What are probe cards and what are their types?

Probe card (Probe card) may not have heard of many people, but has seen KYS Semiconductor on CP (Circuit Probing, Chip Probing) test, that is, wafer testing articles should not be unfamiliar with the people, which has been mentioned in the probe card. The wafer test process is very important, and the reason why it can be earlier screening of defective products, to avoid the flow of bad die to the packaging process, the probe card is indispensable.

Probe card is a test interface, by the probe, electronic components components, wires and printed circuit board (PCb) composition. Depending on the situation, an electronic component element, a hardener, etc., is required, mainly for bare-core testing, i.e., wafer-level testing.

During wafer testing, the object under test is placed on the probe table, and then the probe on the probe card directly contacts the pads or bumps on the chip. The chip signals generated by the Atomic Test Equipment (ATE) are extracted and applied to the device under test,wafer test and the feedback signals in the device under test are transmitted back to the ATE, thus completing the entire test. Defective wafer testing is screened out and then packaged for engineering, which has a great impact on the cost of chip manufacturing.

Probe card type

1, U-Probe

U-Probe refers to the data storage technology equipment for the measurement of the probe card (probe card).U-Probe probe area is greater than or equal to the size of the wafer, so as a probe analysis can be placed on the wafer by placing in any one of the position. U-Probe for DRAM has a crescent-shaped DUT layout, which can most effectively improve the utilization of network space, wafer level testing thus getting the full exploitation of the resources of the level tester.

The DUT layout reduces the number of contacts required to test the wafer and achieves uniformity across the wafer for optimal contacts, which significantly improves test yield. In addition, it allows wafer-level inspection using MEMS probe "micro-cantilever beams" and thin-film multilayer technology.

2, Vertical Probe Card

Vertical Probe (Vertical-Probe) refers to the probe card applicable to conventional logic products (including SoC and microcomputer products) of the multi-core test.

It is called a "vertical" probe card because the probe is perpendicular to the substrate. Because of its short needle-like structure and vertical contact with the device, vertical type is most suitable for measuring small pads,failure analysis high-frequency devices.

3, microelectromechanical systems probe card

MEMS-SP refers to a probe card for logic devices, microprocessors and SoC devices for flip-flop testing and fine-pitch bump wafer testing.

MEMS Probe Cards

Thanks to vertical spring-type probes and MEMS technology development manufacturing, MEMS-SP can be tested with high precision and reliability by conducting studies almost always without change.

In addition, the structure allows replacement of individual pins, thus reducing maintenance time.

4、 SP Probe Card

SP-Probe is a probe card with vertical spring-loaded pins. The SP-Probe for NAND flash is suitable for one-touch testing of 12-inch wafers. Its high needle pressure specification helps to achieve stable contact through the contact oxide film under the gasket, also allows the replacement of a single needle, easy maintenance.

5, WLCSP wafer-level packaging technology chip for testing through the probe card

Wafer-level chip-scale packaging (WLCSP) probe card for testing surface array equipment. The tip of the probe has a top and flat specifications, you can choose one according to the test environment.

As the chip manufacturing process is getting smaller and smaller and the foundry process is getting more and more advanced, the test technology is also improving. Probes, as a consumable item in the test phase, are increasingly demanding in terms of precision, yield, lifetime, and consistency.