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Flip chip solder joint structure by copper electrodes on a chip and a carrier Disclosure Number: IPCOM000014139D
Original Publication Date: 2000-Aug-01
Included in the Prior Art Database: 2003-Jun-19

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Disclosed is a flip chip solder joint structure by copper electrodes on a chip and a circuit board. Tin-lead solder bump and gold bump have been used as a chip bump for flip chip attachment. Tin-lead solder and indium system solder are used for tin-lead solder chip bump and gold chip bump respectively for the connection with a copper pad of a circuit board. However there may be the possibility of the exhaustion of copper formed as a part of UBM initially by diffusion reaction with tin in the solder about tin-lead joint structure. And gold-indium joint structure needs advised control of joint quality because of the rapid diffusion reaction of gold with indium in case where this joint is used for high temperature application. This invention provides the chip bump consisted by copper itself that has been used as a part of UBM of the chip bump, and flip chip joint is formed by connecting the copper bump of the chip with the copper pad of the circuit board with solder. Supplied sufficient volume of copper of the chip bump, there is no concern of copper exhaustion. And the solid-solid reaction speed of copper with indium is much slower than that of gold with indium. These advantages can improve joint reliability. Figure is a schematic view of a section of copper bump solder copper pad joint structure. Copper Copper