Learning method and apparatus for detecting and controlling solder defects

An apparatus for determining the quality of an electrical connection comprising:

• an imaging system for producing a first cross-sectional image of a cutting plane of a first electrical connection and a second cross-sectional image of a cutting plane of a second electrical connection;
• and
• an image analysis system for analyzing said first and second cross-sectional images, said image analysis system further comprising:
• a learning processor which acquires a predetermined image characteristic of said first cross-sectional image;
• a correction processor which uses said predetermined image characteristic of said first cross-sectional image to modify said second cross-sectional image;
• and
• a test processor which performs a predetermined test on said modified second cross-sectional image to determine the quality of said second electrical connection.

A method of detecting solder bridging defects on a circuit board comprising the steps of:

• acquiring a first cross sectional image of a cutting plane of a first electrical connection which does not have a bridging defect;
• defining a background around said first electrical connection in said first cross sectional image;
• acquiring a second cross sectional image of a cutting plane of a second electrical connection;
• removing said background from said second cross sectional image of a cutting plane of said second electrical connection to produce a background corrected image;
• comparing the image intensities comprising said background corrected image to a predetermined threshold image intensity level;
• and
• identifying locations on said background corrected image where the image intensities exceed said threshold image intensity level.

An apparatus for monitoring a solder application device which forms solder joints, said apparatus comprising:

• a solder joint inspection device which determines the thickness of each of said solder joints wherein said solder joint inspection device comprises:
• an imager that produces cross-sectional images of cutting planes of solder joints;
• a background compensator which removes a model background from said cross-sectional images of cutting planes of solder joints;
• and
• an image analyzer which analyzes said cross-sectional images with the model background removed to determine the thickness of each of said solder joints;
• and
• a memory which records said determined solder thickness.

A method for inspecting a printed circuit board, said method comprising the steps of:

• producing a cross-sectional image of a cutting plane of a first printed circuit board;
• measuring background image intensity levels at predetermined locations of said image of said first printed circuit board;
• producing a cross-sectional image of a cutting plane of a second printed circuit board having the same design as said first printed circuit board;
• and
• removing said first printed circuit board background image intensity levels from said image of said second printed circuit board.