PRINTING, MOLDING AND HARDCOATING
Silkscreen printing
Graphics can be applied directly to the keytops of the rubber keypad by screen printing. Multiple colors may be printed, with each color requiring an additional process. The optimum keytop for printing is a flat keytop. However, some curved keytops can also be printed.
Spray paint and laser etch
After the translucent rubber is molded into the keypad shape, the entire top surface of the keypad is spray-painted with one or more colors. A laser is used to etch graphics on the keytops to expose either an underlying layer of paint or the raw rubber. When backlit, light will pass through the translucent rubber and be visible in the etched areas.
Two-shot molding
Similar to Dual Durometer, a keypad can be produced using one color of rubber for the key top and a separate color for the base.
Flow molding
This process allows specific areas of a keypad to be molded with different colored rubber. This provides different base colors without requiring complicated spray-paint techniques. Silk screening is typically done on top of these base colors to provide additional graphics.
Key caps
Premolded hard plastic keytops can be applied to the molded rubber keypad. This provides a hard key feel with the economies and efficiencies of a rubber keypad.
PU coating
Silicone rubber keypads can also be spray-coated with PU resin to provide absolute lifetime abrasion resistance and oil resistance. This important technique has already been successfuly developed.
Hard coating
A screen-printing or spray-painting process is used to apply an additional protective clear silicone ink on the keytops. This increases the abrasion resistance of the printed graphics.
Epoxy coating
Silicone rubber keypads can be coated with a layer of epoxy resin to form a hard top and feel like plastic. The epoxy coating also provides additional abrasion resistance for the printed graphics.
Conductive contacts
Silicone rubber keypads can be co-molded with carbon impregnated silicone pills (carbon pills), gold -plated pills and metal pills according to the application requirements. Due to the low cost of production and acceptable resistance (less than 100 ohms), most rubber keypads are co-molded with carbon pills.
Silicone Rubber Keypads are manufactured from elastic, nontoxic silicone rubber compounds and are processed from compression or injection molding. The result is an economical and reliable keypad for small, medium and large production runs. Silicone keypads can be integrated with printed circuit boards or flexible circuits and have excellent resistance to temperature and aging.