A Study of Substrate Models and Its Effect On Package Warpage Prediction

Pham, V.D.; Wang, Huayan; Xu, Jiefeng; Wang, Jing; Singh, Chrandeep; Park, Seungbae

doi:10.1109/ectc.2019.00175

Cited by 18 publications

(4 citation statements)

References 22 publications

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“…Even though the boundary conditions were different from the real condition and the tests were performed in room conditions for the test structure, we expected that the results from the experiment would provide precise knowledge of the thermomechanical responses of the bidirectionally corrugated core sandwich structures before they would be employed in the TPS panel. In this thermomechanical test, the thermal deformation of the test structure was measured using a three-dimensional digital image correlation (DIC) method, which is a non-contact, full-field deformation measurement method and has been considered to be a highly accurate method in various fields of research, such as for large deformation [43,44], high-temperature structures [45][46][47], and small structures [48][49][50][51][52]. The inner surface of the test structure was painted with a white background and black dots known as a speckle pattern.…”

Section: Thermomechanical Testing and Validationmentioning

confidence: 99%

Thermomechanical Performance of Bio-Inspired Corrugated-Core Sandwich Structure for a Thermal Protection System Panel

Goo

2019

Applied Sciences

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A skin structure for thermal protection is one of the most interesting components that needs to be considered in the design of a hypersonic vehicle. The thermal protection structure, if a dense structure is used, is heavy and has a large heat conduction path. Thus, a lightweight, high strength structure is preferable. Currently, for designing a lightweight structure with high strength, natural materials are of great interest for achieving low density, high strength, and toughness. This paper presents bio-inspired lightweight structures that ensure high strength for a thermal protection system (TPS). A sinusoidal shape inspired by the microstructure of the dactyl club of Odontodactylus scyllarus, known as the peacock mantis shrimp, is presented with two different geometries, a unidirectionally corrugated core sandwich structure (UCS) and a bidirectionally corrugated core sandwich structure (BCS). Thermomechanical analysis of the two corrugated core structures is performed under simulated aerodynamic heating, and the total deflection and thermal stress are presented. The maximum deflection of the present sandwich structure throughout a mission flight was 1.74 mm for the UCS and 2.04 mm for the BCS. Compared with the dense structure used for the skin structure of the TPS, the bio-inspired corrugated core sandwich structures achieved about a 65% weight reduction, while the deflections still satisfied the limits for delaying the hypersonic boundary layer transition. Moreover, we first fabricated the BCS to test the thermomechanical behaviors under a thermal load. Finally, we examined the influence of the core thickness, face-sheet thickness, and emittance in the simulation model to identify appropriate structural parameters in the TPS optimization. The present corrugated core sandwich structures could be employed as a skin structure for metallic TPS panels instead of the honeycomb sandwich structure.

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Section: Thermomechanical Testing and Validationmentioning

confidence: 99%

Thermomechanical Performance of Bio-Inspired Corrugated-Core Sandwich Structure for a Thermal Protection System Panel

Goo

2019

Applied Sciences

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“…As a result, RDLs in advanced packages become extremely complex in shape and behavior, posing great challenges in accurately capturing their thermo-mechanical characteristics. Additionally, in advanced packages, substrate is extremely thinned to several microns or even sub-microns [ 16 ] which are similar to or even thinner than RDL, making the RDLs more prominent compared to other package components [ 17 , 18 ]. For this reason, RDLs are playing crucial roles in package thermo-mechanical characteristics.…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, in advanced packages, substrate is extremely thinned to several microns or even sub-microns [16] which are similar to or even thinner than RDL, making the RDLs more prominent compared to other package components [17,18]. For this reason, RDLs are playing crucial roles in package thermo-mechanical characteristics.…”

Section: Introductionmentioning

confidence: 99%

An RDL Modeling and Thermo-Mechanical Simulation Method of 2.5D/3D Advanced Package Considering the Layout Impact Based on Machine Learning

Wu,

Wang,

et al. 2023

Micromachines

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The decreasing-width, increasing-aspect-ratio RDL presents significant challenges to the design for reliability (DFR) of an advanced package. Therefore, this paper proposes an ML-based RDL modeling and simulation method. In the method, RDL was divided into blocks and subdivided into pixels of metal percentage, and the RDL was digitalized as tensors. Then, an ANN-based surrogate model was built and trained using a subset of tensors to predict the equivalent material properties of each block. Lastly, all blocks were transformed into elements for simulations. For validation, line bending simulations were conducted on an RDL, with the reaction force as an accuracy indicator. The results show that neglecting layout impact caused critical errors as the substrate thinned. According to the method, the reaction force error was 2.81% and the layout impact could be accurately considered with 200 × 200 elements. For application, the TCT maximum temperature state simulation was conducted on a CPU chip. The simulation indicated that for an advanced package, the maximum stress was more likely to occur in RDL rather than in bumps; both RDL and bumps were critically impacted by layouts, and RDL stress was also impacted by vias/bumps. The proposed method precisely concerned layout impacts with few resources, presenting an opportunity for efficient improvement.

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“…By tracking movements of exterior features of a structure that appear on digital images captured by cameras, the displacement can be calculated by photogrammetry theory and its modal parameters can be estimated for damage detection. The digital image correlation (DIC) method is a kind of photogrammetry method that measures the full-field deformation of structure in various fields of research, such as for vibration [ 44 ], crack monitoring [ 45 , 46 , 47 ], high-temperature structures [ 48 , 49 , 50 ], electronic packaging [ 51 , 52 , 53 ], and small structures [ 54 , 55 ]. The identification of a whole area displacement field or operating deflection shape (ODS) is one of the most interesting features using the DIC method [ 56 ].…”

Section: Introductionmentioning

confidence: 99%

Dynamic Characteristics and Damage Detection of a Metallic Thermal Protection System Panel Using a Three-Dimensional Point Tracking Method and a Modal Assurance Criterion

Goo

2020

Sensors

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A thermal protection system (TPS) is designed and fabricated to protect a hypersonic vehicle from extreme conditions. Good condition of the TPS panels is necessary for the next flight mission. A loose bolted joint is a crucial defect in a metallic TPS panel. This study introduces an experimental method to investigate the dynamic characteristics and state of health of a metallic TPS panel through an operational modal analysis (OMA). Experimental investigations were implemented under free-free supports to account for a healthy state, the insulation effect, and fastener failures. The dynamic deformations resulted from an impulse force were measured using a non-contact three-dimensional point tracking (3DPT) method. Using changes in natural frequencies, the damping ratio, and operational deflection shapes (ODSs) due to the TPS failure, we were able to detect loose bolted joints. Moreover, we also developed an in-house program based on a modal assurance criterion (MAC) to detect the state of damage of test structures. In a damage state, such as a loose bolted joint, the stiffness of the TPS panel was reduced, which resulted in changes in the natural frequency and the damping ratio. The calculated MAC values were less than one, which pointed out possible damage in the test TPS panels. Our results also demonstrated that a combination of the 3DPT-based OMA method and the MAC achieved good robustness and sufficient accuracy in damage identification for complex aerospace structures such as TPS structures.

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A Study of Substrate Models and Its Effect On Package Warpage Prediction

Cited by 18 publications

References 22 publications

Thermomechanical Performance of Bio-Inspired Corrugated-Core Sandwich Structure for a Thermal Protection System Panel

Thermomechanical Performance of Bio-Inspired Corrugated-Core Sandwich Structure for a Thermal Protection System Panel

An RDL Modeling and Thermo-Mechanical Simulation Method of 2.5D/3D Advanced Package Considering the Layout Impact Based on Machine Learning

Dynamic Characteristics and Damage Detection of a Metallic Thermal Protection System Panel Using a Three-Dimensional Point Tracking Method and a Modal Assurance Criterion

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