YesTek AOI Users Manual YesTek Ltd 511 Ritchie Park Johnstone Renfrewshire PA5 8JP Tel 01505 321528 Fax 01505 350047 aoi@yestek.co.uk www.yestek.co.
Table of Contents
Automated Optical Inspection of Printed Circuit Board In recent years, Automated Optical Inspection (AOI) has become an integral Device of the PCB manufacturing and quality assurance process. AOI systems complement in-circuit testing in areas where probe point access is limited. In comparison to human visual inspection of PCBs, AOI is much faster, more accurate and consistent. In addition, AOI offers SPC tracking and process traceability.
The ScanSpection Systems Yestek currently offers three different AOI systems: ScanSpection AOI Desktop, ScanSpection AOI In-Line and the X-Ray System. ScanSpection AOI is a powerful machine vision inspection systems designed specifically for fast, reliable and accurate inspection of printed circuit boards. The In Line systems have the ability to handle boards up to 450mm x 457mm in size.
Theory of Operation The SCANSPECTION AOI inspection process is based on comparison of PCBs under test with a known good board with all devices placed correctly. The setup process involves storing the images of a correctly assembled, good board. The inspection process compares the images captured from the board under test with the stored images of the known good board. In the real world there are three issues that must be addressed regarding theory of operation: 1.
System Operation User Interface Basics The system has two modes of operation, Operator Mode and Supervisor Mode. The system software starts in Operator Mode. Operator Mode provides limited access to system functionality. Operator Mode allows the user to perform a board inspection using existing board setups. However, the user cannot edit or create new board setups in Operator Mode. This prevents unintentional or unauthorised alterations to the board setups.
Video Window This window displays a video image of the board. A crosshair is provided to indicate the exact image position. The video navigation feature allows the control of the image position from this window. Since the resolution of the Scanner (1280 by 960) is larger than the display resolution (1024 by 768), the video window displays scanner images in 4 magnifications. Magnification No1 is the overall view the 1280 x 960 image is scaled down to be displayed in the 736 by 552 video window.
Map View The Map View Window provides a global view of the entire PCB. Each time a new Device is trained; a small rectangle will appear on the Map View indicating the Device position. A moving red rectangle marks the current Image position. The Map View is also a navigating tool: double-clicking the mouse on the map will move the Image to the corresponding position on the board.
Device List View This dialog contains four pages: Device List, Active Devices, Device Library and Package. Device List lists all the devices that have been trained on this board, the Active Devices page in most case list all the device that failed the inspection. It can also list devices that match selected criteria. The Device Library lists all the devices in the device library. The Package page lists the content of the package library.
Main Menu The main menu will appear differently in Operator Mode and in Supervisor Mode. Please refer to a later section for a description of each menu selection.
Toolbar The toolbar buttons provide a shortcut for a few very commonly used menu selections: Print If the Map or the Video window is active, pressing this button prints either image. Live Displays the scanned image. Capture Captures the current image and displays it as a frozen image. Toggle Toggles the video navigation tools on and off the screen. Zoom 1 Selects magnification 1. Zoom 2 Selects magnification 2. Zoom 3 Selects magnification 3. Zoom 4 Selects magnification 4.
Display ROI Redraws the device overlay. (Only active in Supervisor Mode.) Test Visible Area Inspects the devices in the field of view. (Only active in Supervisor Mode.) Hide Solder ROIs Toggle the display off all the solder ROIs so that the lead area menu can easily be selected. Align Begins the board alignment process. Home Moves to home position, the bottom left corner of the board. (Only active in Supervisor Mode.) Load Moves to board loading position. Stop Stops the inspection process.
Operator Mode The software always starts in Operator Mode. Operator Mode allows users to carry out day to day PCB inspection. All operators of the machine should be familiar with the Operator Mode operation.
Inspecting a PCB To start inspecting a PCB, first observe the caption bar of the main window to verify that the correct board setup is loaded. If so, you may start the inspection process by selecting Test Board from the File Menu. (or by pressing the button on the tool bar) The system moves to the load position and then the following dialog will appear to prompt the user to load in a PCB for inspection: There is one Check box, Enter Board Serial Number.
Board inspection begins according to the board setup. When the inspection is finished, the results dialog will display. This dialog shows the inspection results. The word PASS with a green background appears on the top half of the dialog if all the Devices inspected passed the inspection. If the examined board does not pass the inspection the word FAIL with red background will be displayed. The system is also equipped with a green PASS light and a red FAIL light.
Loading board Setup from Files To retrieve a board setup from disk, select Load Board Setup from the File Menu. If the current board setup has been changed, the system will prompt you to save the current board setup. Select Yes from the prompt dialog if you want the changes to be permanent. Then the following dialog will display: Select the board setup file and press the Open button. The system maintains a list of Most Recent Used (MRU) files for quick reloading. The MRUs are listed under the File menu.
Operator Mode Menu Reference File Test Board Starts the board inspection process. Load Scanned Image Loads image. Step Through Devices Interactively step through all the devices trained. Goto Supervisor Mode Goes to Supervisor Mode. Load Board Setup Loads a board setup from disk. Print Prints Video Image or Map View depending on which window is active. Print Setup... Printer Setup. Exit Exits software. a previously saved scanned View Toolbar Shows or Hides the toolbar.
Supervisor Mode In the Supervisor Mode, users are givens full access to all the system functionality. In this mode, users can create a new board setup or edit an existing one. The Supervisor Mode menu is an extension of the Operator Mode menu; it has many more selections. In addition to its main menu, there are several local popup menus, such as the Device menu and the Lead menu, which will pop up when the right mouse button is pressed. The popping up of the local menus is context sensitive.
Interactive Image Position Control Users can move the viewing position interactively using the Video window, Map View window, and the List View dialog box. The Video window provides the fine position control. There are three basic techniques: 1. Point-And-Shoot Double-clicking anywhere on the video window moves the image to that position.
ROI Manipulation The ROI (Region of Interest) is used as a tool to specify position and size. It is used throughout the software. For example, it is used to specify Device template position and size before the template training. The ROI can be just a rectangular box on the screen or it can have “handles” for users to manipulate its size. To move a ROI, point the mouse so that the cursor is inside the ROI; the mouse pointer changes shape to {bmc bm31.BMP} indicating the ROI is ready to be moved.
Training New Boards To start creating the board setup for a new board, select New Board from the File menu. The load PCB dialog will display prompting the user to load a board into the machine. A dialog appears to prompt user for the name (assembly number) of the board. From this dialog you also select the library mode for the new board training. After pressing OK on the dialog, the process of defining the dimensions of the board begins.
The prompt-guided process for defining the alignment marks begins with the following prompt: The user should position the Image so that the chosen left alignment mark image is near the centre of the screen. After pressing OK, the next dialog prompt appears. At the time this prompt is displayed, two ROIs appear in the video window.
To add a component to the board setup, press the Add Device button , move or size the ROI so that it cover the area of interest on the Device, then press the right mouse button. The system will train the template of the device, and then put up the Set Device Parameter dialog to allow the user to enter other parameters for the Device. The user should enter the Device’s reference ID, such as IC123, R1, etc., via this dialog.
Edit Board Setup An existing board setup can be modified at any time after its initial creation. Users can add new Devices, delete existing Devices, or alter the parameters of an existing Device. The board size can be re-defined, alignment marks can be re-trained, and its parameters can be altered. To add a new Device: 1. Position the Image so that the Device is in the field of view. 2. Press the Add Device button and define the Device. 3. Press the OK button on the small ROI dialog. 4.
Saving and Loading the Board Setup Users can save the board setups to disk for later retrieval. To save a board setup, select File | Save Board Setup from the Supervisor Mode main menu. The Save Board setup dialog will appear; the user should select the desired directory, and then enter a file name for the setup. The board setup file has an extension of .Board Setup. Since Windows allows long file names, a setup name such as “Board X123 Rev 10” will be accepted as a legal setup file name.
Create Defect Category List Users can supply a text file which contains a list of defect types for the software to use as categories for defect classification during defect review. Users can use any text editor to create the file.
Unclassified Missing Device Wrong Device Wrong Polarity Skewed Device Lead Bridge Solder Defect Other Users must save the file as DEFECT.INF in the same directory where the SCANSPECTION.EXE file is located, usually C:\Program Files\AOI. It is possible to use a user defined category number in the DEFECT.INF file.
LogFalseCall=1 .. With LogFalseCall enabled the Ignore button on the review dialog would become FalseCall button. The data logger would track all the False call.
Biscuit Copy and Paste The Biscuit Copy and Paste feature facilitates the creation of board setups for PCBs composed of a palette of identical biscuits of circuitry. With Biscuit copy and Paste, users create Device information for only one of the biscuits. After that, he/she can use biscuit copy and paste to duplicate the biscuits. For biscuits that are flipped 90 or 180 degrees, the System AOI has a special algorithm to rotate the Device information before pasting.
Since the top left corner of the biscuit is used for aligning the biscuit during pasting, while copying from the map view you must make sure that there are Devices near that corner and that they will show up in the video view during pasting. If you copy a biscuit like that shown in the following picture, you will have no way of pasting it correctly.
Enter the certain information and press OK. Here is an example PCB with 6 biscuits arranged in a 3 by 2 array, where X=3 and Y=2. The software will prompt user to select three points, the Bottom Left, Bottom Right and the Top Left reference points. The 3 reference points must be on the same relative position on the biscuits. Base on the position of these three points the software calculates the exact separations and the theta rotation for precise biscuit pasting.
The Paste Biscuit Array operation will automatically delete any previous biscuit devices before creating the biscuit array. So it is safe to experiment. After creating a biscuit array, if user is not satisfied with the placement accuracy he/she can tweak the placement by pressing the Fine Adj. Button in the Paste Biscuit Array dialog. The following dialog will display: Editing the parameters then press O.K. will cause the biscuit array to be recreated using the newly adjusted parameters.
Template Training Guideline The ScanSpection uses a template-matching technique to perform PCB inspection. The precision of the inspection results relies heavily on the quality of the templates selected. The basic idea is to select an area with distinctive and consistent markings on the device. Use the Magnification 2 for all devices larger than 0805. A high magnification amplifies any small differences of the device and increases false failure rate. 1.
5. Tantalum Capacitors: Magnification 1 or 2, pass score 700. Do not include any edge of the device. Enable polarity. 6. Electrolytic Capacitor: Magnification 1 or 2, pass score 650. Because of the rotation variance it is likely to need 6 or more alternates. 7. SOT: Magnification 2 or 3, pass score 650 - 600, select centre All Alternates. Depends on the label quality, it may be difficult to do wrong device detection on SOT device. Present or absent detection should be very robust. 8.
9. QFP-SOIC-BGA: Magnification 1or 2, pass score 700. Avoid the date code, train on the model number of the chip. If it is a long label you may need to break up the template into two or more “Templates”.
User Login and Tracking User can setup the AOI software to require operator login and tracking. To enable the login feature edit the Scanspection.ini file and set: [UserLogin] Required=1 If the login feature is enabled the login event is tracking in the Users.log To establish a list of approved users, system administrator should create the AppUsers.txt file in the same directory that the Scanspection.exe is located. (C:\Program Files\AOI) The AppUsers.
User Interface Basics Like all the software packages written for Windows, the ScanSpection software user interface consists of Windows, Dialog boxes, menus and a toolbar.
SPC Data Log Setup The SCANSPECTION AOI software can send inspection data to Microsoft Excel or an ASCII text file for display or statistical analysis. Because of the need to use long file names, only the Windows 95 version of Excel is compatible (that is, version 7 or Excel 97). This option is disabled by default. The data logger setup is done from the SPC Data Logger Setup dialog. To launch the dialog, select Functions | Setup SPC Log from the Supervisor Mode main menu.
Save Frequency specify how frequent data should be saved to disk. A 10 would mean every 10 board. After a Board Setup is loaded, if the data log is turned on, before any board inspection the software will prompt the user with the following dialog: There are three choices Append, Start New Log, or End Data Log. The Always Append check box in this dialog and in the SPC Data Logger Setup dialog set the automatic respond for this dialog is Append.
As an alternative to logging data into Excel, SCANSPECTION AOI can also log the information into an ASCII text file. Saving data into a text file is much speedier compared to saving data into Excel. To start logging data into a text file, select text file as the data destination, then specify a directory where the data files are to be stored. There are current two formats of ASCII logging. Users may change the format by editing the ScanSpection.INI file. [Excel_Intf] .. DataFormat=0 ..
Since each inspection machine needs to save files into the image folder, user must give write access right for each machine to write to that folder. Data Log Settings Global or Per Board Setup User may choose to set the scope of the Data Log’s configuration to be either global or per Board Setup. If it set to global the settings affects all the Board Setups on this machine. If it set to per Board Setup, then each Board Setup on this machine can have different Data Log settings.
CAD data Interface Overview The AOI is capable of reading CAD data intended originally for pick and place machines. Extracting Device data such as Device reference ID, Device position, and Device size from the board layout, CAD data can greatly simplify the process of creating board setups for inspection. The imported Devices merge with the Devices already existing in the board setup.
specifies the units of the Device co-ordinates. The base unit is micron. Therefore, a number of 1000 indicates the scale mm is used, 25.4 means the unit is mils. InvertXPos and InvertYPos specify whether the co-ordinates data need to be inverted during import. Sometime the position of the Devices on the bottom side of the PCB is represented using top side co-ordinates. In cases such as this, inverting one of the co-ordinates during import would be necessary. Use 1 if inversion is desired, otherwise 0.
prompted to verify the Device position. The three Devices are a Device closest to the bottom left corner followed by a Device closest to the bottom right corner, and then a Device closest to the top left corner of the board. Each time a prompt dialog is displayed, the user should move the highlighted ROI on the video window so that it is on top of the corresponding Device, and then press OK on the prompt dialog.
If the Device is not in the library, user will be prompt to train the Device, and then the software will add it into the Device library. Before pressing O.K on a newly trained Device, it is important to verify the Polarity Enable check box on the Confirm/Adjust Device Position dialog. The software default polarity enable to TRUE for Devices with Reference ID begin with Q, D and U, all other reference ID will have polarity enable default to FALSE.
During verifying Device placement, a menu can be pull down by have the mouse pointer inside the Confirm/Adjust Device Position dialog, and then depress the right mouse button. The Offset Device Position selection in the menu applies the offset user made to this Device’s centroid position (i.e. using the arrow keys) to all the Devices with the same Device number waiting to be placed. This is useful to correct problem CAD data where pin 1 position of an IC is mistakenly given as its centroid position.
Functions Options The System Options dialog sets a variety of options. Users can display the System Options dialog by selecting Functions | Options from the Supervisor Mode main menu. Inspection Auto Re-Start For off-line systems, if the option is enabled, the system will inspect the same board over and over again. For the in-line systems with conveyor, this option causes the next board to be fed into the inspect position for inspection.
Auto Re-Test Failed Devices If enabled, at the end of the inspection process the system will re-visit the Devices that failed and re-test them. This reduces the false failure caused by vibration of the system. This option can also be turned on or off in the Result dialog. Print Defect Map in Report If enabled, a defect map will append to the inspection report. Optional Biscuit Skip (X Out) In a biscuit board, one or more biscuits may be unpopulated (X Out).
Help button Displays the online help information.
SMEMA Conveyor Interface This feature is only applicable to ScanSpection In-Line machines. The AOI uses a conveyor as the means of loading and unloading the PCBs. The AOI’s conveyor interface is SMEMA compatible. The normal flow configuration is from left to right. That is the un-inspected PCBs flow in from the left side, received the inspection, and flow out to the right side of the machine.
Integrated Bar Code Reader Using barcode to serialise boards for tracking purposes is a common practice in the PCB industry. In the case of the AOI, the user can use a hand held barcode reader and have the operator scan every board before inspection. In addition to having a hand held barcode reader, users may purchase a “barcode reader automation kit” which includes a specially modified barcode reader, a triggering cable and a magnetic stand.
to press the START button to initiate the inspection. This is important when the bar-code has to be read with the loading door open. Load and Verify Board Setups This feature has two functions, one is using barcode information on the board to load a Board Setup, and the other is to verify the barcode of every board to ensure proper Board Setup is used for the inspection.
The edit box following the check box allows the user to specify how many characters in the bar code represents the board setup name. Help Button Displays online help information about the bar code reader.
Device Sub Menu The Device menu is a local pop up menu. It will display when the mouse is pointing inside a Device’s overlay box and the right mouse button is pressed. The Device menu is “Device sensitive”. This means it allows the user to change or test the parameters by pointing the mouse at the Device.
The button has the following functions: Close Next Delete Move To First Test -Closes the dialog box. -Displays the next alternate template. -Deletes the alternate from the list. -Moves the position of the alternate. -Moves this alternate to the beginning of the alternative list. -Test the current alternate. Show Template Displays the templates that were trained for the Device. Edit Search Area Sets a search area within which the Device is expected to be found.
Anchor Some fine pitched devices may need an additional fiducial to allow a more accurate test Dependent Some Devices need more than one template to identify the label. The dependent template is for that purpose. Move Device Allows the user to reposition the Device and its attachments (e.g., leads and Solder Inspectors) Label Moves Device without moving its attachments. Outline Move or resize Device outline. The centre of the Device outline defines the reference position for all the Device update.
Update Library Adds this Device to the Device library so that it can be used in different board setups. If the Device is already in the Device library, the following prompt will display: The user can choose from updating the Device already in the library or creating a new Device with a different Device number. If Update Existing Device is selected, you will be asked if you also want to update other instances of the Device in the Device list.
Understanding Device Positions It is important to have a good understanding of the positions used by the software. Here are several terms describing Device positions. Centroid Position A small purple colour cross or dot marks the centroid position. This is the reference position of a Device. Every other position is relative to the centroid position. The centroid position initially comes from the CAD data. The user can change the Device’s centroid position by changing its Device Outline.
Device Library Sub Menu The Device library menu is a local pop up menu. It will display when the mouse is pointing inside the library page in the Device List View and then the right mouse button is pressed. The Device library page of the Device List View allows multiple selections; that is, you can select more than one Device to process. You can also select a range of Devices. The menu selections Edit Active Devices, Delete Active Devices, and Update Board all support multiple selected Devices.
This menu selection supports multiple selected Devices. Edit Alternatives Edit alternative templates of the selected Device. Note: If you change an alternate template here, you need to do an Update All Instances to have the changes reflected on the Device list. Step Thru Selected Devices Step through all the Devices of the same Device number as the selected Device. Delete Selected Devices Deletes the selected library Device from the library. This menu selection supports multiple selected Devices.
Update All Instances After changing the parameters of a library Device, this menu selection can be used to update all the instances of the selected library Device in the Device list to the current parameters. This menu selection supports multiple selected Devices. Print Library Prints a list of all the Devices in the library. Show All Devices/Show Only Devices in Use The menu toggles between “Show All Devices” and “Show Only Devices in Use”.
Map Window Sub Menu The Map Window menu is a local pop up menu. It will display when the mouse is pointing inside the Map Window with the right mouse button pressed. Go to Grid Home Moves the Image to the bottom left grid line crossing. Set Map Reference Sets Map Window Reference position (bottom left corner of the map) to the current position. The Image must be looking down at the bottom left corner of the map when you activate this menu selection.
Board Setup File Structure This section explains how the system stores the Board Setup information on the hard disk. The board setup information is saved when the user selects File | Save Board Setup from the main menu. The user is prompted to enter or select a board setup name from a dialog box. The software then creates a file on the hard disk using the name with extension .Board Setup. However, the .
SETTINGS.PAR SETTINGS.LIB SETTINGS.PKG T0000001.TPT T0000002.TPT T0000003.TPT ... ...
Verify Device Template Quality The AOI system relies on unique, good quality templates to detect board defects such as missing Devices, wrong Devices, etc. False escape can be costly and is not acceptable. Since defects on PCBs are rare, no more than a few Devices per thousand, after training the board, it is difficult to know if all templates are trained good (i.e., that they will not produce any false escapes).
Local and Central Device Library The AOI software allows users to select either local or central Device library. There are advantages and disadvantages of both types of library settings. When using a local library, changes from one board setup will not affect the other board setups. This prevents a mistake from one board setup contaminating other good board setups. However, with local library a desirable change from one board setup will also not cause other board setups to update accordingly.
Reconcile Device List means to update the Device list information to comply with the Device library information. This action is needed when you switch libraries. Check Templates check all the templates in the central library Devices for cross contamination (i.e. template for one Device mistakenly assign to a different Device) Restore Backup The central library is protected by five levels of backups (backup1 to backup5). Backup of the central library file are done automatically every day.
Since the software will always use the currently loaded board setup’s library as the starting point of a new board’s library. You must always remember to load the latest board setup before doing File ,New Board Setup to create the board setup for a new board. This is not always practical especially if you have more than one person programming the machine. You can get around the problem by development the habit of always saving the board you just trained as e.g. LastBoard.bsu.
select Central library, then press the Browse... button to select the settings.lib file in the central lib directory. The sub-directories are normally created with hidden attribute. If you cannot see the central lib sub-directory go to Windows Explorer, View menu, select Option.., then select Show all files. You can create multiple central libraries; make one for each of your customers.
System Check up This section lists a simple test procedure that checks system hardware functionality and parameter integrity: 1. Start the system from a complete shut down. Observe the stage homing sequence. For the off-line Scanspection, the Image moves to the right and the table moves back, then both axes reverse directions and stop near the centre. For the in-line AOI, the Image transport moves towards the front right corner, then both axes reverse directions and stop near the centre.
Map Window Current Position Mismatch In the Map View a red rectangle represents the current position of the Image. It should represent the correct position with respect to the board. If for some reason the map view current position does not correspond to the actual Image position, the following steps should be taken to rectify the situation: 1. Press the Home button on the toolbar. The system should return to the bottom left corner of the board.
ROI box and Actual Device Position Mismatch The system overlays a rectangle on all the Devices that were trained. When the Image moves, those rectangles should stay with the corresponding Device on the board. If they do not, the following steps need to be taken: The rectangle could be slightly off the Device; that is normal, but if the rectangles are drawn at completely wrong positions, the home position may have been lost. To restore the home position, simply press the Align button, on the Toolbar.
Switching Images Changes the Viewing Position The ScanSpection system uses multiple Images to accomplish the inspection process. The Images are located at a fixed offset from each other. To simplify the user interface and to reduce the confusion to the user when the system switches Images, the system automatically repositions the Image every time there is an Image change. This ensures that the video cross hair stays with the same position on the board before and after an Image change.
Error Messages This section lists the common error messages: xxx Device to big (or xxx Lead area to big) All inspection ROIs (for Devices, lead areas and solder area) must be small enough to be inspected in one field of view. To allow for search area the ROIs itself must be smaller than 75% of the field of view. This error message indicates one of the Device exceed this size limit and cannot be inspected. Upon seeing this message user must investigate and fixes the problem Device.
Appendix I Sample CAD Data Exchange File .Scanspection_CAD_EXCHANGE Version 5 BoardName Scale 10 InvertXPos InvertYPos BoardRtn YESB06 IssE 0 0 0 Rot’nOffset 0 .DATA_START Ref.
Solder and Lead Inspection Introduction Statistically solder defects are the most numerous amongst all the PCB manufacturing defects. A few common solder defects are insufficient/no solder, solder bridge between leads, excessive and improper wetting. Due to the fact that variation amongst good solder joints are substantial, solder inspection presents a great challenge to AOI machines. Moreover, determining a solder defect is somewhat subjective.
Extension DLLs To increase the flexibility and extendibility of the solder inspection, we implemented software architecture to allow additional software modules to be added to the core software at a later time. This architecture allows us to easily satisfy special inspection requirement without the risk of compromising the core software integrity. We call the additional module “extension DLL.” An extension DLL can add new vision algorithms and control to the software at Test Board-time.
Appendix VII: Sample LVIDEO.INI File Listing [LiveVideo] Board=M_13 LineWidth=1 StatusFlag=14 XhairX=0.5 XhairY=0.5 XhairLen=0.1 ScaleX=70.0058 ScaleY=70.0058 ScaleRef=0 CScale0X=51524.3 CScale0Y=38643.2 CScale0Ref=0 CScale0XOff=0 CScale0YOff=0 CScale1X=29598.2 CScale1Y=22198.6 CScale1Ref=33 CScale1XOff=0 CScale1YOff=0 CScale2X=24461.2 CScale2Y=18345.9 CScale2Ref=66 CScale2XOff=-1642.74 CScale2YOff=-62632.8 CScale3X=14094.5 CScale3Y=10570.9 CScale3Ref=99 CScale3XOff=-1642.74 CScale3YOff=-62632.
CScale5Ref=115 CScale5XOff=0 CScale5YOff=0 CScale5Theta=0 CScale6X=10000 CScale6Y=10000 CScale6Ref=130 CScale6XOff=0 CScale6YOff=0 CScale6Theta=0 CScale7X=10000 CScale7Y=10000 CScale7Ref=145 CScale7XOff=0 CScale7YOff=0 CScale7Theta=0 CScale8X=10000 CScale8Y=10000 CScale8Ref=160 CScale8XOff=0 CScale8YOff=0 CScale8Theta=0 CScale9X=10000 CScale9Y=10000 CScale9Ref=175 CScale9XOff=0 CScale9YOff=0 CScale9Theta=0 CScale10X=10000 CScale10Y=10000 CScale10Ref=190 CScale10XOff=0 CScale10YOff=0 CScale10Theta=0
Solder and Lead Inspection Introduction Statistically solder defects are the most numerous amongst all the PCB manufacturing defects. A few common solder defects are insufficient/no solder, solder bridge between leads, excessive and improper wetting. Due to the fact that variation amongst good solder joints are substantial, solder inspection presents a great challenge to AOI machines. Moreover, determining a solder defect is somewhat subjective.
Extension DLLs To increase the flexibility and extendibility of the solder inspection, we implemented software architecture to allow additional software modules to be added to the core software at a later time. This architecture allows us to easily satisfy special inspection requirement without the risk of compromising the core software integrity. We call the additional module “extension DLL.” An extension DLL can add new vision algorithms and control to the software at Test Board-time.
Understanding Fiducials ScanSpection software uses two alignment marks to correct for placement difference between boards. Alignment marks have fixed XY locations. The software uses the fixed XY locations as a reference to determine what compensation is needed for a particular board under inspection. There are two kinds of positional compensation; one is translational and the other is rotational. The software uses the left alignment mark to calculate translational compensation.
error mapping. The layering scheme allows the ScanSpections to have transferable Board Setups without requiring the machines to be built identically. (such machines are unable to be manufactured.
Lead Inspection In the AOI software the lead inspection and the solder inspection are treated separately, specifying a lead area is for the detection of solder bridge between the leads of an IC. Solder areas are for the detection of other solder defects such as insufficient or no solder. Training leads area A lead area is associated with a device trained prior to training its leads.
Edit Parameter Launch the Lead Inspector Parameter dialog. Extended Parameter This menu item is disabled for algorithm 10. For algorithm 11, the following dialog display: Pitch - Separation from one lead to the next can be in Thou or microns. (typical values, 20 Thou,25 thou,50 Thou) Regularity Tolerance - High regularity mean the lead to lead separations are almost the same from one another. Set this tolerance to detect bend leads or missing leads.
white image. In the software the threshold is automatically set to the average value of the entire lead sector. However, user can use this Threshold Bias parameter to offset this value. If a 10% bias is applied the actual threshold value would be: average pixel value * 110%. The acceptable range is -100% to +100%. Double Width End Leads -On some board layout the end pad is made twice the width of the other lead pad. This check box informs the software of such layout.
Move/Resize This function allows gross move or re-size of the lead area. Delete Lead Inspector This function deletes the entire training of the current sector independent of the training mode. The sector is totally erased along with its training settings. Train Solder Area This function allows the creation of an array of solder area definition for inspecting solder quality on each lead's tip. The software prompt user to enter the number of lead in this area with the following dialog.
Base on the users' input appropriate number of solder area would be created. Update Lead Areas This menu selection set the parameters of all the lead area on the board base on the current lead area. The software prompts the user for the scope of the update with the following dialog. Train Anchor Train anchor object for runtime position compensation. Test Lead Inspector This Test Boards an inspection over the respective sector.
Solder Inspection The user can define the Solder Inspector only after the Device has been trained. From the Device pop up menu, there is the selection Define Solder Inspector. Upon selecting the item, the software prompts the user to draw a ROI (Region of Interest) around the area where the missing solder condition is to be detected. After defining the area, the following dialog will display: From this dialog, the user enters the parameters for the Solder Inspector.
Pattern Recognition the following dialog display: When using algorithm No1 i.e. Pattern Recognition for solder inspection, user trains the templates of a good solder joint. During inspection every solder joint images are compared with the templates. A score is produced and is compared with the pass score (e.g. 600) to produce a pass or fail indication. The technique is very similar to the way a Device is inspected. However for solder inspection the Top light is recommended.
Algorithm No2 i.e. the histogram analysis can be used to check for missing or insufficient solder condition. It is fast and effective, as long as the ROIs are placed precisely on the solder joints. This limits it effectiveness only to the large to median size discrete devices. To increase its effectiveness on smaller devices Anchors can be used. Using Anchors will increase the complexity and make the Board Setup more difficult to maintain or transfer.
Train Anchor Train anchor object for Test Runtime position compensation. Test Solder Inspector This function verifies the training parameters by performing an inspection on the selected solder area. Depends on the algorithm selected different result dialogs may display. . Set Defaults Set the parameters of the solder area as the default parameter for later solder area creation.
Step Through Devices Solder and lead inspections require a more accurate definition for the inspection area compared to "Device's marking" inspection. The Step Through feature of the software has been extended to allow the fine adjustment of the inspection area. The Step Through feature can be accessed via the File menu Step Through Devices. During Step Through, the arrow keys on the keyboard move the inspection area one pixel at a time while the space bar is used to move to the next Device.
Select Offset Device Position and the following dialog box will display: From this dialog box the user can select the application scope of the offset. For example if "Same Part Number" is selected, the XY adjustments made to the current Device will apply to all the Devices with the same Part Number.
Using Anchor The Anchor provides Test Board-time position compensation for the solder areas and lead areas. The use of anchor is necessary for inspecting solder condition on the fine pitch leaded device with algoritmNo2 (AlgorithmNo1 is self-anchored). To detect solder defect such as missing solder or lifted lead on that fine pitch lead tip it is necessary to have the inspection box (ROI) "lock on" to the lead tip position.
Parameters Launches the parameter dialog for setting anchor parameters Set Search Area Set search area of the anchor object. Set Coverage Area Specify an area of which the offset product by the anchor is applied. Move/Resize Move or change the size of an anchor. If the size changed, the anchor will need to be retrained. Delete Anchor Delete the anchor.
Package Library A package defines the position of the solder and lead area. Common packages for passive devices are 0805, 0602, 1206 etc. For active devices package name such as PLCC, SOIC and QFP are common. In the software Device update can either go through Part Number or through Device package. Since the information for lead and solder areas are the same for the same package, having a package library is a convenient way to update solder and lead area.
User can select the package type from the list of available package. How to Create a New Package? A package is the definition of position and size of the lead and solder areas plus their inspection parameters. To create a new package user should go to a Device, add the lead and solder areas, fine tune their position and size then assign inspection parameter. Then give the package a name and add the package to the package library. Here are the steps to add the new package to the package library: 1.
Train Board for Solder and Lead Inspection If the user wants to perform solder inspection on the board he/she is going to train, they should try to obtain package information for the Devices and list them in the CXF file. Package information is helpful during updates of solder and lead parameters. Training the Device labels first without concerning lead and solder areas is recommended. Be sure each Device has a Device number assigned to it. The lead and solder areas can be added later.
4. 5. 6. 7. direction of the solder area relative to the Device. Select the Image number, and then select algorithm number. The recommended number is 2. From the solder menu select Extended Params, set the parameters accordingly. The recommended parameters are 50%, first threshold 0, second threshold 128. Repeat steps 1 to 3 until all the solder areas are define. Use the Align... from the solder area menu to fine tune the position and size of the solder area.
Converting CAD Data Using Excel In a production environment, the same software package which generates the Pick & Place machine programs can usually generate the CXF file for the AOI automatically, but if you are doing a demo or just evaluating the machine you may need to convert the CAD data to a CXF file manually. The Excel software can be used to format text data into a CXF file. First prepare the CAD data into columns of text. From the Excel menu select File | Open.
Using OTTO-CAD Unless you work with CAD data on a daily basis, figuring out its information such as scale, axis inversions, and board rotation would be difficult. The software provides assistant in form of the OTTO-CAD. To enable OTTO-CAD put the word AUTO in the Scale section of the CXF header. I.e. .Scanspection_CAD_EXCHANGE Version 5 BoardName MyBoard Scale AUTO .DATA_START .. ..
Additional CAD Utilities Two other features only accessible when placing the third reference Device during CAD import: Graph CAD Data is useful when user have to train a board that do not have reference ID silkscreen on the board, and layout drawing is not available. Graph CAD Data graphs the CAD data into the Map View. Printing the Map View afterward will produce a layout drawing of the board.
Using Software to Read Barcode All the inspection Images on the AOIs can be used to read barcode code. Using software can sometimes eliminate the need of using a separated barcode reader to read barcode on the PCB for tracking purposes. Moreover Image barcode is more automated than using the hand held barcode reader. However, there are some limitations. First, the entire barcode label must be small enough to fit into the field of view of the Image.
Train the barcode as a Device, and give it a Reference I.D. BARCODE, in the extended parameter page set algorithm number to 21. Press the Ext. Setup button to setup parameter for the barcode read. Number of Characters -The software will verify the number of character in the barcode base on this parameter. Rotation -Can be 0,90,180 or 270 degree.
Threshold -Threshold is used to binarise the image before reading the barcode. 128 is good for most situation, if the print is very light user may need to use a higher threshold value. The final step in using Image to track barcode is to enable the Enter Board Serial Number check box in the Load untested PCB for Inspection dialog. Here is a summary of the steps: 1. Make sure BARCODE.DLL is loaded as extension DLL. 2.
X-out and BLKTAG In a biscuit board one or more biscuits may be unpopulated (X Out). The Biscuit Skip system option enables the system to skip the unpopulated areas. This option works differently for off-line systems than for in-line systems. When this option is enabled in off-line systems, the user is allowed to interactively select the biscuit or biscuits needed to be skipped from the map view every time a new board is loaded in. In the case of in-line systems, the user will check the by label box.
Inspecting Double Sided Board To inspect double-sided PCB user must create two Board Setups, one for topside inspection, one for bottom side inspection. However, it is possible to have the software to determine which side of the PCB it is going to inspect and automatically switch the Board Setups for you. To use the feature user need to: 1. Name the Board Setup for the top side as ****_TOP.xxx, and the bottom side as ****_BOTTOM.xxx. Where **** is the assembly number for the board. 2.
Colour Inspection on AOI Introduction The AOI machine has the capability of performing colour inspection. The following gives an overview of how colour inspection is implemented and how it can be used to inspect Devices that would otherwise be difficult to handle using only grey-scale information. Theory of Operation The AOI machine utilises a colour Image to capture image colour information. Inside the software colour information is converted into Hue and Saturation values. Hue is a measure of colour.
would normally do and enable colour inspection. Colour Inspection as and Extension DLL Colour inspection is also implemented in an extension DLL the ColourChk.DLL it offers users more versatile colour inspection capability. It is implemented as "Solder Inspector" algorithm 4. As a "Solder Inspector" it can be of any size and of any offset position relative the Device. Before using any of the colour inspection capability users must ensure the ColourChk.DLL is loaded.
Supervisor Mode Main Menu The main menu selections allow users to change parameters that affect the board or system as a whole. The main menu selections allow users to change parameters that affect the board or system as a whole. File Test Board Starts the PCB inspection process. New Board Starts the new board definition process. Save Board Setup Saves a board setup to disk. Load Board Setup Loads a board setup from disk or shared library. Delete Board Setup Deletes a board setup from disk.
Edit Search By Ref ID. Launches a dialog for the user to enter a Device reference ID, then positions the Image to find the specified Device on the board. Rename Part No. Rename a Device number in the Device library, and all instances of the Device in the Device list. Copy Biscuit Duplicates the Device information from one area of the board for later pasting to another area on the board. Users can specify the biscuit either from the Video window or from the map view window, depending on which one is active.
using the same reference ID, the AOI system allows them to be distinguished with a biscuit ID. For example, 01-IC1 refers to IC1 in biscuit number 1 and 02-IC1 refers to the same Device in biscuit number 2. The menu selection launches a dialog for the user to enter a biscuit ID. Update Biscuits The menu selection allows the biscuits to be updated based on the original biscuit. (i.e. biscuit with no prefix.). If the original biscuit has new Devices added.
reduce the system's tolerance for Device variations or differences in appearance, while too low scores can allow wrong Devices to pass. The default is 700. High false failures indicate the score is set too high, while high false accepts indicate the score is too low. Centre Search Area Automatically centres the search area on all Devices. Modify Search Areas Globally changes the search area for all Devices. The following dialog is displayed.
Align Board Starts board alignment if the alignment marks are defined. Define Board Size Starts the process to define the board size. Define Alignment Marks Starts the process that trains the alignment marks template and learns their positions. Edit Alignment Parameters Launches a dialog to allow changing of the alignment parameters. Functions Magnification Select Selects magnification 1 to 4, same as pressing the buttons on the toolbar. Display Live Displays video in the video windows.
Change Password Launches a dialog that allows a user to change the password, which protects the Supervisor Mode from unauthorised entry. Calibration Setup Edit Navigational Parameters Launches a dialog to allow the changing of video navigation scales and Image offsets for the current Image.
Displays an About dialog.
Active Devices Sub Menu The Device list menu is a local pop up menu. It will display when the mouse is pointing inside the Active Devices page in the Device List View and then the right mouse button pressed. List Failed Devices List all the Devices that failed the last inspection. List Passed Devices List all the Devices that passed the last inspection. This is useful during the bare board test of which you are hunting for false escape.
Package Library Sub Menu The Device list menu is a local pop up menu. It will display when the mouse is pointing inside the Package page in the Device List View and then the right mouse button pressed. Rotate Package Rotate the selected package 90 degree. Step Thru Selected Step through all the Devices with the same package. Delete Selected Delete the selected package from the package library. Delete All Delete the entire package library. Load Package Library Load another package library from disk.
P/N Package 111-102-00 1210C 111-162-00 3225C 437-075-00 SOIC28 437-075-00 SOIC28 438-834-00 QFP208 629-133-00 0805R .DATA_END Export Package Name Generate a text file that list the package type for each Device number.
Offline Programming Software (Optional product, purchased separately) Introduction Offline Programming Software allows users to create, edit or verify any inspection program offline on a separate computer. The software is a specially configured version of the AOI software that Test Boards on any PC with Windows. A copy protection key (Dongle) is needed to Test Board this software. The key is provided to the user when the offline programming software is delivered.
Program Transferability The inspection programs (Board Setup) are transferable amongst AOI machines as long as proper calibration is maintained on the machines. The PASS on all items of the automated self-test guarantee Board Setup transferability for AOIs.
Machine I.D. The MachineID setting in the Scanspection.INI identify the machine to the software. The MachineID is automatically set to the network computer name of the control computer. In a multiple machine environment it is important to make sure the computer name on each machine are different. This allows the software to correctly identify the Board Setups created by other machines and compensate the difference accordingly.
Library Configuration Library configuration on multiple machine environments should base on application characteristics. How frequently the machines change job determines the optimal library configuration. On one end of the spectrum, the local library configuration is the most robust, low-risk and flexible but require the most work to keep all the machines in sync. To propagate any change make on one machine user must copy the Board Setups and their libraries to other machines.
Backup Procedures As with any computer system, periodic backups are very important to ensure that critical data is not accidentally lost due to system crashes, etc. The following folders and files should be backed up on a regular basis. Also, whenever a ScanSpection program is created or modified, it should be backed up. The default locations for these files and folders are shown below; if your system differs from these, please make the necessary adjustments.
Appendix II: Drawer Based AOI Scanner Software Guide Yestek' low cost vision system the Scanner Based AOI uses the same application software as the other vision systems. Training a new Board Preparing CAD data Since training board with CAD data is a lot faster than training each Device manually, users should locate the CAD data for the board and format the data in preparation for import.
Make sure the parameter is set as Input: 600DPI Professional size: A3 Unit: mm 1. 1. 1. Press the Preview button to take a picture of the board. Specify the region of interest on the preview screen. Press the Scan button to scan the board image into the software. It may take 30 second or so for the scanner to scan the broad. After the software prompt user to enter the name (assembly number) for the board.
After the board name is entered. The software determines the board size by prompting user to move to 3 corners of the board. Three prompt dialogs will display one after the other the first one is: The 3 corners are bottom left, bottom right and top left corner of the board. After defining the board size, software will prompt user to define the alignment marks (fiducials) for the board. There are two alignment mark, left mark and right mark.
Import CAD data The process begins by the user selecting File | Import CAD File from the main menu. The system opens the specified file to verify its format. If the format is correct the system prompts the user to load a board corresponding to the CAD data into the system. The software analyzes the Device position information from the CAD data and positions the Image over three Devices on the board. Each time, the user is prompted to verify the Device position.
Train Enable; checking it will enable the auto train feature. In auto-train, the system automatically searches for the Device in the expected position; if the Device is found the system adds that Device into the Device list for inspection and then moves on to the next Device in the CAD data. The training process continues automatically (unattended), stopping only if the expected Device is not found or the Device is not in the Device library.
Place the board into the drawer, close the drawer, then press Ok. The system display a dialog. Check the Always Scan Board box, then press the Scan Now button. The system will scan the board afterwards based on the result the following dialog may appear: If the board inspection failed, user can review the failed Devices by pressing the Review Failures button. After reviewing, open the drawer remove the board inspected.
APPENDIX VIII: System Specification File The SysSpec.dat file lists the specifications and tolerances for critical system parameters. During the self-test process the values of these parameters are measured and compared to the specification stored in the SysSpec.dat file. [Spec] ImageOff=150.000 NaviScaleTol0=2.000 NaviScaleTol1=2.000 NaviScaleTol2=2.000 NaviScaleTol2=2.
APPENDIX IX: Device Rotation Worksheet Tantalum Cap Chip resistors and Caps.
