The SPEA NZT 2.0 test is based on the measurement of the nodal impedance value on the nets, independently from the single components on the board.
Instead of physically checking the absence of process errors (as short circuits or open pins) and performing parametric test on each component, SPEA NZT 2.0 checks that each single net behaves coherently with what expected. When an anomaly is pointed out, the system automatically performs, on the components connected to the net, the required parametric measurements to find out the error that alters the net behavior.
The application of this technique brings a double advantage:
- up to 80% test time reduction, compared to the complete in-circuit test execution on flying probe system. It is enough to contact one net to perform, simultaneously, all the measurements required by the NZT test of the connected components. The in-circuit test program can be lightened by eliminating all the tests that are already covered by the NZT 2.0, without losing on test coverage. The optimization is maximized by the fact that also the probe moves are reduced when executing NZT and in-circuit test in combined way: the in- circuit measurements are performed only on the components connected to the nets resulting defective at the NZT.
- increased test coverage. Through the SPEA NZT 2.0 test, it is possible to test also non-contactable areas of the boards, detecting the 100% of the possible short circuits and also detecting hidden faults (not covered by the in-circuit test) related to digital components functionality.
100% test coverage
The SPEA NZT 2.0 can check all the types of anomaly on the nets, including hidden faults not detectable through the in-circuit test, as - for example – those concerning the I/O stages of integrated circuits (side effect), or stray impedance on the ICs.
The main diagnostic advantages deriving from using this test technique are the following:
- 100% coverage of possible short circuits, not depending on the location and physical distance among the tested points (unlikely the algorithms normally used for short test on flying probers)
- Fault detection on non-contactable areas of the board - Test of all the components on the board: active, discrete and passive - Very high measurement accuracy (0.5 pF) and resolution (0.1 pF)
The combination of SPEA NZT 2.0 and in-circuit test, in addition to the test time optimization, makes the flying probe test coverage higher than a bed-of-nails tester.
| Defect |
NZT detectable |
Detectable with other tecnique |
| Short circuit between adjacent points |
Yes |
Short circuit test on flying probe |
| Short circuit between non-adjacent points |
Yes |
Potentially, with functional test |
| Wrong value error |
Yes |
In-circuit test |
| Open pin |
Yes |
Open Pin Scan |
| Errors on I/O stages |
Yes |
Dynamic digital test pattern or functional test |
| Side stray impedance (IC degraded) |
Yes |
Not detected with other techniques |
| Leakage on printed circuits |
Yes |
Not detected with other techniques |
| Fast |
Complete |
Easy |
Accurate |
| Test time reduction: 80% |
100% short circuit coverage |
Autolearn measurement acquisition |
0.1 pF resolution
0.5 pF accuracy |
| 0.5 ms per test |
Test of non-contactable areas of the board |
Easy and direct programming |
Measurement performed on junction tracks between connectors |
| SMART ICT: parametric test only when anomalies are detected on the net |
Test of active, passive, discrete components, open pins, I/O, side impedance, leakage |
No need for board data |
Measurement performed on nets concerning non-connected pins of ICs |