Method and apparatus for verifying the presence or absence of a component

Abstract

Apparatuses and methods are disclosed for verifying the presence or absence of a die in a location, dice in a cut wafer or other components in a pattern. The apparatuses includes a wafer support, a radiation source, a radiation detector and a controller. The radiation source is positioned to direct radiation toward the wafer support and a radiation detector is positioned to detect radiation from the direction of said wafer support. Preferably, a visible light source, such as an arc lamp, is used to illuminate a wafer from the substrate side of the wafer and a charge coupled device (CCD) camera is positioned to detect light from the light source passing through locations in the wafer where the dice have been removed. The charge coupled device camera is connected to the controller, which is preferably a computer connected to a display monitor. The computer calculates the location of the removed dice based on the intensity of the detected light and produces a wafer verification map based on the calculated locations. The wafer verification map is compared to a planned or selected die pick pattern map of dice that were to be picked to identify any mispicked dice. In alternative embodiments, the apparatus can be included semi-integrally or integrally with a die attach machine to provide in-line verification of the die pick process. In a fully integral embodiment of the method, the picked die can be verified as correct prior to being placed onto a substrate.