Advanced Metal Powder Manufacture for MLCC Applications

Sensors, capacitors, and conducting features such as resistors and capacitors on circuit boards are produced from metal and ceramic powders 1-12 These powders are manufactured by liquid phase precipitation routes which often start with reduction of metal salts or by solid-state routes where solid reactants are mixed, heated and then milled. The solid-state processing is generally repeated several times to obtain hamogeneous materials which are then milled down to the final particle sizes. Milling is also required for most liquid phase routes to ceramics. As a result of the milling, the particles usually have wide size distributions, high impurity levels, and large particle size. 1-3 The demand for improved metal and ceramic powder properties in order to produce smaller feature sizes in circuit boards with improved properties is increasing. Metal (Ag, Pd. Ag/Pd, Ni, Cu. Pt. Au) and ceramic (metal ruthenates) powders with well-controlled properties are needed for thick film pastes.1-3 The desired powder properties include controlled size in the micron and submicron range,controlled elemental and phase composition and high purity. These powder characteristics result in lower laydswns, better yields in manufacture of multilayer ceramic capacitors (MLCCs) and the use of less precious metal. The problem with the current technology for producing these materials is that it cannot deliver the quality needed and as a result, there is a drive towards new processes capable of producing powders with these characteristics. This proposed research will address this problem through development of an economical and environmentally benign technique for producing composite metal powders with superior properties that may revolutiQnize the fabrication of multilayer capacitors using thick film pastes. The success of this technology is of critical strategic importance for the united states. The best Ag/Pd and Pd Powder produced in the world are made in Japan by Shoei. Shoei does not sell to most U.S. MLCC manufacturers putting them at a great disadvantage. rhe lack of the highest quality powders now and in the future will increase our reliance Dn Japanese technology at a minimum and put the U.S. further behind in this c