Implantable medical device including a molded planar transformer

Abstract

The present disclosure provides methods and techniques associated with a planar transformer for an apparatus. The planar transformers include a substrate carrying electronic components and a continuous core that is formed by distributing the encapsulant material uniformly around the substrate unit to define a consistent cross-sectional area for the magnetic path. The electronic components include primary windings and secondary windings associated with the transformer. In some embodiments, the encapsulant material is molded to seals air gaps to the substrate unit.

What is claimed is: 
     
         1 . A method of forming a transformer assembly, comprising:
 providing a mold chase having an upper mold chase and a lower mold chase, wherein the upper and lower mold chase define at least one cavity;   providing a substrate unit including primary and secondary windings;   disposing the substrate unit within the at least one cavity of the mold chase;   dispensing an encapsulant material into the at least one cavity of the mold chase, wherein the encapsulant material comprises a mold material that becomes fluid during the dispensing such that the mold material fills the cavity and encapsulates the substrate unit;   curing the encapsulant material to form a core having a shape defined by the upper mold chase and the lower mold chase; and   separating the mold chase from the encapsulated substrate unit.   
     
     
         2 . The method of  claim 1 , wherein the mold chase further includes a receptacle having a first opening at an exterior surface of the mold chase and a second opening into the cavity, said second opening being in fluid communication with the first opening. 
     
     
         3 . The method of  claim 1 , further comprising a plunger disposed within the receptacle, wherein the encapsulant is dispensed into the cavity in response to application of pressure to the plunger. 
     
     
         4 . The method of  claim 1 , wherein the at least one cavity is defined by two mirror-image opposing cavities for receiving the substrate unit, a first of the two cavities being disposed in the upper mold chase and a second of the two cavities being disposed in the lower mold chase. 
     
     
         5 . The method of  claim 1 , wherein the mold chase further comprises an outlet vent for pressure relief within the cavity during the task of dispensing the encapsulant material. 
     
     
         6 . The method of  claim 1 , wherein the at least one cavity in the mold chase includes a plurality of upper cavities within the upper mold chase and a plurality of lower cavities within the lower mold chase, each of the lower cavities corresponding to and aligned with one of the upper cavities. 
     
     
         7 . The method of  claim 6 , wherein the substrate unit is positioned between the plurality of upper cavities and the plurality of lower cavities. 
     
     
         8 . The method of  claim 1 , wherein the cavity defines a predetermined configuration for the core. 
     
     
         9 . The method of  claim 1 , wherein the mold chase includes an upper cavity having a first configuration and a lower cavity having a second configuration that is different from the upper cavity. 
     
     
         10 . The method of  claim 1 , further comprising embedding the primary and secondary windings within the substrate unit. 
     
     
         11 . The method of  claim 1 , wherein disposing the substrate unit within the mold chase comprises placing the substrate unit between the upper mold chase and the lower mold chase and arranging the upper mold chase and the lower mold chase to enclose the substrate unit. 
     
     
         12 . The method of  claim 1 , wherein curing the encapsulant material comprises allowing the encapsulant material to solidify. 
     
     
         13 . The method of  claim 1 , wherein curing the encapsulant material comprises applying heat to the encapsulant material. 
     
     
         14 . The method of  claim 1 , wherein the dispensing of the encapsulant material is performed by transfer molding. 
     
     
         15 . The method of  claim 1 , wherein the dispensing of the encapsulant material is performed to eliminate any air gap within the cavity. 
     
     
         16 . The method of  claim 1 , wherein the encapsulant material includes a polymer bonded magnetic material. 
     
     
         17 . The method of  claim 1 , wherein the substrate unit includes a terminal connector disposed on an exterior of the at least one cavity. 
     
     
         18 . An implantable medical device having electronic circuitry operable to perform a therapeutic and/or monitoring function, comprising:
 a battery;   a capacitor; and   a transformer coupled to the battery and the capacitor, wherein the transformer includes:
 a substrate unit having electronic components and including primary and secondary windings embedded within the substrate unit; 
 a core encapsulating the substrate unit, wherein the core includes a unitary core having a unitary core that are molded to eliminate an air gap therebetween. 
   
     
     
         19 . The implantable medical device, wherein the configuration of the unitary core is selected based on a performance criteria for the transformer. 
     
     
         20 . The implantable medical device, wherein the unitary core comprises a polymer bonded magnetic compound.