Drill coordinate optimization for multi-layer printed circuit board

Claim 3

The method of claim 1 wherein said opening is tapered and formed by a conical cutting tool.

Claim 4

The method of claim 2 wherein said cutting tool includes a cutting tool end defining an included angle of about one hundred degrees.

Claim 5

The method of claim 1 wherein said opening has a stepped cross-sectional configuration defined by a plurality of discrete layer cross-sectional layer dimensions which progressively decrease from a top layer to a layer at an extreme depth of said opening.

Claim 6

The method of claim 4 wherein said opening is formed by use of a plurality of drilling tools, wherein a first tool having a first diameter is used to cut an opening in an uppermost layer to be exposed, a second tool having a second diameter smaller than said first tool diameter is used to cut an opening in a second layer below said uppermost layer, and tools of progressively smaller diameter are used to cut openings in any layers below said second layer.

Claim 7

The method of claim 1 wherein said test patterns comprises first and second orthogonal conductor lines, and said exposed portions of each test pattern are nominally disposed at a 90 degree spacing about a perimeter of said opening.

Claim 8

The method of claim 1 wherein said test patterns each comprise an array of adjacent test patterns defined in said layers, permitting said optimizing to be repeated for a particular board.

Claim 9

The method of claim 1 wherein said image is formed through a telecentric lens and without the use of a zoom lens.

Claim 10

The method of claim 1 further comprising the step of drilling holes in said printed circuit board in accordance with said optimized drill coordinates.

Claim 11

The method of claim 1 further comprising the step of determining from said deviation data whether said board is usable, and rejecting said board if it is not usable.

Claim 12

The method of claim 1 wherein said printed circuit board has a rectilinear configuration having four corners, and said test patterns are located in each of said corners.

Claim 13

An automated drilling system for drilling a hole pattern in a multilayer laminated circuit board at optimized drill coordinates, the board having formed thereon one or more spaced test patterns in at least two of the layers prior to lamination of the layers, arranged at one or more predetermined nominal test pattern locations in the layers, so that a test pattern in at least one layer nominally overlays a test pattern in another layer under nominal board assembly conditions, comprising; means for forming an opening in an exposed surface of said laminated circuit board at each of said test pattern locations, said openings having a depth sufficient to penetrate each layer having said test patterns formed therein and having a cross-sectional dimension which decreases in size from a dimension at said board surface to a smaller dimension at said depth, thereby exposing portions of said test patterns; image forming means for forming from above said surface a single image of each said opening, each said image comprising pixels representing said exposed portions of said test patterns; processing means for processing said images of said openings to determine, from said exposed portions of said test patterns, deviations from nominal positions of said test patterns of said layers; and optimizing means for optimizing a set of drill coordinates to compensate for said deviations.

Claim 14

An automated drilling system for drilling a hole pattern in a multilayer laminated circuit board at optimized drill coordinates, the board having formed thereon one or more spaced test patterns in at least two of the layers prior to lamination of the layers, arranged at one or more predetermined nominal test pattern locations in the layers, so that a test pattern in at least one layer nominally overlays a test pattern in another layer under nominal board assembly conditions, comprising; means for forming an opening in an exposed surface of said laminated circuit board at each of said test pattern locations, said openings having a depth sufficient to penetrate each layer having said test patterns formed therein and having a cross-sectional dimension which decreases in size from a dimension at said board surface to a smaller dimension at said depth, thereby exposing portions of said test patterns; image forming means for forming from above said surface a single image of each said opening, each said image comprising pixels representing said exposed portions of said test patterns; processing means for processing said images of said openings to determine, from said exposed portions of said test patterns, deviations from nominal positions of said test patterns of said layers; and optimizing means for optimizing a set of drill coordinates to compensate for said deviations.

Claim 15

The system of claim 12 wherein said means for forming an opening comprises a counter-sink tool.

Claim 16

The system of claim 13 wherein said tool includes a cutting tip defining an included angle of substantially one hundred degrees.

Claim 17

The system of claim 12 wherein said opening has a stepped cross-sectional configuration defined by a plurality of discrete layer cross-sectional layer dimensions which progressively decrease from a top layer to a layer at an extreme depth of said opening.

Claim 18

The system of claim 12 wherein said test patterns comprises first and second orthogonal conductor lines, and said exposed portions of each test pattern are nominally disposed at a 90 degree spacing about a perimeter of said opening, said opening exposes portions of said patterns disposed at nominal concentric circles, and said processing means comprises means for detecting shifts in positions of said layers in dependence on measurements of positions of said portions represented in said images.

Claim 19

The system of claim 12 wherein said image forming means comprises a telecentric lens spaced away from said board surface for focusing light onto an image plane, and an image retaining means disposed at said image plane for capturing said image for processing.

Claim 20

The system of claim 12 further comprising drilling means for drilling holes in said printed circuit board in accordance with said optimized drill coordinates.

Claim 21

The system of claim 12 further wherein said processing means further comprises means for determining from said deviation data whether said board is usable, and means for rejecting said board if it is not usable.

Claim 22

An automated drilling system, comprising: a work table having means for registering a mounted position of a workpiece; a drilling spindle having a spindle axis mounted orthogonally to said work table; optical image means for capturing digitized optical images of an area of said workpiece mounted on said work table, from an image position generally orthogonal to said work table and spaced from a surface of said workpiece mounted at said registered position; precision positioning means for effecting relative movement between said work table and said spindle and between said work table and said image position in a plane orthogonal to a spindle axis; means for providing a nominal drill pattern program specifying nominal drill size and coordinates of a drill pattern to be drilled into said board; drill coordinate optimization means for compensating said nominal drill coordinates for inter-layer shifts of layers comprising said board from nominal positions, said means comprising means for cutting an opening into said board at said nominal test pattern locations, said opening having an opening depth and cross-sectional dimension which decreases from said board surface to said depth so as to expose portions of said test patterns in said various layers to view from above said surface, means for operating said positioning system for each test pattern location to position said opening relative to said image position so that an optical image of said opening is visible from said location, means for operating said image means to capture said image of said opening and said visible portions of said test patterns, processing means for processing said images to determine deviations from nominal layer locations of said respective layers and to calculate compensation values, and means for modifying said nominal hole coordinates by said compensation values; and system control means for operating said positioning means and said drilling spindle to drill said board in accordance with compensated hole coordinates.

Claim 23

An automated drilling system, comprising: a work table having means for registering a mounted position of a workpiece; a drilling spindle having a spindle axis mounted orthogonally to said work table; optical image means for capturing digitized optical images of an area of said workpiece mounted on said work table, from an image position generally orthogonal to said work table and spaced from a surface of said workpiece mounted at said registered position; precision positioning means for effecting relative movement between said work table and said spindle and between said work table and said image position in a plane orthogonal to a spindle axis; means for providing a nominal drill pattern program specifying nominal drill size and coordinates of a drill pattern to be drilled into said board; drill coordinate optimization means for compensating said nominal drill coordinates for inter-layer shifts of layers comprising said board from nominal positions, said means comprising means for cutting an opening into said board at said nominal test pattern locations, said opening having an opening depth and cross-sectional dimension which decreases from said board surface to said depth so as to expose portions of said test patterns in said various layers to view from above said surface, means for operating said positioning system for each test pattern location to position said opening relative to said image position so that an optical image of said opening is visible from said location, means for operating said image means to capture said image of said opening and said visible portions of said test patterns, processing means for processing said images to determine deviations from nominal layer locations of said respective layers and to calculate compensation values, and means for modifying said nominal hole coordinates by said compensation values; and system control means for operating said positioning means and said drilling spindle to drill said board in accordance with compensated hole coordinates.

Claim 24

The system of claim 20 wherein said optical imaging means comprises a telecentric lens having a sufficient depth of field to image said respective test pattern portions at said layers visible in said opening onto said image location.

Claim 25

The system of claim 20 further comprising optical illumination means for illuminating said opening while said image is being captured.

Claim 26

The system of claim 22 wherein said illumination means comprises red light generating means for illuminating said opening with red light.

Claim 27

The system of claim 20 wherein said opening cutting means comprises a counter sink tool operated by said spindle.

Claim 28

The system of claim 24 wherein said cutting tool includes a cutting tip defining an included angle of substantially one hundred degrees.

Claim 29

The system of claim 20 wherein said test patterns comprises first and second orthogonal conductor lines, and said exposed edges of each test pattern are nominally disposed at a 90 degree spacing about a perimeter of said opening, said opening exposes edges of said patterns disposed at nominal concentric circles, and said processing means comprises means for detecting shifts in positions of said layers in dependence on measurements of positions of said edges represented in said images.

Claim 30

The system of claim 20 further wherein said processing means further comprises means for determining from said deviation data whether said board is usable, and means for rejecting said board if it is not usable.

Claim 33

The method of claim 28 wherein said opening is tapered and formed by a counter sink tool.

Claim 34

The method of claim 29 wherein said tool includes a cutting tool end defining an included angle of about one hundred degrees.

Claim 35

The method of claim 28 wherein said opening has a stepped cross-sectional configuration defined by a plurality of discrete layer cross-sectional layer dimensions which progressively decrease from a top layer to a layer at an extreme depth of said opening.

Claim 36

The method of claim 31 wherein said opening is formed by use of a plurality of drilling tools, wherein a first tool having a first diameter is used to cut an opening in an uppermost layer to be exposed, a second tool having a second diameter smaller than said first tool diameter is used to cut an opening in a second layer below said uppermost layer, and tools of progressively smaller diameter are used to cut openings in any layers below said second layer.

Claim 37

The method of claim 28 wherein said test patterns comprises first and second orthogonal conductor lines, and said exposed portions of each test pattern are nominally disposed at a 90 degree spacing about a perimeter of said opening.

Claim 38

The method of claim 28 wherein said image is formed through a telecentric lens and without the use of a zoom lens.

Claim 39

The method of claim 28 wherein said printed circuit board has a rectilinear configuration having four corners, and said test patterns are located in each of said corners.