Stud Bump Bonding for Implantable Medical Devices
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Solution Overview
Problem
Conventional methods for bonding feedthrough pins to bonding pads in implantable medical devices face challenges such as heat damage and contamination due to the high energy required for joining, particularly with biocompatible materials like platinum, and the need for flux in soldering processes.
Innovation Solution
The use of stud bumps on the bonding pad surface, which act as a thermal energy sink and ductile medium, allows for mechanical bonding of feedthrough pins using methods like ultrasonic bonding, eliminating the need for flux and reducing heat damage by distributing energy and heat effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional high energy bonding methods are used to join feedthrough pins to bonding pads, then reliable electrical connections are achieved, but heat damage and contamination occur
Solution Approach 1:
The patent introduces stud bumps as an intermediary element between the feedthrough pin and bonding pad. These stud bumps serve as a mediator that enables bonding at lower energies, preventing direct high-energy contact that would cause heat damage and contamination to the sensitive bonding pad and surrounding components.
Solution Approach 2:
The bonding process is segmented into two distinct stages: first bonding the stud bumps to the bonding pad at low energy, then bonding the feedthrough pin to the stud bumps. This segmentation allows each bonding step to occur at optimized energy levels, avoiding the need for high-energy direct bonding that causes damage.
2Ease of manufacture
If soldering processes are used to bond feedthrough pins, then electrical connections are formed, but flux contamination occurs requiring post-joining cleaning
Solution Approach 1:
The patent replaces the chemical soldering process with a mechanical bonding approach using stud bumps. This substitution eliminates the need for flux and associated cleaning processes, as the mechanical interlocking and bonding of stud bumps to both the bonding pad and feedthrough pin achieves reliable electrical connections without chemical contaminants.
3Strength
If direct bonding of feedthrough pins to bonding pads is performed, then connection integrity is maintained, but high energy requirements cause damage to biocompatible materials
Solution Approach 1:
The stud bumps act as a thermal buffer and intermediary bonding surface, allowing the feedthrough pin to be bonded to the bonding pad through a lower-temperature intermediate step. This protects the biocompatible materials from excessive temperatures while maintaining connection integrity through the stud bump interlocking mechanism.
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 reliable, non-contaminating electrical connections between feedthrough pins and bonding pads, ensuring the integrity of implantable medical devices without damaging the components and eliminating the need for post-joining cleaning processes.
Implementation Method 1
The stud bumps collectively have a sufficient footprint and mass to function as a thermal energy (e.g., heat) sink for heat based joining methods such as laser welding
Implementation Method 2
The stud bumps collectively have a sufficient footprint and mass to function as a thermal energy (e.g., heat) sink for heat based joining methods such as laser welding and as a ductile medium for mechanical bonding of the elongate conductor to the one or more stud bumps
Data Source
AI summary
Presented herein are stud bump bonding techniques for electrically connecting an elongate conductor, such as a wire or pin, to a bonding pad. A plurality of stud bumps are bonded to a surface of a bonding pad and an elongate electrical conductor is positioned in proximity to the plurality of stud bumps. The elongate conductor is bonded to one or more of the stud bumps.