Microelectronic assemblies having low profile connections

Abstract

A microelectronic assembly includes a first microelectronic element having a first face and contacts accessible at the first face, and a layer of a dielectric material having a bottom surface contacting the first microelectronic element, a top surface facing away from the first microelectronic element and holes extending between the top and bottom faces in alignment with the contacts on the first microelectronic element. The assembly includes conductive protrusions extending through the holes to the contacts, the conductive protrusions projecting beyond the top surface of the dielectric layer. The assembly also has a second microelectronic element having a first surface with conductive elements being accessible at the first surface thereof, the second microelectronic element being assembled with the first microelectronic element so that the contacts of the second microelectronic element are connected with the conductive protrusions and the top surface of the dielectric layer is spaced from the first surface of the second microelectronic element.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application is a continuation of U.S. patent application Ser. No. 10 / 699,328, filed Oct. 31, 2003, which claims the benefit of U.S. Provisional Application Ser. No. 60 / 426,478 filed Nov. 13, 2002, the disclosures of which are hereby incorporated by reference herein.FIELD OF THE INVENTION [0002] The present invention relates to methods of making microelectronic assemblies and to microelectronic assemblies. BACKGROUND OF THE INVENTION [0003] Microelectronic elements are typically packaged and assembled with a microelectronic component to facilitate connection to external circuitry. Heat is generated in use, as well as during manufacturing operations such as, for example, bonding. When heat is generated within the assembly, the various parts of the assembly expand and contract according to the coefficient of thermal expansion for the particular part. Incorporating various materials having different coefficients of thermal expan...

AI Technical Summary

Benefits of technology

This approach reduces stress on conductive elements by allowing the dielectric layer to flex more freely, enhancing the reliability and stability of microelectronic assemblies during thermal cycles.

Problems solved by technology

However, the larger the dielectric layer, the more stress the leads experience.

This is compounded by the presence of bonding material between the contacts and the leads, which interferes with the flexibility of the dielectric layer.

However, some connections incorporate a significant amount of bonding material, which adds to the height of the connection between the leads and contacts, and impacts the reliability of the assembly.

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