Method and materials for warpage thermal and interconnect solutions
Embodiments describe a semiconductor package that includes a substrate, a die bonded to the substrate, and a solder paste overmold layer formed over a top surface of the die. In an embodiment, the solder paste comprises a high-melting point metal, a solder matrix, intermetallic compounds and a polymer. The overmold layer has a high elastic modulus, a coefficient of thermal expansion similar to the substrate, and reduces the warpage of the package. In an embodiment, interconnects of a semiconductor package are formed with a no-slump solder paste that includes vents. Vents may be formed through a conductive network formed by the high-melting point metal, solder matrix and intermetallic compounds. In an embodiment, vents provide a path through the interconnect that allows for moisture outgassing. In an embodiment, a mold layer may be mechanically anchored to the interconnects by the vents, thereby providing improved mechanical continuity to the mold layer.
1. A method of forming a semiconductor package comprising:
bonding a die to a substrate;
forming an overmold layer over a top surface of the die, wherein the overmold layer is a solder paste comprising a high-melting point metal, a solder matrix, and a polymer;
forming a plurality of interconnects having an aspect ratio greater than 2:1 on a peripheral region around the die with the solder paste; and
curing the solder paste.
2. The method of claim 1 , wherein curing the solder paste comprises a liquid phase sintering process.
3. The method of claim 1 , wherein the high-melting point metal includes copper particles and the solder matrix is a SnBi solder.
4. The method of claim 1 , wherein the polymer has a molecular weight less than approximately 2,000 Da.
5. The method of claim 1 , wherein the overmold layer is printed over the top surface of the die with a stencil printing process.
6. The method of claim 5 , wherein the overmold layer is printed over the top surface of the die before the die is singulated from a wafer comprising a plurality of dies.
7. The semiconductor package of claim 1 , wherein a mold layer is mechanically anchored to the one or more interconnects by vents, wherein the vents provide mechanical anchoring points for the mold layer.