A self-latching switch is an electronic switch that uses a mechanical structure to achieve a “press to lock, press again to unlock” function. The “7×7″ designation generally refers to the switch’s overall dimensions (e.g., a 7mm×7mm square package). This type of mechanical switch is compact and highly integrated. The following describes its structure and function:
1. Structure: Miniaturized and Highly Reliable Mechanical Design
The core structure of a 7×7 self-latching switch revolves around “compactness” and “self-latching reliability,” primarily consisting of the following components:
Casing and Package
The casing is typically injection-molded from engineering plastics (such as PBT or LCP), with dimensions strictly controlled at approximately 7mm×7mm and a thickness typically between 2 and 5mm, resulting in a thin and lightweight design. The casing may feature anti-slip patterns or markings (e.g., ON/OFF direction) to enhance both operational feel and structural strength. Pins are reserved on the bottom or side for electrical connections. The number of pins is generally 2-6 (depending on the specific model), with a pitch of 0.6-1.2mm, making them suitable for PCB soldering or surface mount technology (SMT).
Internal Mechanical Structure: Trigger and Lock Mechanism
The core of the self-locking function lies in the internal “trigger-lock” mechanical linkage design. Two common solutions are available:
Seesaw-type locking: A springy metal seesaw inside the switch is normally in the off position. When the button is pressed, the seesaw deflects downward, pushing the internal moving contact into contact (conduction). Simultaneously, the seesaw is locked by a retaining structure (such as a hook or groove), maintaining the locked state. When the button is pressed again, the spring force on the seesaw lifts, disengaging the hook and separating the contacts (opening).
Push-button locking: A slider with an axially movable top and a bevel or raised surface is attached to the bottom of the button. When pressed, the slider moves downward, pushing the moving contact and the stationary contact together. Simultaneously, a latch on the slider engages a locking groove in the housing, maintaining the contact. When pressed again, the latch is squeezed and deformed out of the locking groove, and the slider, acting on a spring, returns to its original position, disconnecting the contact.
Electrical Contact System
Contact materials are typically beryllium copper, phosphor bronze, or silver-plated stainless steel, ensuring low resistance (≤50mΩ) and high wear resistance (typically ≥100,000 cycles). The stationary contact is fixed to a plastic base, while the moving contact is linked to the button/slider. Contact pressure is provided by a spring (0.1-0.5N) to prevent loose connections. Some models include a waterproof rubber ring (such as silicone) to enhance dust and water resistance (up to IP54).
II. Function: The Core Value and Application Scenarios of the Self-Lock Feature
The core function of the 7×7 self-locking switch is “manual control state retention.” This feature makes it irreplaceable in small devices:
Self-locking Function: No continuous force required, simplifying operation.
Unlike conventional push-button switches (press to turn on, release to turn off), self-locking switches maintain the on or off state through a mechanical lock, allowing users to switch states with a single press (e.g., “press once to turn on, press again to turn off”). This feature is widely used in applications requiring “state memory.”
Post time: Sep-05-2025