Method of inspecting an array of solder ball connections of an integrated circuit module
First Claim
1. A method of inspecting balls within a ball grid array, the balls used as connections of integrated circuit modules, using an inspection apparatus having a microprocessor, a support for holding in place the modules to be inspected, wherein positioning of the support is controlled by the microprocessor, at least one camera connected to the microprocessor, the camera providing images of the balls, the balls being illuminated by a light source, said method comprising the steps of:
- measuring a centrality of the grid array by taking views of successive adjoining sub-arrays of said grid array and combining said views to form a composite image of the module;
from said composite image, measuring the X and Y coordinates of each of the balls forming said grid array to determine a best fitting grid of said balls;
determining the Z coordinate measured from the top of each of said balls to define a best fitting plane applicable to said array, based on said best fitting grid;
offsetting said best fitting plane so that the plane includes the lowest ball of said array of balls;
computing a deviation in the Z direction between each of said balls of said array and said offset plane; and
comparing the computed deviation against a predetermined specification and discarding as defective any said modules exceeding said first deviation and said deviation in the Z direction.
1 Assignment
0 Petitions
Accused Products
Abstract
A method of inspecting an array of balls used as connections in integrated circuit modules such as Solder Ball Connection modules, by means of an inspection apparatus that includes a microprocessor (34), a support (32) for holding in place the modules to be inspected (30), the microprocessor controlling a vertical camera (38) and a tilted camera (40) for obtaining images of the balls, wherein said method includes measuring the X and Y coordinates of each ball of the array to determine a best fitting grid of the balls, detecting the Z coordinate of each ball to determine the best fitting plane for the array of balls, offsetting the best fitting plane such that the offset plane also includes the lowest ball of the array, computing the deviation between each ball and the offset plane, and comparing the computed deviations with predetermined specifications to ascertain whether the inspected module is in compliance with the specifications.
150 Citations
17 Claims
-
1. A method of inspecting balls within a ball grid array, the balls used as connections of integrated circuit modules, using an inspection apparatus having a microprocessor, a support for holding in place the modules to be inspected, wherein positioning of the support is controlled by the microprocessor, at least one camera connected to the microprocessor, the camera providing images of the balls, the balls being illuminated by a light source, said method comprising the steps of:
-
measuring a centrality of the grid array by taking views of successive adjoining sub-arrays of said grid array and combining said views to form a composite image of the module; from said composite image, measuring the X and Y coordinates of each of the balls forming said grid array to determine a best fitting grid of said balls; determining the Z coordinate measured from the top of each of said balls to define a best fitting plane applicable to said array, based on said best fitting grid; offsetting said best fitting plane so that the plane includes the lowest ball of said array of balls; computing a deviation in the Z direction between each of said balls of said array and said offset plane; and comparing the computed deviation against a predetermined specification and discarding as defective any said modules exceeding said first deviation and said deviation in the Z direction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A method of inspecting balls within a ball grid array, the balls used as connections of integrated circuit modules, using an inspection apparatus having a microprocessor, a support movable in the X and Y directions controlled by said microprocessor, first and second cameras coupled to said microprocessor for providing images of the balls, said method comprising the steps of:
-
a) measuring a centrality of the grid array by taking views of successive adjoining sub-arrays of said grid array and combining said views to form a composite image of the module; b) combining said views to form an image of said array of balls; c) from said image, measuring the position of each said balls, computing a best fitting grid and a first deviation in the X and Y directions between each of said balls and said best fitting grid; d) determining the height of said balls with said second camera tilted with respect with said module, taking views of successive rows, while said balls are illuminated by a source of light placed opposite to said wherein an image of said balls in each said views corresponds to light reflections at the top of said balls; e) computing a best fitting plane formed by said tops of said balls; f) offsetting said best fitting plane by an amount determined by the top of the lowest of said balls in said array of balls to form an offset plane; g) computing a deviation in the Z direction between said best fitting plane and said offset plane; and h) comparing said first deviation and said deviation in the Z direction with predetermined specifications, and discarding as defective any said modules exceeding said first deviation and said deviation in the Z direction. - View Dependent Claims (12, 13, 14, 15, 16, 17)
-
Specification