Electrical Connection Methods Research Articles

Operating characteristics study of a dual-opposed free-piston Stirling generator

Dual-opposed Free-piston Stirling generators (dual-opposed FPSGs) offer advantages of reduced vibration and increased power density, making them promising candidates for space and distributed energy applications. So far, operational characteristics of the dual-opposed FPSG have yet to be completely understood. This study focuses on a 3 kW dual-opposed FPSG prototype designed to integrate heat pipes. Through computational fluid dynamics and thermoacoustic analysis, a novel hot end heat exchanger with evenly-distributed heat pipe bore was discovered to deliver 12 kW heating power with a gas–solid temperature difference of 21 K. Subsequently effort combined thermoacoustically-based calculations with experiments to investigate the impact of two electrical connection methods of linear alternators on FPSG performance. Experimental results validated the numerical model, showing heat-to-electricity efficiency deviations within 5 % under different electrical connection modes. The FPSG consistently achieved its rated power in both series and parallel connection modes, exhibiting a thermal-to-electric efficiency of 25.2 %. Notably, the series connection mode demonstrates superior sensitivity and consistency compared to parallel connection. Further experiments revealed that charge pressure, load resistance and external capacitance all exerts limited impact on the consistency, while external capacitance significantly influenced acoustic impedance. This resulted in an enhancement in both hot-end wall temperature and heat-to-electricity efficiency, while minimizing power piston displacement and damping temperature when resonating with the inductance.

Numerical analysis of semiconductor-based energy conversion technologies for offshore applications

This study analyzes the physical principles and characteristics of thermoelectric energy conversion phenomena utilizing p-n semiconductor couples to propose a design methodology for thermoelectric generators (TEGs) capable of energy recovery in marine environments. To design TEGs with practical power generation and energy conversion efficiency, the development of a numerical analysis model that can predict and analyze the behavior characteristics of TEGs is required. We present the necessary conditions for a numerical analysis model that simulates the generation characteristics of TEGs at the system level, along with a comparison and analysis of experimental results. The electrical connection method of the thermoelectric modules (TEMs) significantly affects the power generation performance of TEGs; however, there is a lack of research on the electrical connections between TEMs in existing studies. This paper examines the reasons for performance changes due to electrical connections between TEMs and proposes an optimal electrical connection method. Additionally, it is demonstrated that improving the thermal flow distribution within the TEG can enhance system performance and maximize the effects of electrical connections between TEMs. We analyze the characteristics of technologies that can improve the level of thermal flow distribution within the TEG, such as finned and porous structures, and present optimal utilization strategies.

Influence of HCl Concentration on Corrosion Behavior between Au or Cu Bonding Wires and the Bond Pad for Semiconductor Packaging

Wire bonding, one of the methods for electrically connecting a semiconductor chip with a substrate, involves attaching thin metal wires to pads. It is the oldest electrical connection method that exhibits high compatibility with other processes. The metal wires used for electrical connection in wire bonding are mainly made of Au, Cu, and Ag. After the wire bonding, molding is performed using the epoxy molding compound (EMC). However, EMC inevitably contains ions such as halogen elements. In addition, it absorbs moisture due to its hydrophilicity, creating a corrosive environment with electrolytes. In this study, we evaluated the influence of hydrochloric acid concentration on corrosion behavior between Au or Cu bonding wires and sputtered Al bond pads. The electrochemical factors such as corrosion potential difference (ΔE), galvanic corrosion current density (ig), and anodic and cathodic Tafel slopes were found to influence galvanic corrosion behavior. Galvanic corrosion tendency in first bond and second bond areas of PCB unit specimen was confirmed.

Energy conversion models and characteristics under various inner connections of a novel packaged piezoelectric transducer for pavements

The piezoelectric effect in piezoelectric transducers converts the mechanical energy into electrical energy to supply power to road facilities. The piezoelectric transducer designed in the 3–3 piezoelectric mode has been widely studied due to the consideration of power generation performance and load-bearing requirements. However, the conservative design of some external packages and the lack of theory in the internal connection design are two deficiencies of existing research on 3–3 piezoelectric mode transducers. Given the shortcoming of packages cannot make full use of the compressive properties of piezoelectric ceramics which weakens the energy conversion ability of the piezoelectric transducers, a novel piezoelectric transducer with full-pressure packaging was designed. For the lack of theoretical and systematic research on the spatial arrangement and electrical connection of piezoelectric materials inside piezoelectric transducers, from a theoretical point of view, the energy conversion models of piezoelectric transducers in four connection modes: stacked series, stacked parallel, array series, and array parallel were derived. Subsequently, through model verification tests, the influence of the four connection modes on the energy conversion characteristics of the piezoelectric transducer was systematically studied. Finally, the effect of connection mode on energy conversion was explained in a unified manner. Five methods of promoting the energy conversion of piezoelectric transducers were proposed. The study indicated that the connection mode affected the energy conversion of the piezoelectric transducer. Specifically, the maximum energy conversion potential of the piezoelectric transducer is only affected by the spatial arrangement. The electrical connection method determines the matching resistance, which can facilitate the piezoelectric transducer to exert the maximum energy conversion potential. In the stacked type, the peak energy conversion monotonously increases with the number of stacked layers, whereas the array type exhibits the opposite trend. Regardless of the spatial arrangement of the piezoelectric materials, when piezoelectric ceramics are connected in series, the optimal value of resistance increases with the number of piezoelectric ceramics, and the opposite is true when the connection is made in parallel. The normalization analysis pointed out that the connection mode affects the energy conversion of the piezoelectric transducer can be summarized as the volume index of the piezoelectric ceramic group affects its energy conversion. A larger ratio of height to diameter of the piezoelectric ceramic group can improve the energy conversion of the transducer. This article provides ideas for the packaging design of piezoelectric transducers and a theoretical reference for the design of internal piezoelectric ceramic connection methods.

Surface Mount Technology for Silica-Based Planar Lightwave Circuit and Its Application to Compact 16×16 Multicast Switch

We demonstrated a compact 16×16 multicast switch (MCS) made from a silica-based planar lightwave circuit (PLC). The switch utilizes a new electrical connection method based on surface mount technology (SMT). Five electrical connectors are soldered directly to the PLC by using the standard reflow process used for electrical devices. We reduced the chip size to half of one made with conventional wire bonding technology. We obtained satisfactory solder contacts and excellent switching properties. These results indicate that the proposed method is suitable for large-scale optical switches including MCSs, variable optical attenuators, dispersion compensators, and so on.

Overview of Recent Advancements in the Microbial Fuel Cell from Fundamentals to Applications: Design, Major Elements, and Scalability

Microbial fuel cell (MFC) technology offers an alternative means for producing energy from waste products. In this review, several characteristics of MFC technology that make it revolutionary will be highlighted. First, a brief history presents how bioelectrochemical systems have advanced, ultimately describing the development of microbial fuel cells. Second, the focus is shifted to the attributes that enable MFCs to work efficiently. Next, follows the design of various MFC systems in use including their components and how they are assembled, along with an explanation of how they work. Finally, microbial fuel cell designs and types of main configurations used are presented along with the scalability of the technology for proper application. The present review shows importance of design and elements to reduce energy loss for scaling up the MFC system including the type of electrode, shape of the single reactor, electrical connection method, stack direction, and modulation. These aspects precede making economically applicable large-scale MFCs (over 1 m3 scale) a reality.

The electric feature synergy in the photovoltaic - Thermoelectric hybrid system

The thermoelectric (TE) module can be used to convert the heat generated by the photovoltaic (PV) cell to electricity, therefore the photovoltaic-thermoelectric hybrid system (PV-TE) has attracted extensive attention. The energy loss caused by the mismatch between the PV current and the TE current is studied. Two different electrical connection methods of the PV-TE system are studied in this paper. The choice of the electrical connection method depends on the temperature variation. When the PV temperature changes with the solar radiation, it is better to use the series-connection to connect the electrodes of the PV-TE system. However, if the PV temperature does not vary with the solar radiation, the parallel-connection is a better choice for the PV-TE system. According to these phenomena, it can be known that the PV-TE system without the phase change material must choose the serial connection and the parallel connection is a good choice for the PV-TE system incorporated with the phase change material.

큐브위성 탑재를 위한 MEMS 고체 추력기의 구조설계 및 검증

MEMS solid thruster module is composed of solid thruster and its control board. It was developed for the purpose of an academic research. Therefore, thermo-mechanical design and verification for space usage were not considered in the design phase. To mount it on a cube satellite without any design modification, technical efforts at the system level structure design is required. In this study, we proposed a structural design concept to mount the MEMS thruster module by using brackets for guaranteeing structure safety under launch loads and easier mating and de-mating of MEMS thruster module during test phase. The effectiveness of the design has been verified through structural analysis and vibration test. In addition, electrical connection method using spring pins between MEMS thruster and control board is effective for guaranteeing the structural safety under launch vibration loads.

Luminous Flux and Current Uniformity Analysis in Linear LED Modules

ABSTRACTA linear light emitting diode (LED) module with multiple parallel LED strings driven by a constant current source could display luminous flux variations along its length. This effect is caused by current imbalance among LED strings. Three commonly used electrical connection methods were compared and analyzed with computer simulations and actual experiments. Recommendations are made on how to minimize the imbalance.

MEMS Wafer‐Level Packaging Technology Using LTCC Wafer

SUMMARYThis paper describes a versatile and reliable wafer‐level hermetic packaging technology using an anodically bondable low‐temperature co‐fired ceramic (LTCC) wafer, in which multilayer electrical feedthroughs can be embedded. The LTCC wafer allows many kinds of microelectromechanical systems (MEMS) to be more flexibly designed and more easily packaged. The hermeticity of vacuum‐sealed cavities was confirmed after 3000 cycles of thermal shock (–40 30 min/+125 30 min) by the diaphragm method. To practically apply the LTCC wafer to a variety of MEMS, the electrical connection between the MEMS on a Si wafer and feedthroughs in the LTCC should be established by a simple and reliable method. We have developed a new electrical connection method: the electrical connection is established by porous Au bumps, which are part of the Au vias exposed in wet‐etched cavities on the LTCC wafer. A 100% yield of both electrical connection and hermetic sealing was demonstrated. A thermal shock test up to 3000 cycles confirmed the reliability of this packaging technology.

MEMS Wafer-level Packaging Technology Using LTCC Wafer

SUMMARY This paper describes a versatile and reliable wafer-level hermetic packaging technology using an anodically bondable low-temperature co-fired ceramic (LTCC) wafer, in which multilayer electrical feedthroughs can be embedded. The LTCC wafer allows many kinds of microelectromechanical systems (MEMS) to be more flexibly designed and more easily packaged. The hermeticity of vacuum-sealed cavities was confirmed after 3000 cycles of thermal shock (–40 30 min/+125 30 min) by the diaphragm method. To practically apply the LTCC wafer to a variety of MEMS, the electrical connection between the MEMS on a Si wafer and feedthroughs in the LTCC should be established by a simple and reliable method. We have developed a new electrical connection method: the electrical connection is established by porous Au bumps, which are part of the Au vias exposed in wet-etched cavities on the LTCC wafer. A 100% yield of both electrical connection and hermetic sealing was demonstrated. A thermal shock test up to 3000 cycles confirmed the reliability of this packaging technology.