Counter-bored Feedthrough Capacitors for Reliable EMI Filtering
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Solution Overview
Problem
Existing methods for connecting feedthrough capacitors to lead wires in active implantable medical devices are time-consuming, costly, and prone to reliability issues due to the migration of conductive materials during high-temperature re-flow operations, leading to potential short circuits and inefficient EMI filtering.
Innovation Solution
The use of counter-drills, counter-sinks, or counter-bores on the feedthrough capacitor to create wells for the placement of conductive materials, allowing for efficient dispensing and secure attachment of lead wires to electrode plates, reducing the need for multiple centrifuge steps and minimizing material migration during re-flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional methods are used to connect feedthrough capacitors to lead wires, then electrical connection is achieved, but the process is time-consuming and costly with multiple centrifuge steps
Solution Approach 1:
The capacitor is pre-formed with recesses (counter-bores, counter-sinks, or counter-drills) during the capacitor manufacturing process itself, before assembly with the lead wires. This preliminary preparation eliminates the need for subsequent material containment structures and reduces the number of manufacturing steps required during final assembly.
Solution Approach 2:
The invention combines multiple functions into the capacitor structure itself: the capacitor electrodes, the EMI filtering function, and the material containment feature (recesses) are all integrated into a single component. This merging eliminates separate parts and reduces assembly complexity.
2Reliability
If conductive material is placed without wells, then electrical connection is made, but material migration during re-flow causes short circuits
Solution Approach 1:
The capacitor surface is modified with localized recesses at specific positions where conductive material needs to be placed. These recesses provide local containment exactly where needed, preventing material migration in critical areas while maintaining the overall simplicity of the capacitor structure.
Solution Approach 2:
The recesses act as intermediary structures that mediate between the conductive material and the capacitor surface. They provide a physical containment feature that guides and restricts material flow, preventing direct migration across the capacitor surface that would cause short circuits.
3Reliability
If multiple centrifuge steps are used, then conductive material is secured, but manufacturing cost and complexity increase
Solution Approach 1:
The containment feature (recesses) is built into the capacitor structure in advance, during capacitor manufacturing. This preliminary action eliminates the need for multiple subsequent centrifuge steps to secure the conductive material, as the material is naturally contained by the recess geometry from the beginning of the assembly process.
Solution Approach 2:
The invention extracts the material containment function from the manufacturing process steps (centrifuge operations) and transfers it to the capacitor structure itself (recesses). This extraction eliminates the need for complex multi-step processes while maintaining reliable material securing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables a reliable, single-operation electrical connection with increased process yield, reducing the risk of short circuits and improving the manufacturing efficiency of EMI filtered terminal assemblies in medical devices.
Implementation Method 1
The conductive material is heated to melt and flow into the well
Implementation Method 2
The conductive material is heated to melt and flow into the well, and when cooled, forms an electrical connection
Data Source
AI summary
An EMI filtered terminal assembly including at least one conductive terminal pin, a feedthrough capacitor, and a counter-bore associated with a passageway through the capacitor is described. Preferably, the feedthrough capacitor having counter-drilled or counter-bored holes on its top side is first bonded to a hermetic insulator. The counter-drilled or counter-bore holes in the capacitor provide greater volume for the electro-mechanical attachment between the capacitor and the terminal pin or lead wire, permitting robotic dispensing of, for example, thermal-setting conductive adhesive.