Conductively coated embossed articles

#This invention relates to articles with conductive coatings for electronic applications and to processes for producing the articles. In particular this invention relates to metallized plastic or ceramic articles having raised bas-relief or embossed coated surfaces in connective configurations. The invention thus relates to the fabrication of ceramic or plastic articles such that areas to be metallized are formed in raised bas-relief on one, two or more surfaces of a substrate and are integral with the substrate. Conductive material is applied by convenient transfer processes to the raised bas-relief surfaces of the substrate and sintered or hardened to form a pattern of electrical conductors on the substrate. Package covers with mating patterns of recessed bas-relief to fit the contours of the substrate are also provided. The articles of the invention are particularly suitable for high-volume, automated electronic circuit assembly, e.g., by process known as tape-carrier packaging.

#Metallization of ceramic pieces for electronic uses such as packages, chip carriers, substrates and the like has been accomplished quite conventionally by silk-screening processes in which a metallic pigment in selected vehicle is first laid down on the surface of a green or fired ceramic. The vehicle is then volatilized and the metallic pigment, such as molybdenum-manganese, platinum, palladium, is sintered to give adherent conductive patterns. This procedure is illustrated in Stetson, U.S. Pat. No. 3,189,978 for multilayer devices in which interconnections between layers are by via holes or metallized edge notches. A device for a chip carrier is described by Landron U.S. Pat. No. 3,436,605 in which a chip is mounted among three legs and suitably connected to metallized coatings thereon. Each leg has a rounded end which is metallized together with other portions of the leg and which end is bonded to a suitable mother board. Pedestals with sprayed metal coatings connected by leads to a semiconductor device on the upper side of the modular package are described by Wakely, U.S. Pat. No. 3,483,308.

#Metallizing processes of the prior art present many problems. Screens become clogged and must be cleaned regularly or incomplete patterns result. There is also a problem of registration of the pattern of the screen or mask with the ceramic part-resulting in misplaced patterns which occur on a random basis according to the placement of each ceramic part with relation to the pattern of screen. Warpage of the ceramic parts results in distorted and incomplete patterns. Stretching and distortion of the screen also results in distorted patterns.

#Having now described the invention in broad general terms it is more particularly illustrated by the drawings wherein

#FIG. 1 shows diagrammatically in exploded view the pressing of a green ceramic chip carrier of the invention.

#FIG. 2 shows diagrammatically the steps of one procedure for metallizing a fired or green ceramic chip carrier of the invention.

#Referring particularly to FIG. 1 it will be seen that upper punch (100) lower punch (101) and die block (102), broken away from their bases at (103) and (105) respectively, form green ceramic chip carrier (20). The structure of green ceramic chip carrier (20), which is illustrative of articles of the invention prepared by the process of the invention, is described in more detail hereinbelow. It will be recognized that these parts are shown much enlarged.

#The green ceramic article, such as chip carrier (20), may be fully or partially fired or, if sufficiently compacted, can be used in the green form for the steps shown diagrammatically in FIG. 2 and in other Figures. The step of firing is not shown.

#In FIG. 2 the green, or partially or fully fired, ceramic chip carrier (30) is coated with metallizing on upper and lower surfaces by metallizing ink by suitable means here shown diagrammatically as transfer rolls (34) and (36). Means for applying ink to transfer rolls (34) and (36) are not shown but may be in the form of hoppers, sprays, pads, troughs, doctor blades, etc. as is convenient. Likewise other means of applying conductive coatings may be employed as, for example, use of a metallizing transfer tape.