Method of constructing a capacitor stack for a flat capacitor

#The present invention concerns implantable medical devices, such as defibrillators and cardioverters, and more specifically to a method of manufacturing a capacitor stack for a flat capacitor.

#Since the early 1980s, thousands of patients prone to irregular and sometimes life-threatening heart rhythms have had miniature heart monitors, particularly defibrillators and cardioverters, implanted in their bodies. These devices detect onset of abnormal heart rhythms and automatically apply corrective electrical therapy, specifically one or more bursts of electric current to the heart. When the bursts of electric current are properly sized and timed, they restore normal heart function without human intervention, sparing patients considerable discomfort and often saving their lives.

#The typical defibrillator or cardioverter includes a set of electrical leads, which extend from a sealed housing into the wall of a heart after implantation. Within the housing are a battery for supplying power, monitoring circuitry for detecting abnormal heart rhythms, and a capacitor for delivering bursts of electric current through the leads to the heart.

#FIG. 1 is a perspective view of a flat capacitor according to one embodiment of the present invention.

#FIG. 2 is an exploded perspective view of a capacitor stack constructed in accordance with one embodiment.

#FIG. 3 is an exploded perspective view of an anode stack constructed in accordance with one embodiment.

#In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the present invention. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents.

#FIG. 1 shows a partially exploded view of an exemplary embodiment of capacitor 18. The present embodiment shows a D-shaped capacitor. In other embodiments, capacitor 18 may be designed in a variety of flat shapes to conform to various housing shapes. The capacitor includes a metallic case 20 defining a chamber 22, in which is placed a capacitor stack 24. In one embodiment, case 20 is manufactured from a conductive material, such as aluminum. In another option, the case 20 is manufactured using a nonconductive material, such as a ceramic or a plastic.

#Case 20 includes a base 26 and a lid 28 overlying and resting on an upper rim of base 26. Stack 24 has a face 30 and a top surface 32. Stack 24 has a cutout region 34 at its periphery, with cutout region 34 being positioned when the stack 24 is installed in case 20 to provide space for electrical connections. An anode feedthrough post 36 passes through to stack 24 and is electrically insulated from case 20. The capacitor stack 24 is covered with insulating tape 38. A space 40 exists between the lid 28 and the top surface 32 of the stack 24 and between the face 30 of the stack 24 and a lateral wall of the base 26 of the case 20. In some embodiments, space 40 is a line-to-line interference fit between portions of stack 24 and case 20. In other embodiments, space 40 is a gap or opening within the case and between the stack and the case.