Acoustic substrate
View Patent ↗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 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 first 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.
2. The method of claim 1 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.