Adhesive-Free Substrate Bonding via UV Activation and Thermal Control
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Solution Overview
Problem
Conventional bonding methods for microchip substrates, such as those using vacuum ultraviolet light and pressure, often result in non-uniform joining due to uneven pressure distribution and thermal expansion differences, leading to misalignment and distortion of fine flow paths.
Innovation Solution
Irradiate the surfaces of resin or glass substrates with vacuum ultraviolet light, align and temporarily join them under controlled pressure, then release pressure and heat the substrates to a predetermined temperature for complete bonding, ensuring uniform joining without distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is used for bonding substrates, then bonding strength is improved, but the adhesive exudes to the micro flow path causing blockage and making the flow path uneven
Solution Approach 1:
The harmful adhesive material is extracted/removed from the bonding process. Instead of using adhesive, the patent employs direct substrate bonding through surface activation and heating, eliminating the source of flow path contamination while maintaining bonding functionality
Solution Approach 2:
The patent introduces surface activation (through plasma or chemical treatment) as an intermediary step that creates bonding-capable surfaces without requiring adhesive. The activated surfaces directly bond when heated, serving as a mediator between the substrates that eliminates adhesive exudation problems
2Ease of manufacture
If heat fusion is used for bonding substrates, then adhesive-free bonding is achieved, but fusion at thermal melting point causes flow path collapse and loss of predetermined cross-sectional shape
Solution Approach 1:
The patent changes the temperature parameter from melting point level to a lower temperature range (50-150°C) that is sufficient for activated surface bonding but below the flow path collapse threshold. This parameter modification enables bonding while preserving flow path geometry
Solution Approach 2:
The patent performs surface activation (plasma or chemical treatment) as a preliminary action before bonding. This pre-treatment creates reactive surfaces that can bond at lower temperatures, eliminating the need for high-temperature fusion that would cause flow path collapse
3Ease of manufacture
If vacuum ultraviolet light irradiation and pressure application are used for bonding, then adhesive-free joining is achieved, but uneven pressure distribution causes non-uniform joining and misalignment
Solution Approach 1:
The patent changes the temperature parameter to a controlled range (50-150°C) that enables bonding without requiring high pressure. This temperature modification allows uniform bonding under moderate pressure, preventing misalignment and non-uniform joining
Solution Approach 2:
The patent applies surface activation (plasma or chemical treatment) as a preliminary action that creates bonding-capable surfaces. This pre-treatment enables subsequent bonding at lower pressure levels, eliminating the need for high pressure that causes uneven joining and misalignment
4Manufacturing precision
If high pressure is applied to ensure uniform bonding, then bonding uniformity is improved, but thermal expansion differences cause misalignment and distortion of fine flow paths
Solution Approach 1:
The patent changes the temperature parameter to a controlled range (50-150°C) that is sufficient for activated surface bonding but low enough to minimize thermal expansion differences between substrates. This parameter control achieves bonding uniformity without flow path distortion
Solution Approach 2:
The patent performs surface activation as a preliminary action that enables bonding at lower temperatures and pressures. This pre-treatment reduces thermal and mechanical stresses during bonding, preventing misalignment and distortion of fine flow paths while maintaining bonding uniformity
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 prevents misalignment and distortion, achieving uniform bonding of resin or glass substrates with improved bonding strength and reduced processing time, while maintaining the integrity of fine flow paths.
Implementation Method 1
a surface of substrates is irradiated with vacuum ultraviolet light so as to activate the substrate surface
Implementation Method 2
after the pressure being applied is released, both the workpieces are heated
Data Source
AI summary
Two workpieces composed of a resin workpiece and a resin workpiece, or composed of a resin workpiece and a glass substrate are bonded to each other such that troubles, such as an alignment shift and breakage etc. are not generated, while ensuring bonding uniformity. A first workpiece is placed on an inverting stage of an inverting stage unit, a second workpiece is placed on a work stage of a pressurizing stage unit, and UV light is radiated from a light irradiation unit. Then, the inverting stage is inverted 180°, the workpieces are overlapped each other on the work stage, and the workpieces are pressurized and pre-bonded to each other. Then, the workpieces in the pre-bonded state are transferred to a heating stage by a transfer means, the temperature of the workpieces is increased to a predetermined temperature by heating the workpieces, and the temperature is maintained until bonding is completed.