Jim,
     
     There's more to this but I'll be brief.
     
     Basically both tests are the same when it comes to the software, you 
     need a Netlist Test to effectively test the bareboard.  
     
     We used a Flying Probe Tester at previous employer, I think it was 
     called a Probot (the model escapes me).  The basic Flying Head Tester 
     is vertical with two flying test heads on either side of the 
     bareboard, 4 total.  Two independent probes will make contact to where 
     a NET begins and ends, if it be on one side or both.
     
     One big advantage of using the Flying Head Tester, it allows you to 
     test non-grid layouts and grid layouts tighter than 20mils, very fine 
     pitch devices (feature size) or basicallly tight densities that are 
     outside the Bed-of-Nails capabilities (even if Clam Shell Testing is 
     used).  The Flying Head Testers are used extensively with ATE cards 
     specific to the Semiconductor industry that have tight DUT areas.
     
     The big disadvantage of a Flying Head Tester is TIME.  If you have 
     2500 NETS, you have to individually test each net wheras Bed-of-Nails 
     testing allows for complete coverage of the bareboard via test nails, 
     unless you do a split Clam-shell test (Bed-of Nails but both sides and 
     two separate fixtures).
     
     I'm not positively sure, but the cost for a Flying Head Test Unit is 
     much cheaper than a Bed of Nails Unit and you do not have to pay 8 to 
     10K for a Test Fixture each time a major revision occurs.
     
     Someone whom I would recommend and consider very knowledgable on the 
     PROs and CONs of the Flying Probe Tester is Luis Rivera 
     ([log in to unmask]).  He's extremely busy but is very helpful. 
     
     John Gulley - QA
     INET Inc.
     1255 W. 15th St. Ste 600
     Plano, TX 
     
     
     
     


______________________________ Reply Separator _________________________________
Subject: test: FLYING PROBE VS. HARD TOOLING
Author:  Jim Marsico 516-595-5879 <[log in to unmask]> at Internet
Date:    12/12/96 3:09 PM


Helloooo, again....
     
Could anyone explain the difference between flying probe PWB testing and a hard 
tooled bed-of-nails test?  Pros and Cons?
     
Thanks,
     
Jim Marsico
(516) 595-5879
[log in to unmask]
     
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