GB2317496A

GB2317496A - Systems for surfacing mounting components.

Info

Publication number: GB2317496A
Application number: GB9619922A
Authority: GB
Inventors: Joseph O'keeffe
Original assignee: Motorola BV Branch Ireland
Current assignee: Motorola BV Branch Ireland
Priority date: 1996-09-24
Filing date: 1996-09-24
Publication date: 1998-03-25
Anticipated expiration: 2016-09-24
Also published as: GB2317496B; IE970658A1; KR19980025143A; JPH10117094A; GB9619922D0

Abstract

The system includes a plurality of feeders, each feeder (12) being respectively identified by a first bar-code label and holding a component reel identified by a second bar-code label. At least one bar code scanner (16, 18) is provided. The first and second bar-code labels are scanned automatically by the at least one bar code scanner (16, 18). A component part number is then assigned to the respective first feeder number to prevent the placement of wrong components. The system also includes a sensor array for sensing the position of a feeder and makes a comparison between the sensed position and part number, and stored valves of these parameters. Any error causes the system to be turned off.

Description

CHIP SHOOTER MANUFACTURING SYSTEM AND METHOD OF OPERATION Field of the Invention This invention relates to Surface Mount manufacturing processes and their operation. The invention is applicable to, but not limited to, the automatic control of chipshooter manufacturing systems.

Background of the Invention The manufacture of printed circuit boards is nowadays performed using automatic Chipshooters. A chipshooter is a robot-controlled component placing system. To place a large number of different value, size, shape and orientation of components, Chipshooters require a significant number of feeders, e.g. 240 different feeders each having different reels components. These feeders are mounted on a moving axis at the back of the chipshooter, known as the d-axis. During a chipshooter process set-up or a product changeover, a problem can occur when operators load incorrect reelsl components, perhaps in incorrect positions.

In addition, when a reel runs out of components, there is also the possibility of replacing it with an incorrect reel. Such mistakes can lead to hundreds of products being built with incorrect parts before the mistake is discovered. This could well lead to products being recalled and major rework of incorrect products to be made.

Most Chipshooter vendors offer as an option, in an attempt to prevent such human mistakes, a bar-code system. This bar-code system is based on the operator scanning the part number of the component of the part/reel being loaded into the feeder and scanning a bar-code on the position on the d-axis of the system where the feeder is being loaded. A problem associated with such bar-code systems is that there is no guarantee that the operator will load the feeder in the actual position scanned. Hence, it is totally operator dependent and still prone to human mistakes.

An alternative to this is the Panasonic IPC (Intelligent Parts Cassette) system. The IPC system is based on the fact that each feeder has its own memory module. This module stores information regarding the component reel which is located on the feeder. When the Chipshooter is operating the information is read real-time. The IPC system is restricted to the new Panasonic Chipshooters and requires particular feeders that are compatible with the IPC module. Such a system is renowned as expensive. It also assumes that the set-up file on the Chipshooter has upto-date information on the actual d-axis set-up of the manufacturing process.

This invention seeks to provide an improved and flexible manufacturing apparatus and process.

Summarv of the Invention In a first aspect of the present invention, a method for controlling feeders in a chipshooter manufacturing system is provided. The chipshooter manufacturing system includes a plurality of feeders, each feeder of the plurality of feeders respectively identified by a first bar-code label and holding a component reel identified by a second bar-code label.

The chipshooter manufacturing system includes at least one bar code scanner. The method includes the steps of scanning the first bar-code label of a respective first feeder automatically by the at least one bar code scanner, scanning the second bar-code label of the respective first component reel by the at least one bar code scanner and assigning a component part number to the respective first feeder number.

Preferably, the chipshooter manufacturing system includes a sensor array and the method further includes the steps of sensing a position of the first feeder in at least one plane by the sensor array and determining a component part number for the position of the first feeder in the at least one plane. In the preferred embodiment of the invention, the at least one plane is a d-axis of the chipshooter manufacturing system and at least one terminal is operably coupled to a controller and to the manufacturing system via at least one interface element and a data communication link.

In this manner, the correct component for the correct feeder is checked, together with monitoring the correct position of the feeder/component reel in the chipshooter manufacturing system.

Furthermore, the component part number and position of the first feeder is compared with a stored component part number and stored position in a master record of the at least one terminal to determine whether the chipshooter manufacturing system is ready for correct operation. If there are any errors, the chip shooter manufacturing system will be automatically turned off, thereby preventing incorrect placement of components.

Advantageously, automatic tracking of the number of components held on a component reel on a first feeder is performed to determine whether the number of components is below a threshold value thereby indicating that the component reel needs to be replaced. Furthermore, the number of placements by each feeder of the plurality of first feeders is automatically tracked to determine whether the number of placements of a respective feeder is above a threshold value indicating that the respective feeder requires a maintenance check.

In a second aspect of the present invention, a chipshooter manufacturing system is provided. The chipshooter manufacturing system includes a plurality of feeders wherein each feeder of the plurality of feeders is respectively identified by a first bar-code label and each feeder holds a component reel identified by a second bar-code label. At least one bar code scanner is provided for scanning at least the first bar-code label and at least one sensor array for scanning a position of a respective first feeder in the manufacturing system. At least one terminal is operably coupled to the at least one bar code scanner and the sensor array for monitoring operation of the chipshooter manufacturing system and determining a respective component reel for the respective first feeder in a respective feeder position. A controller is operably coupled to the at least one terminal via at least one first interface element and a first data communication link for controlling at least one operation of the chipshooter manufacturing system.

A preferred embodiment of the invention will now be described, by way of example only, with reference to the drawings.

Brief Description of the Drawings FIG. 1 is a diagram of a Chipshooter (top view) of a manufacturing system according to a preferred embodiment of the invention.

FIG. 2 is a diagram of a Chipshooter (bottom view) of a manufacturing system according to the preferred embodiment of the invention.

FIG. 3 is a more detailed diagram of a Chipshooter (bottom view) of a manufacturing system with a sensor array according to the preferred embodiment of the invention.

FIG. 4 is a diagram of an architecture of a manufacturing system according to the preferred embodiment of the invention.

FIG. 5 is a timing diagram showing signals transmitted from two sensors to a P.C. according to the preferred embodiment of the invention.

Detailed Description of the Drawings Referring first to FIG. 1, a diagram of a Chipshooter (top view) of a manufacturing system, according to a preferred embodiment of the invention, is shown. The Chipshooter 10 holds a number of feeders 12.

The Chipshooter is divided into a number of carriages; four carriages in the example shown. The feeders 12 contain reels of components, each individually defined by a bar-code label, and the feeders 12, also individually defined by a bar-code label, are so arranged that they pass either a first bar-code scanner 16 or a second bar-code scanner 18, positioned at the side of the Chipshooter 10, before components are picked from each feeder. The chosen feeder, with the desired reel of components, is positioned at the pick-up point 14. It is within the contemplation of the invention that only one bar-code scanner may be used to fulfil the scanning operation in both directions Referring now to FIG. 2, a diagram of the bottom view of the Chipshooter of the manufacturing system of FIG. 1, according to the preferred embodiment of the invention, is shown. The feeders 12 are defined by first carriage markings indicative of the feeder pitch 32 and second carriage markings 34 to indicate the carriage number. Preferably, the carriage markings are monitored by a first sensor array 36 to read the carriage position and a second sensor array 38 to read the carriage number, although it is within the contemplation of the invention that only one sensor array may be used to fulfil both functions.

Referring now to FIG. 3 a more detailed diagram of the bottom view of the Chipshooter of FIG. 2, is shown. The first carriage markings indicative of the feeder pitch 32 and second carriage markings 34 are shown monitored by the first sensor array 36. The first sensor array 36 has five sensors associated with each of the bar-code readers. These are optic fibre sensors which switch when their light is reflected (white surface).

They have a very low switching time of 200 microseconds which is needed for the speed of the carriages, as shown in FIG. 3. Two sensors are used to identify the Carriage (by using black or white strips), e.g. a first carriage identification bit 40 and a second carriage identification bit 42, giving a total of 3 possible different carriages passing under each scanner. This allows a total of 6 carriages. In the Sanyo TCM 1000 case, this will cater for the new expanded d-axis with 6 carriages and a total of 240 feeder positions. The initialisation sensor 44 is used to get the scanner ready to read. The other two sensors, e.g. the feeder sensor 37 and the direction sensor 39, are used to track which feeder position is under the scanner at a particular time. This information is needed to assign the feeder ID presently being scanned to a feeder position. The tracking system must be able to cater with the Carriage travelling backwards and forwards. The two carriage ID sensors are half of one feeder pitch out of phase. This provides signals to the Personal Computer (PC) as shown in FIG. 5. These signals are used to track position and direction using the same principles as used in rotary encoders.

In operation, each feeder of the Chipshooter as described in FIG.s 13, is given a unique feeder ID stored on a bar-code on the feeder. An operator loads the feeders with component reels at a loading station. As part of the feeder loading operation, the operator scans the feeder for the feeder number bar-code, and scans the component reel for the component part number and part number quantity (bar-coded on the reel by the vendors). The manufacturing system now assigns this component part number to the feeder number. This is done at the user interface on the Xterminal, as shown in FIG. 4. When the feeder is on the d-axis, it passes one of the bar-code scanners before it reaches the pick point, as shown in FIG. 1, on the Chipshooter. If the feeder is in the incorrect position or the incorrect component is on the feeder, the system will stop the Chipshooter and inform the operator where the error is. As there are different numbers of feeders on different chipshooter models, and the total d-axis is split into different numbers of carriages depending on the model, it is necessary to consider each carriage as a separate unit. Therefore, each carriage has a unique ID number.

A screen printed plate is made and attached to each Carriage. Each feeder position is aligned to a black mark on this screen. Each feeder position is made up of this black mark (strip) and a white mark (strip), as shown in FIG. 3. Two scanners are needed, one at each side of the pick-up point, so that no feeder can approach the pick-up point before passing a scanner. In the case of the Sanyo TCM 1000 the carriages always park after the machine stops for feeder replacement or some other error.

Therefore the ideal location for the scanners in this case is just as the carriages go from the parked position into the working position, as shown in FIG. 1 and FIG. 2. As the carriages move past the scanners at very high speed the scanners must be of very high speed, e.g. 1 Carriage with up to 40 feeders in 1.5 sec. Tests showed that there was not bar-code scanner on the market which could match this speed. Our solution was to use the highest speed PC available as a buffer between the scanners and the application (on the UNIT). The solution was 2 x Intermec MS 4200 STD scanners connected to a Dell 486 66 MHz PC.

It is within the contemplation of the invention that the manufacturing system described is the preferred embodiment of the invention and that the scope of the invention applies to any variants of the elements and processes, or indeed the orientation or number of said elements and processes described herein.

Referring now to FIG. 4, a diagram of an architecture of a manufacturing system, according to the preferred embodiment of the invention, is shown.

In operation, the PC is NFS (Network File System) mounted on the UNIX system, giving it a remote hard disk on the UNIX system. This eliminates the complications and time delays introduced by communication protocols. All information transfer is done via files which are readable from the UNIX application and the PC. The main set-up files are maintained on the UNIX system and it is against this, that the d-axis is checked. All data loading and user interface is via the x-terminal which accesses data directly on the UNIX system.

All feeders are bar-coded. On feeder loading, the operator scans the feeder number and the P/N bar-codes, thereby assigning a P/N to a feeder.

There are two high speed bar-code scanners mounted on the back of the Sanyo 1000. No vendor system was found which was fast enough to match the speed of the d-axis moving. A 486 PC (66 MHz) is used to buffer the data from the scanners, to match the speed of the machine. The scanners read the feeder bar-codes every time the machine restarts, after an error occurred or after the machine has been stopped. The PC compares the data with a set-up file mounted on the CAM system. If there is a difference a signal will be sent to the machine, thereby stopping the machine before a wrong component has been placed.

The PC is NFS mounted on the CAM UNIX system thereby eliminating the need to upload and download data. The system also tracks feeders usage. After a certain amount of placements a feeder will be locked because a service/ maintenance is required. After service/ maintenance of the feeder it is ready to be used again.

The system also tracks feeder reject rate. If a part is picked from a particular feeder are being rejected at a large %, a message will be displayed to the operator allowing them to take some corrective action. The system will inform the operator when a feeder is running low, thereby allowing the operator to load another feeder and have it ready for a fast replacement. This will increase the machine utilisation.

The system will also indicate to the operator what other feeders are running out (underneath a certain threshold). The operator can then prepare replacements. When the machine stops they can then chance all the feeders in one go. The number of machine stops for feeder replacement will be increased thereby increasing machine utilisation.

Advantageously, the manufacturing system continuously scans the feeders (all feeders have bar-codes) and checks the set-up during the chipshooter's operation, without interfering with the production run. If the system finds a wrong component in the wrong position it immediately stops the machine before the wrong component is placed.

In summary, a number of vendors have implemented systems to check that chipshooter d-axes are set-up correctly. The advantages and requirements of such a system are obvious to anyone skilled in the art of surface mount technologies. Experience has shown that it is inevitable that wrong components and/or feeders will be loaded on the wrong position on the chipshooter. This can result in a large number of defects and rework costs. The challenge of unmarked components and bulk feeders has increased the necessity for such a manufacturing system.

Existing concepts, including the monitoring of feeders for removal and ensuring that they are checked before production is restarted, have proved unsatisfactory and costly. The manufacturing system proposed herein continuously scans the feeders, with the feature that each feeder has an individually assigned bar-code, during the chipshooter's operation.

Such a system required the development of a high speed bar-code scanning system and a d-axis position monitoring system, as described. These are combined to give a continuous real-time monitoring capability of the d-axis of the manufacturing system. The manufacturing system also includes a loading station and feeder reservation for particular component families.

Advantageously, the ability to track feeder usage, the scheduling of preventative maintenance checks, tracking feeder reject rate and highlighting problem feeders to the operator, informing the operator when a feeder is running low and allowing them to prepare replacement feeders, is provided.

Thus a manufacturing apparatus and method of operation are provided that are an improvement over, and more flexible than, prior art manufacturing systems and processes.

Claims

1. A method for controlling feeders in a chip shooter manufacturing system comprising a plurality of feeders, wherein each feeder of the plurality of feeders is respectively identified by a first bar-code label and holds a component reel identified by a second bar-code label, and at least one bar code scanner, the method comprising the steps of: scanning the first bar-code label of a respective first feeder automatically by the at least one bar code scanner to obtain a respective first feeder number; scanning the second bar-code label of a respective first component reel held in the respective first feeder by the at least one bar code scanner to obtain a respective component part number; and assigning the respective component part number to the respective first feeder number.

2. The method for controlling feeders in a chip shooter manufacturing system in accordance with claim 1, wherein the chipshooter manufacturing system includes a sensor array, the method further comprising the steps of: sensing a position of the respective first feeder in at least one plane by the sensor array; and determining a respective component part number for the position of the respective first feeder in the at least one plane.

3. The method for controlling feeders in a chipshooter manufacturing system in accordance with claim 2, wherein the at least one plane is a axis of the manufacturing system.

4. The method for controlling feeders in a chip shooter manufacturing system in accordance with claims 1, 2 or 3, wherein the manufacturing system further comprises at least one terminal operably coupled to a controller and to the chipshooter manufacturing system via at least one interface element and a data communication link.

5. The method for controlling feeders in a chipshooter manufacturing system in accordance with any one of the preceding claims, the method further comprising the steps of: comparing the respective component part number and position of the respective first feeder with a stored component part number and stored position in a master record of the at least one terminal to determine whether the chipshooter manufacturing system is ready for correct operation.

6. The method for controlling feeders in a chip shooter manufacturing system in accordance with claim 5, the method further comprising the steps of: stopping operation of the chip shooter manufacturing system automatically when there exists a difference between the respective component part number and position of the first feeder with the stored number and stored position in the master record of the at least one terminal.

7. The method for controlling feeders in a chipshooter manufacturing system in accordance with any one of the preceding claims, the method further comprising the step of: tracking automatically a number of components held on a component reel on a respective first feeder to determine whether the number of components is below a threshold value indicating that the component reel needs to be replaced.

8. The method for controlling feeders in a chipshooter manufacturing system in accordance with any one of the preceding claims, the method further comprising the step of: tracking automatically a number of placements by each feeder of the plurality of first feeders to determine whether the number of placements of a respective first feeder is above a threshold value indicating that the respective first feeder requires a maintenance check.

9. A chipshooter manufacturing system comprising: a plurality of feeders wherein each feeder of the plurality of feeders is respectively identified by a first bar-code label and each feeder holds a component reel identified by a second bar-code label; at least one bar code scanner for scanning at least the first bar-code label; at least one sensor array for scanning a position of a respective first feeder in the manufacturing system; at least one terminal operably coupled to the at least one bar code scanner and the at least one sensor array for monitoring operation of the chipshooter manufacturing system and determining a respective component reel for the respective first feeder in a respective feeder position; and a controller operably coupled to the at least one terminal via at least one first interface element and a first data communication link for controlling at least one operation of the chipshooter manufacturing system.

10. A manufacturing system substantially as described herein with respect to FIG. 1, FIG. 2, FIG. 3 or FIG. 4 of the drawings.

11. A method for controlling feeders in a manufacturing system substantially as described herein with respect to FIG. 6 of the drawings.