A soldered assembly such as a packaged semiconductor chip includes elongated solder columns connected to the pads on the chip and a dielectric sheet having pads connected to the distal ends of the solder columns remote from the chip. Terminals on the sheet are connected to the pads of the sheet. The assembly can be handled and mounted using conventional surface-mount techniques, but provides thermal fatigue resistance. The solder columns may be inclined relative to the chip surface, and may contain long, columnar inclusions preferentially oriented along the lengthwise axes of the columns.
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims benefit of U.S. Provisional Patent Application No. 60/059,225, filed Sep. 18, 1997, the disclosure of which is hereby incorporated by reference herein.
A structure for improving electrical performance and interconnection reliability of an integrated circuit in a Wafer Level Packaging (WLP) application comprises an air pad located under an interconnection metal solder pad. Using a low dielectric material such as air underlying the interconnection pad, pad capacitance is reduced, thereby improving the speed of associated electrical signal transitions. By configuring the structure to have interconnection pad supports at only a limited number of pad periphery points, a cured soldered connection can absorb mechanical stresses associated with divergent movement between a connecting wire and the interconnection pad. Such a structure can be manufactured using the steps of: 1) depositing a soluble base material in a cavity on an IC substrate, 2) depositing a metal pad layer on the soluble base layer, and 3) dissolving the soluble base layer, leaving an air gap under the metal pad layer which is supported by the periphery supports.
A structure for improving electrical performance and interconnection reliability of an integrated circuit in a Wafer Level Packaging (WLP) application comprises an air pad located under an interconnection metal solder pad. Using a low dielectric material such as air underlying the interconnection pad, pad capacitance is reduce, thereby improving the speed of associated electrical signal transitions. By configuring the structure to have interconnection pad supports at only a limited number of pad periphery points, a cured soldered connection can absorb mechanical stresses associated with divergent movement between a connecting wire and the interconnection pad. Such a structure can be manufactured using the steps of: 1) depositing a soluble base material in a cavity on an IC substrate, 2) depositing a metal pad layer on the soluble base layer, and 3) dissolving the soluble base layer, leaving an air gap under the metal pad layer which is supported by the periphery supports.
6890795 - Wafer level super stretch solder - Owned by Agency for Science, Technology and Research (Singapore,SG) National University of Singapore (Singapore,SG) Georgia Tech Research Corporation (Atlanta, GA)
We disclose a technique to generate stretched solder columns (bumps) at the wafer level, suitable for wafer level packaging. This is accomplished through use of using two wafers--the standard (functional) wafer that contains the integrated circuits and a master (dummy) wafer on whose surface is provided an array of solder bumps that is the mirror image of that on the functional wafer. After suitable alignment, both sets of solder bumps are melted and then slowly brought together till they merge. Then, as they cool, they are slowly pulled apart thereby stretching the merged solder columns. Once the latter have fully solidified, they are separated from the master wafer only.
A plurality of electrical interconnections may be formed in an electrical device including a first component having a plurality of contact pads and a second component having a plurality of contact pads. The two components are placed in a confronting spaced relationship such that each contact pad of the first component locationally corresponds to one of the contact pads of the second component. The contact pads of the second component are further arranged such that at least two of the contact pads are laterally offset relative to their locationally corresponding contact pads on the first component with one of the at least two contact pads being offset in a first direction while the other is offset in another direction. A mass of conductive material is disposed between each contact pad of the first component and its corresponding contact pad of the second component. The masses of conductive material may be formed into columnar members wherein the columnar members are skewed when formed between a pair of relatively offset contact pads.
A plurality of electrical interconnections may be formed in an electrical device including a first component having a plurality of contact pads and a second component having a plurality of contact pads. The two components are placed in a confronting spaced relationship such that each contact pad of the first component locationally corresponds to one of the contact pads of the second component. The contact pads of the second component are further arranged such that at least two of the contact pads are laterally offset relative to their locationally corresponding contact pads on the first component with one of the at least two contact pads being offset in a first direction while the other is offset in another direction. A mass of conductive material is disposed between each contact pad of the first component and its corresponding contact pad of the second component. The masses of conductive material may be formed into columnar members wherein the columnar members are skewed when formed between a pair of relatively offset contact pads.
