Automatic warp compensation for laminographic circuit board inspection

An inspection device comprising:

• a source of penetrating radiation which emits radiation through a test object from a plurality of positions;
• a detector system positioned to receive the radiation produced by said source of penetrating radiation which has penetrated the test object, said detector system further comprising an output which emits data signals corresponding to a penetrating radiation image of the test object produced by the radiation received and detected by said detector system after penetrating the test object;
• and
• an analysis system comprising:
• an image memory which stores said detector data signals thereby forming an image database which contains information sufficient to form a cross-sectional image of a cutting plane of the test object;
• and
• an image processor which searches said image database for a specific pre-determined feature located at a first Z-axis level in the test object and combines said detector data signals with reference to said first Z-axis level to form a specific Z-level image database which contains information sufficient to form a cross-sectional image of a cutting plane of the test object at a second Z-axis level in the test object.

A method for inspecting an electrical connection comprising the steps of:

• directing X-rays through the electrical connection from a plurality of positions;
• detecting X-rays transmitted through the electrical connection from said plurality of positions with an X-ray detector system having an output which emits data signals corresponding to an X-ray image of the electrical connection produced by X-rays received and detected by said X-ray detector system after penetrating the electrical connection;
• storing said X-ray detector data signals corresponding to said X-ray image of the electrical connection;
• creating a database of information from said X-ray detector data signals which contains information sufficient to form a cross-sectional image of a cutting plane of the electrical connection;
• searching said database of information for a specific pre-determined feature located at a first Z-axis level in the electrical connection;
• and
• combining said X-ray detector data signals with reference to said first Z-axis level to form a specific Z-level image database which contains information sufficient to form a cross-sectional image of a cutting plane of the electrical connection at a second Z-axis level in the electrical connection.

An apparatus for producing cross-sectional images of an object at a first Z-level of the object with reference to a second Z-level of the object comprising:

• an imaging system for producing a first transmission shadowgraph image of the object from a first perspective and a second transmission shadowgraph image of the object from a second perspective, wherein said first transmission shadowgraph image includes an image of a specific pre-determined feature located at the second Z-level of the object and said second transmission shadowgraph image includes an image of the specific pre-determined feature located at the second Z-level of the object;
• and
• an image analysis system comprising:
• an image memory which stores said first and second transmission shadowgraph images;
• an image processor which searches said first and second transmission shadowgraph images for the images of the specific pre-determined feature located at the second Z-level of the object and combines said first and second transmission shadowgraph images with reference to the second Z-level of the object to form a cross-sectional image of the first Z-level of the object wherein the location of the first Z-level of the object is determined by reference to the location of the second Z-level of the object.