Abstract: A method for the reduction of oxides in a powder metal requires a predetermined quantity of powder to be loaded into a retort tube or other type of furnace which is pumped down to a vacuum less than about 5.times.10.sup.-6 Torr. The retort is ramped up to a temperature of about 500.degree.-750.degree. C. and maintained at that temperature under high vacuum for about 30-60 minutes to obtain reduction of oxides and de-gasing of copper powders of screen mesh sizes of -100. A hydrogen partial pressure of 150 microns to 20 mm of Hg may be valved into the system from standard grade hydrogen gas 15 minutes into approximately the 30-60 minute hold temperature ramp and then valved off on cooling to 400.degree. C. to improve oxide removal. The system is returned to the high vacuum mode and furnace cooled to room temperature.

Abstract: Electrical conductors on printed circuit board substrates are made from metal particles having a particular particle size range distribution used to control the flow of molten metal when entering the liquid phase such as during fusing. The distribution can follow a bimodal curve wherein the mixture contains approximately 45% by weight of large copper particles between 44-74 microns, 45% by weight of small copper particles less than 5 microns in size with the remaining 10% by weight being particles with sizes between the smaller and larger sizes.