In-Circuit Testing

Out of the many white board testing techniques known to test engineers, in-circuit testing is one of the major techniques used. Being a type of white board testing technique, in-circuit testing involves testing of a fully populated printed circuit board (PCB) for the finding of various faults and discrepancies. This technique of circuit testing can also be used for testing basic circuit quantities, such as capacitances, resistances, etc. The purpose behind performing in-circuit testing is to ensure the entire circuit assembly was correctly and optimally fabricated.

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In order to perform the actual testing procedure, a probe is generally used to reach all the various modules on the circuit board. There are different types of circuit testing platforms used in the industry, such as:

• Agilent 3070
• Agilent i5000
• Agilent i3070
• i1000
• Genrad
• SPEA
• Digitaltest
• SEICA

Although in-circuit testing is an able means of performing efficient testing of PCBs, the procedure does have limitations. The first one amongst these has to do with the testing of electrolytic components. Such components can be tested for polarity, only through the means of a very specific set of configurations. In order to perform in circuit testing for PCBs containing electrolytic components, special set of sensors, (eg SPEA ElectroScan) are employed. Apart from this, the major drawback of in-circuit testing of PCBs is that using this technique, the quality of the electrical contacts cannot be determined or be tested for.

In-circuit testing has emerged as the underlying motivation for a host of technologies as well as further innovations in the field of testing. Some of the major ones amongst these include the following:

• AXI - Automated X ray inspection
• JTAG - Joint Test Action Group
• AOI - Automated Optical Inspection

Article published February 1st 2010
Versatyle.com – In-Circuit Testing