How to Choose the Right Coating
Choose between conformal coating, Parylene and advanced functional coating solutions
Choosing a coating is not about selecting a material β it is about defining what the coating needs to do. This includes technologies such as conformal coating, Parylene and advanced functional coatings.
Different coating technologies deliver different types of protection, including physical protection, hydrophobic behaviour, moisture resistance, chemical resistance, thermal performance and electrical functionality.
These can be applied at very different thicknesses, from ultra-thin surface treatments (<50 nm) through to full barrier coatings (>50 Β΅m).
The key step is to define the required performance. Once this is clear, the appropriate coating technology, application method, masking strategy and cost structure can be identified.
Use this quick process to identify the right coating approach before reviewing detailed options below.
Coating selection process comparing conformal coating, Parylene and advanced functional coatings based on exposure, severity and constraints
Step 1: Identify your primary exposure or requirement
Start by identifying the main condition your coating needs to manage. This defines the coating approach before considering constraints such as thickness, masking, application method or cost.
You can use the scenarios below to understand the main coating routes, then refine your selection in Step 2.
- Moisture / humidity exposure
- Condensation or liquid droplet exposure
- Water exposure and immersion
- Chemical exposure: vapour, splash or intermittent contact
- Chemical immersion
- Mixed environmental exposure: dust, contamination and humidity
- Surface behaviour control: water and oil repellency
- High temperature or thermal stress
- Functional or electrical performance
Step 2: Identify secondary effects and constraints
Most coating decisions involve more than one requirement. Once the primary exposure or requirement is clear, identify any secondary effects and practical constraints that may change the coating choice.
- Tight thickness or dimensional limits
- Complex geometry or difficult-to-coat areas
- Masking or keep-out requirements
- Temperature range or thermal cycling
- Exposure duration: intermittent or continuous
- Chemical compatibility constraints
- Mechanical stress or flexing
- PFAS-free or material restrictions
- Production volume, cost or automation requirements
Step 3: Compare possible coating routes
Use the primary exposure and secondary constraints together to identify a practical set of coating options. In many cases, more than one route may be technically possible.
At this stage, the goal is to narrow the options to a small number of viable coating approaches before comparing them in more detail.
In many cases, there is no single correct answer. The aim is to identify the most suitable and practical coating approach based on the balance of requirements.
Important: As constraints increase, the number of viable coating options typically reduces. The remaining solutions will usually require trade-offs between performance, thickness, masking, application method and cost.
Not sure which route is right?
SCH can quickly confirm the most suitable coating approach based on your environment, constraints and reliability requirements β before you commit to a process or material.
The comparison below shows how coating thickness and protection level influence which technologies are practical.
Coating capability map comparing advanced functional coatings, conformal coating and Parylene by thickness and protection level
However, coating selection is not linear β the most effective solution depends on the dominant failure mode.
Coating selection overlap model showing how coating technologies apply depending on failure mode, reliability requirements and application constraints
Typical application pathways
The examples below show how coating decisions are made in practice. Start with the primary exposure, then refine based on severity, constraints and failure risk.
If your application doesnβt clearly fit one category, it usually requires a combined or optimised coating approach.
Jump to your scenario:
- Moisture / humidity (clean environment)
- Condensation / liquid droplets
- Water exposure / immersion
- Chemical exposure (vapour / splash)
- Chemical immersion
- Mixed environment (contamination + humidity)
- Surface behaviour (water / oil repellency)
- High temperature / thermal stress
- Functional / electrical performance
Need a quicker route? If you already understand your requirement, go directly to the coating solution pathways or contact SCH for confirmation.
Moisture / humidity exposure
Selection depends on: humidity level, exposure duration and environmental cleanliness.
Typical decision driver: long-term moisture resistance in clean, controlled environments.
Most likely coating routes:
- Conformal coatings: cost-effective baseline for general protection
- Parylene: preferred where long-term reliability and barrier performance are critical
- Advanced functional coatings: for low build or selective protection
Next stage: Explore the coating solution pathways or contact SCH to confirm the correct approach.
Condensation or liquid droplet exposure
Selection depends on: geometry, drainage, tip coverage, capillary gaps and inspection quality.
Typical decision driver: immediate failure risk from liquid water. Coverage quality is critical.
Most likely coating routes:
- Parylene: preferred where failure is not acceptable and uniform coverage is required
- Conformal coating: viable where geometry is manageable and process control is high
Important: hydrophobic coatings may reduce water retention but do not prevent electrical failure.
Next stage: Explore the coating solution pathways or contact SCH to confirm the correct solution.
Water exposure and immersion
Selection depends on: immersion duration, pressure, ingress risk and sealing strategy.
Typical decision driver: need for a true barrier vs system-level protection.
Most likely coating routes:
- Parylene: continuous, uniform barrier performance
- Encapsulation / sealing: where coating alone is insufficient
- Conformal coating: only for low-risk or short-duration exposure
Next stage: Explore the coating solution pathways or contact SCH to confirm suitability.
Chemical exposure: vapour, splash or intermittent contact
Selection depends on: chemical type, exposure mode, temperature and frequency.
Typical decision driver: severity vs process complexity.
Most likely coating routes:
- Advanced functional coatings: targeted resistance, minimal build
- Conformal coating: general chemical resistance
- Parylene: aggressive or reliability-critical environments
Next stage: Explore the coating solution pathways or contact SCH to confirm the correct route.
Chemical immersion
Selection depends on: chemical compatibility, temperature and exposure duration.
Typical decision driver: long-term chemical resistance.
Most likely coating routes:
- Fluoropolymer / specialist coatings: high chemical resistance
- Parylene: viable depending on compatibility
Next stage: Explore the coating solution pathways or contact SCH to confirm compatibility.
Mixed environmental exposure
Selection depends on: contamination type, particle load, humidity and cleaning quality.
Typical decision driver: interaction between contamination and moisture.
Most likely coating routes:
- Conformal coating: robust baseline for real-world environments
- Parylene: higher reliability and consistency
- Advanced functional coatings: targeted improvements
Next stage: Explore the coating solution pathways or contact SCH to confirm the correct solution.
Surface behaviour control
Selection depends on: liquid type, durability and contamination risk.
Typical decision driver: controlling wetting and contamination without adding thickness.
Most likely coating routes:
- Advanced functional coatings: controlled, durable surface behaviour
- Hydrophobic / oleophobic coatings: repellency-focused solutions
Important: these do not provide environmental protection or barrier performance.
Next stage: Explore the coating solution pathways or contact SCH to confirm suitability.
High temperature or thermal stress
Selection depends on: temperature range, duration and thermal cycling.
Typical decision driver: material stability under heat.
Most likely coating routes:
- High-temperature coatings: primary temperature resistance
- Conformal coating / Parylene: combined protection + thermal performance
Next stage: Explore the coating solution pathways or contact SCH to confirm suitability.
Functional or electrical performance
Selection depends on: required electrical behaviour and operating environment.
Typical decision driver: achieving performance without compromising protection.
Most likely coating routes:
- Functional coatings (ProShieldESD): controlled electrical behaviour
- Combined systems: protection + electrical performance
Next stage: Explore the coating solution pathways or contact SCH to confirm the correct solution.
Select the right coating route for your application
Use the pathways below to move from understanding coatings to selecting the most suitable solution for your application. Each route is based on the primary problem you are trying to solve.
Know what you need? Speak to us directly and weβll help you move forward quickly with the right coating solution.
Need specific surface behaviour?
For hydrophobic, anti-contamination or electrical function requirements.
Dealing with water, condensation or fluid exposure?
For applications where wetting control or liquid repellency is the primary issue.
Need minimal thickness or no dimensional impact?
For assemblies where coating build, clearance or tolerance is tightly limited.
Looking for general environmental protection?
For moisture, dust, contamination and general PCB reliability requirements.
Need high-reliability uniform barrier protection?
For complex geometries, critical environments or consistent all-round coating coverage.
Need controlled static dissipation or ESD-safe surfaces?
For plastics, floors, equipment, packaging or surfaces that require static control.
Not sure which route fits your application?
We can review your part, environment and requirements and guide you to the correct coating strategy.
Why Choose SCH Services?
SCH Services provides coating selection, application and process support across a full range of coating technologies.
- Coating selection based on real application requirements
- Access to multiple coating technologies and material systems
- Support from early feasibility through to production
- Integrated services including coating, masking, inspection and training
Conformal Coating Services
Parylene Training & Support
Coating Equipment & Support
Contact SCH to Discuss Your Coating Requirement
This content is provided for general technical guidance only. Coating selection and process decisions must be validated against applicable standards and application-specific qualification requirements.
