... by PCB,metal dome,overlayer 2.used for meter 3 with special connector 4.more than 300,000 times 5.100% test ... 1. Structure:made by PCB,metal dome,LED,overlayer2. with special connector3.The PCB thickness is 1.6 mm,goldish FR4 ... %,240 hoursOur factory sceneAutomatic silk-screen printer PCB membrane switch with metal dome keypad