Tungsten needle is an important part of a wafer probe card, so it is also known as tungsten probe in such a probe card. According to the experts, a probe card, as a main tool for wafer testing, is usually composed of a test circuit board and a conical tungsten needle bent at 95-105 degrees on the circuit board. During the test, the tip of the tungsten probe is directly contacted with the pad of the wafer to be tested, thereby realizing the electrical performance test of the dies of wafer.
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During test, when the tip of tungsten probe touches the wafer pad, the platform of the probe card will give the ascending standard height, leaving a mark on the wafer pad. As tungsten needle is tapered, the diameter of tip of the needle becomes larger and larger after multiple tests. Conventionally, when the tungsten probe is stuck on the wafer pad, the contact area cannot exceed one quarter of the wafer pad, if exceeded, the probe card must be scrapped.
