What I do is I make a drill drawing of each board, call our fab house 
     and ask them for a quote on each board, then send them the drill 
     drawings.  They usually send me back a quote for both types of boards 
     the same day.
     
     M. J.


______________________________ Reply Separator _________________________________
Subject: Re: 4-layer vs 6-layer
Author:  [log in to unmask] at _INTERNET
Date:    7/1/96 12:06 PM


Shepard Scott D wrote:
> My customer is curious as to what would cost more a 4 layer board or a six
> layer board. 
> so here is the difference of 2 signal layers or 4 signal layers . The 4
> layer was routed to 96% and 2500+ vias and the six layer routed to 100% with
> 1450+ vias. We all can surmise that the six layer version will be more
> reliable in the long run.  I am told that the cost is drilling alone is
> about a $100 difference per board. Can any body help with the cost analysis?


The only difference you mentioned was the via count, so assuming everything 
else is roughly the same (trace width, clearance, etc) I'm almost sure you 
meant the NRE cost would be $100 more, not "per board" (otherwise, call some 
other vendors for quotes!). Even so, I haven't seen too much emphasis on drill 
count these days if you supply a drill tape/file and if it is not a high volume 
order (does ANYONE bombsight anymore?)

As for your question, I have noticed from our vendor's quotes that I can divide 
the layer counts and get a rough estimate (take it with a grain of salt but it 
has been pretty reliable for me). In other words a 4-layer will cost about 
twice as much as a 2-layer (4/2), a 6-layer will cost about 1.5 times as much 
as a 4-layer (6/4), and so on...

chat later,							Jack

P.S. Without more facts, I would question the statement that a 6-layer is more 
reliable than a 4-layer.