Hi,everyone,the manufacturing of silicone rubber keypads requires a highly precise process to ensure a high-quality final product. In this article, we will walk you through each stage of the production process, providing a comprehensive overview of the steps involved in creating these keypads. By the end, you’ll have a clear understanding of how the entire process comes together. Let’s dive in!
A silicone rubber keypad, also known as an elastomeric keypad, is a specialized input device made from compression-molded silicone rubber. These keypads are typically designed around a printed circuit board (PCB) and are widely used across various applications. The material itself is a silicone-based elastomer composed of silicon, oxygen, hydrogen, and carbon, offering flexibility and durability.
Key Advantages of Silicone Rubber Keypads in Harsh Environments:
Silicone rubber keypads function by using embedded carbon contacts to trigger electrical switches, providing a tactile response when pressed. Their versatility and ease of customization make them a popular choice for a range of industries.
Silicone rubber keypads offer exceptional compression molding characteristics, combining a unique set of mechanical and chemical properties that surpass those of standard rubber. These keypads are particularly favored for their resistance to environmental wear and tear, making them ideal for use in demanding conditions.
Silicone rubber keypads are highly durable, exhibiting superior tear strength, elongation, and tensile strength, even under extreme temperatures. Their non-reactive nature ensures reliable performance in harsh environments. Additionally, their natural light diffusion properties allow for seamless LED backlighting, while their waterproof design prevents spills from damaging the underlying circuit board.
The Manufacturing Process of Silicone Rubber Keypads:
Step 1: Tool Creation
The manufacturing process begins by designing a two-part mold consisting of a silicone compression molding tool (top half) and a molded keypad (bottom half). Precision tools such as EDM or CNC milling machines are employed to ensure the mold is fabricated to exact specifications. The tool is pre-heated to optimize results.
Each keypad is designed with specific tactile feedback requirements, typically requiring around 0.060 inches of travel for the ideal tactile response. Key actuation forces vary, with cone-shaped keys typically requiring between 20 and 250 grams, while flat keys may need 20 to 100 grams. The molded silicone keypad should retain a minimum return force of 30 grams to avoid any sticking.
Step 2: Selecting the Ideal Silicone Material
Two types of silicone are commonly used: liquid silicone rubber (LSR) and gum stock silicone.
LSR, a platinum-cured silicone, is highly resistant to extreme temperatures and has a consistency similar to petroleum jelly, making it ideal for cost-effective custom molding. In contrast, gum stock silicone has a thicker, dough-like consistency and requires a more complex preparation process, involving high-temperature mixing and the addition of a peroxide catalyst.
Step 3: Preform Preparation
In compression molding, the key to producing high-quality silicone keypads is preparing silicone preforms. Silicone is weighed, cut, and colored as needed to meet client specifications. These preforms are placed in the mold cavities, ensuring precise amounts fill each cavity for consistent production.
Step 4: Loading Preforms into the Mold
Silicone preforms are loaded into the mold tool, and the mold is closed in a compression molding press. Proper alignment of the material within the cavity ensures that the molding process results in minimal flash (excess material around the edges). Heat and pressure are applied to transform the silicone into the desired shape.
Step 5: Curing and Ejecting the Keypads
Curing typically takes around 5 minutes at 180°C. Once fully cured, the silicone keypads are carefully removed using protective gloves and compressed air to prevent damage to the hot molded parts.
Step 6: Screen Printing
To define the function of each key, screen printing is used for applying the necessary symbols and letters. This process involves a precise screen mesh that ensures the paint is applied evenly to the keytops, delivering high-quality, cost-effective results suitable for mass production.
Step 7: Laser Etching
For finer detail, laser etching is applied after curing. This technique allows for precise, high-definition markings, ensuring clear and consistent keypad nomenclature.
Step 8: Tactile Response Creation
Tactile feedback in silicone keypads can be achieved either through conductive carbon pills or metal dome switches. Carbon pills are molded directly into the keypads, providing contact with the switch when pressed, while metal dome switches create a tactile “snap” as they complete the circuit with the PCB.
Step 9: Testing and Quality Control
Multiple tests are conducted to ensure durability and performance. A button life test ensures longevity through repeated keypresses, an alcohol abrasion test verifies that printing will not fade, and actuation force testing confirms that each keypad meets the required tactile standards.
Conclusion
The production of silicone rubber keypads involves several key stages, including casting, molding, trimming, printing, and final assembly. A thorough understanding of these processes enables businesses to achieve uniform quality, minimize defects, and deliver reliable, high-performance keypads to their customers.
Custom Silicone Rubber Keypads Tailored to Your Design Requirements
We specialize in producing custom silicone rubber keypads designed to meet your specific requirements. With our deep expertise in silicone rubber keypad design and manufacturing, we ensure precision and quality in every product.
Since 1998, Rockeypad has been a leading manufacturer of custom silicone rubber components in China. We offer a wide range of silicone rubber products, including compression-molded keypads and die-cut parts. To explore our extensive collection of premium products, visit our product page.