Polymeric materials play a vital role in modern printed circuit board (PCB) assembly and the manufacturing of electronic devices. These materials contribute to structural integrity, electrical insulation, and environmental protection. At MJS Designs, our team of engineering and manufacturing experts can help select the right polymeric materials for each application, from consumer electronics to aerospace systems. The following are four major types of polymeric applications that MJS Designs has experience with.
Epoxies
Epoxies serve both as structural adhesives and protective coatings in PCB assemblies. They create strong, durable bonds that secure components in place, reducing mechanical stress from shock, vibration, or thermal expansion. Applied as a finish, epoxy coatings shield sensitive electronics from moisture and corrosion. When repairing damaged boards, epoxies can be used as structural material to fill in broken areas of fiberglass and restore mechanical integrity.
Different epoxies exhibit a broad range of characteristics, but in electronics manufacturing, they are often categorized by their flow, curing, and mechanical properties:
- Low-Viscosity Epoxies
Low-viscosity epoxies flow easily into small gaps, making them ideal for precision applications such as underfill for microelectronics. Their capillary action allows them to stabilize components like BGAs and fill voids in potting applications. These formulations cure over several hours at room temperature, although accelerated options are available for faster processing. Their ease of flow ensures reliable protection and stability in confined spaces.
- Medium-Viscosity Epoxies
Balancing flow and gap-filling capability, medium-viscosity epoxies are versatile for bonding, coating, and staking applications. Commonly used in PCB assembly, they provide mechanical stability and controlled coverage. Curing may occur at ambient temperatures within 8–24 hours or under heat in as little as 1 hour, optimizing production efficiency while ensuring robust performance.
- High-Viscosity Epoxies
High-viscosity epoxies, designed for structural bonding and staking, deliver superior mechanical strength and durability. Ideal for aerospace, defense, and industrial applications, they stabilize large components and endure harsh environments. Heat curing for these epoxies typically completes within 30-60 minutes, and maximizes their strength and reliability, making them indispensable for demanding conditions.
Potting Compounds
Potting compounds protect PCB components, connectors, and cable junctions by encapsulating them in solid material. These compounds safeguard electronics from environmental stressors such as moisture, vibration, or temperature extremes. Potting can also be used to prevent tampering of finished devices, by creating a physical barrier that conceals and prevents access to the sensitive components underneath. There are various potting compound chemistries, and selecting the right one depends on the specific application:
- Epoxy-Based Potting Compounds
Epoxy-based compounds are the standard for superior mechanical strength and chemical resistance, making them ideal for protecting components exposed to harsh conditions. Their strong, durable bonds provide long-lasting protection, especially in high-stress environments. They are commonly used in industrial, aerospace, and automotive electronics.
- Silicone-Based Potting Compounds
Silicone-based potting compounds offer flexibility and heat resistance, making them ideal for applications that require thermal stability and adaptability to environmental fluctuations. These compounds are often used in automotive and medical devices where flexibility is crucial.
- Urethane-Based Potting Compounds
Urethane potting compounds strike a balance between toughness and flexibility. They are often used for applications that require moderate protection against mechanical stress while maintaining some degree of flexibility. These compounds are common in consumer electronics and industrial equipment.
Staking Compounds
Staking compounds stabilize tall or vibration-sensitive components by affixing them to the PCB, preventing movement due to mechanical shock or thermal cycling. This reinforcement is especially critical for large capacitors, inductors, and other high-profile parts prone to vibration-induced failures. Staking compounds are available in different formulations to meet various application needs:
- Epoxy-Based Staking Compounds
Epoxy-based staking compounds provide high mechanical strength, making them suitable for large components that require durable bonding. These are often used in industrial and aerospace applications.
- Silicone-Based Staking Compounds
Silicone-based staking compounds offer greater flexibility to accommodate component movement, making them ideal for applications exposed to thermal cycling or vibration.
These materials have a moderate work life, providing enough time for precise positioning before setting, ensuring stability and ease of application.
Conformal Coatings
Conformal coatings apply a thin protective layer over PCBs, shielding them from environmental hazards such as moisture, dust, and chemical exposure. These coatings enhance product longevity and reliability, particularly in applications subject to humidity or corrosive elements. Some of the most commonly applied conformal coatings are:
- Acrylic Conformal Coatings
Acrylic coatings are fast-drying and easy to rework, providing effective moisture resistance and electrical insulation. They are a popular choice for commercial electronics. These coatings typically cure at room temperature within a few hours but can also be accelerated with heat for faster processing.
- Urethane Conformal Coatings
Known for their superior chemical resistance and durability, urethane coatings are often used in industrial and automotive applications where exposure to harsh substances is expected. These coatings can be heat-cured in about 1 hour, offering excellent protection in challenging environments.
- Silicone Conformal Coatings
Offering flexibility and excellent thermal stability, silicone coatings are ideal for applications exposed to extreme temperature variations. These coatings can be cured at room temperature or with mild heat, depending on the formulation.
The MJS Difference
Polymeric materials are indispensable for ensuring the protection, stability, and longevity of PCB assemblies and electronic devices. By selecting the right materials for specific applications, manufacturers can optimize product performance and reliability. At MJS Designs, our PCB design and manufacturing specialists support polymeric applications at any stage of the production process. Contact us today to learn how we can help with your electronics manufacturing needs.