Cyclic Thermal Loading Research Articles

Thermal cycling effects on the mode-I delamination of multilayer laminated composites: An experimental-numerical approach

In this research, the influence of thermal cycling on the fracture toughness and maximum load in the mode-I delamination of polymer matrix composites (PMCs) was investigated. To reduce the effect of the remote ply orientation on the fracture toughness during initiation and propagation delamination, double cantilever beam (DCB) specimens with a stacking sequence of unidirectional [0]16 were considered. The specimens were subjected to thermal-cycled loading between 15°C and 65°C for 50-150 number cycles. One group of un-cycled specimens was examined at the commencement of the research as a control group to determine the effects of thermal cycling loading on mechanical characteristics of the second group specimens. During the DCB experiment, the specimens were inspected by 2 real-time cameras to record the delamination length and initial crack tip opening displacement (ICTOD). The strain energy release rate (SERR) approach was used for obtaining the critical fracture toughness from the experimental data. By employing the digital image correlation (DIC) method, the initial crack tip separation profile was obtained. The measured bridging laws with the cohesive zone elements model are used to accurately simulate the delamination propagation in DCB specimens. Investigation of load variations revealed that critical fracture toughness in the mode-I of delamination is firmly affected by the thermal cycling process.

Analysis of anchor force for pipeline walking induced by SCR tension

The deep-sea pipeline exposed on the seabed is prone to pipeline walking under the influence of thermal loading cycles. Anchors are commonly used to prevent the pipeline walking from causing the end connection of the pipeline system to break. The development of a simple and practical method for calculating anchor force is essential for the preliminary design of the project. In this paper, a finite element model for calculating anchor force is established, and the factors affecting the accumulated length of effective axial force are analyzed. A strain diagram method is proposed for calculating the anchor force under partial accumulated length, and an analytical solution for the rigid anchor force is derived based on the strain diagram method. To address the problem of large anchor force at the end anchor, a flexible anchor is proposed to reduce the anchor force, and a formula for predicting the flexible anchor force is fitted. The study shows that the accumulated length proportion of anchor force increases with the increase of loading temperature and SCR tension, and decreases with the increase of pipeline length and friction coefficient. Flexible anchors can significantly reduce the anchor force. The proposed analytical solution for anchor force can comprehensively consider the influence of factors such as pipeline length, SCR tension, loading temperature, and friction coefficient, and has certain advantages over traditional analytical solutions.

Physical and numerical investigation of integral bridge abutment stiffness due to seasonal thermal loading

Integral Abutment Bridges (IABs) are increasingly popular due to their reduced maintenance cost compared to traditional bridges with expansion joints. However, the widespread construction of IABs is currently limited by design code prescriptions resulting from the significant uncertainties associated with how the backfill interacts with the (integral) abutment and the deck. Under cycles of seasonal thermal loading, the backfill properties change, affecting the distribution of lateral earth pressures acting on the abutment walls. Moreover, the stiffness of the abutment can significantly influence the soil-structure interaction (SSI) in IABs. This research work investigates the effect of abutment stiffness (flexural rigidity) on soil-structure interaction in IABs under seasonal thermal loading through experimental analyses and numerical modelling. To better understand this mechanism and reliably assess the performance of IABs within their life cycle, a 1 g small-scale instrumented physical model was built to simulate the backfill under accelerated seasonal expansion and contraction of the bridge deck. The experimental results were modelled numerically in PLAXIS and ABAQUS to assess the sensitivity to different flexural stiffnesses of the abutment and discuss suitable options for modelling such SSI systems through finite elements either using a geotechnical-oriented or a structural-oriented software package. It was found that flexible IABs can be more suitable for controlling earth pressure built-up within the early lifecycle of the soil-structure systems. The simplified numerical models can provide a first-order prediction of pressure distributions in the small-scale 1-g rig. This preliminary dataset informs necessary larger-scale experiments to assess the scaling and feasibility of 1-g tests.

Analytical study on anchor force for pipeline walking laid on inclined seabed

Unburied subsea pipelines under cyclic thermal loading are often prone to axial walking. The axial movements accumulate over operational cycles, which can lead to potential failure at the mid-line or end connections. Anchoring is a commonly adopted method to -control pipeline walking, however, it requires accurate estimation of anchor force for efficient pipeline design. In view of this, the present study proposes a calculation method for anchor force of full mobilized lengths for different anchoring positions. Furthermore, the anchoring mechanism for partial mobilized lengths is analyzed. The anchor force is then determined using a strain diagram method for partial mobilized lengths. Finally, an analytical solution for anchor force based on the strain diagram method is derived and validated against finite element results. The results show that the mobilized length ratio of pipeline anchor force increases with the loading temperature and seabed slope but decreases with the pipeline length. The proposed analytical solution for anchor force which has advantages over traditional analytical solutions can comprehensively consider the effects of pipeline parameters, load parameters, and contact parameters.

Comparison of bond strength to three restorative materials after contamination and the use of two cleaning agents

Statement of problemScientific data on the decontamination effectiveness of a newly introduced cleaning agent are lacking. PurposeThe purpose of this in vitro study was to evaluate and compare the tensile bond strength (TBS) of 3 different restorative bonding surfaces after contamination with saliva following different cleaning protocols. Material and methodsA total of 192 disk specimens were made out of 3 materials (n=64); Katana Avencia (A), Katana Zirconia (Z), and e.max CAD (L). The bonding surfaces of all disks were polished, steam cleaned, and then pretreated by following the recommended protocol for each material. The specimens of each group were divided into 4 subgroups (n=16). The first subgroup served as the reference (R), where no contamination was applied. The 3 other subgroups were contaminated with saliva and subsequently rinsed with water for 20 seconds and dried with oil- and water-free air spray. They were then either not treated with any cleaning method (0), cleaned with Katana Cleaner (K), or cleaned with Ivoclean (I). The bonding surfaces of the specimens were perpendicularly luted to plexiglass tubes filled with dual-polymerizing composite resin (Clearfil DC Core) with resin cement (Panavia V5) after the recommended surface conditioning. Each subgroup was further subdivided into 2 groups: stored in 37 °C water for 3 days or subjected to thermal-cyclic loading for 150 days with 37 500 thermal cycles (7500 per month), temperature 5 to 55 °C, and dwell time of 30 seconds. All specimens were subjected to TBS testing in a universal testing machine. Three-way ANOVA was applied. A significant interaction (P<.01) was detected between the 3 different variables (material, treatment, aging). After significant interactions had been revealed by 3-way ANOVA, additional statistical analysis was performed by using separate 2-way ANOVAs, then separate 1-way ANOVAs followed by the Tukey-HSD test for post hoc pairwise comparisons among groups (α=.05 for all tests). All specimens underwent failure mode analysis after TBS testing ResultsAll specimens survived the storage with thermocycling except for group Z-0, where all specimens debonded during thermocycling. The mean ±standard deviation TBS values ranged from 18.3 ±5.3 MPa to 34.0 ±5.4 MPa after 3 days and from 6.7 ±5.5 MPa to 26.9 ±5.4 MPa after 150 days. ConclusionsContaminated groups that did not receive any cleaning had significantly lower TBS. Thermocycling had a negative effect on the TBS but was not statistically significant for all groups. Using the same cleaning method, the restorative material did had a significant effect on the TBS after 150 days.

Temperature-controlled tunable zigzag metamaterial beams to manipulate flexural waves

The study of artificially structured materials to control waves is ongoing, owing to their unprecedented properties. However, their narrow working frequency ranges significantly hinder their applications. In this study, a kind of tunable zigzag metamaterial beams with wider working frequency ranges are proposed by incorporating springs and damping elements into our previously proposed pure zigzag beams. The complex band structures of these tunable zigzag metamaterial beams are characterized by the spectral element method (SEM), and a parametric analysis of spring rigidity and damping is conducted. The results show that the full stopbands of our tunable zigzag metamaterial beams are highly sensitive to spring rigidity, which confirms their good tunability. Actuators serving as spring and damping elements are then designed and 3D printed using a thermally sensitive material, VeroPureWhite. The actuators are glued to pure zigzag aluminum beams to generate integrated tunable zigzag metamaterial beams. The transmission spectra are measured for the integrated tunable zigzag metamaterial beams under several thermal loading cycles. Both the numerical and experimental results demonstrate the wide tunability of our proposed tunable metamaterial beams.

Stability and wear of zirconia crowns with micro-layering

ObjectivesTo investigate stability and wear of tooth-supported zirconia single crowns with micro-layering in-vitro. Materials and methodsMolar crowns and specimens were fabricated from 5Y-TZP zirconia (Gen-X, Amann-Girrbach). Three groups were investigated: ML I: 0.1 mm cutback/painted/glazed (MiYO, Jensen); ML II: occlusal 0.3 mm cutback/painted/veneered/glazed (MiYO), and a monolithic control group (polished). After thermal cycling and mechanical loading (TCML), crowns were loaded to failure in a universal testing machine. Two-body wear test was performed. Wear (mean, maximum, antagonist) and roughness (Ra, Rz) were determined with a 3D laser-scanning-microscope. ResultsAll crowns survived TCML. In the control (2501.5 N) and ML II group (1775.3 N) significantly lower fracture forces were observed than in ML I (3636.4 N) (p ≤ 0.003). Significant wear differences were found (p ≤ 0.001) but not for antagonist wear (p ≥ 0.202). Lowest wear was observed in the control group 10.2 ± 1.5 µm/28.8 ± 6.4 µm, ML I 112.8 ± 37.3 µm/152.9 ± 42.8 µm, and ML II 192.4 ± 49.1 µm/340.7 ± 54.2 µm. Roughness was characterized by a Ra from 1.6 µm (control) to 3.0 µm (ML II), and a Rz from 11.8 µm (Control) to 24.0 µm (ML II). Roughness significantly differed between control group and ML I (p = 0.002) as well as ML I and ML II (p = 0.020). ConclusionsGood in-vitro performance and fracture stability without chipping or fracture were found for all systems. Wear and roughness were comparable to conventional ceramic veneering systems. Clinical RelevanceThe micro-layering of zirconia restorations can be recommended, yet the micro-layering could be worn during clinical application.

Aging and fracture resistance of screw-retained implant-supported molar crowns fabricated from lithium disilicate containing virgilite.

Purpose To investigate aging and fracture resistance of screw-retained implant-supported single crowns (iSCs) fabricated from lithium disilicate containing virgilite (VLD). Materials and Methods iSCs were fabricated from VLD (CEREC Tessera, Dentsply Sirona) and lithium disilicate (control; n=8, e.max CAD, Ivoclar) and bonded to a Ti-base abutment. VLD crowns were luted either with (VLDc, n=8) or without (VLDw, n=8) a coupling agent. iSCs were cleaned, sterilized, and screw-retained on implants. Fracture force was determined after thermal cycling and mechanical loading (TCML). Results All crowns survived TCML. No significant differences in mean fracture forces were identified between VLDc 1583 N, VLDw 1694 N, and control 1797 N (P=0.639 ANOVA, P=1.000 Bonferroni). Conclusion Screw-retained iSCs fabricated from VLD provide acceptable stability, which is independent on the usage of a coupling agent for bonding to Ti-base abutments and sterilization. Int J Prosthodont 2023. doi: 10.11607/ijp.8369.

Survival dependence of 3D-printed temporary materials on the filler content.

The aim of the present study was the evaluation of the in vitro performance and fracture force of 3D-printed anterior implant-supported temporary partial dentures (TPDs) with different filler content. Identical anterior resin-based TPDs (tooth sites 11 to 13; n = eight per material) were 3D printed from methacrylate resins with different filler content. A cartridge polymethyl methacrylate (PMMA) material was used as a reference. After temporary cementation, combined thermal cycling and mechanical loading (TCML) was performed on all the restorations to mimic clinical application. Behavior during TCML and fracture force was determined, and failures were analyzed. Data were statistically investigated (Kolmogorov-Smirnov test, one-way ANOVA; post hoc Bonferroni, Kaplan-Meier survival; α = 0.05). Failure during TCML varied between three failures and total failure during loading time. Mean survival time varied between 93 ± 206 x 103 cycles and 329 ± 84 x 103 cycles. Significantly different survival cycles between the individual materials could be determined (Mantel Cox log-rank test: chi-square: 21,861; degrees of freedom (df) = 4, P < 0.001). A correlation between filler level and survival cycles could be found (Pearson: 0.186, P = 0.065). Fracture values of the surviving TPDs varied between 499 and 835 N. Failures were characterized by fracture of the connector (n = 24) followed by fractures at the abutment (n = 10). TDPs showed different filler-dependent survival. Individual 3D-printed materials provided comparable or even better performance than a standard cartridge system and might be sufficient for temporary application of at least half a year.

Phase transformation behavior of aluminum under high hydrostatic pressure: A molecular dynamics study

The atomic mechanism of phase transformation under high pressure has been the focus of researches. In the present study, the roles of hydrostatic pressure (P) on phase transformation temperature and microstructural evolution in aluminum (Al) during cyclic thermal loading are studied from molecular dynamics simulations. The FCC → Liquid → FCC, FCC → liquid → FCC + BCC, FCC → BCC → Liquid → BCC and BCC → Liquid → BCC transformation pathways were observed under 0 ≤ P ≤ 14 GPa, 15 ≤ P ≤ 21 GPa, 22 ≤ P ≤ 25 GPa and 26 ≤ P ≤ 100 GPa, respectively, during cyclic thermal loading. It should be noted that the melting temperature predicted by the used potential at high P is obviously lower than experimental results. The FCC → BCC transformation involves nucleation and growth of BCC phase. The nucleation of BCC phase undergoes by the continuous deformation of FCC lattice, corresponding to the Bain transformation path. The growth of BCC phase is completed by the atomic diffusion. With increasing P, the 111<112̅> twin and {111} stacking fault in FCC phase evolve to five-fold twin and HCP phase, respectively. The microstructure of BCC phase is dominated by the {112}<110> twin. Insight obtained in this work paves the way for understanding the atomic mechanism of high pressure phase transformation.

Experimental and numerical life evaluation of TBCs with different BC and diffusion coating under cyclic thermal loading

AbstractThis paper experimentally and numerically investigates the thermally grown oxide (TGO), lifetime, and stress values in thermal barrier coatings with different bond coat (BC), without top coat (TC), and diffusion coating under cyclic thermal loading. Scanning electron microscope (SEM) analysis shows that the atmospheric plasma spraying (APS) and high‐velocity oxygen fuel (HVOF) fabricated sample has the highest and lowest TGO thickness and growth rate, respectively. The new coating with two BCs has a maximum lifetime of 102 cycles. After that, the lifetime of the coatings with HVOF‐BC, diffusion coating, and APS‐BC reach 84, 56, and 44 cycles, respectively. The diffusion coating does not have much effect on the TGO thickness; however, it delays the Al interdiffusion to the substrate. In the sample without the TC layer, oxygen contact with the BC layer has increased, leading to a rise in the BC oxidation rate. The numerical analysis of the stress values based on SEM images shows that the more intense TGO layer growth in APS coating caused an increase in TC layer stress values. Furthermore, the results show that the new coating with two‐layer BC has the lowest stress values. The TC absence causes the loss of compressive stresses caused by TC on TGO and increases the tensile stress values in this layer.

In vitro fatigue and fracture testing of temporary materials from different manufacturing processes in implant-supported anterior crowns.

The aim of this study was to investigate the in vitro fatigue and fracture force of temporary implant-supported anterior crowns made of different materials with different abutment total occlusal convergence (TOC), with/without a screw channel, and with different types of fabrication. One hundred ninety-two implant-supported crowns were manufactured (4° or 8° TOC; with/without screw channel) form 6 materials (n = 8; 2 × additive, 3 × subtractive, 1 × automix; reference). Crowns were temporarily cemented, screw channels were closed (polytetrafluoroethylene, resin composite), and crowns were stored in water (37°C; 10days) before thermal cycling and mechanical loading (TCML). Fracture force was determined. Kolmogorov-Smirnov, ANOVA; Bonferroni; Kaplan-Meier; log-rank; α = 0.05. Failure during TCML varied between 0 failures and total failure. Mean survival was between 1.8 × 105 and 4.8 × 105 cycles. The highest impact on survival presented the material (η2 = 0.072, p < .001). Fracture forces varied between 265.7 and 628.6 N. The highest impact on force was found for the material (η2 = 0.084, p < .001). Additively and subtractively manufactured crowns provided similar or higher survival rates and fracture forces compared to automix crowns. The choice of material is decisive for the survival and fracture force. The fabrication is not crucial. A smaller TOC led to higher fracture force. Manually inserted screw channels had negative effects on fatigue testing. The highest stability has been shown for crowns with a low TOC, which are manufactured additively and subtractively. In automix-fabricated crowns, manually inserted screw channels have negative effects.

ANALYSIS OF THERMAL CRACK FORMATION IN WATER-CHARGED AIR-COOLED HEAT EXCHANGERS FOR HEAVY-DUTY VEHICLES

The non-uniform flow distribution at the inlet severely affects the thermal cycling loading of the water-charged air-cooled (WCAC) systems resulting in crack formation after periods and hence leakage in the internal coolant. WCAC cracks are serious since having crucial effects on performance and durability. The thermal crack can be identified by testing the WCAC for various fatigue boundary conditions. The present study developed a custom thermal fatigue test rig to precisely determine the crack formation's location and cycle time in WCACs. The test rig was designed to reflect the vehicle's situation by simultaneously controlling the air and waterside of the WCAC continuously. Accordingly, the thermal fatigue tests of the WCAC parts were performed through the developed custom thermal fatigue test rig. The formation crack was observed periodically by carrying out tests with different critical cycles on the test rig, and the thermal cycling profile was generated. It was seen that the crack formation in the WCAC can be predicted at the same cycle time and exact location with the developed custom test rig compared to the vehicle tests. Moreover, the total cost, time, and man-hours per test increased by 80 %,75 %, and 60, % respectively, compared to traditional vehicle tests. Subsequently, the modified WCAC design was proposed to prevent non-uniform flow distribution at the inlet of the WCAC. The thermal fatigue tests of the modified WCAC design were performed using the developed test rig for stressful operating conditions. The results showed that the modified WCAC design is more robust to thermal fatigue than the old design. There was no crack formation in the modified WCAC design under various stressful operating conditions.

Expectation–maximization machine learning model for micromechanical evaluation of thermally-cycled solder joints in a semiconductor

This paper aims to study the microstructural and micromechanical variations of solder joints in a semiconductor under the evolution of thermal-cycling loading. For this purpose, a model was developed on the basis of expectation–maximization machine learning (ML) and nanoindentation mapping. Using this model, it is possible to predict and interpret the microstructural features of solder joints through the micromechanical variations (i.e. elastic modulus) of interconnection. According to the results, the classification of Sn-based matrix, intermetallic compounds (IMCs) and the grain boundaries with specified elastic-modulus ranges was successfully performed through the ML model. However, it was detected some overestimations in regression process when the interfacial regions got thickened in the microstructure. The ML outcomes also revealed that the thermal-cycling evolution was accompanied with stiffening and growth of IMCs; while the spatial portion of Sn-based matrix decreased in the microstructure. It was also figured out that the stiffness gradient becomes intensified in the treated samples, which is consistent with this fact that the thermal cycling increases the mechanical mismatch between the matrix and the IMCs.

A Numerical Procedure for Shakedown Analysis of Thick Cylindrical Vessels with Crossholes under Dual Cyclic Loadings.

A modified numerical procedure for the shakedown analysis of structures under dual cyclic loadings, based on the Abdalla method, is proposed in this paper. Based on the proposed numerical procedure, the shakedown analysis of the thick cylindrical vessels with crossholes (TCVCs) under cyclic internal pressure and cyclic thermal loading was carried out. The effects of material parameters (elastic modulus and thermal expansion coefficient) and crosshole radius on the elastic shakedown limit of TCVCs are discussed and, finally, normalized and formularized. Furthermore, the obtained shakedown limit boundary formulation is compared with FEA results and is verified to evaluate the shakedown behavior of TCVCs under cyclic internal pressure and cyclic thermal loading.

Thermal-hydraulic study of the Primary Heat Transport System of the DEMO Divertor Cassette Body

The EU-DEMO reactor is supposed to undergo a pulsed duty cycle under normal conditions, which might challenge the qualified lifetime of the main equipment inducing undue thermal and mechanical cycling loads. Moreover, during power operation it is not possible to exclude the occurrence plasma overpower transients that might jeopardize the structural integrity of the plasma-facing components. In this context, the University of Palermo in cooperation with ENEA has launched a research campaign within the framework of the EUROfusion action to investigate the thermal-hydraulic behaviour of the Primary Heat Transport System (PHTS) of the EU-DEMO Divertor (DIV) Cassette Body (CB) during the typical DEMO duty cycle. The study was primarily intended to start the definition of the strategies to be followed to minimize thermal fluctuations due to the pulsed operation. In particular, the attention has been focussed on the assessment of the DIV CB PHTS temperature behaviour during the pulse-dwell transition so to check the potential effectiveness of a direct coolant temperature control by properly tuning the feedwater mass flow rate. The activity has been led following a computational approach based on the adoption of the TRACE thermal-hydraulic system code. Models, assumptions, and outcomes of the analyses are herewith reported and critically discussed.

Influence of ambient temperature and structural parameters on thermal conductivity of carbon nanotube arrays after secondary segmentation

Vertically arranged carbon nanotube (CNT) arrays have good flexibility, elasticity, and thermal conductivity. As a new type of thermal interface materials (TIMs), it is increasingly used in heat conduction applications. The thermal conductivity of CNT arrays is an order of magnitude higher than that of traditional silicone oil and solid-state interface composites. However, their thermal properties are susceptible to the ambient temperature and internal structural parameters, and the underlying influence mechanism remains unclear. This lack of understanding hinders the design and application of CNT arrays in practical settings. Therefore, a secondary segmentation method was proposed to establish the structural model of CNT microcolumn arrays. Then, the thermal properties of the array material were simulated, and the influence of different environmental temperatures and structural parameters on thermal properties were analyzed. Simultaneously, the dynamic thermal conductivity of the CNT array was explored by thermal cyclic loading. Simulation results indicate that the increase of structural parameters have a positive effect on the thermal conductivity of the array at different ambient temperatures, but the low temperature environment is more conducive to the improvement. Furthermore, the influence of different array densities predicted by the model on thermal properties is consistent with the corresponding experimental results, which illustrates the feasibility of the segmentation method of the model and provides a new theoretical method for studying the thermal properties of CNT arrays.

The Thermal Resistance Performance of WTi Alloy-Thin-Film Temperature Sensors Prepared by Magnetron Sputtering

The microstructure and properties of WTi alloy films with 0~23 at.% Ti prepared by magnetron sputtering were investigated. The electrical resistivity gradually increased with the increase in the Ti content. When the Ti content was 6.8 at.%, the temperature coefficient of resistance of the alloy film reached the maximum value of 19.5 × 10−4 K−1, which is 3.6 times higher than that of the pure W film. After several thermal resistance tests, the temperature coefficient of resistance of the WTi alloy film with 6.8 at.% Ti decreased gradually. After five measurements, the temperature coefficient of resistance decreased gradually from 19.5 × 10−4 to 16.3 × 10−4 K−1. After annealing at 500 °C for 30 min, the grain size of the WTi alloy film (6.8 at.% Ti) increased, a few pores appeared, and the density of the film decreased. The temperature coefficient of resistance decreased from 19.5 × 10−4 K−1 to 14 × 10−4 K−1. When the annealing time was increased to 60 min, the structure and properties of the WTi alloy film remained basically unchanged. After conducting the annealing treatment for 30 min, the WTi films showed excellent stability in the thermal resistance tests, and their temperature coefficient of resistance was basically consistent after cyclic thermal loading, which has promising application prospects for the temperature measurement of tools and dies.

Cyclic medium heat flux testing of a WTa lattice structure on the HIVE facility

Testing fusion components in high-heat flux conditions is key for assessing the performance of plasma facing components. A novel limiter mock-up design was tested under cyclic thermal loading in the “Heating by Induction to Verify Extremes” (HIVE) facility at UKAEA. The results demonstrated both the capability of the HIVE facility for cyclic thermal loading and the performance of the mock-up limiter.The mock-up comprised a Tungsten-Tantalum additively manufactured lattice brazed to a copper heatsink. Heat fluxes up to 10 MW/m2 were achieved in the testing and a total of 507 pulses were performed with measured heat fluxes of 8 MW/m2 or higher. HIVE diagnostics (IR camera and thermocouples mounted in the sample) found no measurable change in the steady state thermal behaviour of the mock-up. Visual inspection of the sample after testing revealed cracking had occurred in the lattice structure. IR data also revealed that the cracked region of the lattice had a longer cool-down period to the rest of the structure.Preliminary EM analysis to estimate the variation of heat load between a lattice and a solid block was conducted. To gain confidence in such analysis, more computational time as well as thermal and electrical material properties of AM W at temperature are required.

Thermomechanical Oriented Reliability Enhancement of Si MOSFET Panel-Level Packaging Fusing Ant Colony Optimization With Backpropagation Neural Network

Considerable advancements in power semiconductor devices have resulted in such devices being increasingly adopted in applications of energy generation, conversion, and transmission. Hence, we proposed a Fan-Out Panel-Level Packaging (FOPLP) design for 30V Si based Metal Oxide Semiconductor Field Effect Transistor (MOSFET). To achieve superior reliability of the packaging, we applied the Nondominated Sorting Genetic Algorithm with elitist strategy (NSGA-II) and Ant Colony Optimization–Backpropagation Neural Network (ACO–BPNN) to optimize the design of redistribution layer (RDL) in FOPLP. We first quantified the thermal resistance and thermo-mechanical coupling stress of the designed package under thermal cycling loading. Next, NSGA-II and ACO–BPNN were used to optimize the size of the RDL blind via. Finally, the effectiveness of the proposed reliability optimization methods was verified by performing thermal shock reliability ageing tests on the prepared devices.