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Wire Attach Point Offset

July 13, 2010

Several package designers have requested a way to express in AIF a wire that is not attached to the center of a bond finger. This is not a trivial request because a fundamental assumption made during the design of the AIF database is that a wire attaches directly to the center (i.e. the insertion point) of the bond finger.

Consider the layout below with a portion of the AIF file used to generate it.

wire attached to center of bond finger

    [PADS]
    BF=RECT 90 254
    BP750=CIRCLE 750
    DP100=SQ 100


    [NETLIST]

   ;NET    DIE PAD & COORDS     BALL PAD & COORDS          FINGER PAD & COORDS
    NET3 3 DP100 -5270 4750     D3 BP750 -13335 12065      3 BF -8262.55 7648.42 45.92	
    NET4 4 DP100 -5270 4655     E4 BP750 -12065 10795      4 BF -8324.01 7444.40 47.59	

Suppose we wanted the wire to be offset by 50 um towards the front of the finger instead of landing in the center of the finger. [See below] How would we modify the AIF file to support this description?

wire attached to center of bond finger

Well without "breaking" the AIF behavior we could implement this with two entries: a) Create a line to place the bond finger leaving off the die data so that we don't generate a wire. Create a new line with the die pad and a "dummy" bond finger to generate the wire where we want it.

    [PADS]
    BF=RECT 90 254
    BP750=CIRCLE 750
    DP100=SQ 100
    DUM=CIRCLE 25


    [NETLIST]

   ;NET    DIE PAD & COORDS     BALL PAD & COORDS          FINGER PAD & COORDS
    NET3 - -     -     -        D3 BP750 -13335 12065      3 BF  -8262.55 7648.42 45.92
    NET3 3 DP100 -5270 4750     D3 BP750 -13335 12065      3 DUM -8226.5  7613.7  0


    NET4 - -     -     -        E4 BP750 -12065 10795      4 BF  -8324.01 7444.40 47.59
    NET4 4 DP100 -5270 4655     E4 BP750 -12065 10795      4 DUM -8286.80 7410.80 0

This feature has been added to the most recent AIF Exporter for Cadence 16.3 which can be obtained from Cadence by downloading the ISR.