Drill coordinate optimization for multi-layer printed circuit board

• Main Authors: KOSMOWSKI; WOJCIECH B, RUDOLPH; JOHN M
• Format: Patent
• Language: English
• Published: 25.06.1996
• Edition: 6
• Subjects: CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOTDIRECTED TO A PARTICULAR RESULT; DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g.ARRANGEMENTS FOR COPYING OR CONTROLLING; ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; MACHINE TOOLS; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OFPARTICULAR DETAILS OR COMPONENTS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS; METAL-WORKING NOT OTHERWISE PROVIDED FOR; PERFORMING OPERATIONS; PRINTED CIRCUITS; TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION; TECHNICAL SUBJECTS COVERED BY FORMER USPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TRANSPORTING

A system and method for optimizing drill coordinates in a multi-layer printed circuit board, to correct for interlayer shift during lamination. A set of test patterns, in the form of a cross formed by two orthogonal conductor lines, are defined at each corner of each layer in the same nominal location. Under ideal conditions, the test patterns of the layers in each corner are lined up one above the other, without any offset. A counter sinking tool is used to cut a conical bore in the location of the test patterns, so that every test pattern cross is interrupted in four places, generating a four segment pattern in each layer. A high resolution camera is placed above the countersunk bore to form a single image of the exposed segment edges of all the test patterns exposed by the bore. The image is analyzed to determine the amount of shift of each layer. If all patterns are perfectly concentric, all crosses are perfectly aligned. By measuring the shift of each pattern from the nominal position, the amount of shift in each layer is determined. The process is repeated for the test patterns at each corner of the board, and the resultant layer shift data is processed to optimize the drilling pattern for the board.