Western Electric Company, Inc.

At&t Bell Laboratories

At&t Technologies, Inc.

Frank H Blitchington

Edwin Arthur Chandross

Lloyd Shepherd

Jack C Hetherington

David E Haught

George David Hudson

Circuit boards with advantageous properties are produced through the addition of a fluorescent dye. The presence of the dye allows an expeditious inspection of the metallic pattern on the circuit board by induced fluorescence. If the circuit board is two-sided, to maintain the effectiveness of the dye, a material such as a light scattering composition is added to the circuit board substrate.

Inspection of multipattern circuit boards

Disclosed is a method and apparatus for identifying the lot codes of workpieces, such as printed circuit board panels, as they progress down a manufacturing line. At an initial stage of processing, a hole pattern is drilled along one edge of the pieces. The hole pattern includes the lot code number of that piece in binary form. The hole pattern can be addressed by appropriate optical means such as an LED-phototransistor combination or by a video camera as the pieces pass by in order to determine the lot code or other information at any desired point in the processing.

Identification of workpiece information

A system for generating a substantially-continuous stream of binary signals representative of the presence of copper on the surface of a fluorescent, substrate of a board. A beam is swept by mirror facets of a rotating mirror drum along a path on the board. When the beam strikes copper it is merely reflected. When the beam strikes the substrate, a fluorescence is produced. The resultant light is gathered by cylindrical lenses and fiber optic bundles. The color of the light is blocked by filters and the fluorescence color energizes photomultiplier tubes. A threshold setting and sensing circuit senses the output of the photomultiplier tubes and controls their bias voltage to produce a constant level of output from fluorescence and then produces a stream of binary signals that are representative of the presence/absence of copper on the surface of the board. The swept beam is split to send a portion of its energy through an optical grating. The intermittent light passing through the optical grating is gathered by a fiber optic bundle and is sensed by a photomultiplier tube. The output of the photomultiplier tube is doubled in frequency and used to sample and store the binary signals in the memory of a scanning converter. The binary signals arrive in short bursts of higher-frequency signals separated by periods of absence of binary data. The binary signals stored in the scanning converter are then read out substantially continuously for subsequent processing at a lower frequency.

Scanning sample, signal generation, data digitizing and retiming system

A system for generating a substantially-continuous stream of binary signals representative of the presence of copper on the surface of a fluorescent substrate of a board. A beam is swept by mirror facets of a rotating mirror drum along a path on the board. When the beam strikes copper it is merely relected. When the beam strikes the substrate, a fluorescence is produced. The resultant light is gathered by cylindrical lenses and fiber optic bundles. The color of the light is blocked by filters and the fluorescence color energizes photomultiplier tubes. A threshold setting and sensing circuit senses the output of the photomultiplier tubes and controls their bias voltage to produce a constant level of output from fluorescence and then produces a stream of binary signals that are representative of the presence/absence of copper on the surface of the board. The swept beam is split to send a portion of its energy through an optical grating. The intermittent light passing through the optical grating is gathered by a fiber optic bundle and is sensed by a photomultiplier tube. The output of the photomultiplier tube is doubled in frequency and used to sample and store the binary signals in the memory of a scanning converter. The binary signals arrive in short bursts of higher-frequency signals separated by periods of absence of binary data. The binary signals stored in the scanning converter are then read out substantially continously for subsequent processing at a lower frequency.

Inspection scanning system

In the process of aligning an image sensor (33) with a datum mark (23) on an artmaster (21), each of a plurality of elements of the sensor accumulate a charge based on the level of light sensed. The elements of the sensor (33) are repetitively scanned to obtain data pulses relating to the charges on the elements as an indication of the level of sensed light. Data pulses from selected elements of the sensor (33) are counted and compared to develop a signal representative of, and to facilitate visual indication of, the alignment or misalignment of the sensor (33) and the datum mark (23). If the sensor (33) and the datum mark (23) are misaligned, the developed signal facilitate control of servo motors (28 and 29) to move the sensor (33) into alignment with the datum mark (23). Data pulses derived from all elements of the sensor (33) are used to facilitate an electronic reproduction on a display board (40) of the position of the datum mark (23 ) relative to the sensor.

Methods of and system for aligning a device with a reference target

A continuous flexible web includes a flat, flexible, non-conductive substrate with copper cladding on at least one major surface of the substrate. Prepunched holes may be formed in and through the web and may provide through-hole connections between printed circuits ultimately formed on opposite sides of the substrate. Successive sections of the web are indexed through a screen printing apparatus. A photocell system cooperates with preformed through-slots formed selectively in the web and windows formed in a platen beneath the section to precisely locate the platen with the section and relative to a circuit pattern formed in a screen above the section. The underside of the section is then held with the platen and the screen is positioned over the top side of the section. Ink is then flooded onto the screen and ultimately wiped through circuit-pattern openings in the screen and onto the section to form an inked impression of the circuit pattern on the section.

Apparatus for precisely aligning a pair of elements

A laminate (32), having holes of different sizes and shapes formed therein, is moved above successive scans of light from a light source (48). A light sensor (58), responsive to light passing through each of the holes, develops a light pulse for each hole during each scan having a level proportional to the amount of light sensed. The level of each light pulse is compared with a preset threshold level and a threshold pulse is developed when the light pulse level exceeds the threshold level. The threshold pulse facilitates the reduction of the preset threshold level so that, when the next subsequent light pulse from the same hole exceeds the reduced threshold level, an additional threshold pulse is produced. The threshold pulses are used within a system (46) to generate an indication of the number of holes formed in the laminate (32).

Method of and system for automatically adjusting a threshold level of a

A continuous web or laminate (32) of flexible material is indexed through a punch press (44) whereat holes of different shapes and sizes are punched in repetitive patterns through successive sections of the laminate. The laminate (32) is then moved beneath a light source (48) so that light passes through the holes and is sensed by a light-sensing camera (52) which laterally and cyclically scans at a rapid rate the underside of the moving laminate. During the rapid scanning by the camera (52), each hole may be scanned many times due to the size and shape of the hole. Consequently, light is sensed many times for the same hole and a corresponding number of signals are developed by the camera. A hole counting system (46), which receives the developed signals from the camera (52), includes a delay-and-compare circuit (66) wherein each signal related to a given hole is delayed by one scan cycle and compared with the next signal related to the same hole. When the given hole has passed, the camera (52) does not sense light on the next scanning cycle. This condition, when compared with the immediately previous light-sensed condition, results in the development of an output hole-count pulse from the delay-and-compare circuit (66). The count pulses of each section of the laminate (32) are fed to a counter-comparator circuit (70), and are counted and compared with a desired preset count for each section. If the actual and preset counts of a selected number of successive sections do not compare, an alarm is sounded and a signal is fed to the punch press (44) to stop the punching operation.

Methods of and system for counting holes and for detecting missing holes

A continuous flexible web includes a flat flexible insulation substrate, copper cladding on at least one major surface of the substrate and a film of photoresist material adhesively bonded longitudinally to the copper cladding. Prepunched holes are formed in and through the web to ultimately provide through-hole connections between printed circuits formed on opposite sides of the substrate. Successive sections of the web are indexed through an apparatus where the sections are positioned adjacent to a circuit pattern master and exposed to resist-developing ultraviolet rays. A photocell system cooperates with through-slots formed selectively in the web to precisely align the web sections with the circuit pattern master prior to exposure to the ultraviolet rays.

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Richmond, VA, United States of America

Frank H Blitchington