Automatic HBM 2-Pin Testing
Mechanical switching
2-pin HBM testing solves many of the difficulties that are caused from the wiring parasitics of large automatic relay matrix testers. However, to meet the testing speed and pin combination accuracy, a robotic solution is needed as moving two probes manually is not practical for today’s large pin count ICs. The GTS solution is to use a pair of Signatone motorized positioners with probe needles so that all pin combinations can be stressed according to the HBM standards, and measured by DC curve trace to determine if physical damage occurs from that stress. ANSI/ESDA/JEDEC JS-001-2014, the major HBM standard in use today, defines two-pin testers.
Definition from ANSI/ESDA/JEDEC JS-001-2014 page 3
The mechanical switching of test equipment connections to the device under test (DUT) allows very flexible testing, but has its limitations. Since the two probes must not collide with each other, once the left probe has been placed on a DUT pin, the right probe cannot reach all the remaining pins as some of the pins are blocked by the left probe. The GTS Maestro software enforces the rule that the right-side probe is never placed to the left of the left-side probe. While this prevents collisions, it is not obvious how GTS complies with the “Terminal A” and “Terminal B” labels defined in the HBM specification.
Figure 1 from ANSI/ESDA/JEDEC JS-001-2014 page 5
Which pins are Terminal A and Terminal B?
Fortunately, the labels Terminal A and Terminal B do not specify the two pins of our 2-pin tester. Either probe can function as either Terminal. This is made clear in the HBM standard.
Definition from ANSI/ESDA/JEDEC JS-001-2014 page 3
In the GTS 2-pin system, when testing DUT pins, let’s call them Pin A and Pin B, and if Pin A is to the left of Pin B in the package, then the left-probe is always placed on Pin A and the right-probe on Pin B. If the pin combination table (either Table 2A or 2B in JS-001) defines the DUT Pin A as Terminal A with respect to Pin B as Terminal B, then a positive pulse will have the HBM current flowing from the left-probe to the right-probe (a positive pulse is applied by the left probe). In the other case when Pin A is defined as Terminal B and Pin B as Terminal A, then Maestro software will cause the current to flow from the right-probe to the left-probe by driving a negative pulse on the left-probe. The current flow direction will always be correct.
JS-001-2014 Annex B.4 explains how a low-parasitic tester can be verified. As part of this verification, the GTS HBM tester has shown that when reversing both the probes and pulse polarity, the same HBM current and stress direction is obtained. When making DC measurements (leakage and curve tracing) the GTS HBM system has the same high accuracy measurement capability in both directions and will reverse the polarity and probes when needed. When not operated in an automatic mode, such as when manually placing the probes and using the Manual Pulse capabilities of Maestro, the operator should remember that the left-probe is assumed positive (current flows from the left-probe to the right-probe for a positive pulse) and must change the polarity of the manual pulse when appropriate.
The GTS PurePulse HBM tester fully complies with JS-001-2014 with all polarities and waveforms meeting the standards. The GTS HBM tester qualifies as low parasitic and all testing is measured and recorded with the proper polarity for every DUT pin.