Environmental Sealing

Many of CSI Keyboards’ customers require environmentally sealed switches and keypads built to last in extreme and harsh environments. CSI Keyboards has over 30 years of experience designing keypads that are completely environmentally sealed and switches that need to meet specific requirements for Water, Temperature, Humidity, Dirt, Dust, Altitude, Impact resistance, Vibration, and Chemical resistance.

Some of our technologies for environmentally sealing keypads include the Seal Frame design, rubber keypad sealing designs, copper flex circuitry, environmentally resistant polyester technology, and other proprietary sealing techniques.

Copper Flex Circuitry
CSI Keyboards uses copper flex circuitry in the majority of our keypad designs due to its excellent dielectric strength, thermal stability, chemical resistance and flexibility. Copper flex, also known as Kapton circuits, has become the superior choice over printed silver especially for outdoor applications. A printed silver circuit can be replaced with a copper and polyimide construction with minimal additional cost. Copper flex circuitry construction designs offer a significant advantage over printed silver.

Copper Flex membrane switch panels are produced using polyimide (Kapton) as the base material. Copper flex switches are manufactured by laminating a thin sheet of copper to a flexible film substrate. The copper is then chemically etched away, leaving the copper traces. An additional layer of polyimide is laminated to the circuit leaving the gold contacts exposed.

Advantages of copperflex over printed silver circuitry is as follows:

  • Improved creasability – the ability to fold or crease without causing open circuits which you are susceptible to using silver ink
  • Ability to put solder components directly on flex, better adhesion than bonding to silver ink
  • Much more resistant to thermal shock
  • No potential problems with silver migration
  • Greater conductivity
  • Lowering the closed loop resistance and switch bounce will be reduced by gold plating the contacts. We will have a gold to gold contact with no bounce versus silver to gold dome
  • Applying stiffener to tail end using heat lamination versus cold lamination which provides better adhesion and better for pinning
  • Ability to have a 0.5mm pitch vs. the 1.0mm minimum with printed silver
  • Tighter trace routing capabilities

The CSI “Seal Frame”
CSI Keyboards’ proprietary perimeter “Seal Frame” switches have proven to be as robust as other sealing methods such as perimeter temperature sealing and can be included in your design at minimal additional cost.

Sealed Rubber Keypad Assemblies
CSI Keyboards has become the go-to membrane keypad manufacturer for environmentally sealed rubber keypad designs. Sealing can be designed into the rubber and our proprietary bonding methods can also be designed in to create NEMA 2, 3 and 4 assemblies. We can design and customize gaskets per your requirements or IP standards which include both IP67 rated keypads and IP68 rated keypads. We have designed sealed rubber switches for marine navigation controls, medical equipment, military applications, industrial controls and food packaging equipment.

Proprietary Potting Solution
CSI Keyboards developed a proprietary potting solution that will protect your user interface and product from all of the elements. This solution was originally intended for marine interfaces as marine controls and instrumentation face some of the greatest challenges when it comes to the environment they must to perform in. The potting solution and design 100% seals the interface that is being constantly exposed to all of the elements which include heavy UV exposure, extreme levels of moisture, and temperature extremes.

Environmentally Resistant and High Performance Adhesives
CSI Keyboards utilizes the top of the line adhesives specially formulated to provide high bond strength to surfaces. Our adhesives are resistant to humidity, UV, water, temperature, and chemicals.

Environmentally Resistant and High Performance Polyester
CSI Keyboards utilizes polyester specially formulated to resist ultraviolet light, moisture and wide variations in temperature. CSI Keyboards offers both fine and velvet polyester textures specifically designed for outdoor applications. Our membrane keypads are UV, humidity and chemically resistant.

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