摘要:
A method for direct chip attach of a semiconductor chip to a circuit board by using solder bumps and an underfill layer is disclosed. In the method, a layer of in-situ polymeric mold material is first screen printed on the top surface of the semiconductor chip exposing a multiplicity of bond pads. The in-situ polymeric mold layer is formed with a multiplicity of apertures which are then filled with solder material in a molten solder screening process to form solder bumps. A thin flux-containing underfill material layer is then placed on top of a circuit board over a plurality of conductive pads which are arranged in a mirror image to the bond pads on the semiconductor chip. The semiconductor chip and the circuit board are then pressed together with the underfill layer inbetween and heated to a reflow temperature of higher than the melting temperature of the solder material until electrical communication is established between the bond pads and the conductive pads. In the bonded assembly, the in-situ polymeric mold layer and the underfill material layer forms a composite underfill to replace a conventional underfill material that must be injected between bonded chip and substrate by a capillary action in a time consuming process.
摘要:
A method for direct chip attach of a semiconductor chip to a circuit board by using solder bumps and an underfill layer is disclosed. In the method, a layer of in-situ polymeric mold material is first screen printed on the top surface of the semiconductor chip exposing a multiplicity of bond pads. The in-situ polymeric mold layer is formed with a multiplicity of apertures which are then filled with solder material in a molten solder screening process to form solder bumps. A thin flux-containing underfill material layer is then placed on top of a circuit board over a plurality of conductive pads which are arranged in a mirror image to the bond pads on the semiconductor chip. The semiconductor chip and the circuit board are then pressed together with the underfill layer inbetween and heated to a reflow temperature of higher than the melting temperature of the solder material until electrical communication is established between the bond pads and the conductive pads. In the bonded assembly, the in-situ polymeric mold layer and the underfill material layer forms a composite underfill to replace a conventional underfill material that must be injected between bonded chip and substrate by a capillary action in a time consuming process.
摘要:
A method for joining a multiplicity of multi-alloy solder columns to an electronic substrate and the structure formed by such method are disclosed. In the method, a mold plate equipped with a multiplicity of cavities is first filled by an injection molded solder technique with a high temperature solder forming a multiplicity of solder columns. The mold plate is then sandwiched between an extraction plate and a transfer plate by utilizing a multiplicity of displacement means equipped in the extraction plate to displace the multiplicity of solder columns from the mold plate into a multiplicity of apertures equipped in the transfer plate. The multiplicity of cavities in the transfer plate each has a straight opening and a flared opening. The flared opening is then filled with a low temperature solder paste to encapsulate one end of the high temperature solder column. The low temperature solder paste is then reflown on top of a conductive pad on an electronic substrate at a temperature lower than the melting temperature of the high temperature solder to form a bond between the solder column and the conductive pad.