Method and apparatus for attaching a workpiece to a workpiece support

Abstract

A method for attaching a workpiece, for example a semiconductor die, to a workpiece holder, for example a lead frame die support, comprises the steps of interposing an uncured adhesive between the semiconductor die and the die support and preheating the adhesive from an ambient temperature to a preheat temperature of between about 150° C. and about 160° C. over a period of about 1.5 seconds. Next, the preheat temperature is maintained for about 1.5 seconds, then the adhesive is further heated to a temperature of between about 190° C. and about 200° C. over a period of about 1.0 second. The inventive method quickly cures the adhesive to secure the die to the support with acceptably low levels of voiding. An apparatus which may be adapted to perform the inventive method is further described.

1 . An apparatus for heating a workpiece comprising: 
 a plate having a nonplanar face comprising at least first and second surfaces;    a heater adapted to heat the plate to a generally uniform temperature; and    a transporter adapted to advance the workpiece over the face along a generally planar path which does not contact at least the first surface, wherein a first distance between the path and the first surface is greater than a second distance between the path and the second surface.    
     
     
         2 . The apparatus of  claim 1  further comprising a wire bonder adapted to electrically connect a semiconductor die and a semiconductor die support.  
     
     
         3 . The apparatus of  claim 1  wherein the first surface intersects the second surface at an oblique angle.  
     
     
         4 . The apparatus of  claim 1  further comprising the plate having a channel therein which is adapted to receive a heated material.  
     
     
         5 . The apparatus of  claim 1  wherein, during use, the first and second surfaces of the nonplanar plate are at about the same non-ambient temperature.  
     
     
         6 . An apparatus for heating a workpiece, comprising: 
 a heated plate having at least first and second planar surfaces, wherein the first planar surface intersects the second planar surface at an oblique angle; and    a transporter adapted to move a workpiece over the first and second planar surfaces in a generally planar path, wherein the planar path of the transporter is at an oblique angle with respect to the first planar surface of the heated plate and at a generally parallel path respect to the second planar surface.    
     
     
         7 . An apparatus for heating a workpiece, comprising: 
 a heated plate comprising: 
 a first planar surface,  
 a second planar surface, wherein the first planar surface intersects the second planar surface at an oblique angle;  
 a third planar surface, wherein the plane of the third surface is generally parallel with the plane of the second surface;  
   a transporter for transporting a workpiece, the transporter having a generally planar path which is generally parallel with the planes of the second and third surfaces, and wherein the generally planar path is at an oblique angle with respect to the plane of the first surface.    
     
     
         8 . The apparatus of  claim 7  further comprising a fourth planar surface, wherein the fourth planar surface intersects the second and third planar surfaces at a generally perpendicular angle.  
     
     
         9 . The apparatus of  claim 7  wherein the path of the transporter is sufficiently near the third planar surface such that a transported workpiece contacts the third planar surface.  
     
     
         10 . The apparatus of  claim 9  wherein at least the third planar surface is part of a wire bonder.