Capillary Micro Device Bonding via Condensed Vapor
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Solution Overview
Problem
The transfer process of micro devices to substrates is challenging, particularly in bonding them securely without causing damage from shear forces, as existing methods fail to provide a stable and efficient attachment mechanism.
Innovation Solution
A method involving the formation of a conductive pad on a substrate, an elevated bonding layer, and a liquid layer formed by condensing vapor or gas, which grips the micro device via capillary forces and evaporates to establish a stable electrical connection with the bonding layer, preventing damage from shear forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bonding methods are used to attach micro devices to substrates, then bonding can be achieved, but shear forces cause damage to the micro devices
Solution Approach 1:
The patent introduces a liquid layer as an intermediary substance between the micro device electrode and the elevated bonding layer. This liquid layer creates capillary forces that provide gentle, distributed bonding pressure, eliminating the need for direct mechanical contact that would generate harmful shear forces. The liquid mediator allows the micro device to be securely attached without exposure to damaging mechanical stresses.
Solution Approach 2:
The patent utilizes phase transitions of the liquid layer to achieve bonding. The liquid layer is applied in liquid form, creates capillary bonding, and then undergoes evaporation to transition to vapor phase, leaving behind a solidified bond structure. This phase transition process enables reliable bonding while avoiding the application of harmful shear forces during the attachment process.
2Productivity
If direct bonding methods are used, then attachment can be achieved, but the process lacks stability and efficiency
Solution Approach 1:
The patent replaces traditional mechanical bonding systems with a capillary force-based liquid bonding mechanism. Instead of using mechanical pressure or thermal processes that are time-consuming and unstable, the liquid layer creates immediate capillary adhesion when contacted by the micro device electrode. This substitution provides both rapid bonding (improving productivity) and stable attachment (improving reliability).
Solution Approach 2:
The patent changes the physical parameters of the bonding interface by introducing a liquid layer with specific capillary properties. The liquid's surface tension and capillary action create optimal bonding conditions that simultaneously improve attachment stability and bonding efficiency. The controlled evaporation process further refines the bonding parameters to achieve reliable, stable attachment.
3Strength
If vapor or gas is condensed to form liquid layer, then capillary force can grip the micro device, but temperature control is required
Solution Approach 1:
The patent utilizes the phase transition from vapor/gas to liquid through controlled condensation. By adjusting the temperature to a selected dew point, the vapor condenses into a liquid layer that provides the necessary capillary forces. This phase transition approach enables strong capillary gripping (improving strength) while the controlled temperature process ensures manageable thermal conditions (mitigating the temperature control challenge).
Solution Approach 2:
The patent changes the temperature parameter to a specific dew point value to enable condensation of vapor into liquid. This precise parameter control creates the liquid layer with optimal capillary properties for gripping the micro device. The temperature is controlled only during the condensation phase, after which the liquid layer provides stable capillary forces without requiring continuous temperature management.
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 enhances the stability of the micro device attachment, reducing the risk of damage from shear forces and improving the yield of subsequent manufacturing processes by creating a robust binding structure.
Implementation Method 1
adjusting a temperature of the elevated bonding layer to a selected temperature point in an environment comprising a vapor or showering a gas on the elevated bonding layer such that at least a portion of the vapor or the gas is condensed to form a liquid layer on the elevated bonding layer
Implementation Method 2
disposing the micro device over the elevated bonding layer such that the micro device is in contact with the liquid layer and is gripped by a capillary force produced by the liquid layer between the micro device and the elevated bonding layer
Implementation Method 3
evaporating the liquid layer such that the electrode is bound to the elevated bonding layer and is in electrical connection with the conductive pad
Data Source
AI summary
A method for binding a micro device on a substrate is provided. The method includes forming a conductive pad on the substrate; forming an elevated bonding layer on the conductive pad; lowering a temperature of the elevated bonding layer in an environment comprising a vapor such that at least a portion of the vapor is condensed to form a liquid layer on the elevated bonding layer; disposing the micro device over the elevated bonding layer such that the micro device is in contact with the liquid layer and is gripped by a capillary force produced by the liquid layer between the micro device and the elevated bonding layer, wherein the micro device comprises an electrode facing the elevated bonding layer; and evaporating the liquid layer such that the electrode is bound to the elevated bonding layer and is in electrical connection with the conductive pad.