Micro-Scale Sapphire-Titanium Diffusion Bonding for Hermetic Joints
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Solution Overview
Problem
Existing methods for bonding optically transparent ceramics like sapphire to conductive metals like titanium result in weak and hermeticity issues, particularly for applications in medical devices and optical sensing, where increased strength and hermeticity are needed.
Innovation Solution
A kinetically limited micro-scale diffusion bond is formed using a Gaussian-Bessel laser beam to connect optically transparent ceramics to opaque conductive metals, with a thickness greater than 1 micron and a weld width greater than 45 microns, ensuring minimal energy absorption by the ceramic and significant absorption by the metal, while maintaining undisturbed portions of the materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a laser pulse is used to create a diffusion bond between sapphire and titanium, then the bond connects the dissimilar materials together, but the bond strength and hermeticity are insufficient
Solution Approach 1:
The patent changes the laser pulse energy parameter to a specific range (0.5 μJ to 2.0 μJ) and adjusts pulse duration and frequency parameters to create optimal bonding conditions that achieve both sufficient bond strength and hermeticity without causing material damage
Solution Approach 2:
The patent uses periodic laser pulsing with specific frequency ranges (1 kHz to 80 kHz) to create controlled thermal cycles that promote diffusion bonding while maintaining material integrity and achieving hermetic seals
2Strength
If laser pulse energy is increased to strengthen the bond, then bond strength increases, but visible cracking occurs in the bond
Solution Approach 1:
The patent identifies and implements a critical laser pulse energy range (0.5 μJ to 2.0 μJ) that provides sufficient bonding strength while avoiding the threshold for crack formation, demonstrating precise parameter control to eliminate harmful effects
3Length of stationary object
If the laser spot size is reduced to create a thinner bond, then bond thickness decreases, but the bond may not provide sufficient strength
Solution Approach 1:
The patent optimizes the laser spot size parameter to a specific range (10 μm to 20 μm) that creates an optimal balance between bond thickness and bond strength, achieving thin bonds (<1 μm) that maintain sufficient mechanical properties
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
The method produces a strong, crack-free, hermetic, and corrosion-resistant bond with minimal material distortion, suitable for medical and optical applications, providing enhanced durability and reliability.
Implementation Method 1
The optically transparent ceramic has properties that allow an electromagnetic beam of a select wavelength to pass there through without more than minimal energy absorption
Implementation Method 2
The opaque conductive metal has properties that significantly absorb energy from the electromagnetic beam
Implementation Method 3
A kinetically limited micro-scale diffusion bond is formed using a Gaussian-Bessel laser beam to connect optically transparent ceramics to opaque conductive metals
Data Source
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AI summary
A kinetically limited micro-scale diffusion bond between sapphire as an optically transparent insulating ceramic and titanium as an opaque conductive metal is provided. The diffusion bond is formed using an electromagnetic beam emanating from a Gaussian-Bessel laser. The micro-scale diffusion bond has a thickness that is greater than 1 micron, and preferably greater than 4 microns, with a weld width that is greater than 45 microns. Importantly, the diffusion bond is spaced from and intermediate undisturbed portions of the optically transparent ceramic and the opaque conductive metal.