The Influence of Soldering Profile on the Thermal Parameters of Insulated Gate Bipolar Transistors (IGBTs)

The effect of solder joint fabrication on the thermal properties of IGBTs soldered onto glass-epoxy substrate (FR4) was investigated. Glass-epoxy substrates with a thickness of 1.50 mm, covered with a 35 μm thick Cu layer, were used. A surface finish was prepared from a hot air leveling (HAL) Sn99Cu0.7Ag0.3 layer with a thickness of 1 ÷ 40 μm. IGBT transistors NGB8207BN were soldered with SACX0307 (Sn99Ag0.3Cu0.7) paste. The samples were soldered in different soldering ovens and at different temperature profiles. The thermal impedance Zth(t) and thermal resistance Rthof the samples were measured. Microstructural and voids analyses were performed. It was found that the differences for different samples reached 15% and 20% for Zth(t) and Rth, respectively. Although the ratio of the gas voids in the solder joints varied between 3% and 30%, no correlation between the void ratios and Rth increase was found. In the case of the different soldering technologies, the microstructure of the solder joint showed significant differences in the thickness of the intermetallic compounds (IMC) layer; these differences correlated well with the time above liquidus during the soldering process. The thermal parameters of IGBTs could be changed due to the increased thermal conductivity of the IMC layer as compared to the thermal conductivity of the solder bulk. Our research highlighted the importance of the soldering technology used and the thermal profile in the case of the assembly of IGBT components.

Analysis of Void Formation Mechanism in the Vacuum Reflow Soldering Process of Semiconductor Laser Diode

In this paper, the vacuum reflow soldering technology for semiconductor laser chips in optoelectronic devices was studied and analyzed in a systematic manner. Through the study on the key elements in the reflow soldering process, such as the selection of solders, <a>chamber</a> vacuum, flux, and the pressure applied by the fixture on the chip, this paper focused on exploring the formation mechanism of voids in the solder layer when the device was resoldered. Also, the change in the movement of gas bubbles in the voids with changing reflow oven chamber conditions and its underlying law were analyzed, by preparing 200 C-package semiconductor laser diodes and verifying the reliability and stability of the theoretical analysis through inspection and test aging. which could provide a theoretical basis for the use of the vacuum reflow soldering technology to reduce the void rate in the soldering process of devices.

Analysis of Void Formation Mechanism in the Vacuum Reflow Soldering Process of Semiconductor Laser Diode

In this paper, the vacuum reflow soldering technology for semiconductor laser chips in optoelectronic devices was studied and analyzed in a systematic manner. Through the study on the key elements in the reflow soldering process, such as the selection of solders, <a>chamber</a> vacuum, flux, and the pressure applied by the fixture on the chip, this paper focused on exploring the formation mechanism of voids in the solder layer when the device was resoldered. Also, the change in the movement of gas bubbles in the voids with changing reflow oven chamber conditions and its underlying law were analyzed, by preparing 200 C-package semiconductor laser diodes and verifying the reliability and stability of the theoretical analysis through inspection and test aging. which could provide a theoretical basis for the use of the vacuum reflow soldering technology to reduce the void rate in the soldering process of devices.

Plated TOPCon solar cells & modules with reliable fracture stress and soldered module interconnection

This work demonstrates that the application of plated Ni/Cu/Ag contacts for TOPCon solar cells and modules is a reliable alternative to screen-printed metallization. Key advantages of plated metallization is a significant reduction of material costs [B. Grübel et al., in Proceedings 11th SiliconPV Conference, Hamelin, 2021, to be published] due to the substitution of a fully printed silver finger by a stack of a thin nickel seed layer (0.5-1 μm height), highly conductive copper finger (3–10 μm height) and an ultra-thin surface finish by tin (1–3 μm height) or silver (<0.5 μm height). In this study it will be shown that conventional soldering technology can be used to interconnect plated TOPCon solar cells. We manufactured a 60-cell module using industrial processes. The right choice of plating electrolyte allows low stress and ductile metal finger leading to similar reliability in cell breakage experiments compared to state-of-the-art screen-printing metallization.

PHASE FORMATION IN CONTACT LAYERS DURING CONTACT MELTING OF COPPER AND ALUMINUM

В настоящей работе предпринимается попытка выявить особенности структуры контактных прослоек при контактном плавлении меди с алюминием марки АМГ-2 (состав мас. %: Mg - 1,8-2,8, Mn - 0,2-0,6, Cu - 0,1, Zn - 0,2, Fe - 0,4, Si - 0,4, остальное - алюминий) и алюминий-литиевым сплавом ( Al - 0,4 ат. % Li ). Изучение контактного плавления в системе Cu / Al важно для разработки технологии контактно-реактивной пайки, получения слоистых интерметаллических композиционных материалов, создания теплоотводов полупроводниковых приборов, моделирование дендритообразования. Установлено, что в контактных прослойках образуются интерметаллиды, влияющие на хрупкость соединений меди с алюминием и эвтектические структуры. In this work, an attempt is made to identify the features of the structure of contact layers during the contact melting of copper with aluminum brand AMG-2 (mass composition, %: Mg - 1,8 - 2,8, Mn - 0,2 - 0,6, Cu - 0,1, Zn - 0,2, Fe - 0,4, Si - 0,4, rest - aluminum) and aluminum-lithium alloy (Al - 0,4 wt.% Li). The study of contact melting in the system is important for development of contact-reactive soldering technology, obtaining layered intermetallic composite materials, creating heat sinks for semiconductor devices, modeling dendrite formation. It was established that intermetallic compounds are formed in the contact layers, which affect the brittleness of copper-aluminum compounds and eutectic structures.

A Practical Learning Simulation Software with Specific Applications for Printed Circuit Board Soldering/De-soldering Ability Certifications

This paper mainly develops a practical learning printed circuit board (PCB) soldering/de-soldering simulation software to be the reference of the specialized characteristic curriculum for a school. The proposed learning simulation software can train students with the soldering knowledge, the soldering technology, the electronic component identification, and the usage of the instruments. The research aims at inspiring students to be interested in circuitry soldering technology and have different thoughts on electronic/information/mechanical related technology applications. In this paper, the developed practical learning simulation software utilizes Visual Basic programming language as the developing tool and adopts the Bluetooth voice- activated tracking self-propelled vehicle and the number guessing game main control PCBs as the circuitry soldering training targets which was developed by Taiwan Embedded Microcontroller Development Institution (TEMI). The proposed simulation tool has been used as the learning exploration with the students at Kao Yuan University in Kaohsiung City, Taiwan. According to the experimental results, the developed simulation tool could provide three contributions. First, it can be an interactive- and interesting-oriented learning tool. Second, it can cultivate and inspire students learning soldering technology efficiently and effectively to meet the needs in the industry. Third, it can cultivate more professional and technical students actively participate in seeking solutions to problems.

Development of resource-saving and environmentally safe beryllium bronze soldering technology

The composition of the solder, which provides the necessary technological properties of the product, namely, electrical conductivity and mechanical strength of the junction was selected. The possibility of brazing beryllium bronze with a silver contact plate by furnace brazing using fluxes based on NaCl: CaCl2: CaF2 salts, respectively (24: 61: 15% mass) in the atmosphere was established. The possibility of brazing BrB2 beryllium bronze in the atmosphere using a research flux based on the eutectic of the NaCl – CaCl2 system (28…72% wt.) adding 15% CaF2 over a copper layer is shown. The technology for brazing beryllium bronze BrB2 with silver contact plates with silver solder PSr68 has been developed. The brazing process is combined with the hardening operation, which allows avoiding additional thermal operations; flux residues are removed during hardening and do not actually need additional cleaning operations; applied solder, flux components and technologies for applying a layer of copper are not scarce and relatively cheap, which can significantly reduce the cost of the product, subject to the requirements of the technical specifications. A technological process that makes it possible to refuse of using vacuum systems and toxic fluxes has been developed.

X-Ray Fluorescence Analysis of a Gold Ibex and other Artifacts from Akrotiri

In-situ X-ray fluorescence analysis (XRF) of ancient artifacts from the excavation area was performed using a novel X-ray instrumentation, composed of a portable silicon PIN thermoelectrically cooled X-ray detector, a miniature X-ray source, and portable data acquisition devices. The main objective of the analyses in Akrotiri was to explore the potential of the technique to provide answers to a wide range of archaeometric questions regarding the bulk composition of metal alloys, especially of gold, the characterization of corrosion products in bronze artifacts, identification of inorganic elements which are fingerprints of the minerals used in wall-painting pigments, and of the painting materials and techniques used for the decoration of clay vase surfaces. Among the analysed artifacts are a unique gold ibex, a bronze dagger and blade, various pigments from the wall paintings of room 3 in Xeste 3, decoration pigments from rosettes of faience, a bichrome jug, and other clay vases. The results of the in-situ XRF survey, primarily those of the bulk composition and soldering technology of the gold ibex, are discussed and compared with literature.