Laser-Brazed Molybdenum Pin Joint for Aluminum Leads
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Solution Overview
Problem
Existing methods face challenges in consistently forming robust weld joints, particularly for small diameter configurations and materials like aluminum and molybdenum, which are difficult to join using laser welding due to incompatibility and potential brittle intermetallic formation.
Innovation Solution
A method involving laser brazing is used to join molybdenum and aluminum components by melting only the aluminum material, forming a stable joint around the molybdenum pin to minimize mixing and prevent brittle intermetallics, with specific configurations and apparatuses aiding alignment and joining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser welding is used to join metals, then the two pieces melt and coalesce to form a weld joint, but obtaining consistent and robust weld joints is challenging for small diameter configurations and round pin on flat lead geometries
Solution Approach 1:
A filler material is introduced as an intermediary substance between the two metal pieces to be joined. This filler material facilitates the joining process by filling gaps and creating a more reliable joint, particularly for challenging geometries like round pin on flat lead configurations, thereby improving weld joint consistency without requiring precise control of small diameter welds
2Strength
If laser welding is used to join aluminum to molybdenum, then the materials are joined, but a brittle weld joint is formed due to molybdenum and aluminum mixing creating highly brittle intermetallics
Solution Approach 1:
A filler material acts as an intermediary between aluminum and molybdenum, preventing direct mixing of these incompatible materials. The filler material creates a transition zone that avoids the formation of brittle intermetallic compounds, thereby maintaining joint strength while eliminating the harmful brittle phase formation
Solution Approach 2:
The filler material serves as a sacrificial element that is consumed during the joining process to prevent harmful reactions between the base materials. By using this disposable filler material, the system prevents the formation of brittle intermetallics without requiring complex control mechanisms
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 results in a strong, consistent, and qualifiable joint between molybdenum and aluminum components, reducing the likelihood of brittle intermetallic formation and ensuring reliable attachment even for challenging geometries.
Implementation Method 1
irradiating the joint surfaces with at least a laser beam
Implementation Method 2
the second material of the lead is melted at the first joint
Data Source
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Figure 3
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AI summary
In various examples, a component is for use in an implantable medical device. The component includes a pin including a first material attached to a lead including a second material different from the first material of the pin. At least a portion of the lead includes a channel in which at least a portion of the pin sits, the channel including a channel opening defined at least partially by opposing first and second channel sides extending a channel length. At least a first joint is formed along at least a portion of the first channel side. The first joint includes the second material of the lead deformed to at least partially close the channel opening to retain the pin within the channel to attach the lead to the pin. In some examples, the first material includes molybdenum and the second material includes aluminum.