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: 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.

Abstract: A solid solution of zinc oxide and magnesium oxide and/or calcium oxide when added to a halogen-containing plastic composition serves as a smoke and/or fire retardant agent.This solid solution agent may be added to the plastic composition, preferably with an antimony compound.