SMT007 Magazine

SMT-June2015

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20 SMT Magazine • June 2015 TeST MATCH—PARTneRInG SPeCIALIST BOunDARy-SCAn WITH ICT continues Flying probe testers can offer an alternative to ICT that eliminates some disadvantages such as the cost and lead times associated with bed- of-nails test fixtures and the PCBA modifications they require. On the other hand, devices like BGAs with inaccessible pins restrict the cover- age possible using ordinary flying probe testing. Augmenting flying probe with boundary-scan can help overcome this problem and delivers additional valuable benefits. Test Without Touching The native boundary-scan test capability of a system such as the Keysight 3070 ICT station is able to generate tests for boundary-scan de- vices connected to the boundary-scan chain. Testing non boundary-scan devices on nets connected to the boundary-scan chain is possi- ble, using Keysight's optional Silicon Nails tool. As the name suggests, Silicon Nails uses the scan capable IC in a boundary-scan chain to probe the pins of the connected non boundary- scan device. However, some amount of manual interaction may be required, particularly if any pin on the non boundary-scan device is not con- nected to a boundary-scan cell. The VCL (vector construction language) libraries assume that all pins on the target device are accessible. If this is Figure 1: Simplified diagram of a boundary-scan component. Feature

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