PCB Inspection and Measurement System
  Aero Space
  Process Automation
  Data Acquisition
  Vision & Motion
  Semi Conductor
To develop an application for inspection of both bare and mounted PCBs, artworks etc. This software is designed to provide appropriate scan speeds and range of traverse as well as conduct measurements on the object under test.

Challenges were:

Communicating with the PLC (Fatek)  
Establishing the three different modes of traverse incase of measurement window  
    namely, Manual Mode, Jog Mode, Step mode  
  Solution offered:  
  The application will involve the following
Lab VIEW 7.1  
Report Generation Toolkit  
MS Office 2003  
Win 2000 or later  
Sanyo Denki motors (6 wire) 13 kg-cm, Sanyo Drives with power down facility  
1:2.5 pulley ratio i.e. screw faster than motor  
Fatek FBs 24 MCT PLC  
5 micron linear scales  
Computer with Pentium IV processor, 512 MB RAM  

The System required Log in facility, Setting the Master files using which the remaining PCB’S can be scanned , choice of the type of scan, Perform some geometric measurement on the features to extract their dimensions . Note: This system is part of another system that takes care of the illumination and magnification of the PCB.

  Schematic Diagram:  
Process Description:

This system allows two level access, i.e. administrator, operator.
Various user interfaces are provided to enable the user to create master scan file for a particular batch of PCB’s .These master files can be recalled and a scan can be conducted. The measurement interface enables the user to obtain fine distances using three different modes of travel namely, Manual Move, Jog Mode, and the Step Mode .The points of interest can be downloaded and the geometrical feature measurement will be reported.

Two types of scan is provided. For a particular design of PCBs which has a large production run and each of the PCBs needs to be scanned end to end, then the type of scan to choose is ‘Raster Scan’. Shown below is a Raster Scan Pattern.

If it is already concluded that a given design or the inspection stage of a PCB has only a number of pre-known points of inspection such as possible solder errors, potential polarity changes etc. then the type of scan to choose is ‘Vertex Scan’. Shown below is a typical Vertex Scan Pattern.
The Generate Master menu enables you to set up the appropriate scan of either type. It helps you enter a possible scan , check out its suitability by actual run, and then allows you to modify and save the Master Scan file for subsequent use for the batch inspection by the operator. At operator level no editing of master scan is provided to ensure that the inspection points are not missed. The master scan files are Excel files and they are saved with a date-time stamp. These can be subsequently opened and edited (say, for stating as to what items are to be found at a particular Vertex location.). These files can be printed through excel for record. This is discussed in more detail later.

As the inspection proceeds under the Scan mode, the operator may find defects, which he may be required to record for future inspection, or at an accompanying repair station. He can download the defective component coordinates, along with his comments to a ‘Rerun file’ with the serial number of the particular PCB with which they are associated. This is a new vertex scan file that enables quick reinspection of the said PCB. If the User needs to conduct some measurements on the PCB e.g. measure the distance between two fiduciary marks on the PCB, a utility is provided that allows the user download the desired points and then report the results.

Screen Shot:
This is one of the User interfaces, the panel allows the user to maneuver the XY Stage in three ways, to achieve the required distance, download these points and perform measurements.
NI LabVIEW was used to develop the inspection and measurement system, for Automated Inspection, to include control and decision making functionality, and LabVIEW Application builder to deploy the visual quality control system for the customer. Thus the NI LabVIEW was the single platform used to complete the system within moderate time and cost.
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