Automatic Optical Inspection of electronic boards

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1 Automatic Optical Inspection of electronic boards Fahrenheitstraße Bremen Tel : +49 (0) Fax : +49 (0) info@prueftechnik-sk.de April

2 Automatic Optical Inspection of electronic boards

Presence and polarity verification on THT- and SMD components with an angle of 0-360 Test of component position (offset, angle) Solder joint inspection on all components (SMD and THT) Short-circuit

3 Presence and polarity verification on THT- and SMD components with an angle of Test of component position (offset, angle) Solder joint inspection on all components (SMD and THT) Short-circuit tests (solder bridges) Coplanarity and components height measurements Optical character verification (OCV) on components Display test (DOT-Matrix, Multisegment, LCD, LED) Barcode detection via camera Offline programming, offline debug with original test images Initial sample test LaserVision Testfeatures High efficiency and test depth up to 0201/0,3 mm pitch even for limited-lot production and a wide product range Optimized for fast throughput while retaining a high fault coverage Fast and comfortable test program creation Increase of fault coverage by combination of camera and laser test methods Economical solution for standalone operation or integration into production lines 2

As electronic components and devices manufactured with the aid of modern production technologies are being miniaturised to ever greater levels, conventional electrical test methods are only of

Focus on production efficiency Therefore test methods are required to meet the stringent quality requirements.

Optical test methods satisfy these requirements. There is no electrical contacting and tests which go beyond conventional electronic methods can be performed.

4 As electronic components and devices manufactured with the aid of modern production technologies are being miniaturised to ever greater levels, conventional electrical test methods are only of limited suitability and are very costly. Also, less and less time is left to gear up the production line to manufacture new products in large numbers. Focus on production efficiency Therefore test methods are required to meet the stringent quality requirements. They should be independent of the structural parameters of the items under test and electrical access to the nodes as well as being fast and easy to implement. Optical test methods satisfy these requirements. There is no electrical contacting and tests which go beyond conventional electronic methods can be performed. Furthermore manual visual inspection as an additional stage in conventional testing becomes part of the automatic test procedure. Optical test methods are ideal for monitoring the production process. Faults can be detected and eliminated at an early stage so that electrical testing may be limited to the electrical functions. Process monitoring The LaserVision system is designed to test insertion and soldering. This covers both the conventional assembly of components with leads (THT) as well as SMD technology. Production faults such as missing or wrongly inserted components, dry joints and shorts can be detected reliably without much programming effort. The optical test system combines three different test methods and so ensures extremely high fault recognition and low false alarm rate. This makes LaserVision system ideal for monitoring electronic production process. Also the inspection of lead free soldered assemblies, that becomes more and more important is can be done reliably with the LaserVision. 3

5 CombiVision - a custom-made solution Test of selectively soldered THT-components Special-purpose solutions are to be integrated into existing production processes. These can be e.g. the inspection of selectively soldered THT-components, which can be fed to the optical test via inline conveyor belts or robots. The parameters to be tested can be adjusted according to the IPC 610C norm. 4

Display test displays, for example dotmatrix, multisegment, LCD, LED can be tested.

By means of an additional function test device the combination with an electric test is also possible.

This combination saves a lot of space and handling time.

6 Display test displays, for example dotmatrix, multisegment, LCD, LED can be tested. Every pixel is tested for brightness and contrast. By means of an additional function test device the combination with an electric test is also possible. Complete test solution in one device The combination electric test and optical test with an UUT adapter. This combination saves a lot of space and handling time. Apart from that, the shared repair station concept and statistic analysis optimizes the workflow and saves expenses. Functional optical features e.g. displays and LEDs can be tested additionally. This results in a larger test range as with the classical AOI and therefore a higher product quality with lower total costs. 5

Flexible configuration LaserVision has a modular system architecture and offers numerous options for the easy adaptation to a wide variety of requirements.

7 Flexible configuration LaserVision has a modular system architecture and offers numerous options for the easy adaptation to a wide variety of requirements. The system comes in a stand-alone and an inline version. An expanded working area is available. The system is equipped with a transport system and a barcode scanner to facilitate its integration into automatic production lines. Communication between the system and the production line complies with the SMEMA standard. LaserVision The basic configuration comprises: Process controller, PC last generation X/Y positioning unit 2 CCD cameras and Laser-Height-Measurement unit or digital Megapixel cameras (lenses with different resolutions) Illumination-unit LaserVision software including self test and offline-serialdebug function and remote service system Software for repair and components position search (LV-Repair, LV-Board) Software to convert CAD-datas (LV-Cad) and the Statistic Module (LVStat) Documentation The AOI System LVCompact with it s performance as a standalone tabletop unit for a fair prize is especially interesting for: - Limited-lot production and pre-production - Repair station - Initial sample test - Incoming goods inspection The system comes with an operating range of 200mm x 300mm that is captures by means of a X/Y moving unit with one analog camera. The software is completly adopted from time-tested system LaserVision and therfore offers the same advantages, such as the comfortable creation of test programs from the CAD-data, statistics, offline programming and the possibility for a seperated repair station. 6

Inline application LaserVisison with repair station LaserVision Cameras Camera type Resolution Operating range THT 65 µm 51 mm x 34 mm OCR 21 µm 15,7 mm x 11,4 mm SMD 16 µm 19,8 mm x 16,3 mm FINE 10

8 Inline application LaserVisison with repair station LaserVision Cameras Camera type Resolution Operating range THT 65 µm 51 mm x 34 mm OCR 21 µm 15,7 mm x 11,4 mm SMD 16 µm 19,8 mm x 16,3 mm FINE 10 µm 12,2 mm x 10,0 mm The options Additionally the LaserVision can be adjusted to the individuel requirements by several amplifications: Megapixel cameras to increase the test speed Up to max. 4 cameras to increase the throughput Different camera resolutions e.g. for fine pitch or THT Expanded operating range for inspection of very large assemblies Software for character verification (OCV) Additional camera and LED-flash for detecting laser engravings Unique offline-programming software (faciltates world-wide programming, application support and troubleshooting with original production data, via modem) Display-test toftware for: Dot-Matrix, Multisegment, LCD, LED Statistic Module Laser-Height measurement systems In its basics configuration the LaserVision can be used for example as a stand-alone solution for production process monitoring. The PCBs to be inspected are manually placed into a drawer with adjustable DUT adapter. A basic version and an enhanced version are available depending on the scope of functions required. 7

All systems, ranging from the customized special solution to the high volume inline system are implemented with a longtime

This facilitates a continuing improvement of the software and the extensive functionality of the individual systems.

production as well as a standalone solution for a selective soldering machine.

9 All systems, ranging from the customized special solution to the high volume inline system are implemented with a longtime estabished software. This facilitates a continuing improvement of the software and the extensive functionality of the individual systems. All systems can be freely configured by means of their options and can be engaged according to the demands of an high volume production as well as a standalone solution for a selective soldering machine. The following owerview offers the possibility to choose individually the solution best suited to the own demands. Our systems and their performances 1 Customized special solutions such as display test, THT solder inspection, 2 LV Compact AOI table top unit Camera 20µm resolution 0402 / 0.65 Pitch components / h 8

3 LV4 S AOI Standalone 2 CCD cameras optional extendible SMD and THT 0402/0.

000 components / h 4 LV4 HS digital AOI Standalone Technology CameraLink optional

000 components / h 5 LV4 HI digital AOI inline Technology CameraLink optional

10 3 LV4 S AOI Standalone 2 CCD cameras optional extendible SMD and THT 0402/0.65 Pitch components / h 4 LV4 HS digital AOI Standalone Technology CameraLink optional extendible SMD (MPixel) 0201 / 0.35 Pitch components / h 5 LV4 HI digital AOI inline Technology CameraLink optional extendible SMD (MPixel) 0201 / 0.35 Pitch, components / h 6 LV4 HI 4M digital AOI inline Technology CameraLink optional extendible SMD (4MPixel) 0201 / 0.35 Pitch components / h 9

Any test method has its strengths and weaknesses.

Image processing allows visible characteristics to be detected optically and analyzed, whereas with laser triangulation height differences can be measured accurately.

Combined test methods Image processing Up to four CCD-cameras in vertical plane take images of sections of the PCB under test.

The different resolutions of the two cameras and the height clearance provided make it possible to check both very small and very large or tall components.

11 Any test method has its strengths and weaknesses. Therefore, we combine three different test methods: Optical image processing Laser height-measurement Character verification (OCV) Each method has its own specific advantages. Image processing allows visible characteristics to be detected optically and analyzed, whereas with laser triangulation height differences can be measured accurately. The component inscription is checked by means of character verification. Only combining these three methods guarantees an optimal test depth. Combined test methods Image processing Up to four CCD-cameras in vertical plane take images of sections of the PCB under test. The integral lighting ensures optimum and reproducible illumination, which is a prerequisite for reliable inspection results. The different resolutions of the two cameras and the height clearance provided make it possible to check both very small and very large or tall components. An X/Y positioning device positions the test head, compromising cameras, laser and lightning, above the board to cover the region of interest (ROI) defined in the inspection plan. The selection and positioning of the cameras is optimised so that every picture includes the maximum possible number of components. Camera homogeneous illumination The components are detected with the aid of standardised routines that search specific features, so that the presence, the exact position, the right polarity and solder joints of the components can be checked. Supplementary position correction using local fiducial marks for fine positioning of the inspection area guarantees reliable measurements. Also solder shorts on SMD components and bridges between adjacent pins up to fine pitch scale are found. In conjunction with additional hardware for PCB stimulation, also displays can be tested (Dot-Matrix, Multisegment, LCD, LED). The display test is a sensible enhancement that supports electrical tests. vertical reflection (missing solder joint) lateral reflection...electrolytic capacitor with wrong polarity...solder joint missing...ssop with solder bridge... upright chipcapaciter (tombstone) 10

Laser heightmeasurement The laser beam of our Laser triangulation unit is focused on the DUT for contact less distance

integrated Circuits it is essential not only to verify the presence and orientation of components, but also to check whether

Therefore the system can be extended with an optical character verification (OCV) option which allows the inscription on

The inscription is detected by a camera and compared with stored fonts by a special software package based on artificial

12 Laser heightmeasurement The laser beam of our Laser triangulation unit is focused on the DUT for contact less distance measurement. The distance is measured by evaluating the diffusely reflected laser light with a position-sensitive detector. Standard routines such as height difference and coplanarity measurement and options such as height profile scanning, facilitate program generation. f Fotoempfänger a k Laserdiode l A B Laser-scan profile of a component Laser height-measurement is a useful back-up to image processing as it can also be used where inadequate contrast, changing structures and colors prevent the reliable evaluation by image processing. Character verification Laser engraving on IC only visible through special lighting Character verification In the case of integrated Circuits it is essential not only to verify the presence and orientation of components, but also to check whether the correct component type has been inserted. Therefore the system can be extended with an optical character verification (OCV) option which allows the inscription on components or PCBs to be examined. The inscription is detected by a camera and compared with stored fonts by a special software package based on artificial neural network. Conventional OCR software is not suitable as it cannot handle non-uniform colour distributions, indistinct contours or line breaks. With an additional camera and special lighting even characters generated by stamping or laser engraving, which are difficult to handle with other approaches, can be read. The combined of the different test methods and types of lighting considerably improves the test depth of the system and the reliability of the results, even when the engraving is illegible and differs during production period. 11

Generation of inspection programs Inspection programs are generated either manually by graphic-based selection of teststeps or by importing CAD data.

13 Generation of inspection programs Inspection programs are generated either manually by graphic-based selection of teststeps or by importing CAD data. The automatic generation of an inspection program is always based on the board assembly data. A software package which provides extremely flexible format conversion and easy adaptation to different CAD systems converts the CAD data into the LaserVision format. Wide range of operation, easy to use The entire program is generated from the type and position information of the individual components as well as with the aid of the component-specific routines stored in the library. Many parameters for each routine can, if required, be subsequently determined and modified with a computer. LaserVision comes with a manageable number of standard routines and inspects any commercially available components by using a combination of these routines. Furthermore, the user can generate his own tests by modifying and combining existing test types. Depending on the system configuration, he can create his own component libraries. Parameterization interface CAD data Test program CAD conversion, automatic inspection test program creation Local parameterisation (debugging) Optimized test program Principle of program generation The complete inspection program and single steps are ready to run as and when required without prior compilation. Direct editing is also possible. Because menus guide the user through the operation and programming of the system, there is no need to learn a special programming language. Automatic test route and camera optimisation After the inspection program has been generated, camera and test route can be automatically optimised. The test step sequence is changed so that camera positions and selection have to be modified as little as possible, which minimises the overall run time of the program. 12

Offline programming Most of the programming and optimisation can be performed with a separate workstation within the network, using the offline-version of the programming software, available as an

The offline programming software works with the real allocated production images, a serial debug is very fast, because a change of parameter can be tested over several board-images at same time: Our

14 Offline programming Most of the programming and optimisation can be performed with a separate workstation within the network, using the offline-version of the programming software, available as an option. This means that Laser Vision is always available for board inspection and never blocked out by program generation. The offline programming software works with the real allocated production images, a serial debug is very fast, because a change of parameter can be tested over several board-images at same time: Our unique Offline programming software, enables world wide programming-, application support and troubleshooting with original production data. Tools for the production floor The system also features a wide range of functions that support its use in electronic production: Inspecting variants of components and PCB-assembly Programming of alternative test criteria Disabling the inspection of non-assembled panels (BAD-Board) Barcodes can be read by camera or an additional scanner. The corresponding program is started automatically. Fast prototype inspection When the production line has to be reequipped for a new product, the set up of the insertion systems is usually checked prior to series production start up. In most cases, this check take several hours because the board that is produced has to be compared manually with a sample board or bill of material. The System has computer-aided image comparison which cuts inspection time by typically 75%. Solder paste inspection Visual comparision The basis of good soldering results is a fault free solder paste print. The LaserVision checks the presence and defects of the solder paste in a defined test region. The test region is adjusted exactly at the border of the test. For automatic test generation the CAD data is used. In the first step the presence of older paste is checked, second the system checks the quality of the print. A further (optional) test step checks the solder paste for defects. 13

Results and Statistic The results, including the date and time of day and information about the program version used and the machine number, are stored in a result file.

Verifying and repairing faults The faults LaserVision has detected on the board can be displayed and classified by the LVRepair software package.

Note: The images of the total boards can be generated by LaserVision. The CAD- Data applying to each component and position are processed by the LaserVision opera ting system.

With LVBoard faults can be localised easily. If there is a tolerable fault, the user can go on to the next picture. During repair, the faults can be classified to customer needs e.g. as: true, pseudo, tolerable or repaired.

15 Results and Statistic The results, including the date and time of day and information about the program version used and the machine number, are stored in a result file. This means that all the details of a completed inspection run are stored and can be reproduced as required by the ISO 9000 standard and product liability legislation. Verifying and repairing faults The faults LaserVision has detected on the board can be displayed and classified by the LVRepair software package. The picture of the fault is enlarged and can be assessed within a few seconds during the inspection process. Faults found what to do? Note: The images of the total boards can be generated by LaserVision. The CAD- Data applying to each component and position are processed by the LaserVision opera ting system. This feature can be used also on each repair station independently of LaserVision. The generation of the data is one of the services offered by Prüftechnik Schneider&Koch. With LVBoard faults can be localised easily. If there is a tolerable fault, the user can go on to the next picture. During repair, the faults can be classified to customer needs e.g. as: true, pseudo, tolerable or repaired. Customer-specific repaircodes and description can also be allocated to each fault. The fault codes and data formats are user-configurable. The software can also control a component dispenser so that the correct replacement components are always available. The LVBoard which localises faults, is working parallel to Repairsoftware, but can also be used separately or together with the System Vision software or as a separate tool. On the basis of the CAD data and the board picture, it is possible to show the position of a component on the board or its designation and material code. The fast localisation of faults considerably increases repair region productivity. Faults are teaching the process, SPC All data collected can, irrespective of format, be transferred to a super ordinate quality management system. This feature guarantees that this valuable information can be used for statistical analysis showing weak points and remedial action to be taken to optimise the production processes. For the stand alone operation of LaserVision, a statistics module can be installed directly on the system. 14

16 LaserVision Systems Technical Data System Version Standalone-System Image processing with CCD cameras, resolution SMD with adapter for PCBs High Speed Standalone-System Image processing with 1 digital camera, resolution SMD, drawer with adapter for PCBs High Speed Inline-System Equipment version as LV4/HS but with transport system with PCB clamping and support System components, hardware Image processing computer Pentium with operating system Windows 2000, Image processing card Matrox, exchangeable hard disk, ethernetcard, ISDN/Modem for remote support LCD-Monitor 17 XY-positioning unit Working area Standard configuration Enlarged area (Optional): Other cameras to increase throughput and test coverage (CCIR or digital) Digital Resolution 65µm (THT, CCIR) Resolution 20µm (SMD, digital) Resolution 9µm (FINE, digital) Additional camera with special lighting for optical character verification (OCV) on components with laser gravures Color camera Height measurement by laser triangulation Laser: safty class 2; red 675 nm Choice of two working areas: Working area l: mm, accuracy ±20 µm Working area II: mm accuracy±100 µm Accurays depending on test surface reflection Pass through height Above: mm (depending on configuration) Below: mm (depending on configuration) Inspection speed Depending on board design and configuration: on request General Data Power supply Certificat Dimensions in mm Weight Operating temperature Operating humidity Inline-System Compressed air Assembly line height Communication with assembly line LV4 / S LV4 / HS LV4 / HI 437 mm x 330 mm on request 110V / 6A o. 230V / 3A CE (EU-standarts, machine-directives incl. EMC etc.) 1550 x 1000 x 1040 (H x W x D) Approx. 200 kg 10 C to 35 C <80%, none-condensing 6 bar 840 mm +/- 25 mm 890 mm +/- 25 mm 940 mm +/- 25 mm SMEMA Software Standard routines for image processing Component angel supported Presence and polarity verification on all THT and SMD components Measurement of component position (offset, angle) Solder joint inspection on SMD and THT components Solder joint inspection on IC's, including THT Short-circuit tests (solder bridges) Solder paste inspection (2-D) Standard routines for laser height-measurement Height difference measurement to measure presence and height of components Height profile measurement in a specific region Coplanarity measurement Production tools, documentation Automatic storage of test results User definable result messages Data logging of test results, flexible output (ASCII) format, transfer to an external QMS Fault Statistic, yield-meter, SPC (LVStat) Graphical repair station, (LVRepair) Graphical board view, (LVBoard) Offline serial debugging Remote service / debugging via modem/ ISDN Communication with production line over various interfaces Barcode readable with camera Options Optical character verification (OCV) on components, license Display test to test each dot (Dot-Matrix, contrast and brightness) CAD data conversion tool, license for LVCAD Offline programming, remote station additional License for LVRepair, LVBoard, LVStat Program generation Automatic program generation from CAD data CAD-Overlay, automatic changemanagement of board revisions Integrated user guidance (Wizard) for CAD-data conversion Automatic camera and test route optimisation Automatic generation of panel board inspection plan from a master program (max. 999 boards per panel) Skipping of non-assembled boards in the panel Array test for easy reproduction of similar individual routines Automatic generation of programs for first off (comparison with golden board) Board position and local area alignment with up to 3 fiducials Inspection alternatives for component versions Support of insertion variants (up to 255) Inverting of test results of not assembled components Test of components not to be assembled Output of user-definable Pass/FAIL messages 15

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