Advanced device assembly structures and methods

Abstract

A microelectronic assembly includes a first substrate having a surface and a first conductive element and a second substrate having a surface and a second conductive element. The assembly further includes an electrically conductive alloy mass joined to the first and second conductive elements. First and second materials of the alloy mass each have a melting point lower than a melting point of the alloy. A concentration of the first material varies in concentration from a relatively higher amount at a location disposed toward the first conductive element to a relatively lower amount toward the second conductive element, and a concentration of the second material varies in concentration from a relatively higher amount at a location disposed toward the second conductive element to a relatively lower amount toward the first conductive element.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS[0001]The present application is a divisional of U.S. patent application Ser. No. 13 / 692,148, filed on Dec. 3, 2012, the disclosure of which is incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]Packaged microelectronic devices and related connection components, such as interposers or the like, use various structures to facilitate attachment with other packaged microelectronic devices or connection components to form various microelectronic assemblies. Such structures can include contact pads in the form of enlarged areas of a conductive metal exposed at surfaces of the devices or components. Alternatively, such structures can be in the form of exposed ends of metalized vias, conductive pins, posts, or the like. When aligned with similar connection features in another device or component, the connection features can be joined together using, for example, a conductive joining material, such as a solder mass or the like. Solder ma...

AI Technical Summary

Benefits of technology

The present patent is about a microelectronic assembly that includes two elements with conductive elements that are joined together with a conductive alloy mass. The alloy mass is made up of three materials that have different melting points. The concentration of each material in the alloy mass varies from higher to lower amounts, and the melting point of the alloy mass is greater than the melting point of the individual materials in an unalloyed state. The assembly can be made using a method that involves aligning the elements and joining them together. The technical effects of this invention include improved thermal stability, reduced melting point, and increased reliability of the joint.

Problems solved by technology

The use of such joining masses can have some deficiencies, however, in particular such joints, when melted in order to form joints between, for example, contact pads or the like, can undergo lateral deformation.

Further, such widening can increase during normal use of the microelectronic assembly due to heating of the joints.

This dishing can adversely affect bond strength and is generally not desirable.

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