The inside of the surface-mounted device (SMD) piezoelectric sounder is divided into
air chambers by a piezoelectric diaphragm and silicone adhesive. These air chambers are connected to the
outside through the sound-emitting hole and open hole established on the top and sides of the product.
If flux or coating agent enters through the sound emitting-hole or open hole, the
diaphragm and the case may stick to each other. That may cause the vibrations of the diaphragm to be
inhibited. The sound pressure may then drop.