Protect ruggedised PC components with foam gasket

  • Development of foam gasket components to bond & seal LCD screen & keypad

    Our customer, a supplier of military grade ruggedised electronics equipment required assistance in the development, prototyping and manufacture of two components that will bond and seal the LCD screen and keypad into a ruggedised PC. The product is used in hostile environments, subject to heat extremes, dust, dirt, vibration and shock.

    We specified high performance materials for three components to go into the device that could withstand the extreme environments. We produced a foam gasket to bond and seal the LCD screen using VHB tape, which offers a strong and durable bond, as well as excellent sealing and vibration dampening properties. To bond the keypad we produced a component using a double coated differential tape, with a silicone adhesive one side to attach to the keypad and an acrylic adhesive the other side to attach to the aluminium chassis.

    A gap filling component using Poron™ high performance polyurethane foam was incorporated, for placement behind the PCB to protect it from keyboard pressure. The final parts were presented to aid assembly, e.g. with split back liners.

    Read about this project in more detail below.

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  • Project requirements
    1. Adhesive gasket to bond and seal LCD screen to casing
    2. Adhesive component to bond and seal the silicone keypad to the aluminium chassis
    3. Adhesive component to maintain keypad contact with the PCB below
    4. All parts must provide reliable bonding in extreme temperatures
    5. All parts must provide reliable bonding when subjected to vibration and shock
    6. Keypad and screen gaskets must seal from contaminants e.g. dust and moisture
    7. Components must be easy to use
    Our solution
    1. To bond and seal the LCD screen we produced a foam gasket using 3M 4941 VHB tape. This product offers strong and durable bonds, as well as excellent sealing and vibration dampening properties.
    2. To bond and seal the keypad to the casing we designed and produced a component using 3M 9731 tape. This is a double coated tape with a silicone adhesive on one side (for attachment to the keypad) and an acrylic adhesive on the other side (for attachment to the aluminium chassis)
    3. To bond the keypad to the PCB we produced a gasket using 3M 9088 double coated tape, this product was used as it’s thin, bonds to a wide range of substrates and has an internal PET carrier for dimensional stability.
    4. A gap filling component using Poron™ high performance foam grade 4701-40-15188-04 was also incorporated into the design, for placement behind the PCB to protect it from keyboard pressure. This material has excellent compression set resistance therefore ensuring long term consistent gap filling properties
    5. We presented parts to aid assembly, for example, with split back liners
    Key benefits
    1. We were able to achieve all of the customer’s key requirements
    2. The adhesive materials specified will withstand environmental extremes and will perform throughout the life span of the product
    3. Using a die-cut adhesive component meets more than one requirement e.g. bond and seal and bond and cushion in one part
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