In modern electronic devices, the tactile switch, as a key component for human-computer interaction, is widely used in consumer electronics, industrial equipment, medical instruments, automotive electronics, and other fields. As product usage environments become more complex, users demand higher dustproof and waterproof performance from tactile switches. Especially in outdoor, industrial control, or high-humidity scenarios, tactile switches with an IP67 protection rating have become a mainstream requirement.

This article will delve into how to achieve the IP67 dustproof and waterproof rating from the perspectives of structural design, sealing technology, material selection, and process control. Combining practical application cases and industry experience, it provides systematic technical guidance.

I. Definition and Significance of IP67 Rating

IP Rating (Ingress Protection), defined by the IEC 60529 standard:

• The first digit "6" indicates complete dust protection, meaning no dust can enter the switch interior.

• The second digit "7" indicates protection against immersion in water, meaning the product can withstand immersion in 1 meter of water for 30 minutes without water ingress.

Therefore, achieving IP67 protection requires sealing against dust and resisting short-term water immersion impact. This poses significant challenges for small devices like tactile switches, which primarily rely on mechanical contact.

II. Core Design Elements for Achieving IP67 Dustproof and Waterproof Performance

1. Sealing Structure Design

(1) Overall Enclosed Structure

The key to IP67 protection is the gapless design of the structure itself. Tactile switches often adopt the following structural encapsulation:

• Upper and Lower Shell Cladding Structure: The upper cover and lower base are joined airtightly through methods like hot riveting or ultrasonic welding.

• Middle Frame Gasket Design: Adding a middle frame and sealing gasket in the button travel area forms a "labyrinth blocking" path.

(2) Dynamic Sealing Area Treatment

Since tactile switches require a pressing action, their structure cannot be completely static-sealed. Optimization can be achieved through:

• Using Elastic Silicone Sealing Caps (Rubber Boot): Placing flexible sealing caps in the finger contact area that can withstand repeated pressing while maintaining the seal.

• Setting Guide Pillars: Guiding the movement path to reduce seal damage caused by oblique pressure.

• "Umbrella-Shaped" Shield Design between Button and Shell: Effectively blocks water droplet penetration.

Case Example: An industrial handheld terminal used tactile switches with a silicone waterproof cap + integrated injection-molded structure design. By setting an O-ring at the junction between the shell and PCB and using conformal coating to protect solder joints, it successfully passed IP67 protection tests.

2. Sealing Film and Button Cap Design

(1) Selection of Sealing Film Material

Dustproof and waterproof films are typically placed between the switch top cover and the operation area. Key materials include:

• PET Film + Fluorine Coating: Waterproof while offering good breathability.

• High-Elasticity Silicone Film: Can be formed into raised "blisters" to accommodate multiple presses.

Such films require:

• High tear resistance (≥30 N/mm)

• Excellent elastic recovery (>95%)

• Long-term crack resistance (>1 million cycles lifespan)

(2) Special Structure of Button Caps

Button caps need to balance user feel and sealing. Common designs include:

• Screw-Lock Button Cap: Cannot be easily removed after installation, preventing moisture ingress.

• Integrated Silicone Button Cover: Button and shell formed as one piece, reducing joint gaps.

• Flexible Groove Design: Presetting deformation zones at the press point improves pressing efficiency while maintaining the seal.

3. Shell and Material Selection

(1) Shell Material Requirements

Shells require not only mechanical strength but also long-term stable waterproof, dustproof, and corrosion-resistant properties:

(2) Sealants and Waterproof Coatings

To enhance sealing, sealants or waterproof coatings are often applied at shell edges or seams:

• Epoxy Resin Sealant: Used for bottom potting.

• PU/Silicone Waterproof Coating: Suitable for protecting domes and solder joints.

• Nano Waterproof Coating: Adds a surface hydrophobic layer to ultra-thin switches.

III. Impact of Production Process Control on IP67

1. Ultrasonic Welding vs. Hot Riveting

• Ultrasonic welding creates strong fusion points on shell edges, suitable for mass production.

• Hot riveting is suitable for precise fitting of small components, ideal for size-constrained tactile switches.

2. Automated Dispensing Sealing

Use precision dispensing equipment to apply sealant (e.g., UV glue) at key gaps. The following parameters need control:

• Dispensing volume consistency ±5%

• Curing time matching assembly cycle

• Preventing glue overflow affecting action travel

3. Online Seal Testing (IP Leak Test)

Use pressure testing equipment to perform seal detection on assembled switches:

• Apply positive pressure to 30kPa; pressure drop ≤1kPa within 30 seconds is qualified.

• Or perform water immersion verification via a vacuum chamber to confirm no bubble leakage.

IV. Practical Case Study: IP67 Tactile Switch in Outdoor Smart Controller Application

A customer developed an outdoor lighting control terminal, requiring a tactile switch with volume <7×7mm, SMT support, and IP67 rating. We implemented the following solution:

• Selected surface-mount tactile switch + sealed silicone cap combination.

• Shell used PA66 glass fiber-reinforced plastic, featuring UV resistance and hydrolysis resistance.

• Embedded high-rebound light-guiding silicone at the button area, balancing waterproofing and backlighting.

• Protected PCB via conformal coating spray + epoxy potting.

• The final product passed salt spray test for 120 hours and waterproof test (1m/30 minutes) without issues.

Ultimately, the switch entered mass production smoothly, with annual shipments exceeding 300,000 units, receiving positive customer feedback.

V. Future Trends and Technological Evolution Directions

• Higher Protection Ratings (IP68): Adapting to extreme scenarios like diving or high-pressure washing.

• Miniaturized Waterproof Structure Design: Meeting the dual requirements of extremely small size and sealing for devices like smartwatches and earphones.

• Visual Simulation Design: Introducing CFD (Computational Fluid Dynamics) simulation to predict water ingress paths and stress deformation.

• Eco-friendly Waterproof Materials: Promoting the use of halogen-free, waterproof materials compliant with ROHS/REACH regulations.

Conclusion

Achieving IP67 dustproof and waterproof performance for tactile switches requires comprehensive consideration of structural sealing, material selection, and process control. Especially in industrial and outdoor applications, their reliability directly impacts the stability of the entire machine. Through rational design of sealing films, selection of weather-resistant materials, optimization of shell structures, and mature manufacturing processes, it is entirely possible to create highly protected tactile switches that balance tactile feedback and environmental adaptability.

Against the backdrop of increasingly stringent market demands, tactile switches with dustproof and waterproof capabilities will become standard for high-end equipment, and also represent a significant manifestation of technological differentiation for switch manufacturers.