Compressed Electrode Connection to Protect Wire Weld Heat-Affected Zones
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Solution Overview
Problem
The existing methods for connecting conductor wires to electrodes in medical devices, particularly in lead or catheter construction, result in premature breakage due to the heat affected zone (HAZ) created by welding, leading to mechanical property degradation and potential disruption of electrical connections.
Innovation Solution
A connection method where a conductor wire is welded to an electrode, and the electrode is compressed to sandwich the wire, creating a mechanical and electrical coupling that constrains motion and reduces the likelihood of breakage within the HAZ, potentially eliminating the need for secondary welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductor wire is welded to electrode using laser or resistance welds, then electrical connection is established, but heat affected zone degrades mechanical properties and causes premature breakage
Solution Approach 1:
A laser weldable transition piece is introduced as an intermediary component between the conductor wire and the electrode. This transition piece has a first end that is laser-welded to the conductor wire and a second end that is resistance-welded to the electrode, thereby mediating the connection process and distributing the thermal impact across two separate welding zones rather than concentrating it in a single heat-affected zone.
Solution Approach 2:
The invention replaces traditional direct resistance welding of the conductor wire to the electrode with a two-stage welding process using the transition piece. This substitution allows for better control of thermal effects and mechanical properties by separating the welding operations and using materials optimized for each welding method.
2Strength
If multiple welds are used to ensure connection durability, then connection strength improves, but heat affected zone expands and increases breakage risk
Solution Approach 1:
The connection structure is segmented into distinct functional zones: the conductor wire, the laser-weldable transition piece, and the electrode. Each segment is optimized for its specific function and welding method, allowing the connection to achieve sufficient strength through two targeted welds rather than multiple welds on the same components, thereby limiting the cumulative heat-affected zone.
3Ease of operation
If conductor wire is made flexible for normal use, then ease of operation improves, but wire bends in HAZ and prematurely breaks
Solution Approach 1:
The transition piece is designed with specific local qualities: it has a geometry and material composition optimized for laser welding at its first end, and different properties optimized for resistance welding at its second end. This local differentiation allows each end to be joined optimally while the overall structure maintains flexibility for normal operation but resists breakage through the strengthened connection points.
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 enhances the durability and fatigue resistance of the electrode-wire connection, reducing the risk of breakage and eliminating the need for additional welds within the HAZ, thereby increasing the reliability and longevity of medical devices.
Implementation Method 1
the conductive tube is compressed at least partially around the connection portion of the conductor wire to at least partially surround and couple to the connection portion
Implementation Method 2
the connection portion is laser welded to the electrode
Implementation Method 3
the connection portion is resistance welded to the electrode
Data Source
AI summary
In various examples, a component for a medical device is described. The component includes a conductor wire including a connection portion. An electrode is formed from a conductive tube. The conductive tube is compressed at least partially around the connection portion of the conductor wire to at least partially surround and couple to the connection portion.