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PCB REDESIGN TO IMPROVE COMPONENT RECOGNITION BY A VISION SYSTEM

IP.com Disclosure Number: IPCOM000008758D
Original Publication Date: 1998-Jun-01
Included in the Prior Art Database: 2002-Jul-10
Document File: 1 page(s) / 53K

Publishing Venue

Motorola

Related People

Conor Hilliard: AUTHOR

Abstract

Vision Systems have great difficulty in detecting if darkly or brightly coloured parts are missing from a PCB. This is due to the colour of the PCB, which could be either dark or light depending on the type of solder resist used.

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MOTOROLA Technical Developments

PCB REDESIGN TO IMPROVE COMPONENT RECOGNITION BY A VISION SYSTEM

by Conor Hilliard

PROBLEM TO BE SOLVED

  Vision Systems have great difficulty in detecting if darkly or brightly coloured parts are missing from a PCB. This is due to the colour of the PCB, which could be either dark or light depending on the type of solder resist used.

PROPOSED SOLUTION

  The idea is to print ink on the regions of the PCB between the pads provided on the PCB for component mounting. The ink would be black on lightly coloured photo-resist PCBs. On darkly coloured photo-resist PCBs the ink would be white. The ink should be confined to regions of the PCB which will be obscured when component's leads are correctly mounted on the pads. When a component is placed correctly, it would cover the areas printed with ink.

  The Vision System would then be programmed to fail a board if it detects the printed ink (no com- ponent covering the ink) and pass the board if it does not detect the ink. Existing vision systems can detect the presence or absence of a lead over a pad provided for it. This is the "inverse" of the vision system proposed here.

  To detect for Off-Pad components the printed ink area could be slightly smaller than the compo- nent body. If the component were precisely located, then none of the ink would be visible. If the compo- nent's leads were not correctly located on their pads, then varying amounts of ink would be visible depending on the amount the...