Abstract: Copper is deposited onto a substrate by plating a first layer of copper onto the substrate from an electroless plating bath and plating a second layer of copper onto the first layer of copper from a second and different electroless plating bath. The first and second plating baths differ from each other in at least the cyanide content. The process reduces plating void defects and reduces nodule formation.

Abstract: A method for preparing and maintaining an electroless plating bath. Seeded surfaces include a palladium and tin coating which receives plating from an electroless plating bath. The plating bath conditions are maintained by measuring the open circuit potential of the bath with a potentiostat. The chemical constituent concentration levels are adjusted to a first open circuit potential for the bath. Air is removed from the bath and the open circuit potential increases to a second level representing a bath chemical activity which produces optimum electroless plating on the seeded surfaces. Parts having seeded surfaces are inserted in the bath and a flow of air is re-established in the bath, rendering less negative the open circuit voltage potential during plating of the parts.

Abstract: Copper is plated onto a substrate from an electroless plating bath having a mix potential relative to a saturated calomel electrode of about minus 630 to about minus 675 millivolts at a temperature of about 73.degree. C. The mix potential of the bath is monitored and adjusted during the plating to maintain it at about minus 630 to about minus 675 millivolts with respect to a calomel electrode at a temperature of about 73.degree. C. The number of of plating void defects is thereby reduced.

Abstract: An electroless plating bath is selectively cleaned of organic contaminants. The organic contaminants are detected by measuring the capacitance between a working electrode and counter electrode with a potentiostat. The capacitance measurements are used to indicate the level of organic contaminants. Exposure of the dummy plating surface in the electroless plating bath is controlled such that the exposed surface is directly proportional to the detected level of organic contaminants.

Abstract: A method and apparatus for controlling surface chemistry on objects plated in an electroless plating bath. Cyclic voltammetry measurements are made for different pH conditions of the bath. Pourbaix diagrams are determined from these measurements which indicate the transition between metal species being plated by the bath. The open circuit potential of the bath is monitored by a potentiostat and compared with a setpoint open circuit potential which represents a desired metal species on the pourbaix diagram. The monitored open circuit potential and the setpoint are utilized to derive an error voltage. The error voltage will control the concentration of a chemical constitutent of the plating bath to maintain the desired method species on the plating surface.

Abstract: A substrate is prepared for subsequent electroless deposition of a metal by contacting the substrate with a surfactant and with an organic carboxylic acid, and subsequently contacting the substrate with sulfuric acid.

Abstract: Method and apparatus for determining the deposition capability of an electroless metal plating bath by monitoring the difference in instantaneous electrical potential between a pair of test coupons immersed in the bath in which one coupon is seeded to initiate plating thereon of the bath metal and the other coupon has a surface of the bath metal. The magnitude of the difference in potential and its change with respect to time during concurrent immersion of both coupons indicate the probable rate and quality of the bath deposition onto work pieces.