PROCESS FOR SELECTIVELY DEPOSITING A NICKEL-BORON COATING OVER A METALLURGY PATTERN ON A DIELECTRIC SUBSTRATE AND PRODUCTS PRODUCED THEREBY

摘要

Process for Selectively Depositing a NickelBoron Coating Over a Metallurgy Pattern on a Dielectric Substrate and Products Produced Thereby A process for simultaneously selectively depositing a high purity nickel containing alloy (i.e. a nickel-boron alloy having a nickel content in excess of 93.5 percent) over a preformed metallurgy pattern (including the individual, electrically isolated contact pads and the seal band area thereon) on the topside dielectric surface of a multi-layer ceramic module. The metallurgy pattern on such top-side surface of such module is appropriately catalyzed and then immersed in a bath which is essentially lead-free and which includes a source of nickel ions, a borane reducing agent, and an effective amount of an organic divalent sulfur compound, preferably thiodiglycollic acid. The contact pads and the seal band area so plated exhibit an exceptionally uniform layer of nickel-boron alloy, free of surface irregularities, which layer is characterized by low contact resistance, excellent wire bonding and eutectic diode bonding characteristics and is both crack-free at the time of its being deposited and remains crack-free under brazing conditions throughout the life of the component.