Acoustic substrate

Abstract

A micromachined microphone or speaker embedded within, or positioned on top of, a substrate suitable for carrying microelectronic chips and components. The acoustic element converts sound energy into electrical energy which is then amplified by electronic components positioned on the surface of the substrate. Alternatively, the acoustic element may be driven by electronics to produce sound. The substrate can be used in standard microelectronic packaging applications.

1 . A device comprising
 a laminate structure having a plurality of layers including conductive and non-conductive layers, and   an acoustically sensitive element positioned in a cavity formed in the layers, the being in electrical contact with one or more conductive layers of the plurality of layers.   
   
   
       2 . The device of  claim 1  with a second laminate covering the cavity. 
   
   
       3 . The device of  claim 1  further comprising one or more electronic chips bonded to the laminate and electrically connected to conductive elements on the laminate. 
   
   
       4 . An acoustic element comprising
 a laminate layer having a thin diaphragm layer suspended above a conductive base layer.   
   
   
       5 . The acoustic element of  claim 4  wherein the thin diaphragm is made from a conductive material forming a capacitor. 
   
   
       6 . The acoustic element of  claim 4  wherein the thin diaphragm is made from an insulating material that is given an electric charge 
   
   
       7 . The acoustic element of  claim 4  wherein the thin diaphragm includes one or more openings. 
   
   
       8 . The acoustic element of  claim 4  wherein the thin diaphragm is connected to a second conductive layer in the laminate, the second conductive layer being patterned to produce an electrical trace connectable to other conductive traces in the laminate. 
   
   
       9 . An acoustic element comprising a laminate layer supporting resonating elements. 
   
   
       10 . The element of  claim 9  wherein the resonating elements are cantilevers. 
   
   
       11 . The element of  claim 9  wherein the resonating elements are suspended above a conducting layer in the laminate. 
   
   
       12 . An acoustic element comprising a laminate layer supporting a thin conductive ribbon material. 
   
   
       13 . The element of  claim 12  wherein the ribbon is shaped to form a corrugated structure. 
   
   
       14 . A microelectronic package
 a standard laminate substrate,   one or more microelectronic chips mounted on the substrate and electrically connected to conductors on the surface of the substrate,   one or more spacers positioned around the edges of the substrate,   a top laminate comprising an acoustic element, the spacer providing a vertical offset between the laminate and the substrate and providing electrical connections from the bottom substrate to the top laminate.   
   
   
       15 . A method for building an acoustic element within a laminate structure comprising the steps of
 forming a first laminate structure having a first laminate layer with a first metal foil bonded to the laminate layer,   patterning a second metal foil over the first metal foil,   forming a second laminate structure having a second laminate layer with a cavity formed therein and a third metal foil bonded to the second laminate layer beneath the cavity,   bonding the first and second laminate structures together placing the patterned second metal foil over the cavity,   forming an opening in the first laminate layer to expose the first metal foil,   introducing a chemical etchant through the opening to etch away the first metal foil leaving the patterned second metal foil, wherein a portion of the patterned second metal foil freestanding and movable.   
   
   
       16 . The method of  claim 15  wherein the second laminate structure includes a charged electret material in the second laminate layer below the cavity. 
   
   
       17 . The method of  claim 15  wherein the cavity in the second laminate structure passes through the second laminate layer exposing the third metal foil leaving an air gap between portions of the second and third metal foils. 
   
   
       18 . The method of  claim 17  further comprising the step of patterning a fourth metal foil on the third metal foil between the third metal foil and the second laminate structure. 
   
   
       19 . A method for building an acoustic element within a laminate structure comprising the steps of
 bonding a first metal foil on a surface of a first laminate layer,   patterning a second metal foil on a top of the first metal foil,   bonding a second laminate layer to the first laminate layer, the second laminate layer having an opening exposing the second metal foil,   introducing a chemical etchant through the opening to etch away the first metal foil leaving the patterned second metal foil, wherein a portion of the patterned second metal foil freestanding and movable.   
   
   
       20 . The method of  claim 19  further comprising the step of patterning a third metal foil on the bottom of the first metal foil between the first metal foil and the first laminate layer. 
   
   
       21 . The method of  claim 19  wherein the second first laminate layer includes a charged electret material. 
   
   
       22 . A method of packaging a microacoustic elelment element on a lead frame comprising the steps of
 forming a lead frames having a body with openings passing through the body,   forming a laminate structure comprising a first metal film with a second metal film patterned on top of the first metal film and a third metal film bonded to the top of the second metal film, wherein the first and third metal film comprise a metal that is different from the metal of the second metal film,   bonding the laminate structure to the lead frame above the openings in the body,   mounting and electrically connecting microelectronic components to the lead frame,   encapsulating the lead frame, laminate structure and microelectronic components in a protective enclosure, and   passing etchant through the holes in the body of the lead frame to etch the laminate structure to etch the first and third metal films leaving a portion of the second metal film freestanding and moveable.