Method of balanced coefficient of thermal expansion for flip chip ball grid array
AssigneeLSI Logic Corporation
InventorsKumar Nagarajan, Zafer Kutlu, Shirish Shah
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Abstract
A flip chip ball grid array package includes a thin die having a die thickness reduced from a wafer thickness to reduce mismatch of a coefficient of thermal expansion between the thin die and a substrate; a plurality of thin film layers formed on the thin die wherein each of the plurality of thin film layers has a coefficient of thermal expansion that is greater than that of the thin die and is less than that of the substrate; and a plurality of wafer bumps formed on the thin die for making electrical contact between the thin die and the substrate.
Claims9
A method for making a flip chip ball grid array package comprising the following steps:
- reducing the thickness of a die from a wafer thickness to a selected thickness to make a thin die for reducing mismatch of a coefficient of thermal expansion of the thin die to that of a substrate;
- forming a plurality of thin film layers on the thin die wherein each of the thin film layers has a coefficient of thermal expansion that is greater than that of the thin die and is less than that of the substrate;
- and
- forming a plurality of wafer bumps on the thin die to make electrical contact between the thin die and the substrate.
A method for making a flip chip ball grid array package comprising the following steps:
- reducing the thickness of a die from a wafer thickness to a selected thickness to make a thin die for reducing mismatch of a coefficient of thermal expansion of the thin die to that of a substrate;
- forming a plurality of thin film layers on the thin die wherein each of the thin film layers has a coefficient of thermal expansion that is greater than that of the thin die and is less than that of the substrate;
- and
- forming a plurality of wafer bumps on the thin die to make electrical contact between the thin die and the substrate wherein the plurality of thin film layers comprises a first, a second, and a third thin film layer having successively graduated coefficients of thermal expansion from about 7-10 parts per million per degree Kelvin for the first thin film layer, 10-14 parts per million per degree Kelvin for the second thin film layer, and 15-19 parts per million per degree Kelvin for the third thin film layer, respectively.
A method for making a flip chip ball grid array package comprising the following steps:
- reducing the thickness of a die from a wafer thickness to a selected thickness to make a thin die for reducing mismatch of a coefficient of thermal expansion of the thin die to that of a substrate;
- forming a plurality of thin film layers on the thin die wherein each of the thin film layers has a coefficient of thermal expansion that is greater than that of the thin die and is less than that of the substrate;
- and
- bonding the thin die to the substrate to make electrical contact between the plurality of wafer bumps on the thin die and a plurality of contact pads on the substrate.
A method for making a flip chip ball grid array package comprising the following steps:
- reducing the thickness of a die from a wafer thickness to a selected thickness to make a thin die for reducing mismatch of a coefficient of thermal expansion of the thin die to that of a substrate;
- forming a plurality of thin film layers on the thin die wherein each of the thin film layers has a coefficient of thermal expansion that is greater than that of the thin die and is less than that of the substrate;
- and
- bonding the thin die to the substrate to make electrical contact between the plurality of wafer bumps on the thin die and a plurality of contact pads on the substrate wherein the plurality of thin film layers comprises a first, a second, and a third thin film layer having successively graduated coefficients of thermal expansion from about 7-10 parts per million per degree Kelvin for the first thin film layer, 10-14 parts per million per degree Kelvin for the second thin film layer, and 15-19 parts per million per degree Kelvin for the third thin film layer, respectively.
Dependencies are inferred from the claim text.