Method and apparatus to detect capillary indentations

• US 5,642,158 A
• Filed: 05/02/1994
• Issued: 06/24/1997
• Est. Priority Date: 05/02/1994
• Status: Expired due to Term

• Current Assignee: Cognex Corporation
• Original Assignee: Cognex Corporation
• Inventors: Michael, David J., Petry, John P. III, Garakani, Arman
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US08/236,212
• Time in Patent Office: 1,149 Days
• Field of Search: 382/8, 382/146, 348/87, 348/126
• US Class Current: 348/87
• CPC Class Codes: G01R 31/2853 Electrical testing of internal connections or -isolation, e.g. latch-up or chip-to-lead connections G01R31/31717 takes precedence; test of chip-to-PCB or lead-to-PCB connections G01R31/66
• CPC Class Codes: G01R 31/311 of integrated circuits G01R31/31728 takes precedence
• CPC Class Codes: H01L 21/67271 Sorting devices
• CPC Class Codes: H01L 21/67288 Monitoring of warpage, curvature, damage, defects or the like
• 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 2224/45099 Material
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• 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 2224/78301 Capillary
• CPC Class Codes: H01L 2224/85 using a wire connector
• 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 2924/01039 : Yttrium [Y]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H04N 7/18 : Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast

Abstract

This invention provides a method and apparatus for automatically inspecting the connection of a wire to a lead on lead frame containing a semiconductor chip or similar device. Using an image processor to locate the general position of a soldered lead in a digitized image, the present invention creates a template of an idealized optical indentation left by a good bond; determines parameters such as wire angle, idealized position and shape thresholds for applying the template; conducts a normalized correlation search of the digitized image; compares the results returned to the parameters and reports the resulting signals generated by this comparison to a host controller or other control module.

Claims

1. In a machine vision system having a means for optically sensing objects and digitizing and analyzing images of said objects, a method for automatically detecting an indentation formed by a bonding device in a wire bonded to a lead:

a. constructing a grey level model of an idealized indentation including parameters indicating threshold values for location, wire angle and acceptable image correlation;

b. acquiring a digitized image of said lead;

c. conducting a normalized correlation search of said digitized image using said model;

d. comparing results of said normalized correlation search to said parameters;

e. passing results signals to a decision-making mechanism.

2. In a machine vision system having a means for optically sensing objects and digitizing and analyzing images of said objects, an apparatus for automatically detecting an indentation formed by a bonding device in a wire bonded to a lead comprising:

a. means for constructing a grey level model of an idealized indentation including parameters indicating threshold values for location, wire angle and acceptable image correlation;

b. means for acquiring a digitized image of said lead;

c. means for conducting a normalized correlation search of said digitized image using said model;

d. means for comparing results of said normalized correlation search to said parameters;

e. means for passing results signals to a decision-making mechanism.