John,

I recommend you get your hands on a catalog from IDI.  Page 102 has a thorough description of
pointing accuracy calculation, including examples.  IdI's address is 5101 Richland Ave., Kansas
City, KS 66106.  913-342-5544

Richard
[log in to unmask]

[log in to unmask] wrote:

>      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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