Indium Corporation

Amanda Hartnett

Jordan P Ross

Robert N Jarrett

Paul Socha

Methods and apparatus are provided for attaching a heat spreader to a die and includes disposing a solder thermal interface material between a first surface of a die and a first surface of a heat spreader without disposing a liquid flux between the die and the heat spreader to form an assembly, wherein at least one of the first surface of the die and a first surface of the heat spreader have disposed thereon a metallization structure comprising a transition layer and a sacrificial metallization layer, the sacrificial metallization layer disposed as an outer layer to the metallization structure adjacent the solder thermal interface material; and heating the assembly to melt the thermal interface and attach the die to the heat spreader.

Low void solder joint for multiple reflow applications

A method is provided for the forming of a metallic solder joint without a liquid flux to create a solder joint that has minimal voids and can be reflowed multiple times without void propagation. This process can be done for any solder alloy, and is most specifically used in the application of first level thermal interface in a IC or micro processor or BGA microprocessor.

A solder preform has gaps extending from the boundary of preform towards the preform center. During reflow soldering, the gaps close from the center towards the boundary. This allows flux and gasses to escape the interface between the solder and the substrate. Particularly, flux accumulates in the spaces formed by the gaps and is forced to the edge of the solder preform as the gap closes. In further embodiments, channels are formed on one or both surfaces of the solder preform. In addition to further assisting in the escape of gas and flux during reflow, the channels and gaps increase the effectiveness of oxygen purging using inert or reducing gasses in the reflow chamber. Additionally, the channels and gaps increase the effectiveness of vacuum solder.

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Utica, NY, United States of America

Amanda Hartnett