Apparatus for automated optical inspection objects

• US 5,861,909 A
• Filed: 07/02/1996
• Issued: 01/19/1999
• Est. Priority Date: 10/06/1993
• Status: Expired due to Term

• Current Assignee: Cognex Corporation
• Original Assignee: Cognex Corporation
• Inventors: Garakani, Arman M., Koljonen, Juha
• Primary Examiner(s): BRITTON, HOWARD W
• Application Number:
  US08/675,506
• Time in Patent Office: 931 Days
• Field of Search: 348/87, 348/90, 348/92, 348/94, 348/95, 382/145, 382/146, 382/147, 382/149, 382/150
• US Class Current: 348/87
• CPC Class Codes: B23K 20/007 Ball bonding
• CPC Class Codes: B23K 31/12 relating to investigating the properties, e.g. the weldability, of materials
• CPC Class Codes: B23K 37/04 for holding or positioning work
• CPC Class Codes: G01R 31/309 of printed or hybrid circuits or circuit substrates
• CPC Class Codes: G01R 31/66 Testing of connections, e.g. of plugs or non-disconnectable joints testing for incorrect line connections G01R31/55
• CPC Class Codes: G06T 11/00 2D [Two Dimensional] image generation
• CPC Class Codes: G06T 2207/30152 Solder
• CPC Class Codes: G06T 7/001 using an image reference approach
• CPC Class Codes: G06T 7/30 Determination of transform parameters for the alignment of images, i.e. image registration
• CPC Class Codes: H01L 2224/05553 being rectangular
• CPC Class Codes: H01L 2224/05554 being square
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/0603 Bonding areas having different sizes, e.g. different heights or widths
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48463 the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond
• CPC Class Codes: H01L 2224/49171 Fan-out arrangements
• CPC Class Codes: H01L 2224/78 Apparatus for connecting with wire connectors
• CPC Class Codes: H01L 2224/7865 Means for transporting the components to be connected
• CPC Class Codes: H01L 2224/85205 : Ultrasonic bonding
• CPC Class Codes: H01L 2224/859 : involving monitoring, e.g. feedback loop
• CPC Class Codes: H01L 24/48 : of an individual wire connector
• CPC Class Codes: H01L 24/49 : of a plurality of wire connectors
• CPC Class Codes: H01L 24/78 : Apparatus for connecting with wire connectors
• CPC Class Codes: H01L 24/85 : using a wire connector wire bonding in general B23K20/004
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01015 : Phosphorus [P]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01039 : Yttrium [Y]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/14 : Integrated circuits

Abstract

This invention provides a method and apparatus for automatically locating the bond of a wire to a lead frame and semiconductor chip or similar device as an in-process operation to facilitate in-process inspection. The apparatus includes a wire bonding machine, or similar apparatus, having a movable platform such as an X-Y table for holding semiconductor chips situated in lead frames; a video camera or other optical sensing or imaging device for generating images, which camera is typically positioned over the target chip and lead frame to be bonded; illumination means for illuminating the chip in a lead frame; an image processor capable of digitizing and analyzing the optically sensed images; a bonding mechanism; and a host controller connected to the bonding mechanism, the movable platform, the camera and the image processor. The apparatus generates and stores a pre-bond digital image of the semiconductor chip in the lead frame before bonding has occurred; connects one or more wires between the chip and lead frame by any of a number of means such as ultrasonic bonding, heat bonding, conductive glue bonding or other means; generates and stores a post-bond digital image of the now-bonded chip in its lead frame; registers the pre-bond and post-bond stored digital images so that analysis can be done; and permits inspection of the results of the wire bonds according to appropriate criteria.

Claims

1. A machine vision apparatus for inspecting object bonding, the apparatus comprising:

an image processor for generating digital image signals corresponding to an optically sensed pre-bond view of an object which is to be bonded to another member;

a bonder, in communication with said image processor and capable of sending a signal to said image processor, said bonder also being capable of placing a bond between said object and said other member;

a signal emanating from said bonder when a bond is completed to cause said image processor to generate digital image signals corresponding to an optically sensed post-bond view of said object bonded to said other member;

a computer, cooperative with said image processor, for subtracting said post-bond view from said pre-bond view to identify a bond; and

a machine, cooperative with said computer, for verifying said bond.

2. A machine vision method for inspecting object bonding, the method comprising the steps of:

generating digital image signals corresponding to an optically sensed pre-bond view of an object which is to be bonded to another member;

placing a bond between said object and said other member;

generating digital image signals corresponding to an optically sensed post-bond view of said object bonded to said other member;

subtracting said post-bond view from said pre-bond view to identify a bond; and

verifying said bond.

3. A machine vision apparatus for inspecting object bonding, the apparatus comprising:

an image processor for generating digital image signals corresponding to an optically sensed pre-bond view of an object which is to be bonded to another member;

a bonder, in communication with said image processor and capable of sending a signal to said image processor, said bonder also being capable of placing a bond between said object and said other member;

a signal emanating from said bonder when a bond is completed to cause said image processor to generate digital image signals corresponding to an optically sensed post-bond view of said object bonded to said other member;

a computer, cooperative with said image processor, for subtracting said post-bond view from said pre-bond view to identify a bond, and for verifying said bond.