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Technique to Isolate Charge Electrodes

IP.com Disclosure Number: IPCOM000051832D
Original Publication Date: 1981-Mar-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Patel, HN: AUTHOR [+2]

Abstract

We have developed a technique to isolate charge electrodes which consists of masking laminated charge plates with sputter or vacuum-deposited copper, and then slotting, sputtering, plating and testing, followed by copper etching using appropriate copper etchant. The etchant dissolves copper and at the same time removes undesirable rhodium from tines and surfaces of the substrate. That results in complete isolation of electrodes.

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Technique to Isolate Charge Electrodes

We have developed a technique to isolate charge electrodes which consists of masking laminated charge plates with sputter or vacuum-deposited copper, and then slotting, sputtering, plating and testing, followed by copper etching using appropriate copper etchant. The etchant dissolves copper and at the same time removes undesirable rhodium from tines and surfaces of the substrate. That results in complete isolation of electrodes.

The isolation technique can be accomplished by the following steps: (1) Clean the laminated charge plate thoroughly for thin film deposition. (2) Load the parts in fixture and sputter or vacuum deposit 2 to 4 microns of copper on both faces as well as the top surface of the charge plate. (3) Remove the parts and load them in a slotting fixture, and perform a slotting operation in a normal manner. Thus, one will have copper over the entire front, back and top face of the charge plate except in the slots. (4) Remove the parts, and preclean for sputter deposition. (5) Sputter deposit the desired amount of rhodium. Remove the parts. (6) Plate the rhodium in slots and the copper on the pads. (7) Test the parts for continuity. (8) Remove the copper by using a copper etchant, such as a mixture of ferric chlorides and hydrochloric acid at 100 degrees F.

This will dissolve the sublayer of copper from both sides as well as the top of the tines. At the same time, it will remove the undesirable top surface metal...