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Organic solvents, used in various fields, are currently an indispensable part of the chemical industry, and it is difficult to completely stop their use. In the cleaning sector as well, while the amount of organic solvents used has been decreasing, they are still used extensively. However, recent legal reforms and global circumstances have accelerated the movement to reduce the use of organic solvents, making it essential to reassess their usage. *For detailed case information, please refer to the related links. For more information, please check the PDF materials or feel free to contact us.*

No-clean solder is a type of solder used in the assembly of electronic components, characterized by the absence of a need for a cleaning process. No-clean solder is primarily composed of low-activity flux, which stabilizes the flux residue even after the product is assembled, eliminating the need for cleaning. This no-clean solder possesses excellent bonding, insulation properties, and resistance to environmental factors. *For detailed case information, please refer to the related links. For more information, please check the PDF materials or feel free to contact us.*

Cleaning agents can be broadly classified into "water-based," "semi-water-based," and "solvent-based." Water-based cleaning agents have overwhelming safety considerations for the working environment. Solvent-based cleaning agents are available on the market either as single components for direct use or as blends with organic solvents and other substances. *For more details, please refer to the related links. For further information, please check the PDF materials or feel free to contact us.*

Organic solvents, which are used in various fields, are currently an indispensable part of the chemical industry, and it is difficult to completely stop their use. In recent years, due to technological advancements and corporate efforts in various industries, the amount of organic solvents used and their atmospheric emissions have been significantly reduced. However, in the flux cleaning of electronic devices in Japan, cleaning agents primarily based on organic solvents are widely used. However, flux cleaning has essentially transformed into "complex residue cleaning," and while solvent-based cleaning agents are very effective against organic components such as rosin, they are almost unable to dissolve ionic substances or insoluble metal salts, making removal by "dissolution" methods difficult. *For more detailed information, please refer to the related links. For further details, please check the PDF materials or feel free to contact us.*

Spray cleaning is a method of cleaning that involves spraying a liquid in a fine mist onto specific objects or surfaces. In this cleaning method, a certain physical force is generated by the flow of liquid ejected at high speed from the nozzle, effectively removing dirt and impurities from the target object. Spray cleaning is easy to adjust in terms of physical force and also excels in liquid replaceability. *For more details, please refer to the related links. For further information, please check the PDF materials or feel free to contact us.*

Flux cleaning refers to the act of selectively removing substances from the surface of a workpiece (the item being cleaned) that are intended to be eliminated. In other words, flux cleaning means removing flux residues (contaminants) while protecting components such as printed circuit boards, power modules, semiconductor packages, and lead frames. Incidentally, if the removal target includes the work surface and does not have selectivity, it is generally classified as "etching." *For more detailed information, please refer to the related links. For further details, please check the PDF materials or feel free to contact us.*

Cleaning agents can be broadly classified into "solvent-based," "semi-aqueous," and "aqueous." At Zestron, we define "aqueous cleaning agents" as those where water is the primary component (with a water content of 50% or more). Even if they are referred to as aqueous cleaning agents domestically, there are specifications where organic components are the primary component, and even in cases referred to as semi-aqueous, many of the components may consist of solvent ingredients. While definitions and expressions vary, when discussing aqueous cleaning agents, we would like you to focus on the percentage of water content in the cleaning agent and understand its characteristics. *For more detailed information, please refer to the related links. For further details, please check the PDF materials or feel free to contact us.*

We are performing flux cleaning, and although no residues are visible after cleaning, reliability assessments show localized migration and corrosion of metal parts. The likely cause of this defect is the presence of invisible residues (ionic residues). If left unaddressed, various issues may arise, and in the worst case, it could lead to a fire. On this page, we will introduce how to check for the presence of invisible ionic residues. *For detailed information, please refer to the related links. For more information, please consult the PDF materials or feel free to contact us.*

The joining technology of silver sintering (silver sinter) has been attracting attention in recent years. With the increase in electrical capacity and the utilization of new materials, there is a need for "new joining technologies" that can withstand higher temperatures, higher voltages, and larger currents. The silver sintering process can form a high-density bonding layer through pressing and sintering, resulting in high bonding strength. *For more details, you can view the related links. Please refer to the PDF materials or feel free to contact us for more information.*

This page provides an explanation of the key points to consider in metal mask cleaning. By selecting the appropriate cleaning agents and methods, it is possible to improve cleaning efficiency and work productivity, as well as reduce running costs, ensure worker safety, and implement environmentally considerate cleaning practices. Please check again. *For more details, you can view them through the related links. For further information, please refer to the PDF materials or feel free to contact us.

"5G," which has gained even more attention due to the new coronavirus. In Japan, commercial services started in the spring of 2020, and it is said to have an impact not only on mobile phones but also in various fields such as automobiles, industrial equipment, and healthcare. Since it is a technology that has evolved further from 4G, it is easy to imagine that there were many challenges in its development. Curious about the background, I spoke with companies involved in the development of 5G. *For more details, you can view the related links. Please refer to the PDF materials or feel free to contact us for more information.*

On this page, we will discuss how to solve the technical challenges associated with 5G, providing an example of a solution. In the previous discussion, we learned that there are cases in 5G-related work where failure can occur if cleaning is not performed. Now, regarding "how to clean," there are important points to consider in the case of 5G work. *For detailed information, please refer to the related links. For more information, please check the PDF materials or feel free to contact us.*

Last time, we introduced solutions to the technical challenges associated with 5G. We recommended using a spray method and water-based cleaning agents, but a question arose: is cleaning really necessary if coating is applied? Taking the above into consideration, I will explain why it is necessary to clean flux residues. *For more details, you can view the related links. Please refer to the PDF materials or feel free to contact us for more information.*

Flux residue refers to the residue derived from flux that remains on the workpiece after soldering (contamination), and its components include ions, metal salts, and organic substances. Cleaning paste is formulated with the premise of cleaning, so if left as is, the likelihood of insulation failure due to migration and corrosion increases. Depending on the application, this can also affect human life and infrastructure, making cleaning necessary in some cases. On the other hand, in the case of no-clean paste, the flux residue stabilizes, but the number of cases requiring cleaning for reliability assurance is also increasing. *For detailed content of the column, please refer to the related link. For more information, feel free to contact us.*

In this column, we will introduce one of the key points to consider when examining flux cleaning methods: the types of "cleaning methods" and how to select them. Flux cleaning refers to the removal of flux residues (contaminants) while protecting components such as printed circuit boards, power modules, semiconductor packages, and lead frames. The presence of flux residues can lead to issues such as the occurrence of migration and poor adhesion in molding, making flux cleaning necessary in certain cases. *For more detailed information, please refer to the related links. Feel free to contact us for further inquiries.*

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 to ensure high reliability, cleaning has become essential. 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. * You can view the detailed content of the column from the related links. For more information, feel free to contact us.

Solder paste is required to have characteristics such as halogen-free and high wettability in high-reliability areas like the automotive industry. However, even in high-reliability fields, there is a demand for residue-free performance, even for no-clean types, and there are situations where cleaning is necessary. This paste contains difficult-to-dissolve substances that make effective cleaning challenging with conventional "solvent cleaning" methods, revealing issues related to cleaning. Therefore, we conducted cleaning performance verification in collaboration with the developers of the paste. Detailed information can be viewed through the related links. *Detailed information can be viewed through the related links. *The PDF document is a technical material that explains the evolution and challenges of power devices.

In the flux cleaning of high-performance control boards, we adopted an organic solvent-based cleaning agent combined with a jet flow method. While this method was able to clean the exposed surfaces of the boards, it could not completely clean the underside of components with a standoff of less than 20μm, resulting in defects where the required performance was not achieved. This page introduces the method that solved this issue. *For more details, please refer to the related links. *The PDF document is a technical material that explains cleaning technology for advanced electronic components.

Formic acid reflow is a revolutionary joining process that allows solder bonding without flux by using a corresponding dedicated solder. By substituting the reducing action, one of the functions of flux, with formic acid, the amount of flux components can be significantly reduced. In the field of power devices, soldering using the formic acid reflow method is becoming more widespread due to its significant advantages in suppressing the occurrence of voids and enabling bonding at low temperatures. *For more details, you can view the related links. *The PDF document is a technical material that explains the cleaning technology for advanced electronic components.

In the soldering process, excellent no-clean technology has been established in the Japanese market; however, there is an increasing number of cases where various challenges arise, and the demand for cleaning is growing year by year. One of the backgrounds for the continuously increasing demand for cleaning is the response to ionic residues. Ionic residues are fundamentally difficult to see and may change into various forms over time, directly leading to the occurrence of leakage currents and deterioration of insulation resistance. *For more details, please refer to the related links. *The PDF document is a technical material that explains the challenges and analysis methods related to ionic residues.

The electronics market is increasingly advancing in research and development of EV vehicles, robotics, and communication technologies, and there are signs of full-scale mass production of the new joining technology known as sintering, indicating that the momentum of power semiconductor devices is not waning. The ions, which are the theme of this discussion, are widely used as dopants and as activators in solder paste, making them an essential component for electronic devices. Additionally, recent research is progressing on new types of semiconductors that use sodium and potassium as ionic materials as dopants, and new activators with enhanced reactivity are also being observed. *For more details, you can view the related links. *The PDF document is a technical material that explains the issues and analysis methods regarding ion residues.

The no-clean solder paste, which continues to evolve, generates significant heat in fields such as 5G devices and high-power devices for electric vehicles (EVs). As environmental burdens increase, it is necessary to pay attention to long-term changes even in stabilized flux residues. Recent market trends have led to the miniaturization of high-performance electronic devices, resulting in reduced distances between components. This, along with the demand for high-speed calculations and increased capacity, has resulted in high currents and voltages. Consequently, even slight flux residues that were previously not problematic can pose various risks, making cleaning necessary in high-reliability devices, even for no-clean flux residues. Together with Mr. Hiroki, who is developing high-performance solder paste, we conducted joint research on the morphological changes of flux residues after soldering and their impact on cleanability. *For more details, please refer to the related links. *The PDF document is a technical material explaining the evolution and challenges of power devices.

Advanced electronic devices, such as 5G-compatible communication equipment and control units for electric vehicles, are becoming smaller and thinner. Consequently, the development of solder paste for fine bonding is becoming increasingly active. These electronic devices require long-term high reliability, and there is a growing trend for the need for flux cleaning. Due to high-density mounting and the diversification of components, there is an increase in electronic devices with low stand-off. *For more details, please refer to the related links. *The PDF document is a technical resource that explains the cleaning technology required for sintering bonding.

The Sn-Bi solder paste has various advantages, but in high-reliability fields, there are situations where cleaning is required, and one of the cleaning challenges is the formation of metal salts (Bi salts) after sintering. Bi salts can potentially cause migration issues, are difficult to dissolve in organic solvents, and make cleaning challenging. To address the issue of Bi salt formation, we conducted a joint verification of the cleaning properties of the low-melting-point Sn-Bi solder paste developed by Japan Superior Inc. *For more details, please refer to the related link. *The PDF document is a technical material that explains the evolution and challenges of power devices.

The theme of this discussion is ions, which are essential for electronic devices. However, unintended ions can remain on the device surface, between electrodes, or in low stand-off areas, resulting in "ion residue." Moreover, since these residues can be supplied from various contamination pathways that include not only raw material factors but also environmental factors, achieving a residual amount of zero is technically very challenging. In this instance, we have collaborated with solder manufacturers to assess the ion residue levels for each implemented component. *For more detailed information, please refer to the related links. *The PDF document is a technical resource that explains the issues and analysis methods related to ion residue.

In recent years, from the perspective of environmental conservation and human protection, countries have been strengthening regulations regarding 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 burdens, some companies are moving to avoid procuring materials that have a significant environmental impact, and cleaning agents are no exception. Taking into account initiatives overseas, we will introduce regulations related to cleaning agents. *For detailed information, please refer to the related links. For further inquiries, feel free to contact us.*

Electronics assembly refers to the technology of mounting electronic components onto a substrate. Specifically, it involves 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 technologies are also evolving. This has a significant impact on the cleaning processes as well. We will explain the evolution of joining technologies and cleaning in fine joining. *For detailed content of the article, you can view it through the related links. For more information, please download the PDF or feel free to contact us.*

In recent years, the miniaturization and high density of electronic devices have progressed, and along with this, the evolution of the bonding materials used has also coincided, making contamination more complex. In particular, in fields such as automotive, aerospace, space, and high-capacity communication, there is an increasing number of cases that require high reliability, and concurrently, there is a demand for reliable cleaning from the perspective of quality assurance. Inadequate cleaning can lead to issues such as poor wire bonding, poor 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. *For more detailed information, please refer to the related links. For further inquiries, feel free to contact us.*

We would like to introduce a case study on the investigation of factors leading to cleaning failures due to flux cleaning troubles caused by the high density of component mounting. With the increase in the density of component mounting, 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 hypotheses and proposed both temporary and permanent measures tailored to the customer's circumstances based on the results. [Case Overview] ■ Issues - Cleaning performance of flux in low stand-off areas ■ Conclusion - Stable operation is difficult under the current cleaning conditions ■ Permanent improvement measures and proposals - Review of cleaning agents and cleaning processes suitable for the work shape and flux *For more details, please download the PDF or feel free to contact us.

Water-soluble flux is a flux based on water, using water-soluble polymers such as polyoxyethylene alkyl ether. Currently, rosin-based flux is the mainstream for soldering in electronics assembly in Japan, but due to the increasing environmental awareness such as the SDGs, there is a movement to explore the transition to water-soluble flux, which is expected to reduce VOCs. *For more details, you can view the related links. Please feel free to contact us for more information.

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 high functionality and 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, a solder manufacturer, and conducted a detailed analysis comparing the cleanability of both types of resistors. *For more detailed information, please refer to the related links. Feel free to contact us for further inquiries.

In current electronics assembly in Japan, rosin-based flux is predominantly used for soldering. However, due to the promotion of the SDGs and the increasing 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 situation of water-soluble flux, which is recognized as easier to clean than rosin-based flux. *For detailed information, please refer to the related links. For more details, you can download the PDF or feel free to contact us.*

In recent years, the advancement of electronic devices has led to a demand for advanced bonding technologies that can withstand high heat, 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 environmental regulations and cost considerations, as it can form a high-density bonding layer. This article examines effective cleaning methods utilizing spray cleaning and ultrasonic cleaning, and introduces the features and application examples of cleaning agents VIGON PE 305N and VIGON PE 216A for power electronics. *For detailed content of the article, please refer to the related links. For more information, you can download the PDF or feel free to contact us.

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, whether they have a flash point, precautions for use, 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. *For more detailed information, please refer to the related links. Feel free to contact us for further inquiries.*

The miniaturization and high-density integration of electronic devices have progressed, and in recent years, there has been advancement in multifaceted operations utilizing AI for automatic control and complex communications. In this context, the reliability required of electronic devices has become increasingly important. Among these, one of the causes of trouble that was not previously anticipated is "unintended metal salts." The formation of metal salts during the soldering process is an essential reaction for establishing solder joints, but there are cases where "unintended metal salts," which do not contribute to the joint, occur as side reactions. *For more detailed information, please refer to the related links. For further details, please check the PDF materials or feel free to contact us.*

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 document summarizing our analysis service overview for free. If you are struggling with cleaning processes or defect analysis, please take a look.

Semiconductor devices, which function as the brains of various electronic devices ranging from smartphones, automobiles, to home appliances that are essential in our daily lives, are supported by their high reliability. One of the key technologies that ensure this reliability is "resin encapsulation." The process of covering and solidifying semiconductor chips with resin is indispensable for protecting them from external environments and maintaining stable performance over long periods. However, as products require higher reliability, there are increasing cases where simply solidifying with resin is not sufficient. To fully realize the true performance of resin encapsulation, it is extremely important how well the surfaces of the semiconductor chips and substrates to be encapsulated are prepared, which is referred to as "surface design." *For more detailed information, please refer to the related links. Feel free to contact us for further inquiries.*

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 the advancement of no-clean technologies. However, as the miniaturization and high density of electronic substrates progress rapidly, ensuring insulation has become increasingly difficult, and the risk of ion migration is once again rising. 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 occurrence. *For more detailed information, please refer to the related links. For further inquiries, feel free to download the PDF or contact us.*

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 whether similar trends are observed with rosin-based fluxes, evaluating the impact of differences in cleaning and rinsing conditions on insulation reliability and surface condition. Furthermore, we also examined the differences in post-cleaning characteristics based on the type of flux through comparisons with water-soluble fluxes. *For detailed content of the article, please refer to the related link. For more information, please download the PDF or feel free to contact us.*

As electronic devices become more advanced and compact, the importance of fine solder paste in high-reliability fields such as power semiconductors, automotive, and industrial equipment is increasing. However, the growing demand for reduced electrode spacing, fine pitch, and low stand-off mounting has brought to light the risks associated with flux residue after soldering, which previously did not pose a problem, affecting insulation reliability and the quality of subsequent processes. For these reasons, there is an increasing number of situations where a decision must be made regarding whether or not to perform flux cleaning from the perspective of ensuring reliability, making the cleaning of high-performance solder paste and flux a new challenge. In this study, in collaboration with Japan Superior Co., we focused on the "high-reliability solder paste for fine bonding" developed by the company, examining the cleaning characteristics in fine bonding and verifying the usefulness of evaluation through FT-IR and SEM-EDS based on chemical analysis. *For detailed content of the article, please refer to the related link. For more information, feel free to download the PDF or contact us directly.*

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 densification of semiconductors are accelerating, the sources of leakage current vary widely, stemming from physical limitations within the device or minor issues during the manufacturing process. This article will explain the fundamentals 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.*