Laser-Assisted Substrate Bonding Without Thermal Stress
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Solution Overview
Problem
Existing methods for direct bonding of substrates at room temperature result in weak connections that require subsequent high-temperature treatment to achieve sufficient adhesion strength, which can be detrimental to substrates with different thermal expansion behaviors.
Innovation Solution
A laser-assisted bonding method where substrates are initially pressed together and then strengthened through localized laser irradiation, converting energy into electronic excitation without reaching the melting temperature, promoting new chemical bonds and adhesion without altering the substrate surface shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If direct bonding is performed at room temperature, then substrates can be connected without thermal stress, but the adhesion strength is weak and insufficient
Solution Approach 1:
The patent applies parameter changes by using laser irradiation to locally modify the physical and chemical state of substrate surfaces at the bonding interface. The laser energy activates surface atoms and molecules, increasing their reactivity and enabling strong chemical bonds to form at room temperature, thus achieving high adhesion strength without thermal stress
Solution Approach 2:
The patent replaces the conventional thermal activation mechanism with a laser-induced electronic excitation mechanism. Instead of heating the entire substrate to high temperatures to achieve bonding, the invention uses laser irradiation to directly excite electrons at the bonding interface, enabling chemical bond formation without thermal stress
2Strength
If tempering at increased temperatures is applied, then adhesion strength is significantly increased, but substrates with different thermal expansion behavior are adversely affected
Solution Approach 1:
The patent applies local quality by concentrating laser energy precisely at the bonding interface between substrates. Only the localized region at the interface receives sufficient energy for activation and bond strengthening, while the bulk substrates remain at room temperature, avoiding thermal expansion mismatches and thermal stress
3Strength
If laser irradiation is applied to strengthen the connection, then adhesion strength is increased, but the substrate surface shape may be altered if melting temperature is reached
Solution Approach 1:
The patent applies partial action by using laser irradiation parameters that provide sufficient energy for electronic excitation and bond strengthening at the interface, but deliberately keep the energy below the threshold that would cause melting or significant thermal diffusion. This ensures the substrate surface shape is maintained while achieving the desired adhesion strength
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 method enables high adhesive strength between substrates with different thermal expansion behaviors without thermal stress, maintaining the substrates' shape and allowing for precise control of bonding strength through laser parameters.
Implementation Method 1
the supplied energy is converted into electronic excitation of the surface atoms/molecules. Excitation of electrons thereby occurs from the occupied orbitals in the basic condition into unoccupied orbitals in the excited condition
Implementation Method 2
strengthening of the connection between the substrates is effected by activation in regions which is induced with laser irradiation at the interface between the substrates
Implementation Method 3
a chemical and/or a thermal excitation of molecules and/or atoms in at least one of the substrates is made possible in the region of the interface by means of the laser irradiation
Implementation Method 4
initiates diffusion processes in at least one of the substrates in the region of the interface
Implementation Method 5
By relaxation of the electronic excitation conditions, energy is also transferred into the solid lattice which can lead to further approach of the adjacent substrates and formation of new chemical bonds (reactions) between the surface atoms/molecules of both substrates via oscillation excitation of the surfaces
Data Source
AI summary
The present invention relates to a method for laser-assisted bonding of substrates, in which these are connected together firstly frictionally by pressing together and subsequently strengthening of the connection between the substrates is effected by activation in regions which is induced by laser irradiation. The invention likewise relates to substrates produced accordingly.