The pins of semiconductor device are important parts to connect the internal circuit and the peripheral circuit. The failure of pins are caused by vibration and static electricity.
A contact test is a test to verify the connection between the internal circuit and the peripheral circuit. It includes two tests, a open test and a short test.
This test can be detected the following failures:
- Short-circuited
- Bonding failure
- Open
Open Test
A open test is a test to verify the connection between the internal circuit and the peripheral circuit. Generally, semiconductor devices have protection diodes which are implemented as internal circuit at each pins. A protection diode is a circuit to protect the internal circuit from a non-rating high voltage applied to the pin. It is implemented on a ground side and a power supply side.
A open test measures the voltage generated on the pin when applying a forward current to the pin. At the time, the other pins are opened.
If the continuity of the pin is good, the measured voltage is a forward voltage of the diode(near 0.7V). If the pin is opened, the measured voltage is a clamp voltage of the measurement instrument.
Short Test
A short test is a test to verify whether the pins are short-circuited each other. The failure is occurred by such as bonding failure.
A short test measures a voltage generated on the pin when applying a forward current to the pin. At the time, the other pins are applied 0V.
If the pin is short-circuited, the measured voltage is 0V. If the pin is not short-circuited, the measured voltage is the forward voltage of the protection diode(near 0.7V).
If the semiconductor device uses a pull-up resistance and a pull-down resistance instead of a protection diode, the measured voltage is the voltage drop by the resistance.