Apparatus and method of inspecting solder printing

• US 5,134,665 A
• Filed: 02/14/1991
• Issued: 07/28/1992
• Est. Priority Date: 03/08/1990
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Jyoko, Nobuhiro
• Primary Examiner(s): Boudreau, Leo H.
• Application Number:
  US07/655,055
• Time in Patent Office: 530 Days
• Field of Search: 382/8, 382/34, 358/101, 358/106, 358/107, 304/513
• US Class Current: 382/150
• CPC Class Codes: G01B 11/0608 Height gauges
• CPC Class Codes: G01N 21/95684 Patterns showing highly reflecting parts, e.g. metallic elements
• CPC Class Codes: H05K 13/0817 Monitoring of soldering processes inspection of solder joints or of printed solder paste G01N21/95684

Abstract

A displacement sensor is attached to the XY direction movable body adapted to move over the land pattern of a printed circuit board in an X direction and Y direction, and rotatable in a direction parallel to the printed circuit board. The rotary mechanism allows the displacement sensor to be rotated in a direction which is orthogonal to the movement direction of XY direction movable body. The signals from said displacement sensor will be processed so that the film thickness and the print pattern of the solder on the land pattern may be detected. An ITV area sensor is also provided at said XY direction movable body so that the signals from the ITV area sensor may be processed to detect any print deviation of the soldering deviation on said land pattern.

Claims

1. A solder printing inspection apparatus comprising:

a body;

means for moving the body in at least a first direction and a second direction perpendicular to the first direction, whereby the body can move over the land pattern of a printed circuit board;

a displacement sensor rotatably attached to said body having a direction of scanning, and providing signals indicative of the distance between the sensor and the printed circuit board;

a rotary mechanism for rotating said displacement sensor about an axis substantially perpendicular to said printed circuit board so that the direction of scanning is orthogonal to the direction of movement of said body;

a first means for processing the signals from said displacement sensor so as to obtain the film thickness and the printing pattern of the solder on said land pattern;

an ITV area sensor attached to said body and providing signals indicative of the printing pattern on the land pattern; and

a second means for processing the signals from said ITV area sensor so as to detect print deviation of The solder on said land pattern.

2. A method of solder printing inspection, for inspecting a pattern of solder printing on a land pattern of a printed circuit board, comprising the steps of:

acquiring projection data of the land pattern of the printed circuit board and the pattern of printed solder on said land pattern using an ITV sensor;

converting said projection data into binary values by using a predetermined threshold value;

calculating a width of portions of the land pattern without solder from said binary values;

calculating an amount of print deviation of the solder on the land pattern from said width;

moving a rotable displacement sensor, having a scanning direction, in a moving direction over the printed circuit board, maintaining the scanning direction substantially orthogonal to the moving direction, thereby obtaining a distance between the sensor and the printed circuit board; and

calculating the thickness and pattern of the solder on said land pattern from said distance.

5. A method as set forth in claim 2, further comprising the steps of:

detecting any defective print on the printed circuit on the basis of said calculated print deviation, film thickness and print pattern.

6. A method as set forth in claim 2, further comprising the steps of:

providing the calculated print deviation and the calculated thickness and pattern of solder on the land pattern to the printing apparatus to compensate for detected defective printing.

3. A solder printing inspection apparatus for inspecting a printed circuit board, comprising:

a body;

means for moving the body in a plane parallel to the printed circuit board;

a displacement sensor rotatably attached to the body for scanning the land pattern of the printed circuit board and having means for providing a signal indicative of the distance between the sensor and the printed circuit board,

a first means for processing the signal provided by said displacement sensor having means for providing a signal indicative of the thickness and pattern of solder on said printed circuit board,

an ITV sensor for projecting an image of a land pattern on a printed circuit board and having means for providing a signal indicative of projection of the land pattern on the printed circuit board, and

a second means for processing the signals from the ITV sensor having means for detecting print deviation of the solder on the land pattern.

4. A solder printing inspection apparatus as set forth in claim 3, wherein said means for moving includes first means for moving said body in a first direction and second means for moving said body in a second direction perpendicular to said first direction.