Jim,

1.  First are you testing SMD pads of less than 50mil pitch?

2.  If you are than your deflection is greater than 70mils this is tough to
accomplish using 1.1" x .059" pins though a .125" plate.  Drill size of .055"
is to small to achieve this desired deflection.  

3.  Shaker tables have been around for years, they use either a X,Y motion or
vibration.  Your .125" plate is placed on the table, then a crate is placed
on top.  Pins are then "dumped" into the crate and shaken about.  Loading
will generally be around 70-80% in about 10-20 mins depending how many times
you shake.  This only works with 1.1"X.059" pins!

4.  Some companies use tubes from adding machine rolls and place pins inside
and shake them in by hand. 

How well do your fixtures run on your tester?  
Do you fight false opens and shorts?  
Does your customer require netlist test?  

If so then I would strongly reccomend looking into multiplate fixtures or
what is called "determined" fixtures.  This requires use of software to
output the drill files based on the "stackup".  Stackups can be as little as
two plates to as many as 10 plates depending on pin length.

Advantages:
    1. Robust testing and trouble shooting on your tester.  Pins will not
cross and if designed correctly not bind.  Also if download capablility,
 learning of know pin count from test program identifies quickly which probes
are not loaded or causing problems.
    2.  Netlist download to your tester.  Use of single plate fixtures does
not guarantee a grid location to a specific test point.  
    3.  Ablility to recall test program, no need to save golden board.

Disadvantages:
    1.  Drilling time.
    2.  More hardware, ie plates and spacers.

If you would like to discuss this further please give me a call.

Jeff Garland 
Sales Engineer
Lavenir Technology Inc.
[log in to unmask]
603-431-6279


***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To unsubscribe from this list at any time, send a message to:           *
* [log in to unmask] with <subject: unsubscribe> and no text.        *
***************************************************************************