Good or bad factors affecting tactile pcb switch
The factors affecting the tactile pcb switch are mainly determined by the protection, solderability, continuity reliability, life, feel, production process and installation dimensions of the tactile switch.
1. Pin substrate: The lead substrate of tactile pcb switch is brass or phosphor bronze (low grade is iron). In order to reduce the contact resistance, the lead is basically silver plated, and the silver meets the SO2 gas in the air. It will oxidize and directly affect the solderability and contact resistance of the switch. Therefore, the high-quality tactile pcb switch must first be controlled in terms of the silver plating thickness and silver plating process of the substrate. The order of silver plating on the market is as follows:
Silver plating thickness: 0.3um or more (post-silver), 0.2um (thin silver), 0.1um (white plating);
Silver plating process: the substrate is pre-plated with nickel and then silver plated, the substrate is pre-plated with copper and then silver plated, and the substrate is directly plated with silver;
Whether the substrate is silver-plated after the protective agent treatment or whether the switch has dustproof and waterproof function is very important, otherwise the switch will be oxidized even if the best silver plating treatment.
2. The key influencing factor of conduction reliability is the structure of the contact point. Because the function of the tactile pcb switch is the contact conduction between the contact point and the shrapnel, the larger the contact surface of the contact point is, the better the contact surface is determined by the structure. There are three types of structures, the order of which is as follows: large bubble (crater type) "O-type contact", slotted type "2 point contact", flat bubble type "1 point contact".
3, life and feel: life and feel is determined by the tactile pcb switch stroke and the cooperation of the shrapnel, the shorter the stroke, the lighter the sound, the longer the life, the longer the stroke, the opposite, in the case of a fixed shrapnel process, mainly look at the itinerary Or the sound determines the life of the tactile pcb switch; in addition, the key factor determining the life of the shrapnel is the stamping technology. The stamping technology of Japan and Taiwan has been popularized in China. Therefore, in the case of technological upgrading, the requirements for materials are imported. Reduced, for example, 160gf shrapnel life in the market is mainly four: 50,000 times (domestic phosphor bronze or relatively backward stamping technology), about 100,000 times, more than 200,000 times (stainless steel), 300,000 times.
4. Production process: After the accessories, the final impact on the quality is the assembly process. The assembly process depends on the management ability of the production company, the quality of the employees and the quality assurance ability. The final product quality of different guarantee capabilities is definitely different. The market assembly methods include labor and machines. Because the current automation capability is further improved, each has its own advantages and disadvantages: the machine assembly cost is low but the product quality is low, and the manual assembly cost is high but the quality is also high.
5, factory inspection: factory inspection methods and projects also affect the quality of the final tactile pcb switch, such as appearance, feel, conduction, resistance and other items are sampling or full inspection, such as some large manufacturers require the scrap rate is measured by PPM Or zero defects, it is necessary to set up sampling or quality inspection after the factory inspection and full inspection.