Moisture Management in Electronics: The Critical Connection to PCB Assembly

Feb 19,2024

Moisture can have a significant impact on electronics, posing various challenges that can compromise the performance and reliability of electronic devices. One primary concern is the potential for moisture to lead to corrosion on electronic components and printed circuit boards. 

When moisture infiltrates electronic assemblies, it can react with metal surfaces, forming oxides and other compounds that can hinder the conductivity of traces and solder joints. This corrosion not only degrades electrical connections but can also cause intermittent faults or complete failure of the electronic system.

Moreover, moisture can contribute to the growth of mold or fungi on PCBs, which may exacerbate corrosion and lead to short circuits. In high humidity environments, moisture absorption by hygroscopic materials like PCB laminates, insulating materials, or even the components themselves can result in a change in electrical properties and performance degradation.

How Moisture Can Impact Electronic Components and Systems

Moisture poses a pervasive threat to electronic components and systems, exerting detrimental effects that can compromise their functionality and longevity. One of the primary concerns is the potential for corrosion, where moisture interacts with exposed metal surfaces, leading to the formation of oxides that impede the conductivity of traces and solder joints. This corrosion not only weakens electrical connections but can also introduce intermittent faults or outright failures within the electronic system. 

Furthermore, moisture absorption by hygroscopic materials, such as PCB laminates and insulating layers, can alter their electrical properties, contributing to performance degradation. In high humidity conditions, the growth of mold or fungi on printed circuit boards (PCBs) can exacerbate corrosion and create conducive environments for short circuits. 

Moisture-related issues extend to the solder joints during the PCB assembly process, where trapped moisture can vaporize during soldering, resulting in voids and weakened connections. These combined impacts underscore the importance of robust moisture management strategies in electronic design and manufacturing to ensure the reliability and longevity of electronic components and systems, particularly in environments where exposure to moisture is prevalent.

Explore the various challenges and risks associated with moisture in electronics

Moisture presents a myriad of challenges and risks in the realm of electronics, posing significant threats to the reliability and performance of electronic components and systems. One of the foremost challenges is the potential for corrosion, as moisture can lead to the formation of oxides on metal surfaces, jeopardizing the integrity of critical connections.

Corroded traces and solder joints can result in increased electrical resistance, signal degradation, and, ultimately, system failure. Hygroscopic materials, commonly found in electronic components and PCBs, absorb moisture, altering their properties and causing shifts in electrical characteristics.

  • Corrosion of Metal Surfaces:

Moisture can induce the formation of corrosive oxides on exposed metal surfaces, jeopardizing the integrity of connections and leading to increased electrical resistance.

  • Hygroscopic Material Effects:

Materials within electronic components and PCBs that are susceptible to moisture absorption may undergo changes in properties, impacting electrical characteristics and performance.

  • Dielectric Property Shifts:

Moisture-induced alterations in dielectric properties of materials can affect the performance of capacitors and insulating layers, potentially leading to electrical issues.

  • Growth of Mold and Fungi:

Moist conditions foster the growth of mold and fungi on PCBs, introducing risks such as corrosion, short circuits, and overall degradation of the electronic system.

  • Systemic Corrosion Challenges:

Corroded traces and solder joints, stemming from moisture exposure, can result in signal degradation, increased electrical resistance, and eventual failure of electronic systems.

  • Assembly Process Issues:

Trapped moisture during the PCB assembly process can lead to the formation of voids in solder joints, compromising the mechanical strength and reliability of connections.

  • Signal Degradation:

Moisture-related corrosion can result in signal degradation, affecting the overall performance and reliability of electronic components and systems.

  • Risk of System Failure:

Cumulative impacts of moisture-related challenges pose a significant risk of system failure, particularly in environments where exposure to humidity is prevalent.

These challenges underscore the importance of robust moisture management strategies in the design, manufacturing, and application of electronic devices to mitigate these risks and ensure the sustained functionality of electronic systems, especially in environments prone to humidity and moisture exposure.

Design Considerations and Strategies for Creating Moisture-Resistant Electronics

Designing moisture-resistant electronics requires a holistic approach that integrates specific considerations and strategies to mitigate the adverse effects of moisture exposure. Firstly, selecting moisture-resistant materials, such as laminates, coatings, and adhesives, is crucial. Encapsulating sensitive components with conformal coatings, which act as protective barriers against moisture, prevents direct contact with the environment.

Ensuring a proper seal on connectors, seams, and openings, through techniques like gaskets and O-rings, adds an extra layer of defense. The strategic placement of components on the PCB, considering potential moisture pathways and employing proper spacing, aids in minimizing the impact of moisture ingress. Additionally, incorporating adequate ventilation and drainage features helps manage any moisture that may infiltrate the system.

The use of moisture-resistant packaging during shipping and storage further safeguards components from environmental humidity. Rigorous testing, including accelerated aging tests and environmental stress testing, should be an integral part of the design process to validate the effectiveness of moisture-resistant measures.

Explore Moisture-Resistant Materials and Coatings Commonly Used in Electronic Components

Moisture-resistant materials and coatings play a pivotal role in enhancing the durability and reliability of electronic components, especially in environments where moisture exposure is a concern. One commonly employed moisture-resistant material is Parylene, a thin and conformal polymer coating that provides a protective barrier against moisture, chemicals, and contaminants.

It adheres uniformly to complex shapes and offers excellent dielectric properties. Silicone-based conformal coatings are also prevalent, known for their flexibility and resistance to moisture, chemicals, and temperature extremes. Epoxy resins, often used in potting or encapsulation, provide an effective moisture barrier and mechanical protection for sensitive components. Polyurethane coatings offer a balance between flexibility and durability, making them suitable for various applications. In addition to coatings, laminates like polyimide or liquid crystal polymer are chosen for their moisture-resistant properties in PCB construction. 

These materials provide high mechanical strength and dimensional stability while effectively preventing moisture ingress. The selection of these moisture-resistant materials and coatings depends on factors such as the application, environmental conditions, and the specific requirements of the electronic components. Integrating these materials into the design and manufacturing processes helps create electronics capable of withstanding the challenges posed by moisture, ensuring prolonged functionality and reliability.