Methods of making acoustic resonator devices and filters are disclosed. A method of fabricating an acoustic resonator device includes fabricating an acoustic resonator chip including: attaching a back surface of a piezoelectric plate to a front surface of a substrate, such that portions of the piezoelectric plate form at least first and second diaphragms spanning at least first and second cavities, and forming a first conductor pattern as one or more conductor layers on the piezoelectric plate. The first conductor pattern includes at least first and second interdigitated transducers (IDTs) and a first plurality of contact pads. The method further includes fabricating an interposer having front and back surface and a second plurality of contact pads on the interposer back surface, forming conductive balls, and bonding each of the first plurality of contact pads to a respective pad of the second plurality of contact pads using the respective conductive ball.