Aluminum ribbon for ultrasonic bonding

Abstract

[Problem to be Solved]The invention providesa bonding ribbon which can guarantee a uniform fusing over the entire joint area throughout hundreds of thousands of continuous ultrasonic bonding cycles and which can realize an improved bonding strength and which also can avoid being broken while it is looped. [Solution]The aluminum ribbon for ultrasonic bonding is formed of an aluminum alloy with aluminum content of 99 mass % or higher, and this ribbon is characterized in that it is in a shape of an extremely thin tape which is obtained by rolling a wire taken from a multi-stage wire drawing, that an average grain size within the cross section of this ribbon is 5-200 micrometers (μm), that the surface(s) of this extremely thin tape is mirror-finished to an extent that the surface roughness R z is 2 micrometers (μm) or smaller, and that the ribbon has been subjected to an immersion treatment or a gas-exposure treatment wherein the liquid or gas comprises a substance having a vapor pressure higher than water such as a water-soluble hydrocarbons solvent, an alcoholic solvent, a ketone solvent, or an ether type solvent.

What is claimed is: 
     
         1 . An aluminum ribbon for ultrasonic bonding made of an aluminum alloy with aluminum content of 99 mass % or higher, the alloy being made from additive elements and the balance aluminum, characterized in that said ribbon is in a shape of an extremely thin tape which is obtained by rolling a wire taken from a multi-stage wire drawing, that an average grain size within a cross section of this ribbon is 5-200 micrometers (μm), that the surface of this extremely thin tape is mirror-finished to an extent that the surface roughness R z  is 2 micrometers (m) or smaller, and that the ribbon has been subjected to a liquid immersion treatment or a gas exposure treatment wherein the liquid or gas is a substance having a vapor pressure higher than water and is selected from water-soluble hydrocarbons solvents, alcoholic solvents, ketone solvents, and ether type solvents. 
     
     
         2 . An aluminum ribbon for ultrasonic bonding as claimed in  claim 1 , wherein said alcoholic solvents are ethanol, methanol, butanol, n-propyl alcohol, phenol, ethylene glycol, tridecanol and grycelin. 
     
     
         3 . An aluminum ribbon for ultrasonic bonding as claimed in  claim 1 , wherein said alcoholic solvents are ethanol, methanol, and n-propyl alcohol. 
     
     
         4 . An aluminum ribbon for ultrasonic bonding as claimed in  claim 1 , wherein said ketone solvents are acetone and methyl ethyl ketone. 
     
     
         5 . An aluminum ribbon for ultrasonic bonding as claimed in  claim 1 , wherein said ether type solvents are methyl n-propyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, dipropylene glycol mono ethyl ether, dipropylene glycol dimethyl ether, and dipropylene glycol mono butyl ether. 
     
     
         6 . An aluminum ribbon for ultrasonic bonding as claimed in  claim 1 , wherein said hydrocarbons solvents are ethylamine and ethyl acetate.