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CONTROL OF Pd/Sn CATALYSTS

IP.com Disclosure Number: IPCOM000037178D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Amelio, WJ: AUTHOR [+7]

Abstract

A specific relationship for characterizing a palladium/tin (Pd/Sn) catalyst, which is used in an electroless copper plating bath, is the comparison between Cyclic Voltammetry of a dilute catalyst bath and the palladium concentration of the same bath. An equation derived from the results provides a vehicle to predict the plating performance of a bath. The procedure for the characterization is as follows.

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CONTROL OF Pd/Sn CATALYSTS

A specific relationship for characterizing a palladium/tin (Pd/Sn) catalyst, which is used in an electroless copper plating bath, is the comparison between Cyclic Voltammetry of a dilute catalyst bath and the palladium concentration of the same bath. An equation derived from the results provides a vehicle to predict the plating performance of a bath. The procedure for the characterization is as follows.

A dilute bath is made by preparing a solution of 160 g/l of sodium chloride (NaCl) in deionized (D.I.) water. Next, a Pd/Sn catalyst is diluted in the ratio of 2:13 by volume with the sodium chloride solution.

Cyclic Voltammetry is a measure of the catalyst's activity by determining the size of the hydrogen desorption peak. The hydrogen desorption peak is obtained by treating a one-ounce copper foil (working electrode) with the dilute catalyst and placing the foil in a polarization cell. The specimen area is precisely 7 cm2. The cell is filled with electrolyte, a calomel reference electrode and platinum counter electrode are then added to the cell. The three electrodes are attached to a voltammetric analyzer which processes the specimen and produces a cyclic voltammetric (C.V.) curve. The hydrogen desorption peak is a portion of the C.V. curve. The size of the hydrogen desorption peak is measured in milliamps (mA).

The palladium concentration of the dilute Pd/Sn catalyst may be determined by several methods including Atomic Absorption (A...