Shorts-open test application illustrates switch-matrix choices
Shorts and opens testing can evaluate a semiconductor package before functional test, and the technique can also be used for failure analysis. According to Pickering Interfaces, one or more source-measure units (PXI or bench-top) and one or more switch matrices are essential for such tests. For short-opens test only, the matrix should support two-wire (Nx2) measurements. For applications requiring low-resistance measurements or precision I/V characterization, the matrix should support four-wire (Nx4), or Kelvin, measurements to compensate for switch and cable-path resistances.
Pickering also outlines the relay types available for matrices for such applications: hermetically sealed reed relays are fast and reliable but are higher cost and offer lower power-switching capacity compared with other types; electromechanical relays (EMRs) have higher switching capacities and lower cost but are slower and have shorter lives; and solid-state relays offer virtually unlimited life and are fast (with no switch bounce) but have bandwidth, leakage, resistance, and voltage limitations.
In addition, customers can select a custom design or one based on VXI, PXI or PXI Express, or LXI platforms.
Pickering provides a specific example of a shorts-open test implementation with regards to Amkor, the contract semiconductor assembly and test company. Amkor’s Korean division required a 3,072×4 matrix switch configuration able to perform four-wire measurements (for I/V characterization) as well as two-wire measurements. Amkor chose three Pickering LXI high-density switch modules that employ electromagnetic relays and allow up to 1,027 simultaneously closed crosspoints. System integrator Testmation put the system together. Visit Pickering Interfaces for more on this project.