Method and apparatus for inspecting a workpiece

• US 6,118,540 A
• Filed: 07/11/1997
• Issued: 09/12/2000
• Est. Priority Date: 07/11/1997
• Status: Expired due to Term

• Current Assignee: ASTI Holdings Limited
• Original Assignee: Semiconductor Technologies & Instruments Incorporated
• Inventors: Zemek, Michael C., Roy, Rajiv, Wahawisan, Weerakiat
• Primary Examiner(s): Pham, Hoa Q.
• Application Number:
  US08/890,814
• Time in Patent Office: 1,159 Days
• Field of Search: 356/394, 356/237, 356/398, 356/375, 356/376, 356/237.1, 356/237.4, 356/237.5, 348/187, 348/189, 348/87, 348/126
• US Class Current: 356/394
• CPC Class Codes: G01N 21/88 Investigating the presence of flaws or contamination
• CPC Class Codes: H05K 13/0812 the monitoring devices being integrated in the mounting machine, e.g. for monitoring components, leads, component placement
• CPC Class Codes: H05K 13/0813 Controlling of single components prior to mounting, e.g. orientation, component geometry H05K13/0812 takes precedence
• CPC Class Codes: Y10T 29/53261 Means to align and advance work part

Abstract

A computer vision apparatus and methods for automatically inspecting 2-dimensional (2D) and 3-dimensional (3D) criteria of objects using a single camera and laser sources. A camera views the object under inspection which is illuminated by a first source of light to highlight the region of interest. This provides image data for 2d analysis by a computer coupled to the system. Subsequently, multiple laser sources mounted on a positioner provide the illumination for collecting images for 3 dimensional analysis. A computer with a monitor is connected to the camera to perform the inspection and analysis and for operator supervision of the system. Specific implementations provided refer to embodiments for inspecting packaged semiconductor devices such as Ball-Grid Arrays (BGAs) packages and Quad Flat Packages (QFPs) packages for package mark inspection, package defect inspection, and solder ball or lead defects. Further, the apparatus and methods of the invention can be applied to the inspection of chip sized packages and to Flip-Chip Bump, and I.C. Die inspection. The system can also be used to inspect bond wire Wire Loop Height and to perform automated Quality Inspection for critical assembly of disk-drives, CD-Roms, keyboards, other assemblies in the computer industry and in other industries.

Claims

1. A system for the inspection of a workpiece, the system comprising in combination:

a camera held in a position facing the workpiece;

a ring light positioned to shine on the workpiece from all sides of the camera;

at least one linear positioner which can move toward the camera and away from the camera; and

at least one laser mounted on the at least one linear positioner at an angle to the direction faced by the camera, wherein the linear positioner can move to a position wherein the laser is aimed at the workpiece.

2. A system according to claim 1 wherein the at least one linear positioner comprises four linear positioners placed on four different sides of the camera, and the at least one laser comprises four lasers, one laser mounted on each of the four linear positioners.

3. A system according to claim 2 further comprising a computer controlling the camera, the ring light, the linear positioners, and the lasers.

4. A system according to claim 2 wherein the workpiece has a substantially flat rectangular top surface and a substantially flat rectangular bottom surface and four edges connecting the two substantially flat surfaces, with a row of electrical leads extending from each of the four edges, and wherein the camera faces one of the substantially flat rectangular surfaces, and the four linear positioners approach the camera from directions which are perpendicular to the four edges of the workpiece and can move to positions wherein the lasers are aimed at the rows of electrical leads.

5. A system according to claim 4 wherein each laser projects a flat beam directly across a row of electrical leads.

6. A system according to claim 4 wherein each laser sweeps a beam directly across a row of electrical leads.

7. A system according to claim 3 wherein the workpiece has a substantially flat rectangular top surface and a substantially flat rectangular bottom surface and four edges connecting the two substantially flat surfaces, with a row of electrical leads extending from each of the four edges, and wherein the camera faces one of the substantially flat rectangular surfaces, and the four linear positioners approach the camera from directions which are perpendicular to the four edges of the workpiece and can move to positions wherein the lasers are aimed at the rows of electrical leads.

8. A system according to claim 3 wherein the workpiece has at least one substantially flat surface and a ball grid array on the at least one substantially flat surface, and wherein the camera faces the at least one substantially flat surface, and the four linear positioners approach the camera from directions which are perpendicular to the ball grid array and can move to positions wherein the lasers are aimed at the rows and columns of the ball grid array.

9. A system according to claim 8 wherein each laser projects a flat beam directly across a row or column of the ball grid array.

10. A system according to claim 8 wherein each laser sweeps a beam directly across a row or column of the ball grid array.

11. A system according to claim 1 further comprising a computer operably connected to and controlling the camera, the ring light, the at least one linear positioner, and the at least one laser.

12. A system according to claim 11 wherein the workpiece has a substantially flat surface and a substantially linear edge with a row of electrical leads extending from the edge, and wherein the camera faces the substantially flat surface, and the at least one linear positioner approaches the camera from a direction which is perpendicular to the edge of the workpiece and can move to a position wherein the at least one laser is aimed at the row of electrical leads.

13. A system according to claim 12 wherein the at least one laser projects a flat beam directly across the row of electrical leads.

14. A system according to claim 12 wherein the at least one laser sweeps a beam directly across the row of electrical leads.

15. A system according to claim 11 wherein the workpiece has at least one substantially flat surface and a ball grid array on the at least one substantially flat surface, and wherein the camera faces the at least one substantially flat surface, and the at least one linear positioner approaches the camera from a direction which is perpendicular to the rows or columns of the ball grid array and can move to positions wherein the at least one laser is aimed at the rows or the columns of the array.

16. A system according to claim 15 wherein the at least one laser projects a flat beam directly across a row or column of the ball grid array.

17. A system according to claim 15 wherein the at least one laser sweeps a beam directly across a row or column of the ball grid array.