Is PCB cleaning necessary? What impact does it have on the reliability of electronic devices?

In modern electronics, the question of whether contaminants should be removed from circuit boards is becoming less common. Instead, a new concern arises: does PCB cleaning have a real impact on the durability and stability of electronic devices?

In practice, the answer is yes – especially in applications where long‑term reliability, production repeatability, and resistance to environmental conditions are critical.

Proper cleaning is no longer considered an ‘optional’ step, but rather an essential element of the quality assurance process in electronic assembly.

Soldering quality and cleanliness – where does the problem arise?

At first glance, soldered joints may appear correct; however, soldering quality cannot be assessed based solely on visual inspection. The surfaces of PCBs often retain:

• residues of fluxes,
• remnants of solder pastes,
• deposits from assembly adhesives,
• ionic and organic contaminants.

It is precisely these substances that, in the long term, lead to reliability issues in electronic devices, even when the solder joints themselves have been executed properly.

Cleanliness control – why is ‘by eye’ not enough?

In many manufacturing facilities, a subjective assessment approach is still commonly used. Meanwhile, precise cleanliness inspection of printed circuit boards makes it possible to:

• detect residues invisible to the naked eye,
• reduce the risk of leakage currents,
• decrease susceptibility to corrosion,
• improve the stability of electrical parameters.

Surface cleanliness is increasingly becoming a key quality parameter, particularly in industrial and specialized electronics.

A PCB with SMD components – PCBs are among the key components of modern electronic devices.

How to professionally clean printed circuit boards?

The question ‘How to professionally clean electronics?’ should always take into account several key aspects:

• the type of flux used,
• the density of component placement,
• the operating conditions of the device,
• the planned subsequent processes (e.g., coating, encapsulation).

There is no single universal solution — which is why selecting the appropriate cleaning method and cleaning agent is so important.

Cleaning of assemblies and circuits – what actually requires washing?

In production practice, individual PCBs are rarely cleaned. Assembly cleaning covers entire modules that include:

• THT and SMD components,
• high‑profile housings,
• hard‑to‑reach areas beneath components.

Circuit cleaning, on the other hand, must take into account areas that cannot be reached by standard surface cleaning methods.

Cleaning printed circuit boards – when is it truly necessary?

Cleaning printed circuit boards becomes essential when:

• the device operates in humid or dusty environments,
• high voltages or very low currents are present,
• the electronics are intended for long service life,
• stable parameters are required over many years.

In such cases, the lack of cleaning significantly increases the risk of failure.

Manual cleaning of electronic components with a brush – a precise method used in the electronics industry.

Types of cleaning agents – how to remove flux, adhesives, and anticorrosion compounds?

Depending on the type of contamination and the stage of the electronic assembly process, various types of cleaning agents are used to effectively remove:

• flux residues,
• deposits from assembly adhesives,
• oils and production‑related contaminants,
• substances that promote corrosion and leakage currents.

The selection of the appropriate chemistry should always be matched to the process, production scale, and the materials used on the printed circuit board. In practice, this means one approach for service work, another for mass production, and yet another for electronics with increased reliability requirements.

The table below provides a practical overview of contamination types, recommended cleaning agents, and methods of application, making it easier to choose the optimal solution for a specific use case.

Selection of PCB cleaning agents – practical table

Type of contamination	Contamination characteristics	Recommended product	Recommended cleaning method	Typical application
Flux residues	No-clean, alkohol-soluble, water-soluble,	Kontakt PCB Plus	Local / manual cleaning	Service, prototypes, small series
	No-clean, alkohol-soluble,	Alcohol PCB cleaner	Manual or semi‑automatic washing	Production, rework
	No-clean, water-soluble,	Water PCB cleaner	Semi‑automatic cleaning	Mass production
	No-clean, water-soluble,	Termosonik PCB	Ultrasonic cleaners	Densely populated PCB, SMD
Deposits from assembly adhesives	SMT adhesives, process adhesives, rework	Alcohol PCB cleaner	Manual / immersion cleaning	Rework, repairs
		PVB Solvent	Specialized cleaning	Coating removal, adjustments
Oils and production-related contaminants	Touch marks, oils, dust	Kontakt IPA Plus	Rapid manual cleaning	Service, PCB preparation
		Kontakt PCB Plus	Localized cleaning	Production and service
		Water PCB cleaner	Batch washing	Production lines
Compounds promoting corrosion	Ionic residues, process moisture	Water PCB cleaner	Semi‑automatic washing	Industrial electronics
		Termosonik PCB	Ultrasonic cleaning	High‑reliability electronics
		Kontakt PCB Plus	Spot cleaning	Critical areas

PCB cleaning and cleaning solutions – what to choose in practice?

In practice, various PCB cleaning methods are used, selected according to the degree of contamination and the application type. The most common include:

• Manual cleaning – used in service work and prototyping
• Aerosol cleaning – fast and convenient for localized contamination
• Water‑based cleaning – safe for delicate assemblies
• Water‑free cleaning – solvent‑based and alcohol‑based agents, e.g., Isopropanol (IPA)
• Semi‑aqueous cleaning – a compromise between effectiveness and safety
• Immersion cleaning – used in serial production processes
• Automatic cleaning – repeatable and scalable
• Ultrasonic PCB cleaning – the most precise for complex assemblies

The choice of the appropriate PCB cleaning method depends on the degree of contamination and the final requirements of the product.

Applications of ultrasonic cleaners – when do they offer the greatest advantage?

The applications of ultrasonic cleaners primarily include:

• cleaning densely populated boards,
• removing contaminants from underneath component packages,
• restoring assemblies after service work.

Exactly in situations where traditional methods fail, ultrasonic cleaners allow for achieving a high level of process repeatability.

PCB cleaning in an ultrasonic cleaner – ultrasonic cleaning devices used in the electronics industry for precise cleaning.

Ultrasonic cleaners and automatic cleaning – quality and repeatability

Ultrasonic cleaners are a foundation of modern processes where the following factors matter:

• accuracy,
• repeatability,
• scalability.

When combined with automatic cleaning, they enable process standardization, reduction of human‑related errors, and effective control of cleaning operations.

PCB cleaning – why is it a quality factor rather than a cost?

PCB cleaning is not an addition to the process but an integral part of it. When carried out correctly, it:

• increases the reliability of electronics,
• reduces the risk of failure,
• improves parameter stability,
• extends the service life of devices.

Does PCB cleaning really matter?

In summary, PCB cleaning is one of the key stages of the process that directly determines whether electronics will operate reliably not only immediately after commissioning but also after many years of service. Removing flux residues, ionic contaminants, and production deposits reduces the risk of corrosion, leakage currents, and degradation of solder joints.

A well‑designed cleaning process is an investment in quality and reliability rather than an unnecessary cost — especially in industries where electronics operate in demanding conditions or perform critical functions. PCB cleaning is particularly recommended in sectors such as the automotive industry, telecommunications industry, aerospace industry, defense industry, space industry, as well as in areas such as medical devices and industrial electronics, where reliability and longevity are absolute priorities.

In these applications, the cleanliness of printed circuit boards is not an option but one of the foundations of safety, quality, and durability of the final product.