Brian McDermott made the comments: "Unfortunately, the diversity of 
     micro-via technologies, the confusion on the pro's/con's and the absence 
     of a low cost process with multiple established suppliers, has prevented 
     large scale implementation of micro-vias."  Which I agree wholeheartedly.
     
     The solution that he seemed to suggest was for every board shop to 
     convert to their way of making boards.  I keep trying to make the point 
     that different board manufacturers are setup differently and what's right 
     for them may not be right for your or me.  I think we should let the 
     market decide what is the best.  We can keep going back and forth about 
     the pros and cons, but that's only going to give potential users the 
     feeling - "maybe we should wait until things settled down".  What's 
     important here is how to reslove the confusion.
     
     It is possible that photo dielectric may result in different electrical 
     properties.  However, I think plasma and laser can use similar and more 
     traditional material (resin coated foil, or Thermount reinforced 
     laminate) to avoid functional differences.  (Glenn, I probably have to 
     ask you to comment on that again! :))  Maybe this is the reason the 
     previous discussions were focused on laser vs. plasma - because they are 
     much more alike.  I think the "Typical" numbers suggested by the folks 
     from IBM seem like something that all technologies can support (based on 
     Glenn's numbers and our numbers).  So, for you designers out there, if 
     you want flexibility (as suggested by Glenn) choose "Typical", if you are 
     more adventurous then sky is the limit.
     
     Minimums(mils)         Typical  Available   Limited Availability
     ---------------------  -------  ---------   --------------------
     
     Line Width                3        3               2
     
     Line Spacing              5        3               3
     
     Photo Via Diameter        5        5               4
     
     Photo Via Land Diameter  12       10               6
     
     PTH Diameter             14       10               8
     
     PTH Land Diameter        24       18              14
     
     I would like to encourage other board manufacturers, whichever technology 
     you are working on, to comment on whether this is a reasonable set of 
     design rules.
     
     There are several factors determine the success of a product/process.  
     Price, quality, reliability, availability all come into play.  I think 
     everyone agrees he/she has the best quality and reliability.  Apparently, 
     everyone think his/her price is the best in the world, also.  Availability 
     is the key to jump start the market.  With a set of common design rules in 
     place, the customers can take their design and ask for the lowest bid, 
     whichever technology it maybe.  This is the best way to resolve 
     availability issue.  The response from Mike Avery clearly supported my 
     view.  I'm sure when the market is up, there will be big enough shares for 
     everyone.
     
     Mason Hu
     Zycon Corporation

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