Resolving Non Compliant Interconnect Escape Rates in Hybrid Boundary Scan in Circuit Testing
Resolving boundary scan escape rates requires weighting fault coverage by defect universe and enforcing active guarding on unprobed parallel nets.
Vector Compression
Memory Efficiency
Algorithmic reduction of the data required to describe digital test patterns allows large programs to fit within the local memory of the tester hardware. Using vector compression minimizes the time spent transferring pattern files from the system controller to the pin electronics during a test run. This technique identifies repeating sequences or predictable bit changes to represent the stimulus more compactly.
Data Reduction
Modern semiconductor devices require millions of cycles to verify internal logic, which can overwhelm the storage capacity of standard testers. Implementing vector compression allows the test equipment to expand these compact files back into full-length pin transitions in real time. The process ensures that the test speed is not limited by the communication bandwidth of the data bus.
Throughput Impact
The choice of compression method affects the flexibility of the test program. Some hardware-based vector compression schemes use cyclical redundancy checks or signature analysis to evaluate the response from the chip without storing the entire output stream. This reduces the amount of memory needed for both the input stimulus and the expected results.
However, high levels of reduction can make it more difficult to diagnose the exact cycle where a failure occurred. Engineers must choose a balance between the speed of the test and the level of detail provided by the diagnostic tools. Efficient patterns lead to lower costs per unit by decreasing the total dwell time on the automated test equipment.