Built on a proven High Frequency TDR platform
STUBView utilizes high frequency electrical measurements to determine the stub length present in up to 100% of all PCB vias. This is done by generating 50GHz step pulses utilizing TDR instrumentation. These test signals are inserted into the DUT at the via location with either single-ended or differential odd mode stimulus. The resultant waveforms from the DUT injection are collected and then processed through a fast fourier transform (FFT) algorithm to generate the frequency domain response. The results produce a characteristic loss vs. frequency (dB/freq) profile for each via from which a stub length is determined and evaluated to ensure that it is less than the maximum accepted length (mils).
Test System Calibrations
System calibrations are simple directed operations conducted prior to stub length testing operations.
Part Number DUT Calibration
STUBView allows the testing of via stub lengths in all locations of the board/backplane. The testing is independent of PWB trace length, layer routing and trace impedance. For each new board part number, a guided calibration procedure is conducted which determines the specific high frequency response of each backdrill depth on the board. STUBView allows the definition of up to 36 separate backdrill depths and utilizes a calibration coupon built one time for the new part number.
Creating Testing Specifications
Prior to start of the testing operations, an operator will create a Test Spec (recipe) which defines the vias to be tested. The test specification includes simply the name of the via location, whether the location is a single-ended or differential structure, and what backdrill depth was assigned to the via. STUBView test spec generation supports the testing of up to 20,000 vias per part number.
Testing operations begin with the operator selection and loading of a previously generated test recipe. The recipe will define how many single-end and/or differential test points will run on a part number. Testing is conducted sequentially with the operator or automated probing system being guided as to where to place the probe for each test point. Serial numbers are automatically incremented at the completion of testing each for each part.
High frequency probes are available to fit most board land configurations including within BGA lands areas and connector grid land patterns on backplanes.
At any time including the completion of all testing, a summary report can be generated that includes all important information of the testing operations includig serial number of the board, location of each via and the corresponding pass/fail results.