IC chip testing cost is an important factor affecting manufacturing and processing costs. In some cases, test costs can account for as much as 40% of the total device cost. In order to reduce the cost of testing, test procedures can be optimized and multi-station tests can be developed. At the same time, the yield rate and test time must be balanced to achieve the best cost control. In this article, Namisoft will share with you the test types of domestic IC chips and
the automated test system for domestic IC chips.
Common test items for IC chip testing:
• Functional testing: truth tables, algorithmic vector generation.
• DC parameter test: open circuit/short circuit test, output drive current test, leakage power supply test, power supply current test, conversion level test, etc.
• AC parameter test: transmission delay test, setup and hold time test, functional speed test, access time test, refresh/wait time test, rise/fall time test.
DC parameter test
The DC test is a steady-state test method based on Ohm's law to determine the electrical parameters of the device. For example, the leakage current test is to apply a voltage to the input pin, which makes a current flow through the resistance between the input pin and the power supply or ground, and then measure the current of the pin. The output driving current test is to apply a certain current to the output pin, and then measure the voltage difference between the pin and the ground or power supply.
Common DC tests include −
• Contact test (short circuit ~ open circuit): This test ensures that the test interface is properly connected to the device. Contact testing determines connectivity by measuring the natural voltage drop across protection diodes on input and output pins. If an appropriate forward bias current is applied to the diode, the voltage drop of the diode will be about 0.7V, so the contact test can be completed by the following steps:
1. All pins are set to 0V,
2. Apply a forward bias current "I" to the pin to be tested,
3. Measure the voltage induced by "I",
4. If the voltage is less than 0.1V, it means the pin is short-circuited.
5. If the voltage is greater than 1.0V, it means the pin is open.
6. If the voltage is between 0.1V and 1.0V, it means the pin is connected normally.
• Leakage current (IIL, IIH, IOZ): Under ideal conditions, it can be considered that there is an open circuit between the input and tri-state output pins and ground. But in reality, there is a high resistance state between them. The maximum current between them is called the leakage current, or respectively called the input leakage current and the output tri-state leakage current. Leakage current is generally caused by the fact that the insulating oxide film inside the device and between the input pins is too thin during the production process, forming a situation similar to a short circuit, causing current to pass through.
• Three-state output leakage (IOZ): It is the current measured when the output pin is driven by VCC (VDD) or GND (VSS) when the pin state is output high-impedance state. The test of the three-state output leakage current is similar to the input leakage test, the difference is that the device under test must be set to the three-state output state
• Transition Level (VIL, VIH): Transition level measurements are used to determine the actual values of VIL and VIH when the device is operating. (VIL is the maximum voltage value required when the device input pin changes from high to low state, conversely, VIH is the minimum voltage value required when the input pin changes from low to high). These parameters are usually determined by repeatedly running common functional tests while raising (VIL) or lowering (VIH) the input voltage value. The critical voltage value that causes the functional test to fail is the switching level. This parameter plus the amount of insurance is the VIL or VIH specification. The amount of insurance represents the noise immunity of the device.
• Output drive current (VOL, VOH, IOL, IOH): The output drive current test ensures that the device can maintain a predetermined output level under a certain current load. The VOL and VOH specifications are used to guarantee the ability of the device to drive as many device input pins as possible under the noise conditions allowed by the device.
• Power consumption (ICC, IDD, IEE): This test determines the power consumption specification of the device, that is, the maximum current consumption of the power pins under the specified voltage conditions. Power consumption test can be divided into static power consumption test and dynamic power consumption test. The static power consumption test determines the maximum power consumption of the device in idle state, while the dynamic power consumption test determines the maximum power consumption of the device in operation.
AC parameter test
AC parametric testing measures the timing relationship when a device's transistors transition states. The purpose of AC testing is to ensure that the device transitions at the correct time. A specified input edge is input at the input and an expected state transition is detected at the output after a specified time.
Commonly used AC tests include transmission delay tests, setup and hold time tests, and frequency tests.
Propagation delay testing refers to the delay time between a state (edge) transition at an input and the resulting state (edge) transition at the corresponding output. This time begins at a certain voltage at the input and ends with a certain voltage at the output.
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