Browse Prior Art Database

Special Misregistration Coupon to Measure/Examine Inner Layer Shift

IP.com Disclosure Number: IPCOM000101344D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 3 page(s) / 73K

Publishing Venue

IBM

Related People

Bednar, P: AUTHOR [+3]

Abstract

Disclosed is a special coupon and method that examines inner layer misregistration in a multilayer printed wiring board. See Fig. 1. Coupon examination method guarantees that the image area will contain a 0.002" minimum annular ring (required by MIL-P-55110D) on all inner layers of the finished printed wiring board (PWB).

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Special Misregistration Coupon to Measure/Examine Inner Layer Shift

       Disclosed is a special coupon and method that examines
inner layer misregistration in a multilayer printed wiring board. See
Fig. 1.  Coupon examination method guarantees that the image area
will contain a 0.002" minimum annular ring (required by MIL-P-55110D)
on all inner layers of the finished printed wiring board (PWB).

      The artwork design of lands within the coupon shall be such
that the land diameter shall represent the smallest land of the image
area minus 0.004".
           LD = DL - 0.004"
           LD = Land diameter (in inches) of coupon
           DL = Diameter (in inches) of the smallest land
                utilized in the image area.

      One land is required in the coupon per each copper (Cu) inner
layer plane, as shown in Fig. 2.  Multiple coupons are placed in
specific areas about the image area.

      The lands (image and coupons) are drilled during production.
If the drill bit drills outside the land, this creates breakout.
When the drill hole is tangent to the circumference of the coupon
land, this equates minimum acceptance.  The minimum acceptance
equates into the 0.002" minimum remaining annular ring in the image
areas of the board.  Fig. 3 shows different possible conditions.

      After drilling the complete panel (coupons and image areas of
the board), the coupons in the four locations can now b...