Defects in the substrate are a serious issue that greatly undermines reliability. In this article, we will discuss 10 common defects that can occur in substrates, including those arising from soldering and assembly processes, as well as defects caused by chemical factors. We will explain the technical background, assessment methods, and countermeasures from the perspective of cleaning.

The circuit board, often referred to as the heart of electronic devices, plays a crucial role in determining the overall quality of the product. However, corrosion of the circuit board directly leads to issues such as circuit shorts and disconnections, which can reduce the reliability of electronic devices. In this article, we will explain how corrosion of the circuit board occurs, its mechanisms, preventive measures, and methods for identifying the causes in the event that corrosion does occur.

In recent years, electronic devices have been miniaturized, made more densely packed, and designed for higher voltages, especially in the automotive and power device sectors, where long-term use under harsh conditions is assumed. Under such conditions, even trace residues on devices can lead to corrosion, ion migration, and insulation degradation, ultimately resulting in market failures. Furthermore, changes in flux composition and the diversification of materials have made the nature of residues more complex than before. Against this backdrop, the importance of post-cleaning analysis is increasing. Cleaning is the process of removing flux residues and contamination, but to objectively demonstrate whether removal has been successful, verification through analysis is essential. While cleaning is a process of removal, analysis can be seen as a process that substantiates the results.

IPA (isopropyl alcohol) is an alcohol-based cleaning agent widely used for cleaning electronic components and equipment. However, in recent years, there has been an increasing demand for alternatives due to limitations in cleaning power, safety concerns, regulatory compliance burdens, and stable procurement. As a substitute for IPA, Zestron offers products that achieve both high cleaning power and safety. We support quality improvement and work environment enhancement across a wide range of applications, from flux cleaning to equipment maintenance. *For more detailed information, please refer to the related links. Feel free to contact us for further inquiries.

In the field of power semiconductors for automotive and industrial applications, the adoption of "sintering bonding" as a joining technology that achieves high resistance and high reliability against thermal stress is expanding, replacing solder bonding. Similar to no-clean solder bonding technology, sintering bonding is fundamentally designed to be "no-clean." However, the currently mainstream sintering bonding methods are conducted under high temperature and high pressure conditions, which can lead to the generation and adhesion of residues during the bonding process, potentially affecting subsequent processes and long-term reliability. Cleaning is one proposed solution to this issue. Although there is a "no-pressure" method for sintering bonding, its applications tend to be limited from the perspective of strength and reproducibility. Additionally, while it is residue-free, it is not "zero residue," so cleaning can also be a viable solution for achieving reliability. Detailed content of the technical column can be viewed through the related link.

In electronic circuits, the current that flows through unintended paths as envisioned by the designer is called leakage current. This invisible current can significantly impact the reliability, performance, and lifespan of products, making it a critical issue in electronic device development. In today's world, where the miniaturization and high density of semiconductors are accelerating, the sources of leakage current vary widely, ranging from physical limitations within the device to minor issues during the manufacturing process. This article will explain the basics of leakage current, its causes, specific risks at the electronic substrate and assembly levels, countermeasures in the design and manufacturing processes, and methods for addressing it through cleaning and cleanliness evaluation. *For more detailed information, please refer to the related links. Feel free to contact us for further inquiries.*

As electronic devices become more advanced and compact, the importance of fine joint solder paste is increasing in high-reliability fields such as power semiconductors, automotive applications, and industrial equipment. From the perspective of ensuring reliability, there is a growing number of situations where a decision must be made on whether or not to perform flux cleaning, making the cleaning of high-performance solder paste and flux a new challenge. In this research, in collaboration with Japan Superior Co., we focused on the "high-reliability solder paste for fine joints" developed by the company, examining the cleaning characteristics in fine joints and verifying the usefulness of evaluation using FT-IR and SEM-EDS based on chemical analysis. Additionally, we introduce our one-stop technical support that covers everything from cleaning to analysis and process optimization. You can view the detailed content of the article through the related link.

Our company conducts residue analysis to examine contaminants such as flux and sinter. We support the identification of defect causes and the resolution of quality issues in manufacturing sites through our analysis and expertise in flux cleaning. We also conduct defect cause investigations to isolate the causes of issues such as assembly defects, as well as cleanliness evaluations to check the cleanliness and residue levels on circuit board surfaces. 【Features】 ■ Residue analysis to identify the presence and type of substances adhered to surfaces ■ Defect cause investigations analyzing foreign substances and causes using analytical equipment and expertise ■ Cleanliness evaluations for process management through regular analysis ■ Proposals for countermeasures and improvements, in addition to analysis results ■ Cleanliness analysis is also possible for flux cleaning agents and circuit boards from other manufacturers ■ Cleanliness verification methods compliant with ISO 9455-18:2024 *For more detailed information, please refer to the related links.

This joint research was conducted as part of ongoing verification based on the research results with Mr. Hiroki in 2025. In this study, we focused on the question of whether similar trends can be observed with rosin-based flux, and evaluated the impact of differences in cleaning and rinsing conditions on insulation reliability and surface condition. Furthermore, through comparisons with water-soluble flux, we also examined the differences in post-cleaning characteristics based on the type of flux. Detailed information about the article can be viewed through the related link.

Modern electronic devices are highly advanced, and even minor malfunctions can lead to significant incidents. Events that undermine insulation threaten the reliability of products, and one phenomenon that can contribute to this is ion migration, which has been considered a past issue. It has been said that this has been overcome due to the evolution of various insulating materials such as coatings and resists, as well as advancements in cleaning-free technologies. However, as the miniaturization and high density of electronic substrates rapidly progress, ensuring insulation has become increasingly difficult, and the risk of ion migration is once again on the rise. This article will explain why ion migration has become a trend again, exploring its mechanisms, specific countermeasures, and evaluation methods to assess the potential for its occurrence. You can view the detailed content of the article through the related links.

"Before the resin encapsulation of semiconductors." We have added a page to the technical document titled "Why Did the 'Silent Evolution' Occur?" The article provides a detailed explanation of the basic concepts of semiconductor resin encapsulation, as well as specific approaches to surface treatment that are key to maximizing quality. Additionally, the technical document systematically organizes the mechanisms behind the deterioration of insulation and the instability of resin bonding strength, and explains advanced insights into surface design and cleaning technologies that are essential for high-reliability devices. We encourage you to read it.

Flux residues require the selection of analytical methods based on their type. By conducting chemical analysis, it is possible to analyze the causes of defects and improve processes. You can download a free document summarizing our analysis service overview. If you are struggling with cleaning processes or defect analysis, please take a look. Zestron offers cleanliness analysis technology that can comply with ISO 9455-18:2024.

The "Printed Circuit Board (PCB)" can be considered the heart of electronic devices; it serves as a foundation for mounting electronic components and electrically connecting them. The fine wiring patterns formed on this board become pathways for electronic signals, and the electronic components are fixed and connected by solder. From smartphones to automobiles, home appliances, and medical devices, PCBs have become an indispensable part of various technologies in modern society. In this article, we will introduce the main types of printed circuit boards (PCBs), the future prospects seen from the development of these boards, and the cleaning technologies that are required. Please see the related links for more information.

An SDS (Safety Data Sheet) is a document that contains important information regarding the handling of chemical substances, relevant regulations, disposal and transportation methods, as well as hazards and toxicity. The applicable regulations for flux cleaning agents, the presence or absence of flash points, usage precautions, the necessity of protective equipment, and disposal methods are detailed over more than 10 pages. In this article, we will explain important points that we particularly want you to pay attention to, as well as frequently asked questions, in a column format. Please see the related links for more information.

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.