To the Originator of the following message:
     
     Please send me your name, affiliation, and email address, if your are 
     interested in discussing this MIL-to-commercial migration any further.
     
     Regards,
     
     
     email: [log in to unmask]
     Michael S. Alderete
     
     
     
     
     
     
     
     
______________________________ Reply Separator _________________________________
Subject: Re: Small Via Formation
Author:  [log in to unmask] at _internet 
Date:    1/23/96 7:24 AM
     
     
     
As designers, we would also like to know how far can "Small Via" technology 
can evolve in the near future.
     
It seems that the commercial world can keep pushing fine line pc boards 
further and further, yet the military is very slow to embrace any new push in 
this kind of area.
     
Is it up to IPC and the PCB fab industry to prove that boards made with these 
.001-.002 wide traces and "micro-vias" are truely reliable and reproduceable?
     
As we now understand, the military is leaning towards using IPC-D-275, etc....
     
Will IPC now change it's proceedures to accept this latest push?
 * Will aspect ratios change?
 * Will mfg process tolerances change?
     
At our military facility here are some of our design parameters:
 * .007 traces on artwork with a .003 process tolerance. 
 * .040 external pad/.034 internal pad/.016 drill via.
 * These sound very generous as compared to what I read on Technet.
     
Until IPC gives it's blessing and changes it's documents the rest of us are not 
going to be able to take advantage of any breakthrough in fine line technology.