Self-Assembly Liquid Drop Confinement via Wettability Gradients

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Solution Overview

Problem

Existing self-assembly methods for electronic circuits face challenges in maintaining the confinement of liquid drops on assembly zones due to difficulties in achieving a significant difference in wettability between assembly and peripheral zones, leading to potential errors in placement and drop displacement during the self-assembly process.

Innovation Solution

The method involves creating a first electronic circuit with exposed, raised pads around its assembly face, where the peripheral zone has a hydrophobic coating and relief structures, increasing the wettability difference with the assembly zone, and using chemical mechanical planarization and etching to form these pads, ensuring the liquid drop remains confined during alignment and bonding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a peripheral zone with low wettability is created to confine the liquid drop on the assembly zone, then the drop confinement is improved, but achieving a significant difference in wettability between assembly and peripheral zones is difficult

Engineering Contradiction:
Improvedrop confinementVSAvoidwettability difference
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by creating distinct wettability characteristics in different zones of the support. The assembly zone is treated to have high wettability (hydrophilic) while the peripheral zone has low wettability (hydrophobic), ensuring the liquid drop remains confined to the assembly zone during self-assembly operations

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements preliminary action by pre-treating the support surface with specific chemical compositions before the self-assembly process. The support is prepared with a peripheral zone containing hydrophobic materials (such as fluorinated compounds or silicones) deposited in advance, creating the wettability gradient needed for drop confinement before the liquid is applied

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If the wettability difference between assembly zone and peripheral zone is increased to improve drop confinement, then placement accuracy is improved, but the process complexity increases

Engineering Contradiction:
Improveplacement accuracyVSAvoidprocess complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by modifying the chemical composition and surface properties of the peripheral zone to achieve optimal wettability characteristics. By adjusting parameters such as the type of hydrophobic material, deposition thickness, and treatment conditions, the process achieves reliable drop confinement without requiring overly complex multi-step procedures

Inventive Principle:
Principle #35Parameter changes

3Reliability

If hydrophobic materials are deposited on the peripheral zone to create low wettability, then drop confinement is improved, but the manufacturing process requires additional steps

Engineering Contradiction:
Improvedrop confinementVSAvoidmanufacturing process
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies merging by combining the creation of the peripheral zone with existing support manufacturing processes. The hydrophobic treatment is integrated into the support fabrication workflow, where the peripheral zone is defined and treated as part of the overall support structure creation, rather than as a separate post-processing step

Inventive Principle:
Principle #5Merging (Combining)

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 approach enhances the confinement of liquid drops on assembly zones, improving the accuracy and reliability of the self-assembly process by maintaining the drop within the assembly area, thereby facilitating precise alignment and hybrid molecular bonding between electronic circuits.

Implementation Method 1

A drop 16 of a liquid, for example demineralized water, is placed on the assembly zone 14

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Implementation Method 2

The forces exerted by the drop 16 on the electronic circuit 10 then move the electronic circuit 10 to the desired alignment

Methodology Applied
Scientific EffectSurface tension: Surface Tension

Implementation Method 3

The support 11 has on the upper face an assembly zone 14 with high wettability surrounded by a peripheral zone 12 with low wettability

Methodology Applied
Scientific EffectWettability difference: Wetting

Implementation Method 4

The greater the difference in wettability, the more the drop 16 tends to remain confined to the assembly zone 14

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 5

The method of fixing the electronic circuit 10 to the support 11, for example by hybrid molecular bonding

Methodology Applied
Scientific EffectMolecular bonding: Chemical Bonding

Data Source

PatentEP3742478B1Self-assembly method with hybrid molecular bonding
Publication Date: 2021.11.24 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
  • EP3742478B1 patent drawingFigure 1~3
  • EP3742478B1 patent drawingFigure 4~6
  • EP3742478B1 patent drawingFigure 7~9

AI summary

This description relates to a method for manufacturing a first electronic circuit (20) comprising a flat face (25), intended to be attached to a second electronic circuit by a self-assembly process with hybrid molecular bonding, and first electrically conductive pads (34) exposed on the face. The method includes the formation of a peripheral zone (26) around the face comprising second exposed and raised pads (30), each at least partially of the same composition as the first pads.