Inspection of solder bump lighted with rays of light intersecting at predetermined angle

• US 6,608,921 B1
• Filed: 08/20/1999
• Issued: 08/19/2003
• Est. Priority Date: 08/21/1998
• Status: Expired due to Fees

• Current Assignee: NEC Electronics Corporation (Renesas Electronics Corporation)
• Original Assignee: NEC Electronics Corporation (Renesas Electronics Corporation)
• Inventors: Ikeda, Hiroshi, Inoue, Masahiko
• Primary Examiner(s): Johnson, Timothy M.
• Assistant Examiner(s): CHAWAN, SHEELA C
• Application Number:
  US09/378,035
• Time in Patent Office: 1,460 Days
• Field of Search: 382/108, 382/147, 382/149, 382/172, 382/150, 382/225, 382/190, 382/146, 348/126, 348/131, 356/237.5, 361/760, 250/559.34, 358/471, 358/484
• US Class Current: 382/146
• CPC Class Codes: G01N 2021/8822 Dark field detection
• CPC Class Codes: G01N 2021/95646 Soldering
• CPC Class Codes: G01N 21/95684 Patterns showing highly reflecting parts, e.g. metallic elements
• CPC Class Codes: G01N 2201/0626 Use of several LED's for spatial resolution
• CPC Class Codes: G01R 31/309 of printed or hybrid circuits or circuit substrates
• CPC Class Codes: G01R 31/71 Testing of solder joints
• CPC Class Codes: G06T 2207/30152 Solder
• CPC Class Codes: G06T 7/0006 using a design-rule based approach

Abstract

A bump inspecting apparatus lights a spherical solder bump mounted on the surface of a circuit board and has a reinforcing resin applied to the lower half thereof from all circumferential directions with rays of light which intersect at a predetermined angle. An image of the lighted solder bump is captured while the amount of light irradiated upon the central portion of a solder bump is reduced. An object is extracted from image data obtained by the image capture and the area and/or the aspect ratio of the object are confirmed. The quality of the state of the reinforcing resin applied to the solder bump can be inspected.

Claims

1. An image processing apparatus comprising:

image converting means for converting multilevel image data of a spherical solder bump into binary form, said bump having a reinforcing resin applied to the lower half, mounted on the surface of a circuit board;

object extracting means for extracting an object corresponding to the portion of a solder bump exposed above the reinforcing resin from the binary image data by said image converting means; and

quality determining means for determining whether the object extracted by said object extracting means is good or bad,

said quality determining means including;

ratio detecting means for detecting the aspect ratio of the object extracted by said object extracting means; and

ratio comparing means for comparing the aspect ratio detected by said ratio detecting means with a predetermined tolerance.

2. An image processing apparatus according to claim 1, further comprising

range limiting means for limiting a processing range of the image data to a circular shape corresponding to the outside shape of a solder bump.

3. An image processing apparatus according to claim 2, wherein said image converting means includes:

average detecting means for detecting an average brightness of the image data in the circumferentially inward portion of the circle limited by said range limiting means; and

threshold value calculating means for adding a predetermined offset value to the average brightness detected by said average detecting means to calculate a threshold value for conversion.

4. An image processing apparatus according to claim 1, further comprising

process controlling means for controlling at least the processing operation of said quality determining means, and wherein:

said object extracting means includes means for successively scanning the image data of one solder bump to successively extract a plurality of objects;

said quality determining means includes means for successively inspecting the plurality of objects corresponding to the one solder bump; and

said process controlling means includes means for completing the processing of said quality determining means at the point in time when one good object is detected from among the plurality of objects.

5. An image processing apparatus according to claim 1, wherein said object extracting means includes means for extracting one object from the image data at a central portion.

6. An image processing apparatus according to claim 1, wherein said quality determining means includes:

area detecting means for detecting the area of the object extracted by said object extracting means; and

area comparing means for comparing the area detected by said area detecting means with a predetermined tolerance.

7. An image processing apparatus according to claim 1, wherein said ratio detecting means includes means for detecting the major axis of the object extracted by said object extracting means and using the detected major axis of the object as a vertical axis.