IC opens are the most prevalent fault class on virtually every SMT manufacturing floor.
TestJet Technology is the most widely used vectorless test technology in the world because it reliably identifies opens around (and inside) almost any IC package with a lead frame or metallic pins or leads to which the TestJet probe can capacitively couple–an enormous variety of device types.
CheckSum systems employ two popular forms of vectorless test:
- Protection Diode-based testing
- TestJet, capacitive-based testing
Both methods provide additional test coverage for the most common type of IC failure on today’s PCBAs – solder opens on device legs.
The inside story: TestJet Technology
TestJet Technology examines the connectivity from each pin on a device to the circuit board. It does not require that power be applied to the device under test.
The TestJet hardware measures the capacitance from a pin of a device to the TestJet probe. The measured value is compared against preset limits by the Analyst system–just like any other in circuit test. If the capacitance falls below the lower tolerance an open pin exists. This measurement is repeated for each pin on the device except power and ground pins. Pins that are tied together are tested as one pin.
A specific test step is accomplished by connecting a low voltage AC stimulus source to the pin being tested, the Sense to the TestJet probe, and then to guard out (ground) all other pins on the device. The signal is amplified and filtered right at the TestJet probe to improve signal quality. Each TestJet probe is connected to a port on a system TestJet board that is mounted in the test system chassis. Depending on the specific test system configuration, up to 384, or more, TestJet probes can be connected to the test system.
Unlike competitive systems, you do not need to add multiplexer cards at a cost of several hundreds of dollars PER FIXTURE. With CheckSum systems the multiplexer is built into the tester, saving you thousands of dollars over the life of the tester!
* TestJet Technology is protected under U.S. Patent Nos. 5,124,660 and 5,254,953