Browse Prior Art Database

Thieving Block

IP.com Disclosure Number: IPCOM000101743D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Bartlett, RA: AUTHOR [+6]

Abstract

Referring to the figure, thieving blocks fabricated from polypropylene 5 are placed onto the retaining rack 6 which is used to hold circuit boards 2 during copper plating. When negatively charged, the thieving blocks draw copper molecules 3 out of solution 1 and prevents them from adhering to the circuit board in the area of the locating notch 7, which is cut into the bottom of the circuit board.

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Thieving Block

       Referring to the figure, thieving blocks fabricated from
polypropylene 5 are placed onto the retaining rack 6 which is used to
hold circuit boards 2 during copper plating. When negatively charged,
the thieving blocks draw copper molecules 3 out of solution 1 and
prevents them from adhering to the circuit board in the area of the
locating notch 7, which is cut into the bottom of the circuit board.

      If these thieving blocks are not used, then copper molecules
adhere to the circuit board around the locating notch area.  This
causes the physical dimensions of the locating notch to change, due
to the copper which plates up along the edges of the notch.

      A separate thieving block is placed on either side of the
circuit board to protect the locating notch from both sides.  The
unique geometry of the thieving blocks causes electrical flux
densities 4 to increase around the corners of the blocks.  This
increased flux density accelerates the copper molecules in solution
towards the blocks where the copper molecules become affixed to the
blocks, rather than to the circuit board.  The upper portion of the
circuit board above the thieving blocks remains unaffected by the
flux densities and plates up with copper as required.