US Patent 7942994 Bonding tool and method

A bonding tool and method A bonding tool and method for bonding together layers of a MEMS transducer device, including at least one layer of a piezoelectric material, and an intermediate reinforcing layer of titanium, or other metal, comprising: positioning the layers above one another and spaced apart by means of spacing members, heating said layers to a bonding temperature, and retracting the spacing members so as to bring the layers together under pressure to effect a bond between adjacent surfaces of the layers, wherein a press head is employed with a compliant caul for evenly distributing the press force; and permitting said layers to cool to an operating temperature in which said piezoelectric layer is under compressive strain and the titanium layer is under tensile strain.