Full Testing

Product quality plays a far greater role and coupled to that is critical timing for market entry in order to maximise market share. There is a number of test and inspection methods available for fault detection and the utilisation of these vary both in cost and effectiveness dependent on the volume profile and technologies under test. The three main test types are  flying probe,in-circuit test (ICT), and functional test

 

1, Flying Probe Test Ideal For Prototypes

Flying probe offers OEM customers the following benefits:

  • No extra cost for making the fixtures as required in ICT.
  • Programming time is very minimal, a couple to few days so customers can quickly check their designs.
  • Quick and easy way to test the prototype and proof of concept for their design and help with time to market.
  • Easy way to detect shorts, opens, missing components, wrong value components, wrong polarities, thereby cutting the debug time for customers
  • Easy change over from one revision of the board to another while it is in prototyping stage where all the debugs are all not complete and customers are making changes on the fly.
  • A quick way to test the product while the comprehensive ICT is developed, which takes a couple to few months for a new development.
  • Debug time for customers is cut in half or more after flying probe is done because this test already detects most manufacturing defects.
  • No extra DFM or data messaging efforts are required for flying probe, reducing the testing time for OEM customers.

 

2，ICT Performs Comprehensive Testing

ICT provides OEM customer such benefits as:

  • Although a costly fixture is required, ICT covers 100% testing so that all power and ground shorts are detected.
  • ICT testing does power up testing and eliminates customer debug needs to almost ZERO.
  • ICT does not take a very long time to perform, for example if flying probe takes 20 minutes or so, ICT for the same time might take a minute or so.
  • Checks and detects shorts, opens, missing components, wrong value components, wrong polarities, defective components and current leakages in the circuitry.
  • Highly reliable and comprehensive test catching all manufacturing defects, design faults, and flaws.
  • Testing platform is available in Windows as well as UNIX, thus making it slightly universal for most testing needs.
  • Test development interface and operating environment is based on standards for an open system with fast integration into an OEM customer’s existing processes.
  • ICT is the most tedious, cumbersome, and expensive type of testing. However, ICT is ideal for mature products requiring volume production. It runs the power signal to check voltage levels and resistance measurements at different nodes of the board. ICT is excellent at detecting parametric failures, design related faults and component failures.

 

 

3,Functional Test: A Final Manufacturing Step

Customer Advantages of Functional Test:

  • Functional test simulates the operating environment for the product under test thereby minimizing the expensive cost for the customer to provide the actual testing equipment
  • It eliminates the need for expensive system tests in some cases, which saves the OEM lots of time and financial resources.
  • It can check the functionality of the product anywhere from 50% to 100% of the product being shipped thereby minimizing the time and effort on the OEM to check and debug it.
  • Prudent testing engineers can extract the most productivity out of functional test thereby making it the most effective tool short of system test.
  • Functional test enhances the other types of tests such as ICT and flying probe test, making the product more robust and error free.

 

Generally speaking, a test strategy’s foundation is to first get a good understanding of the types of printed circuit board testing available and where they are most appropriate from a product and cost point of view. One way to achieve cost justification is to do a cost and benefits evaluation based on each type of test. When quantity is limited from a few boards to maybe 50 or so, a good PCB testing solution could be flying probe, whereas if the quantity is higher, in-circuit test (ICT) usually is a good choice.