USound’s technology is based on piezoelectricity. Crystals with these properties are for example aluminium nitride (AlN) or lead zirconate titanate (PZT). These materials expand or shrink in an electric field. In a practical configuration, such an electric field is generated between electrodes, covering a piezoelectric layer. This stack is put on top of a substrate (for example a silicon plate).
The current versions of Ganymede MEMS speakers have two land pads on the backside. They are shaped differently to mark the polarity. There are different ways on how to bring electricity to these contacts: Hand soldering on the pads. It is worth noting, that the speaker is not able to withstand the normal reflow process (mainly because of the membrane).
Sealing the front from back side of the speaker is critical to obtain the best acoustic output. This can be achieved by two methods: Gluing the speaker into the application’s housing. In this case the glue can be applied around the speaker or on the cover. Care must be taken to: Obtain a fully sealed glue-line Not cover critical parts