A Novel Perspective and Methodology on Evaluating the Reliability and Strength of 12-inch Wafer Level Glass Carriers

Glass carriers play a crucial role in advanced packaging processes, especially in wafer thinning, transportation and handling, packaging, stacking, and testing. Their widespread use is attributed to excellent mechanical strength, a broad range of coefficients of thermal expansion, superior flatness and surface smoothness, optical transparency, as well as high-temperature resistance and chemical stability.

Despite these advantages, glass is a highly brittle material prone to breakage due to micro-cracks and chipping at the glass carrier edge—defects that are difficult to identify at the micrometer scale or even smaller during inspection. These defects often occur during manufacturing processes involving contact, such as transportation and handling, even when the contact forces are very slight. Such defects can cause unexpected failure of glass carriers, posing a significant challenge to manufacturing by leading to production delays, reduced yield rates, and financial losses. Therefore, establishing a reliable methodology for assessing the edge fracture strength and resistance to contact damage of glass carriers is of critical importance.

Currently, conventional mechanical tests used to evaluate the strength of glass carriers—such as the 3-point bending test, 4-point bending test, and ring-on-ring test—primarily measure the overall mechanical strength of the carrier, rather than specifically assessing edge strength. Moreover, the failure modes observed in these tests do not necessarily correspond to edge micro-crack formation, which are common and critical issues in practical applications.

In this study, we propose a novel methodology that utilizes a pendulum impact test to measure the fracture energy related to the edge resistance of 12-inch wafer-level glass carriers against contact or collision. We also compare the strength of two different edge grinding conditions. Simultaneously, we capture and analyze the damage evolution and dynamic response during the pendulum impact test using a high-speed camera operating at over 10,000 frames per second. The pendulum impact test provides a more representative evaluation of edge reliability because it simulates dynamic contact conditions and enables better detection of resistance to damage under realistic contact scenarios. 

Finally, the results demonstrate that glass carriers processed with finer polishing exhibit higher fracture energy in the pendulum impact test. Therefore, this novel methodology provides an effective means to evaluate glass carriers across different suppliers, saw conditions, grinding processes, and geometries, which in turn allows the pendulum impact test to identify glass carriers with the best resistance to contact damage, thereby enhancing their reliability in assembly and packaging processes.