Wafer-Scale Package Laser Bonding for Hermetic Sealing
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Solution Overview
Problem
Existing semiconductor and electronics packaging techniques, such as direct bonding, can cause thermal damage and warping due to elevated temperatures and thermal stress fractures, compromising the hermeticity of the package.
Innovation Solution
A wafer-scale package is fabricated using laser-assisted bonding at low temperatures, ensuring that temperature-sensitive components are not damaged and minimizing stress fractures, with substrates like silicon and glass being bonded without adhesives to form a hermetically sealed cavity housing a control module and energy storage device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct bonding techniques are used to bond substrates together, then hermetic sealing is achieved, but thermal damage and stress fractures occur due to high temperatures and thermal expansion mismatches
Solution Approach 1:
The patent changes the temperature parameter from high (conventional direct bonding) to low (cryogenic or near-ambient temperatures) by using alternative bonding mechanisms such as anodic bonding, eutectic bonding, or plasma activation. This parameter change allows hermetic sealing to be achieved without subjecting temperature-sensitive components to thermal damage or stress fractures caused by thermal expansion mismatches.
Solution Approach 2:
The patent replaces the thermal field (heat-based bonding) with alternative physical or chemical fields such as electrical fields (anodic bonding), chemical reactions (eutectic bonding), or plasma fields. This substitution eliminates the need for high temperatures while maintaining the hermetic sealing function, thereby preventing thermal damage to sensitive components.
2Strength
If conventional bonding processes are used, then substrates are bonded together, but temperature-sensitive components experience thermal damage
Solution Approach 1:
The patent changes the temperature parameter from high to low or controlled, and may introduce additional parameters such as electrical field strength, chemical composition, or pressure to achieve bonding. This allows bond strength to be maintained or improved while preserving component integrity by avoiding thermal damage to temperature-sensitive components.
Solution Approach 2:
The patent introduces intermediary materials or fields such as bonding agents, eutectic layers, plasma treatments, or electrical fields that facilitate bonding between substrates without requiring high temperatures. These intermediaries enable strong bonds to form while protecting temperature-sensitive components from thermal damage.
3Strength
If heating is applied to form direct bonds, then bonding is achieved, but warping and thermal stress fractures develop due to coefficient of thermal expansion mismatches
Solution Approach 1:
The patent changes the temperature parameter from high to low or controlled during bonding, and may introduce additional parameters such as bonding pressure, electrical field, or chemical treatment. This eliminates the thermal expansion mismatches that cause warping and stress fractures while maintaining bond strength through alternative bonding mechanisms.
Solution Approach 2:
The patent performs preliminary actions such as surface treatment, alignment, or pre-bonding at low temperatures before final bonding. This preliminary action ensures proper positioning and reduces the risk of warping or stress fractures by establishing a stable foundation before applying the bonding force, thereby maintaining both bond strength and structural stability.
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 low-temperature bonding process maintains component integrity, enhances hermeticity, and prevents thermal stress fractures, allowing for the creation of robust and reliable medical devices that can be implanted or externally attached.
Implementation Method 1
The substrates may be bonded using a laser assisted bonding technique that maintains a relatively low temperature within the packaged device during bonding
Implementation Method 2
Direct bonding involves bonding different materials together without the aid of a specific bonding agent such as, for example, adhesive, wax, solder, or the like
Data Source
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Figure 3A~3D
AI summary
A medical device includes a first substrate, a second substrate, a control module, and an energy storage device. The first substrate includes at least one of a first semiconductor material and a first insulating material. The second substrate includes at least one of a second semiconductor material and a second insulating material. The second substrate is bonded to the first substrate such that the first and second substrates define an enclosed cavity between the first and second substrates. The control module is disposed within the enclosed cavity. The control module is configured to at least one of determine a physiological parameter of a patient and deliver electrical stimulation to the patient. The energy storage device is disposed within the cavity and is configured to supply power to the control module.