Browse Prior Art Database

BREAK AWAY FIDUCIAL LOCATING MARKS

IP.com Disclosure Number: IPCOM000008777D
Original Publication Date: 1998-Jun-01
Included in the Prior Art Database: 2002-Jul-11
Document File: 5 page(s) / 181K

Publishing Venue

Motorola

Related People

Harry Smithey: AUTHOR

Abstract

Often in manufacturing it is necessary to coor- dinate the program selection of multiple machines in order to produce a variety of products from one base unit (Figure 1, Manual Program Selection). A mistake in program selection can produce costly sorts, reworks or even scrap. In circuit board produc- tion, it is common to use one printed circuit board (PCB) and vary the components on that PCB in order to produce a variety of product options for the customer. This allows for the customizing of the product with a minimum of inventory and lead time.

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MOTOROLA Technical Developments

BREAK AWAY FIDUCIAL LOCATING MARKS

by Harry Smithey

  Often in manufacturing it is necessary to coor- dinate the program selection of multiple machines in order to produce a variety of products from one base unit (Figure 1, Manual Program Selection). A mistake in program selection can produce costly sorts, reworks or even scrap. In circuit board produc- tion, it is common to use one printed circuit board (PCB) and vary the components on that PCB in order to produce a variety of product options for the customer. This allows for the customizing of the product with a minimum of inventory and lead time.

  One way of preventing human errors in pro- gram selection is to use a computer to coordinate the processing of the work (Figure 2, Computer Program Selection). Using this method a computer and associated hardware controls the entire process and thereby reduces the opportunity of human error. The price for the lower risk is added cost, cycle time and complexity to the manufacturing process. The added complexity is in the form of additional hardware, technical support, down time and operator training.

  Break Away Fiducial Locating Marks provide an alternative way of preventing the human error without add@ &a cost and complexity of a com- puter co&&ed production line (Figure 4, Example of Break Away Marks,). Machines often use marks on the work in p,rogress to &ate the product before doing any machining or part placement. These marks are most often read by a camera mounted on the machine. There is a mark set for every possible product option on the PCB or common part. Before the work is introduced to the processing line, all marks are removed except for the marks that relate to the desired product. Each program on a machine is set to search for a unique set of marks. The line of processing machines can now only process the work correctly (Figure 3, Break Away Mark Control). If any machines have the wrong program selected that program can not execute because the location mark for that program can not be found in the programs defined search area. Break Away Fiducial Locating Marks cost a fraction of a com- puter controlled system in the areas of hardware, training and technical support.

The last figure is a drawing of the typical PCB layout for several Motorda pagers.

13 Momola, 1°C. l99S 193 June 1998

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MOTOROLA Technical Developments

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Here is the point that the PCB is marked for the desired product

Machine 1 (solder dispense)

Machine 2 (part placement): This machine has several possible programs or processing options, If the wrong program is selected, the machine will process the PCB and the product will have to be scrapped.

Machine 3 (odd part placement): same as Machine 2

Machine 4 (solder reflow): This machine processes all PCBs the same way and therefore does not need to use the break away marks

Manual Quality inspection

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