Figure 1: Typical curve trace exerciseFigure 1
shows a typical curve trace for a digital microcircuit. The curves indicate whether the pins are making contact to the device. The top middle pane shows a pin that is not making contact; the other panes show pins making contact.
The more proper methodology of electrical testing is to use automatic microcircuit testers that can exercise multiple functional and parametric tests at one time to test the device properly in accordance with its port number requirements.
Automatic or automated test equipment (ATE) is any apparatus that performs tests on a device under test (DUT), using automation to quickly perform measurements and evaluate the results. An ATE system contains dozens of complex test instruments (real or simulated electronic test equipment) capable of automatically testing and diagnosing faults in sophisticated electronic packaged parts or on wafer testing, including ICs and SoCs.
ATE is widely used in the electronic manufacturing industry to test fabricated electronic components and systems. It is also used to test avionics and the electronic modules in automobiles. It is used in military applications like radar and wireless communication, as well as in medical and industrial component manufacturing.
Another form of proper electrical testing is to use an instrumentation board or instrumentation interface between the electronic component, stand-alone test and measurement equipment and PC-based test and measurement equipment to provide specific functional and parametric testing. These tests are either made available by the component manufacturer or are custom designed by the test lab with the end-customer’s review and approval.
The initial connection is provided by parallel and serial interfaces, including the general purpose interface bus (GPIB). However, current technological trends require a more powerful interface, which is provided by implementing universal serial bus (USB), PXI, VXI and LXI/Ethernet ports.
Once a program has been generated and an instrumentation outline has been set up for the test, the device is then ready for electrical testing. All exercises will begin testing at room ambient temperature of approximately 25°C. Two accurate methodologies of testing electronic components under their extreme operating temperatures are to use a precision temperature forcing system (PTFS) or liquid nitrogen to accurately condition the component under test.
A PTFS (Figure 2
) uses compressed forced air with custom-built test fixtures to maintain very cold temperatures as low as -100°C for a DUT as well as to maintain very hot temperatures of up to +300°C.
Figure 2: Illustration of a precision temperature forcing system reparing to condition components on a VLSI test system