ATE Platform Strategy Gains Ground

More than a decade ago, at the urging of Intel, the ATE industry set out to reduce the cost of test in the digital chip market. Backed by companies such as Intel, Motorola, Renesas, Advantest and others, they formed an ATE consortium to make this all work.

The aim of the consortium was to devise an “open architecture” for ATE. This would enable the development of third-party plug-and-play modules. And in theory, the technology was supposed to address the soaring cost of IC test.

At the time, Advantest’s competitors, Teradyne, LTX and Verigy, declined to join the consortium. (In 2011, Advantest officially acquired Verigy, the former ATE unit of Agilent.) But ultimately, the whole industry took a platform approach based upon a standard chassis that can be fitted with modules specifically designed for everything from digital to RF to mixed signal. And for some time, the new approach has made significant gains in test.

At SEMICON Japan, held here in Japan in December, Advantest began showing off specialized and different test handlers and modules that connect to its T2000 digital tester and other systems.

Fig. 1: M4871 handler by Advantest

For example, Advantest introduced the M4871 handler. This handler can handle SoCs with fine pitch of 0.3mm and below. It also helps to significantly reduce the test time when dealing with vigorous temperature change. For instance, to allow changing of temperature settings from -15℃ to +85℃, the duration time needed is usually 40 to 60 minutes. It can be shortened to just 30 seconds. In addition, this handler allows 16X or 32X throughput to be measured simultaneously, where only 2X or 4X throughput was possible before.

The recent evolution of SoC packaging to be widely used for mobile devices has been the driving factor for the development of the handler. For mobile devices such as smart phones and tablets, the terminal pitch has narrowed to 0.3mm. Moreover, stacked packages such as package on packge (PoP) are beginning to be used in mobile devices. It is getting more difficult to ensure accurate positioning of the test terminal for such devices using the conventional pick-and-place aligning.

With the M4871, the mechanical way of pick-and-place aligning is replaced by image recognition aligning, in which two cameras are set on the top and bottom of the package to allow easy aligning. The time needed for the alignment is thus reduced. However, the overall test time does not change significantly as the test itself consumes quite a bit of time.

Because the conventional way of device testing is based on the chamber system, keeping a stable temperature environment was time-consuming. Furthermore, as the temperature is measured by the aid of gas, there was always a question of measurement precision. The M4871 test relies on two-liquid immersion (cold and hot water), which shortens the duration time for temperature stabilizing. Not only the time after the test setup, but also the setup time itself is reduced. It requires only about 30 seconds, plus 10 minutes to complete the overall test and setup. This process previously took 130 minutes.

Heat problems also may occur during the test. For instance, the logic IC may dissipate heat that can cause the device temperature to rise higher than the set value. The newly developed M4871 is equipped with a heat sensor for feedback temperature control purpose, allowing test to be carried out at constant temperature. This temperature control approach is highly reliable, as it has been widely used in the past for testing CPUs for many servers. It is now being used to test application processors (APUs), which has attracted the attention of major APU makers.

Fig. 2: Power-type semiconductor test module by Advantest

Advantest also announced its GVI64 test module for highly integrated ICs, where power management ICs, power amplifiers, and A-to-D/D-to-A converters are integrated on a single chip. This test module is suitable for testing power management ICs (PMIC) and automotive ECUs. A maximum of 64 channels can be measured when connecting this module to the test platform T2000.

As the GVI64 is designed for power purposes, testing a supply voltage from -64V up to +85V is possible. In addition, eight channels can be measured simultaneously in parallel with current up to ±240mA, depending on the rating current. Another module is also available for testing devices with even higher current demand.

With wide voltage ranges of the module, the test on PMIC of most vehicles can be conducted. The test includes the power transistor and PMIC within the ECU, such as engine control system, safety system, drive system and the ABS. Measuring the breakdown voltage of the transistor is also possible.

Advantest also released the ISS IPE2, a test unit specialized for image sensing. This test unit helps to judge the condition of CMOS image sensor. The image processing to check the sensor condition starts once the image sensors of the DUT (device under test) receive and analyze the signal based on the reflection of the light. The test takes 54% of the time as conventional methods. This reduction in time is made possible by using quad-core processors and a high-speed bus. The commercialized product name, IPE, stands for Image Processing Engine. This test unit is also designed for the T2000 platform.