Browse Prior Art Database

Independent GAFAC and EDTA Control System

IP.com Disclosure Number: IPCOM000043725D
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Appelt, BK: AUTHOR [+2]

Abstract

GAFAC* and Ethylenediaminetetraacetic (EDTA) acid are necessary constituents of electroless copper plating baths used in the manufacture of multilayer PC (printed circuit) boards. Process control of GAFAC and EDTA is now done manually, that is, without automatic control, because known analysis techniques do not lend themselves to automatic control. GAFAC and EDTA are controlled exclusively by operator-dependent analyses and control systems. A system was designed to automatically control (without operator intervention) the concentrations of GAFAC and EDTA based on the fact that they are both unconsumable ingredients of particular types of continuous electroless copper plating baths.

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Independent GAFAC and EDTA Control System

GAFAC* and Ethylenediaminetetraacetic (EDTA) acid are necessary constituents of electroless copper plating baths used in the manufacture of multilayer PC (printed circuit) boards. Process control of GAFAC and EDTA is now done manually, that is, without automatic control, because known analysis techniques do not lend themselves to automatic control. GAFAC and EDTA are controlled exclusively by operator-dependent analyses and control systems. A system was designed to automatically control (without operator intervention) the concentrations of GAFAC and EDTA based on the fact that they are both unconsumable ingredients of particular types of continuous electroless copper plating baths. Since the total volume of each bath is fixed by an automatic overflow system, it is possible to control the concentration of GAFAC and EDTA from additions of various bath consumables plus water and then adding the required amount of overflowed unconsumable ingredients. The control scheme involves installing a flowmeter on each bath overflow and microprocessor- controlled feed valves on the delivery systems of standard GAFAC and EDTA feed solutions that will be metered in by the amount of overflow that occurs. * Trademark of GAF Corporation.

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