The analysis of Waterproof Requirements for Touch and Displays
Normally, for our display screens, when a customer mentions waterproofing, we need to clarify which part of the display needs to be waterproof.
The product needs to be waterproof. This requirement is generally for products with touchscreens. The waterproofing of the back of the display relies on the customer’s housing. We mainly focus on the sealing between the cover plate and the customer’s housing, as well as the sealing at the junction between the touchscreen and the display.
- The touchscreen cover plate needs to be waterproof when assembled into the customer’s product. This requirement is quite common, and customers often have specific data requirements for sealing, such as an IP rating – grading the resistance of an enclosure against the intrusion of dust or liquids. In this case, we only need to choose the appropriate 3M double-sided tape to achieve the desired result. If no touch panel in the design, the polarizer will not resist long term water corrosion. Apply an acrylic protective layer on top of the display screen and securely adhere it with glue.
- The area between the display screen and the touchscreen needs to be waterproof. Although some of our touchscreens are bonded to the display with OCA, the sensor part is still exposed. Therefore, it is necessary to use RTV sealant to seal the perimeter around the bonding area between the touchscreen and the TFT.
- Waterproof Touchscreen Functionality. In some cases, customers may use the touchscreen while water droplets are present. The touchscreen needs to function properly in the presence of water droplets (normal touch function with water/no false touches from falling water droplets). For this situation, it is necessary to select an appropriate touch IC and special sensor design to ensure better reliability.
- Waterproof PCB. Sometimes customers require the PCB to be waterproof. In this case, it is necessary to add a layer of Conformal Coating on the PCB. This involves applying a transparent polymer film over the PCB, which maintains the shape of the printed circuit board and protects the electronic components on the PCB from environmental damage, thereby improving and extending their lifespan. For more severe weatherproofing requirements, the entire circuit board is fully encapsulated in glue, effectively immersing the board in the adhesive. It is essential that this glue is neutral, without any acidic or alkaline properties, to prevent corrosion of the components.
- Housing Assembly. After assembling the casing, apply sealant to the seams of the casing to ensure that the entire hardware part is airtight. However, even with these measures, it cannot be guaranteed that no water vapor will penetrate, as water molecules are very pervasive. The goal is to minimize the ingress as much as possible. Incorporate breathable vents like Gore vents that allow air to pass through but block water and moisture. Sometimes, utilizing laser welding for creating precise and strong seals in the device’s casing.
- Other Waterproofing Ideas
- Potting: Apply potting compounds around connectors and cables to seal any potential entry points.
- Sealed Connectors: Use waterproof connectors and cables to prevent moisture ingress at connection points.
- Incorporation of Desiccants: Place desiccants inside the device to absorb any residual moisture.
IP Rating — IP XX
The two digits following IP indicate the level of protection that the device’s enclosure provides against the ingress of solid objects and water. The first digit represents the level of protection against dust and foreign objects, while the second digit indicates the level of moisture and water resistance. The higher the number, the greater the level of protection.
For example, an IP rating of IP54:
- IP: Designates the protection marking.
- 5: The first digit indicates the level of protection against contact and foreign objects.
- 4: The second digit indicates the level of protection against water.
The first digit (5) signifies a level of protection against dust and limited ingress of particles. The second digit (4) signifies a level of protection against water splashes from any direction.
Dust Protection Level
The first digit in the IP rating system represents the level of protection against solid objects, including dust. Here are the possible levels:
- 0: No protection against contact and ingress of objects.
- 1: Protection against solid objects over 50 mm (e.g., accidental touch by hands).
- 2: Protection against solid objects over 12.5 mm (e.g., fingers).
- 3: Protection against solid objects over 2.5 mm (e.g., tools, thick wires).
- 4: Protection against solid objects over 1 mm (e.g., most wires, screws).
- 5: Limited protection against dust ingress (no harmful deposits).
- 6: Complete protection against dust ingress.
Water Protection Level
The second digit in the IP rating system indicates the level of protection against the ingress of water. Here are the possible levels:
- 0: No protection.
- 1: Protection against vertically dripping water.
- 2: Protection against dripping water when tilted up to 15 degrees.
- 3: Protection against spraying water at an angle up to 60 degrees.
- 4: Protection against splashing water from any direction.
- 5: Protection against water jets from any direction.
- 6: Protection against powerful water jets.
- 7: Protection against immersion in water up to 1 meter depth.
- 8: Protection against continuous immersion in water beyond 1 meter.
IP Rating Explanation for Immersion
- 7: The device can be immersed in water under specified pressure for a specified time, ensuring that the amount of water ingress does not reach harmful levels.
- 8: The device can be continuously immersed in water under conditions agreed upon by the manufacturer and the user, typically more stringent than those of IP67.
ISO 16750 and Other International Standards:
- Scope
The waterproof tests include the second characteristic digits from 1 to 8, corresponding to protection levels IPX1 to IPX8.
- Waterproof Test Content for Various Levels
(1) IPX1
- Method Name: Vertical Drip Test
- Test Equipment: Drip test device and its test method
- Sample Placement: Place the sample in its normal working position on a rotating sample table at 1 rotation per minute (r/min). The distance from the top of the sample to the drip outlet should not exceed 200mm.
- Test Conditions:
- Drip rate: 1.0 +0.5 mm/min
- Test duration: 10 minutes
(2) IPX2
- Method Name: Tilted Drip Test
- Test Equipment: Drip test device and its test method
- Sample Placement: Tilt the sample 15 degrees from its normal working position, in four fixed positions, one for each tilted direction.
- Test Conditions:
- Drip rate: 3.0 +0.5 mm/min
- Test duration: 2.5 minutes per tilt direction (total 10 minutes)
(3) IPX3
- Method Name: Spraying Water Test
- Test Equipment: Oscillating spray test device or spray nozzle
- Sample Placement: Place the sample in its normal working position.
- Test Conditions:
- Spray water at an angle up to 60 degrees from vertical.
- Water flow rate: 10 liters per minute.
- Test duration: 5 minutes.
(4) IPX4
- Method Name: Splashing Water Test
- Test Equipment: Oscillating spray test device or spray nozzle
- Sample Placement: Place the sample in its normal working position.
- Test Conditions:
- Splash water from all directions.
- Water flow rate: 10 liters per minute.
- Test duration: 5 minutes.
(5) IPX5
- Method Name: Water Jet Test
- Test Equipment: Nozzle with a 6.3mm diameter
- Sample Placement: Place the sample in its normal working position.
- Test Conditions:
- Water jet flow rate: 12.5 liters per minute.
- Distance: 2.5 to 3 meters.
- Test duration: 3 minutes per square meter for at least 3 minutes.
(6) IPX6
- Method Name: Powerful Water Jet Test
- Test Equipment: Nozzle with a 12.5mm diameter
- Sample Placement: Place the sample in its normal working position.
- Test Conditions:
- Water jet flow rate: 100 liters per minute.
- Distance: 2.5 to 3 meters.
- Test duration: 3 minutes per square meter for at least 3 minutes.
(7) IPX7
- Method Name: Immersion Test
- Test Equipment: Water tank
- Sample Placement: Submerge the sample in water.
- Test Conditions:
- Depth: 1 meter.
- Test duration: 30 minutes.
(8) IPX8
- Method Name: Continuous Immersion Test
- Test Equipment: Water tank
- Sample Placement: Submerge the sample in water under conditions agreed upon by the manufacturer and user.
- Test Conditions:
- Depth: Generally deeper than IPX7, specific conditions defined by agreement.
- Test duration: Typically longer than IPX7, as agreed upon.
These tests ensure that the devices meet specific standards for waterproofing based on their intended use and environmental conditions.
If you have any questions about Display and Touch Waterproofing Requirements, please contact Orient Display support engineers