Ed,
     
     I think scoring is great, especially where array profiles are 
     required.  Your design must sometimes include tooling holes in certain 
     locations to accomodate some scoring machines or the panel at the Fab 
     house will provide them.  What I focus on most is the residual 
     material following scoring.  I use scoring on both our wired and 
     wireless products.  Although a great IDEA, our PCMCIAs (wireless) can 
     not be scored due to the type of Can it is inserted into.  Scoring 
     still does not cut the board profile (Z-axis) straight without cutting 
     into the meat of the PCB.  The residual amount is also critical from 
     the Assembly point.  If there is not enough material remaining and 
     your board spans a great distance in all directions, it may cause 
     problems in component seating.
     
     I've recently seen Floating Head Score Machines, that unlike existing 
     score machines will not score all the way to the panel edge, which 
     allows for more Z-axis rigidity in the panel.  
     
     Your residual will vary going from .062 to a .093 or .0785, with such 
     variables as laminate, copper weight, copper planes, etc.  You will 
     have to look at your overall material recipe in addition to the type 
     of components that are be placed to where they are being place to 
     determine the amount residual.  The angle you have chosen is typical 
     with most scores and can be kept.
     
     One other important note is how will the panel be depanelized.  The 
     method in which you depanelize your boards from the array is critical 
     to the functionality of the final assembly.  Gull wing packages, 
     components close to the edge, mis-oriented components (DFM), etc can 
     cause problems when hand depanelizing.  You may have to use a PIZZA 
     cutter to effectively depanelize the boards from the array and even 
     that gets tricky.
     
     Which now leads us back to routing.  Routing is like one stop 
     shopping, its quick and very cost effective.  99.9% of all PCBs have 
     to visit the Route Dept. at some time in the process.  You can stack 2 
     to 4 panels while routing.  One less set-up then scoring, etc, etc.
     
     Its brief but I hope it helps.
     
     John Gulley -  Process Quality Engineer
     Inet Inc.
     972-578-3928
     


______________________________ Reply Separator _________________________________
Subject: FAB - Scoring PCB panels
Author:  Ed Gavin <[log in to unmask]> at Internet
Date:    5/2/97 10:04 AM


On 0.062 inch thick boards, we currently call for a 30 degree score, 
0.020 inch deep on opposing sides of the board.
We are trying to develop our standard for scoring.  Is this what most use 
for scoring?
Do you score boards thicker than 0.062 and if so what dimensioning do 
you use for those?
If given the choice would you select scoring over routing? why?
     
Thought this might be of general interest to the board community.
     
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