Why Predictive Analysis?
Predictive Fault Spectrum Analysis models the effectiveness of a test technology without having to develop the actual test. This dramatically reduces the time and cost of determining whether or not the test technology is cost-effective for a specific circuit board, and whether additional tests should be considered. For predictive analysis purposes, a given test on a tester is rated for effectiveness in detecting one or more of six possible defects for each part, and three possible defects for each pin on a circuit board. The shorthand for this fault spectrum is PCOA-SOQ-LP.
The PCOA-SOQ-LP Fault Spectrum
Fault coverage for a circuit board refers to the probability that a tester will detect a fault from the spectrum of all possible faults that can occur. TestSight Tactix uses a PCOA-SOQ-LP circuit board fault spectrum. The model incorporates three fault classes:
- part process faults
- pin process faults
- part electrical faults
The two process classes include faults related to how the circuit board is constructed. The electrical class includes faults related to how the part performs in the circuit.
In the PCOA-SOQ-LP model, P (Present), C (Correct), O (Orientation), and A (Alignment) are part process faults. S (Shorts), O (Opens), and Q (Quality) are pin process faults. For the purpose of our fault model, pins are defined as any method of part connection to the circuit, including surface mount, thru-hole, press fit, or any other connection method.
The L (Live) and P (Performance) faults are electrical. A Live fault occurs when the part is non-operational in the circuit. A Performance fault occurs when the part fails to achieve its designed performance specification. The PCOA-SOQ-LP grouping differentiates process and electrical class faults. This is critical for clearly understanding and applying the model to the wide variety of test technologies being used today.