Advanced packaging technologies like Wafer Level Chip Scale Packaging (WLCSP) and System in Package (SiP), enabled by 3D stacking continue to evolve in the semiconductor industry. These new technologies are now enabling the sensor industry to take advantage of wafer level packaging technologies.

This doesn’t mean just new package types but also provides challenges in test and calibration of sensors. Traditional JEDEC-tray based handling with multiple pick & place operations are facing limitations to handle miniature sensors, enabled by wafer level packaging. For magnetometers, package layout 0.8 mm x 0.8 mm is already common and other sensors are following in the same direction.  

There is a continuous need for high throughput and reduced cost of test. In the sensor industry, it is important to utilize the benefits of CSP not only in the packaging process but also in material handling and test. To achieve the continuous need for cost reduction, high throughput and reliable operation new test methods are required. 

Why Not Just Use Common Wafer Prober?

MEMS and other specialized semiconductor devices have been usually tested in wafer level only for basic behaviour. Functional test and especially trimming of sensors, needs accurate physical stimulus to make calibration possible. 

For conventional packages, special stimulus units have been added to handlers to create the required test conditions. To test and calibrate CSP sensors at the wafer level without additional pick & place processes, stimulus should be combined within the wafer prober. 

Two Decades Of Application-Specific Wafer Test Solutions 

AEM, a global leader in providing Intelligent modular test solutions, is now able to leverage two decades of experience in MEMS testing through its acquisition of Afore. Afore has developed a range of temperature, environmental and motion test solutions that can be used in their modular application specific wafer probers.


KRONOS, wafer prober for motion sensors

Wafer Level Test Solution For Motion Sensors

Afore has brought to market KRONOS, to enable true wafer level test of accelerometers, gyroscopes and magnetometers. KRONOS is built around a specialized wafer prober combined with a rate table featuring two rotating axes that enable 6 degrees of freedom (6DOF). The tester (ATE) is integrated on top of the probe card, which eliminates moving and, thereby, the wearing of cables.

Rotating axes with slip rings enable communicating and supplying power to the tester and prober. The axes also make infinite rotation enabling angular rates up to 750 deg/s without wearing any cables. 

Magnetic Stimulus unit can be integrated on the probe card to enable true 9 DOF testing with one wafer insertion.

Afore – An AEM Company Providing Solutions For Specialized Application-Specific Wafer Probing The need for wafer probing in special conditions is not limited to motion sensors. Afore has introduced KRONOS, wafer prober for motion sensors environmental wafer prober AIOLOS. Cryogenic wafer prober, enabling quantum computing. This allows systems to be configured with various environments and stimuli based on a standard platform. Currently portfolio covers, but is not limited to applications like pressure sensors, MEMS-resonators, IR-sensors and gas sensors. Any application where a special environment like a high vacuum or pressurized atmosphere is needed.

Afore, partnering with Bluefors, brought to market in 2019 Cryogenic Wafer Prober with the capability to test 300 mm wafers with chuck temperature below 1K. This solution enables a giant leap in quantum computing development with full wafer level test capability instead of testing single chips on separate cryostats.  Afore has the experience and ability to customize for application specific wafer test requirements for a wide range of devices and package needs. 


Ari Kuukkala

General Manager

Afore – an AEM Company