Layout Dependence Stress Investigation in through Glass via Interposer Architecture Using a Submodeling Simulation Technique and a Factorial Design Approach.

The multi-chiplet technique is expected to be a promising solution to achieve high-density system integration with low power consumption and high usage ratio. This technique can be integrated with a glass interposer to accomplish a competitive low fabrication cost compared with the silicon-based interposer architecture. In this study, process-oriented stress simulation is performed by the element activation and deactivation technique in finite element analysis architecture. The submodeling technique is also utilized to mostly conquer the scale mismatch and difficulty in mesh gridding design. It is also used to analyze the thermomechanical responses of glass interposers with chiplet arrangements and capped epoxy molding compounds (EMC) during curing. A three-factor, three-level full factorial design is applied using the analysis of variance method to explore the significance of various structural design parameters for stress generation. Analytic results reveal that the maximum first principal stresses of 130.75 and 17.18 MPa are introduced on the sidewall of Cu-filled via and the bottom of the glass interposer, respectively. Moreover, the EMC thickness and through glass via pitch are the dominant factors in the adopted vehicle. They significantly influence the stress magnitude during heating and cooling.

Morphological Diagram of Dynamic-Interfacial-Release-Induced Surface Instability.

In this study, a morphological diagram was constructed for quantitatively predicting various modes of surface instabilities caused by the dynamic interfacial release of strain in initially flat bilayer composites comprising an elastomer and a capping layer. Theory, experiment, and simulation were combined to produce the diagram, which enables systematic generation of the following instability patterns: wrinkle, fold, period-double, delamination, and coexisting patterns. The pattern that forms is most strongly affected by three experimental parameters: the elastic modulus of the elastomer, the elastic modulus of the capping layer, and the thickness of the capping layer. The morphological diagram offers understanding of the formation of complex patterns and development of their applications. Critically, the wrinkle alignment can be well controlled by changing the direction of the interfacial release to enable the creation of centimeter-sized and highly ordered lamellar wrinkled patterns with a single orientation on a soft elastomer without the need for costly high-vacuum instruments or complex fabrication processes. The method and diagram have great potential for broad use in many practical applications ranging from flexible electronic devices to smart windows.

Reliability Assessment of Thermocompressed Epoxy Molding Compound through Glass via Interposer Architecture by the Submodeling Simulation Approach.

In glass interposer architecture and its assembly process, the mechanical responses of interposer structure under thermocompression process-induced thermal loading and generated shrinkage of molding material are regarded as a major reliability issue. Thousands of metal-filled via are involved in glass interposers and are regarded as a potential risk that can lead to cracking and the failure of an entire vehicle. In this study, a finite element-based submodeling approach is demonstrated to overcome the complexity of modeling and the relevant convergence issue of interposer architecture. Convergence analysis results revealed that at least four via pitch-wide regions of a local simulation model were needed to obtain the stable results enabled by the submodeling simulation approach. The stress-generation mechanism during thermocompression, the coefficient of thermal expansion mismatch, and the curing process-induced shrinkage were separately investigated. The critical stress location was explored as the outer corner of the chip, and the maximum first principal stress during the thermocompression process generated on the chip and glass interposer were 34 and 120 MPa, respectively.