Ribbon bonding

Abstract

A flexible conductive ribbon is ultrasonically bonded to the surface of a die and terminals from a lead frame of a package. Multiple ribbons and/or multiple bonded areas provide various benefits, such as high current capability, reduced spreading resistance, reliable bonds due to large contact areas, lower cost and higher throughput due to less areas to bond and test.

What is claimed is:  
     
         1 . An electronic package, comprising: 
 an electronic device having a conductive upper surface;    a conductive terminal external to the electronic device; and    a conductive ribbon ultrasonically bonded to a first portion of the conductive upper surface and bonded to the conductive terminal.    
     
     
         2 . The electronic package of  claim 1 , wherein the electronic device is a semiconductor device.  
     
     
         3 . The electronic package of  claim 2 , wherein the semiconductor device is a power MOSFET die, a diode, or an insulated gate bipolar transistor.  
     
     
         4 . The electronic package of  claim 1 , wherein the conductive ribbon is bonded at multiple contact areas of the conductive upper surface.  
     
     
         5 . The electronic package of  claim 1 , further comprising: 
 a second conductive terminal external to the electronic device; and    a second conductive ribbon parallel to the first conductive ribbon and ultrasonically bonded to the conductive upper surface and the second conductive terminal.    
     
     
         6 . The electronic package of  claim 1 , wherein the conductive ribbon has a rectangular cross section.  
     
     
         7 . The electronic package of  claim 1 , wherein the conductive ribbon and the conductive upper surface are aluminum.  
     
     
         8 . The electronic package of  claim 1 , wherein the conductive ribbon comprises a first layer contacting the conductive upper surface and a second layer overlying the first layer.  
     
     
         9 . The electronic package of  claim 8 , wherein the first layer is aluminum and the second layer is copper.  
     
     
         10 . The electronic package of  claim 9 , wherein the first layer is thinner than the second layer.  
     
     
         11 . The electronic package of  claim 8 , wherein the conductive layer further comprises a third layer overlying the second layer.  
     
     
         12 . The electronic package of  claim 8 , wherein the first layer and the conductive upper surface comprise the same material.  
     
     
         13 . The electronic package of  claim 1 , wherein the ribbon is bonded and cut along a line parallel to a side of the conductive upper surface and the conductive terminal.  
     
     
         14 . The electronic package of  claim 1 , wherein the width of the ribbon is between approximately 20 mil and 100 mil.  
     
     
         15 . The electronic package of  claim 1 , wherein the thickness of the ribbon is between approximately 2 mil and 10 mil.  
     
     
         16 . The electronic package of  claim 1 , wherein the aspect ratio of the ribbon is approximately 10.  
     
     
         17 . The electronic package of  claim 1 , wherein the conductive terminal is part of a semiconductor die.  
     
     
         18 . The electronic package of  claim 1 , wherein the conductive terminal is part of a lead frame.  
     
     
         19 . The electronic package of  claim 4 , wherein the multiple contact areas are between gate fingers.  
     
     
         20 . The electronic package of  claim 1 , further comprising a second conductive ribbon overlying the conductive ribbon.  
     
     
         21 . The electronic package of  claim 20 , wherein the second ribbon is ultrasonically bonded to the first portion of the conductive surface.  
     
     
         22 . A semiconductor die package, comprising: 
 a semiconductor die having an upper conductive surface;    a conductive lead external to the die; and    a flexible ribbon electrically connecting the upper conductive surface to the lead, wherein the ribbon is bonded to the upper conductive surface at multiple areas and wherein the ribbon forms at least one loop over the die.    
     
     
         23 . The die package of  claim 22 , wherein the die is a power MOSFET.  
     
     
         24 . The die package of  claim 22 , wherein the bonds are formed by ultrasonic bonding.  
     
     
         25 . The die package of  claim 22 , wherein the ribbon has a rectangular cross section.  
     
     
         26 . The die package of  claim 22 , further comprising: 
 a second conductive lead external to the die; and    a second flexible ribbon parallel to the first flexible electrically connecting the upper conductive surface to the second lead, wherein the second ribbon is bonded to the upper conductive surface at multiple areas and wherein the second ribbon forms at least one loop over the die.    
     
     
         27 . The die package of  claim 26 , wherein the first and second conductive leads are the same.  
     
     
         28 . The die package of  claim 22 , wherein the ribbon comprises a bonding layer and a conductive layer overlying the bonding layer.  
     
     
         29 . The die package of  claim 22 , further comprising a second conductive ribbon overlying the flexible ribbon.  
     
     
         30 . The die package of  claim 29 , wherein the second conductive ribbon is bonded to at least one of the multiple areas.  
     
     
         31 . The die package of  claim 22 , wherein the bonds are formed by thermosonic bonding or thermocompression.  
     
     
         32 . A method of electrically connecting an electronic device to an external lead, comprising: 
 ultrasonically bonding a first portion of a ribbon to a first portion on a conductive upper surface of the device; and    bonding a second portion of the ribbon to the external lead.    
     
     
         33 . The method of  claim 32 , wherein the electronic device is a semiconductor die.  
     
     
         34 . The method of  claim 32 , further comprising ultrasonically bonding a third portion of the ribbon to a second portion on the conductive upper surface of the device.  
     
     
         35 . The method of  claim 32 , further comprising: 
 ultrasonically bonding a first portion of a second ribbon to a second portion on the conductive upper surface of the device; and    bonding a second portion of the second ribbon to the external lead.    
     
     
         36 . The method of  claim 32 , wherein the ultrasonically bonding is performed with a bond tool having a diamond-shaped pattern.  
     
     
         37 . The method of  claim 32 , further comprising cutting the ribbon after the bonding.  
     
     
         38 . The method of  claim 37 , wherein the ultrasonic bonding and cutting are along parallel lines and may be performed at different angles.  
     
     
         39 . The method of  claim 32 , wherein the ribbon comprises a bonding layer and a conductive layer overlying the bonding layer.  
     
     
         40 . The method of  claim 39 , wherein the ribbon further comprises a coupling layer overlying the conductive layer.  
     
     
         41 . The method of  claim 32 , wherein the conductive upper surface is aluminum.  
     
     
         42 . The method of  claim 39 , wherein the bonding layer comprises aluminum and the conductive layer comprises copper.  
     
     
         43 . The method of  claim 35 , wherein the first and second ribbon are parallel to each other.  
     
     
         44 . The method of  claim 34 , wherein the first and second portions on the conductive surface are between gate fingers.  
     
     
         45 . The method of  claim 32 , further comprising ultrasonically bonding a first portion of a second ribbon to the first portion on the conductive surface, wherein the second ribbon overlies the ribbon.  
     
     
         46 . A method of electrically connecting an electronic device to an external lead, comprising: 
 bonding a first portion of a flexible conductive ribbon to a first portion on a conductive upper surface of the device; and    bonding a second portion of the ribbon to the external lead.    
     
     
         47 . The method of  claim 46 , wherein the bonding of the ribbon is by thermosonic bonding or thermocompression.  
     
     
         48 . The method of  claim 46 , further comprising bonding a third portion of the ribbon to a second portion on the conductive upper surface of the device.