Inspection of underfill in integrated circuit package

Abstract

In inspecting for quality of underfill material dispensed in an IC package, a camera image is captured for the IC package having the underfill material dispensed between an IC die and a package substrate. A data processor analyzes the camera image to determine an occurrence of an unacceptable condition of the underfill material. Pre-heating and/or post-heating of the package substrate before and/or after dispensing the underfill material by a contact-less heater ensures uniform spreading of the underfill material.

1 . A method of dispensing underfill material in an IC package, comprising the steps of:
 A. coupling an IC die to a package substrate of the IC package;   B. dispensing the underfill material between the IC die and the package substrate; and   C. performing at least one of pre-heating before the step B or post-heating after the step B, of the package substrate with contact-less heating.   
     
     
         2 . The method of  claim 1 , further comprising the step of:
 blowing hot air toward the package substrate during the step C.   
     
     
         3 . The method of  claim 2 , further comprising the step of:
 performing both pre-heating before the step B and post-heating after the step B, of the package substrate with contact-less heating.   
     
     
         4 . A system for dispensing underfill material in an IC package, comprising:
 a soldering unit for coupling an IC die to a package substrate of the IC package;   a dispenser for dispensing the underfill material between the IC die and the package substrate; and   a contact-less heater for performing at least one of pre-heating before or post-heating after dispensing the underfill material for the package substrate.   
     
     
         5 . The system of  claim 4 , wherein the contact-less heater includes:
 at least one heating element;   a dry air supply; and   at least one air hole for directing hot air toward the package substrate of the IC package.   
     
     
         6 . The system of  claim 5 , wherein the contact-less heater includes a holder for holding the IC package as the package substrate is heated. 
     
     
         7 . The system of  claim 6 , wherein the holder is capable of holding the IC package that has any of a plurality of pin configurations. 
     
     
         8 . The method of  claim 2 , further comprising:
 holding the IC package in a holder while the hot air is blown toward the IC package.   
     
     
         9 . The method of  claim 1 , further comprising:
 inspecting the IC package with the underfill material.   
     
     
         10 . The method of  claim 9 , further comprising:
 curing the underfill material of the IC package if the step of inspecting does not result in detection of an unacceptable condition of the underfill material; and   providing a warning if the step of inspecting results in detection of an unacceptable condition of the underfill material.   
     
     
         11 . The method of  claim 9 , wherein the step of inspecting includes further steps of:
 generating a camera image of the IC package having the underfill material between the IC die and the package substrate; and   analyzing, by a data processor, the camera image to determine an occurrence of an unacceptable condition of the underfill material.   
     
     
         12 . The method of  claim 11 , wherein the camera image is a top view of the IC die placed onto the package substrate. 
     
     
         13 . The method of  claim 12 , wherein the data processor detects for a portion of the underfill material forming a contamination on the IC die or the package substrate. 
     
     
         14 . The method of  claim 12 , wherein the data processor determines a fillet width of the underfill material from the captured image, and wherein the data processor determines a height of an underfill fillet from correlation to the fillet width, and wherein the data processor provides a warning when the height of the underfill fillet is not within an acceptable range. 
     
     
         15 . The method of  claim 11 , further comprising:
 positioning the IC package at a tilted angle with respect to a vertical axis of a camera;   capturing the camera image of a side of the IC package with the camera;   determining by the data processor a height of an underfill fillet from the camera image of the side of the IC package; and   determining by the data processor the height of the underfill fillet from a color contrast between the underfill fillet and the IC die in the camera image of the side of the IC package.   
     
     
         16 . The system of  claim 4 , further comprising:
 an inspection unit for inspecting the IC package with the underfill material.   
     
     
         17 . The system of  claim 16 , further comprising:
 an underfill curing unit for curing the underfill material of the IC package if the inspection unit does not detect an unacceptable condition of the underfill material.   
     
     
         18 . The system of  claim 16 , wherein the inspection unit provides a warning if the step of inspecting results in detection of an unacceptable condition of the underfill material. 
     
     
         19 . The system of  claim 18 , wherein the inspection unit includes:
 a camera for generating a camera image of the IC package having the underfill material between the IC die and the package substrate; and   a data processor for analyzing the camera image to determine an occurrence of an unacceptable condition of the underfill material.   
     
     
         20 . The system of  claim 19 , wherein the IC package is positioned at a tilted angle with respect to a vertical axis of the camera, and wherein the camera captures the camera image of a side of the IC package, and wherein the data processor determines a height of an underfill fillet from the camera image of the side of the IC package, and wherein the data processor determines the height of the underfill fillet from a color contrast between the underfill fillet and the IC die in the camera image of the side of the IC package.