This is the updated version (ver.2) of the popular document "Fundamentals of Flux Cleaning." In this revision, in addition to the existing content (how to choose cleaning agents and cleaning methods), we have added the basics of "Residue Evaluation (Analysis)." This document is recommended for those who are just starting with flux cleaning and for those who want to understand the entire process from cleaning to analysis. In addition to the purpose of cleaning and the fields where cleaning is necessary, we also explain the necessity and methods of chemical analysis, so please take a moment to read it.

What is substrate cleaning? Is substrate cleaning unnecessary? We provide a detailed explanation of areas where flux cleaning is necessary, among other topics. In Japan, many cases adopt no-clean paste, but cleaning has become essential to ensure high reliability. We also address the latest cleaning challenges, such as the impact of ionic residues and metal salts on insulation resistance, in this column. Recommended for those who: * Want to investigate the causes of defects despite cleaning * Want to know the latest cleaning challenges and evaluation criteria * Want to explain and promote substrate cleaning within their company, etc. Please see the related links for more information.

In recent years, the advancement of electronic devices has led to a demand for advanced bonding technologies that can withstand high temperatures, large currents, and high voltages. In particular, in power devices, there are increasing cases where conventional solder types do not provide sufficient performance. While high Pb solder and Au/Sn solder can be applied, the use of "sintered bonding" is expanding due to considerations such as environmental regulations and costs, as it can form a high-density bonding layer. This article will examine effective cleaning methods utilizing spray cleaning and ultrasonic cleaning, and introduce the features and application examples of the cleaning agents VIGON PE 305N and VIGON PE 216A for power electronics.

In current electronics assembly in Japan, rosin-based flux is predominantly used for soldering. However, due to the promotion of the SDGs and the growing interest in reducing environmental impact, there is an active evaluation of water-soluble flux, which is expected to reduce VOC emissions and cleaning burdens. This time, we will present an investigation into the actual cleaning conditions of water-soluble flux, which is recognized as easier to clean than rosin-based flux.

Long-side resistors refer to a type of chip resistor (resistor) on a substrate where the electrodes are arranged along the long side of the component. In recent years, there has been an increase in cases where they are used for the purpose of enhancing functionality and ensuring long-term stability. In this instance, we created a test board using general-purpose rectangular resistors (2012) and long-side resistors (1220), and conducted substrate cleaning using a cleaning agent primarily composed of water (manufactured by Zestron / VIGON PE 304N) and a general-purpose solvent-based cleaning agent primarily composed of organic alkali. For this verification, we received cooperation from Japan Superior Co., a solder manufacturer, and conducted a detailed analysis comparing the cleanliness of both types of resistors.

We have added a page titled "【Free Download】Cleaning Agents for Electronic Devices and SDGs." This document explains what requirements electronic devices have for achieving the SDGs and how cleaning of electronic devices should be approached from the perspective of the SDGs. It is recommended for those who want to achieve "cleaning that balances low-risk performance and cleaning performance" or who want to know about the cleaning technologies required for electronic devices. The content includes information on "Cleaning of Electronic Devices and SDGs" and "Reducing Risks Required for Cleaning Agents for Electronic Devices," so please take a moment to read it.

Water-soluble flux is a flux based on water, using water-soluble polymers such as polyoxyethylene alkyl ether. Currently, in Japan, rosin-based flux is the mainstream for soldering in electronics assembly, but due to the growing environmental awareness such as the SDGs, there is a movement to explore the transition to water-soluble flux, which is expected to have a VOC reduction effect. This document explains the role and applications of water-soluble flux, as well as residues, analysis methods, and cleaning methods.

We would like to introduce a case study on the investigation of factors leading to cleaning defects in flux cleaning troubles caused by the high density of component mounting. With the increase in component mounting density, a change in the solder paste used was made, but there have been reports of defects believed to be caused by cleaning issues. Based on the information gathered, we inferred the current situation. We conducted an analysis and evaluation of the hypothesis, and based on the results, we proposed both temporary and permanent measures tailored to the customer's circumstances.

This document explains the cleaning techniques required for sintered joining devices. It discusses the background for the need for cleaning in sintered joining devices and the differences from flux cleaning, as well as introducing specific cleaning processes. It also includes information on the selection of cleaning agents and methods, as well as cleanliness analysis after cleaning. We encourage you to read it.

In recent years, the miniaturization and densification of electronic devices have progressed, and along with this, the evolution of the bonding materials used has also overlapped, making contamination more complex. Particularly in fields such as automotive, aerospace, space, and high-capacity communications, there is an increasing number of cases requiring high reliability, and concurrently, there is a demand for thorough cleaning from the perspective of quality assurance. Inadequate cleaning can lead to issues such as poor wire bonding, inadequate adhesion of resin in molding, and the occurrence of migration, which is a well-known fact. However, in recent years, there have been many cases where defects occur in later processes despite passing inspections, and we have seen an increase in inquiries to our company regarding this issue. Why do such cases arise? This time, we will explain the importance of cleanliness evaluation after cleaning.

In the publication "Development of High-Heat-Resistant and High-Thermal-Conductive Materials for Next-Generation Power Devices - Thermal Management: Substrates, Joining, Sealing, and Cooling Technologies" by the Technical Information Association, our engineer has written about "Cleaning Techniques Required for Sintered Joining Devices." The text explains topics such as "The Formation and Residual Effects of Contamination in Sintered Joining Devices," "Selection of Cleaning Agents and Cleaning Methods," and "Analysis of Cleanliness After Cleaning." The book also provides a thorough explanation of Si, SiC, GaN, and gallium oxide, as well as the required characteristics in automotive environments and implementation examples. It details guidelines for designing TIMs and thermal sheets that balance "thermal characteristics" and "operational reliability." We highly recommend reading it.

Electronics assembly refers to the technology of attaching electronic components to a substrate. Specifically, it is the process of joining components such as semiconductors, resistors, and capacitors to a printed circuit board to form an electrical circuit. The sizes of these components tend to become smaller in response to the demands for higher performance and space-saving in products, and accordingly, fine joining technology is also evolving. This has a significant impact on the cleaning process as well. This document explains the evolution of joining technology and cleaning in fine joining.

This document provides a detailed explanation of the evaluation methods and added value in flux cleaning. It introduces topics such as "cleanliness analysis in flux cleaning," "substances to be analyzed," "the impact of residual organic matter," and "the pathways and effects of ion contamination." Additionally, it includes an introduction to Zestron's company and examples of analytical methods. We encourage you to read it.

This document explains the analysis of ionic residues on electronic substrates that our company, as a cleaning agent manufacturer, has been working on. It includes explanations about ions and flux, as well as discussions on ion contamination measurement, ion chromatography, and scanning electron microscopy with energy dispersive X-ray spectroscopy. Additionally, it features case studies on the cleaning efficacy of surfactants. Please feel free to download and read it.

In the technical book "Analysis Techniques for Foreign Substances and Sample Pretreatment, Interpretation of Results" published by the Technical Information Association, our engineers have written a section titled "Ion Residues on Electronic Substrates and Their Analytical Methods." It provides detailed descriptions of "What are Ion Residues," "Analysis of Ion Residues Remaining on Electronic Substrates," and "Analytical Case Studies - Cleaning Properties of Surfactants." This book serves as a valuable resource for addressing concerns such as difficulties in library searches or uncertainty about which analytical instruments to use, along with a wealth of analytical case studies.

We have added an article that explains "Compliance with Regulations and Safety Measures for Cleaning Agents" step by step regarding purchasing, using, and storing them. In recent years, from the perspective of environmental conservation and human protection, countries have strengthened regulations concerning the handling of chemical substances, and there is a global trend towards initiatives related to the SDGs (Sustainable Development Goals). In Japan, the Industrial Safety and Health Act will be revised in April 2024, strengthening the handling of chemical substances. To reduce health risks for workers and environmental impacts, some companies are moving to avoid procuring materials that have a significant environmental burden, and cleaning agents are no exception. Taking into account efforts abroad, we will introduce the regulations related to cleaning agents.

This document explains how to choose flux cleaning agents. It provides specific examples of key points to consider when selecting flux cleaning agents and highlights the aspects to focus on. It also includes important considerations for water-based cleaning agents, such as controlling evaporation loss and variations in water content, as well as examples of non-cleaning type flux cleaning cases. We encourage you to read it. [Contents (partial)] ■ Key points for selecting flux cleaning agents ■ Types of flux cleaning agents ■ Considerations when evaluating water-based cleaning agents ■ Examples of non-cleaning type flux cleaning cases

Our company will participate in the "Solder and Fine Joining Subcommittee Symposium - Research and Development Trends in Implementation Technologies and Materials Supporting the DX and GX Era" held by the Japan Welding Society. At this symposium, there will be presentations on the research and development trends of semiconductor devices that support the DX and GX era, as well as the implementation technologies and materials used in them. The Chief Engineer from Zestron Japan Co., Ltd. is scheduled to speak. Additionally, we will introduce new technologies and products, as well as our efforts in the standardization activities of the related cleaning evaluation working group. We hope you will join us.