Silicone is a type of rubber. After vulcanization, silicone rubber exhibits excellent heat resistance, cold resistance, ozone resistance, atmospheric aging resistance, and good electrical insulation properties.
Silicone rubber's drawbacks include lower tensile strength and elongation at break, as well as significant compression deformation.
Parts suitable for use in high and low-temperature, sunlight, atmospheric, and ozone environments, as well as electrical insulation components.
Dimensional Accuracy and Recommended Tolerance Markings
The material of the track is an elastomer, which, compared to plastic materials, has more and more complex direct influencing factors for shrinkage rates. It is more challenging to achieve precision than plastic parts, and this should be fully considered in the specific design. There should be no areas requiring high precision.
If the basic size is too large and cannot meet the required precision for design, the solution is to use positioning pins with wafer deformation. In areas where size precision is required, the design must allow for easy mold modification.
Etched Text and Patterns
Trademark patterns and text can be designed on silicone substrates, which are simultaneously formed during the molding process. The designs on the products, whether in the form of characters or symbols, come in two types: convex and concave. For ease of mold processing, they are generally designed as convex.
For ease of changing markings or model numbers, during mold design, the marking area can be designed as an insert. When the product model changes, only replacing the insert in the mold cavity's marking area is required to meet the marking replacement needs. In the design of such product parts, it should be allowed for burr remnants to exist at the contours of the insert pieces in the marking area.
For conductive rubber, the stroke is generally recommended to be between 0.8 to 1.5mm; the exhaust slots (also known as air pits) are designed to prevent adhesion between the keypad and the PCB board during operation.
For the touch switch, the stroke depends on the switch's own stroke (and the stroke for preventing accidental operation), as detailed later. If the substrate does not fit the PCB board, the air slot structure element can be omitted.
The key design has a tactile issue; different curve graphs correspond to different tactile experiences. According to experience, the tactile feel is better when (FP-FC)/FP is between 40% and 60%.
