Here at SiTech we specialize in a method of silicone injection molding called Insert Molding. Insert Molding consists of pre-manufacturing both silicone or non-silicone inserts, and over-molding these with opaque liquid silicone rubber to form a final keypad assembly or component. Inserts can be used for a variety of benefits in your silicone keypad assemblies, including: Backlighting, Clear Display Windows, Custom Light Blocking Solutions, Light Sensing, Data Transmission, and Metal Shielding or Support. Below we break down some of the unique solutions Insert Molding provides.
Backlit Keypads:
The Traditional Method vs. The SiTech Method
The traditional method for creating custom backlit silicone keypads is molding the entire keypad in clear silicone, then coating the outside in an opaque color, and then lasering the artwork through the black to the clear or translucent base. The biggest issue with this method is the inability to block light. Due to the entire keypad being translucent, light will bleed from annunciators to keys. Custom light blocks are needed to help direct the light away from the keys, but these don’t always work. We have found that light can bleed through very small amounts of clear silicone, which can cause enormous headaches when trying to separate and balance light sources.
The SiTech method consists of pre-molding translucent silicone inserts for keys and indicators. These inserts are then placed into a secondary tool where opaque silicone is shot and over-molded around them. This method of over-molding forms a cross-link bond between the inserts and over-mold. These keypads can now be screen printed or laser-etched with the desired artwork. This method allows for individual keys to have their own unique lighting without the headache of balancing light sources.
Design Tips:
• The location of the LED’s should be behind each key or indicator.
• The maximum depth of an undercut for a feature window opening is 0.250”.
• The minimum size for an insert molded silicone light pipe is 0.060”.
• The minimum thickness for an insert is 0.030”.
• The minimum distance needed between the edge of a keypad or opening and a silicone light pipe or window is 0.030”.
SiTech uses insert molding as a process to isolate light sources, and prevent the spread of light to specific areas of a keypad. This method of molding allows for the elimination of light bleeding into LED indicators or separate keys that are not supposed to be illuminated. The ability to mold an opaque barrier around a translucent insert opens up the possibility to balance light sources by focusing on individual light sources rather than trying to illuminate an entire keypad.
The Traditional Method vs. The SiTech Method
The traditional method for creating custom backlit silicone keypads is molding the entire keypad in clear silicone, then coating the outside in an opaque color, and then lasering the artwork through the black to the clear or translucent base. The biggest issue with this method is the inability to block light. Due to the entire keypad being translucent, light will bleed from annunciators to keys. Custom light blocks are needed to help direct the light away from the keys, but these don’t always work. We have found that light can bleed through very small amounts of clear silicone, which can cause enormous headaches when trying to separate and balance light sources.
The SiTech method consists of pre-molding translucent silicone inserts for keys and indicators. These inserts are then placed into a secondary tool where opaque silicone is shot and over-molded around them. This method of over-molding forms a cross-link bond between the inserts and over-mold. These keypads can now be screen printed or laser-etched with the desired artwork. This method allows for individual keys to have their own unique lighting without the headache of balancing light sources.
Design Tips:
• The location of the LED’s should be behind each key or indicator.
• The maximum depth of an undercut for a feature window opening is 0.250”.
• The minimum size for an insert molded silicone light pipe is 0.060”.
• The minimum thickness for an insert is 0.030”.
• The minimum distance needed between the edge of a keypad or opening and a silicone light pipe or window is 0.030”.
SiTech uses insert molding as a process to isolate light sources, and prevent the spread of light to specific areas of a keypad. This method of molding allows for the elimination of light bleeding into LED indicators or separate keys that are not supposed to be illuminated. The ability to mold an opaque barrier around a translucent insert opens up the possibility to balance light sources by focusing on individual light sources rather than trying to illuminate an entire keypad.
While we offer liquid silicone rubber components that are optically clear, we also can provide optically clear inserts in your silicone keypads. Using the same methods above, we can create unique display windows within your keypads. The cross-linking bond the silicone forms during the over-mold process prevents the possibility of leaks, allowing for seamless transitions between opaque and optically clear silicone. Optically clear silicone inserts are created by polishing the molding surfaces to a mirror-like finish. Doing so not only allows the insert to be used for display windows, but also light sensing, and Infrared Data Association (IrDA).
Not all inserts are required to be silicone rubber. We also have the capability of over-molding metallic inserts for EMI/RFI Shielding and Keypad Structural Support. EMI/RFI shielding helps reduce interference from external electromagnetic sources which can disrupt the functionality of your device.
With over 75 years of experience in silicone keypad design and molding, we are committed to providing complete customer satisfaction with the highest quality products in a successful and timely manner. The customer is and has always been the focus of our business.
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Industries Served
– Aerospace
– Industrial
– Medical
– Military
Silicone Technology Corp. manufactures out of Newport News, Virginia. Custom silicone rubber keypads are just one of the many products manufactured by Silicone Technology Corp. We use a unique injection molding process with Dow and Momentive Silicones. This combination of technology and quality offers you a competitive domestic supplier of custom keypads and other silicone rubber products.
