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May 1998

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Date:
Wed, 27 May 1998 09:54:22 -0500
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     All,

     I luckely found some calculations for determining pin deflection, hole
     diameter, pin length, hold (yes HOLD) diameter, etc. for Testing Fine
     pitch devices (.010", .012") and BGAs.

     Is anyone familiar with these formulas?

     HSmin = SD + PT (tanO)

     0 = sin-1 (Pd/Pl)

     HSmin = (SD + PT)(PD/PL)

     LEGEND

     HSmin - min hold diameter
     SD - shaft diameter
     PT - plating thickness
     0 - angle of deflection
     PD - pin deflection
     PL - pin length


     Can I use these formulas to determine if testability is feasible, for
     a very high dense assembly {4 - 600 I/O BGAs with 30 - .020" pitch
     devices (160-pin nominal) in a 9 x 7 form factor}.  I feel I am
     missing several pieces to the overall formula picture.  Can someone
     advise where I can obtain the rest of the equation.

     John Gulley

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