The **KMS-D-R** series refers to a specific range of **Micro-Miniature SMT (Surface Mount Technology) Side Actuated Switches**, primarily manufactured by C&K (now part of Littelfuse). These are commonly used in mobile devices, hearing aids, and compact consumer electronics. --- ## 1. Technical Specifications The "KMS" series is defined by its extremely small footprint and side-actuation mechanism, allowing it to be mounted on the edge of a PCB to save vertical space. | Feature | Specification | | :--- | :--- | | **Actuation Direction** | Side Actuated (Right Angle) | | **Mounting Type** | SMT (Surface Mount) | | **Contact Arrangement** | SPST, Normally Open (NO) | | **Operating Force** | Typically 1.5 N to 4.0 N (varies by sub-model) | | **Electrical Life** | Up to 100,000 cycles | | **Voltage/Current Max** | 32 VDC / 50 mA | | **Termination** | Gullwing or J-bend leads | --- ## 2. Part Number Breakdown While specific suffixes may vary, the general nomenclature for this series follows this logic: * **KMS**: Series name (Micro-miniature side-actuated). * **D**: Designates the specific height or physical profile (e.g., specific milimeters from the PCB). * **R**: Generally stands for **RoHS Compliant** or **Tape & Reel** packaging, indicating it is ready for automated pick-and-place assembly. --- ## 3. Key Electronic Components & Materials The internal construction of the KMS-D-R is designed for high reliability in a tiny form factor: ### Internal Materials 1. **Contact Dome**: Usually stainless steel with silver or gold plating. This provides the "tactile" click and completes the circuit. 2. **Housing**: High-temperature thermoplastic (LCP - Liquid Crystal Polymer) to withstand lead-free reflow soldering temperatures. 3. **Terminals**: Brass or Phosphor Bronze with silver or gold plating for low contact resistance and excellent solderability. ### Operational Mechanism * **Tactile Feedback**: When the actuator is pressed horizontally (side-actuation), it collapses the internal metal dome. * **Signal Path**: The dome makes contact between the stationary terminals, closing the circuit. --- ## 4. Common Applications Due to the **side-actuated** nature, these parts are found where "top-down" pressing is not possible: * **Wearables**: Power buttons on smartwatches. * **Medical**: Volume or toggle buttons on hearing aids. * **Consumer Tech**: Reset buttons on the sides of cameras or handheld gaming devices. * **Mobile**: Side buttons for volume or camera shutters. ---