Aluminum ribbon for ultrasonic bonding

Abstract

[Problem] To provide a bonding ribbon which can be evenly bonded to the whole bonding surface every time even when used for bonding tens of thousands of times, thereby attaining stabler bond strength and which undergoes no breakage when looped. [Solution] The ribbon for ultrasonic bonding comprises an aluminum-based alloy having a purity of 99 mass% or higher, and has an ultrathin tape structure formed by multistage wiredrawing and subsequent rolling. The ribbon has a cross-section that has an average crystal grain diameter of 5-200 [mu]m, and has been mirror-finished to a surface roughness of Rz<=2 [mu]m. The ribbon has been treated by immersion in or with an atmosphere of a water-soluble hydrocarbon, alcohol, ketone, or ether solvent which has a higher vapor pressure than water.

Description

technical field [0001] The present invention relates to an aluminum ribbon used for connecting a semiconductor element and a lead portion on a substrate side by ultrasonic welding in an electronic component or a semiconductor package. Background technique [0002] In the manufacture of semiconductor devices, in order to electrically connect the connection electrodes (pads) provided on the semiconductor chip and the external lead-out terminals (leads) provided in the semiconductor package, strip-shaped conductor wires with approximately rectangular cross-sections are widely used. body (hereinafter referred to as "ribbon") welding method. [0003] This method applies the ultrasonic lead wire welding method using the conductive lead wire of aluminum. By applying load and ultrasonic vibration on the aluminum strip, the oxide film of about 1 nanometer (nm) naturally formed on the surface of the aluminum strip is destroyed, and the aluminum (Al ) and other metal atoms are exposed...

AI Technical Summary

Problems solved by technology

Like the welded band disclosed in Patent Document 2, even if the tops of a plurality of protrusions that are in contact with the surface to be joined are formed, when one place is welded and the oxide film on a microscopic part is destroyed and plastic flow begins, the overall welding condition The balance is broken, and it cannot be engaged under the same conditions tens of thousands of times

[0014] In this way, in the conventional method of changing the shape of the welded strip, it is difficult to join the same microscopic part under the same conditions tens of thousands of times, and it is impossible to obtain a stable weld with high joint strength.

[0015] However, in ultrasonic welding using the above-mentioned welding tape, when joining is performed by drawing a line arc from the first point to the second point, there is a problem that the mirror-finished aluminum strip breaks when the line arc is formed.

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