Soldering appearance inspection apparatus

• US 5,148,375 A
• Filed: 11/15/1990
• Issued: 09/15/1992
• Est. Priority Date: 11/17/1989
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Horikami, Kinji
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): Zanelli, Michael J.
• Application Number:
  US07/613,990
• Time in Patent Office: 670 Days
• Field of Search: 364/552, 364/551.01, 364/550, 364/506, 364/507, 382/8, 356/237, 358/106
• US Class Current: 382/150
• CPC Class Codes: G01N 21/95684 Patterns showing highly reflecting parts, e.g. metallic elements
• CPC Class Codes: G06T 2207/20061 Hough transform
• CPC Class Codes: G06T 2207/30152 Solder
• CPC Class Codes: G06T 7/0006 using a design-rule based approach

Abstract

A soldering appearance inspection apparatus is for detecting a faulty soldering at a soldered portion on a printed circuit board. The inspection apparatus includes an illuminating device for illuminating the soldered portion, an image pickup device for picking up an image of the soldered portion, a position detecting device for detecting the position of the soldered portion from the picked up image, and a soldered state judging device for judging an excess or insufficiency of the amount of solder, and also for judging a presence or absence of scorching and luster at the soldered portion, based on a ratio of a region of light subjected to regular reflection on the solder to a size of the soldered portion.

Claims

1. A soldering appearance inspection apparatus for detecting a faulty soldering at a soldered portion on a printed circuit board, said inspection apparatus comprising:

illuminating means for illuminating the soldered portion;

image pickup means for picking up an image of the soldered portion; and

image processing means for (1) receiving the image picked up by said image pickup means, effecting a Hough conversion of a differentiation image of the picked up image to obtain a density distribution of the picked up image, and discriminating as a solder edge a location in which the density distribution changes from a region of equal density to a region of non-equal density, (2) determining, from the thus discriminated soldered edge, a region of the soldered portion from the picked up image, (3) determining a ratio of a size of a subregion of the soldered portion in which light illuminated thereon is subjected to regular reflection to a size of the region of the soldered portion, and (4) judging a faulty state of the soldering at the soldered portion based on the thus determined ratio.

2. A soldering appearance inspection apparatus for detecting a faulty soldering at a soldered portion on a printed circuit board, said inspection apparatus comprising:

illuminating means for illuminating the soldered portion;

image pickup means for picking up an image of the soldered portion; and

image processing means for (1) receiving the image picked up by said image pickup means, (2) determining a region of the soldered portion from the picked up image, (3) determining a ratio of a size of a subregion of the soldered portion in which light illuminated thereon is subjected to regular reflection to a size of the region of the soldered portion, and (4) judging a faulty state of the soldering at the soldered portion based on the thus determined ratio;

wherein said image processing means includes;

lead wire position detecting means for detecting a position and direction of a lead wire at an outer side portion of the soldered portion;

differentiation processing means for obtaining a value of a variation in brightness along successive portions of the lead wire;

lead wire intruding position detecting means for detecting an intruding position of the lead wire into the soldering based on the value of the variation of brightness, wherein the intruding position is determined as being at a position in which the value of the variation in brightness ceases to be characterized as a curve having two crests and a valley therebetween; and

lead wire soldered state discriminating means for discriminating a quality of a soldered state of the lead wire based on the lead wire intruding position with respect to the soldered portion.

3. A soldering appearance inspection apparatus for detecting a faulty soldering at a soldered portion on a printed circuit board, said inspection apparatus comprising:

illuminating means for illuminating the soldered portion;

image pickup means for picking up an image of the soldered portion; and

image processing means for (1) receiving the image picked up by said image pickup means, (2) determining a region of the soldered portion from the picked up image, (3) determining a ratio of a size of a subregion of the soldered portion in which light illuminated thereon is subjected to regular reflection to a size of the region of the soldered portion, and (4) judging a faulty state of the soldering at the soldered portion based on the thus determined ratio;

wherein said image processing means includes;

binary coding means for binary coding a partial region which is centered at a lead wire intruding position by an intermediate value of a brightness of the soldering and a concave portion at a position where a lead wire intrudes into the soldering;

means for obtaining a binary projection at said partial region; and

judging means which obtains a size and degree of circularity of said concave portion darkened by the binary coding based on maximum and minimum values of data obtained by dividing a projecting axis into at least three equal portions for judging whether or not said concave portion is of a tunnel-like cavity.

4. A soldering appearance inspection apparatus for detecting a faulty soldering at a soldered portion on a printed circuit board, said inspection apparatus comprising:

illuminating means for illuminating the soldered portion;

image pickup means for picking up an image of the soldered portion; and

image processing means for (1) receiving the image picked up by said image pickup means, (2) determining a region of the soldered portion from the picked up image, (3) determining a ratio of a size of a subregion of the soldered portion in which light illuminated thereon is subjected to regular reflection to a size of the region of the soldered portion, and (4) judging a faulty state of the soldering at the soldered portion based on the thus determined ratio;

wherein said image processing means comprises;

differentiation processing means for obtaining a variation of brightness of a lead wire;

binary coding means for binary coding the differential processed image at levels higher than a predetermined level; and

,

remaining wire detecting means for judging a presence or absence of a binary image configuration having a feature of a lead wire located outside the soldering and present at a position which is different from a lead wire position.