer (thanks Richard 
J.).  I agree with aslagle that any designer worth his/her salt would 
optimize the spacings and use .008 space (.004 grid), but the question asked 
what grid would *guarantee* .006 clearance.  The only correct answer is 
.020. (Using .010 would guarantee .006 trace to pad (if you assumed touching 
the pad was not an option), but not trace to trace)

Sorry IPC, better check those specs - or the wording of the questions. 
 Perhaps it would be useful to know why these questions were thrown out, if 
that info is available.


Ben
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 ----------
>From: Dieter Bergman
>To: designercouncil
>Cc: coonje; ksamuelson
>Subject: Question of the day (QOD)
>Date: Thursday, December 21, 1995 6:46PM
>

>Previous QOD
>
>103     If two 1.5mm [.060"] lands are located on 2.5mm [.100] centers,
>        what is the dimension of the conductor routing grid that should
>        be used to locate two .2mm [.008"] conductors between the lands
>        and guarantee a minimum of .15mm [.006"] clearance?
>        A.      .05mm [.002"]
>
>        Resource: IPC-SM-782, para 3.6.2.1, Figure 3-17, and Figure 3-18
>
>        *************************************************************
>
>Please send comments, constructive critique, or suggestions to Lisa
>Williams at [log in to unmask]
>
>Dieter Bergman
>
>