Choosing the Right Graphic Overlay Material for Your Membrane Keypad

When designing a membrane keypad, one of the most important — yet often overlooked — components is the graphic overlay. It’s the topmost layer that users see and touch, and it plays a crucial role in both appearance and performance.

Choosing the right overlay material affects not only the look and feel of your interface but also its durability, resistance to environmental conditions, and overall user experience.

In this guide, we’ll walk you through the most common materials used for graphic overlays and how to choose the best one for your application.

What Is a Graphic Overlay?

A graphic overlay is the printed surface layer of a membrane switch or keypad. It provides:

Visual cues (symbols, icons, text)
Tactile feel through embossing or coatings
Environmental protection for the internal circuitry
Brand identity with custom designs and logos

Common Materials for Graphic Overlays

There are two main materials used in most membrane keypads:

1. Polyester (PET)

Most Popular for Industrial Applications

High durability and chemical resistance
Excellent flex life — won’t crack over time
Compatible with embossing and tactile feedback
Maintains clarity even with repeated cleaning
Often used in: medical devices, industrial equipment, military-grade interfaces

Best choice if your device will be used frequently or exposed to cleaning agents, solvents, or mechanical wear.

2. Polycarbonate (PC)

Used in Low to Medium-Duty Applications

Easy to print on and die-cut
Good optical clarity and design versatility
Smooth surface options for user-friendly feel
Less resistant to chemicals and abrasion than polyester
Often used in: consumer electronics, office equipment, point-of-sale terminals

Suitable for lower-impact applications or where design flexibility and cost are more important than extreme durability.

Key Factors to Consider When Choosing Overlay Material

1. Environmental Exposure

Use polyester for exposure to chemicals, UV light, and outdoor environments
Use polycarbonate for indoor or clean environments

2. Expected Lifespan

Polyester lasts millions of actuations without fatigue
Polycarbonate is better for shorter lifecycle products

3. Tactile Requirements

Both materials support embossing (pillow or rim)
Polyester holds embossing shape longer, especially in high-use products

4. Aesthetic Preferences

Polycarbonate offers better clarity and options for textured or glossy finishes
Both support transparent windows for displays and backlighting

5. Printing Method

Screen printing and digital printing work well on both materials
For backlit or multi-color designs, polycarbonate may be more cost-efficient

Optional Enhancements for Overlays

No matter which base material you choose, overlays can be customized with:

Adhesive backing – for bonding to the rest of the membrane switch assemblyironments.🔵 Design tip: Proper alignment and material thickness are critical to ensure switch performance.

Hard coat coatings – for scratch resistance

Anti-glare / anti-fingerprint finishes

UV-resistant inks – to prevent fading in sunlight

Laser etching – for light-transmitting icons or backlit legends

Embossing – for tactile buttons or decorative elements

Quick Comparison Table

Feature	Polyester (PET)	Polycarbonate (PC)

Durabilité

★★★★★ (High)

★★☆☆☆ (Moderate)

Chemical Resistance

Excellent

Fair

Print Clarity

Good

Excellent

Embossing Retention

Excellent

Moderate

Cost

Moderate

Lower

Common Use Cases

Industrial, Medical

Consumer, Office Equipment

Real-World Applications

Here are just a few examples of how membrane switches extend equipment durability:

Industry	Use Case	Benefit
Medical	Patient monitors, autoclave controls	Easy to sterilize, resists disinfectants
Industrial	Machine control panels, PLC HMIs	Dust-proof, vibration-resistant
Agriculture	Outdoor irrigation systems	UV, water, and mud resistant
Food Processing	Touch controls on washdown-rated equipment	Chemical- and water-resistant
Transportation	Dashboards, keypads for rugged handhelds	Shockproof, reliable in cold/hot temps

Conclusion

The graphic overlay is more than just a label — it’s a key component of your membrane keypad’s durability, functionality, and user experience. Choosing the right material ensures your product will perform as expected, look professional, and stand up to its working environment.

✅ For rugged, long-lasting applications: choose polyester (PET)
✅ For cost-sensitive or visually rich designs: choose polycarbonate (PC)

👉 Need help selecting the right overlay for your membrane switch?
At Luen Fung, we offer full customization with material, embossing, backlighting, and adhesive options to meet your needs.

📩 Contact us today for expert advice or a free quote.