Metal Bump Structure for Micro LED Driving Substrate

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Solution Overview

Problem

Current methods for forming metal bumps on thin film transistor (TFT) glass substrates in micro LED displays are costly and environmentally polluting due to the lengthy and complex wet electroplating process, which hinders the formation of reliable intermetallic compounds with LEDs or surface mount devices.

Innovation Solution

A dry electro-less plating process is used to form metal bumps with a patterned metal layer on a driving substrate, involving a catalyst layer and activation process, resulting in a simpler, cost-effective method that avoids environmental pollution and enables better structural reliability through the formation of intermetallic compounds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If wet electroplating process is used to form thick copper layer on ITO conductive layer, then the thickness of metal layer is increased to enable reliable bonding, but the manufacturing process becomes lengthy and complicated, increasing cost and causing environmental pollution

Engineering Contradiction:

Improvebonding reliabilityVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the wet electroplating process (chemical/wet system) with a vacuum evaporation process (physical/vapor deposition system). This substitution eliminates the need for complex wet chemical processes, reducing manufacturing complexity and environmental impact while achieving the required metal layer thickness for reliable bonding through physical vapor deposition

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the deposition method from electrochemical plating to physical vapor deposition, fundamentally altering the process parameters from wet chemical conditions to vacuum environment with controlled evaporation rates. This parameter change simplifies the manufacturing process while maintaining the ability to form thick metal layers suitable for bonding

Inventive Principle:

Principle #35Parameter changes

2Reliability

Engineering Contradiction:

Improvebonding reliabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces the wet electroplating process with vacuum evaporation, eliminating the need for chemical baths, waste treatment facilities, and associated environmental compliance costs. This substitution reduces manufacturing complexity and cost while achieving the required metal layer thickness for reliable bonding through a more direct physical deposition process

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If wet electroplating process is used to form thick copper layer on ITO conductive layer, then the thickness of metal layer is increased to enable reliable bonding, but environmental pollution is caused

Engineering Contradiction:

Improvebonding reliabilityVSAvoidenvironmental pollution

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the wet electroplating process (which generates chemical waste requiring treatment) with a vacuum evaporation process that deposits metal directly from vapor phase. This substitution eliminates chemical waste streams, reduces environmental pollution, and maintains the ability to form thick metal layers for reliable bonding through controlled physical deposition

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method simplifies the manufacturing process, reduces costs, and enhances structural reliability by forming metal bumps with a dry process that allows for effective bonding with light-emitting elements, improving the intermetallic compound interface.

Implementation Method 1

An electro-less plating process is performed so as to form at least one metal bump on the patterned metal layer

Methodology Applied

Scientific EffectElectro-less plating: Chemical Beam Epitaxy

Implementation Method 2

a catalyst layer and an activation process are already formed on the driving base. The at least one patterned metal layer is formed on the catalyst layer

Methodology Applied

Scientific EffectCatalysis: Catalysis

Data Source

PatentUS11715715B2Metal bump structure and manufacturing method thereof and driving substrate

Publication Date: 2023.08.01 UNIMICRON TECH CORP

AI summary

A manufacturing method of a metal bump structure is provided. A driving base is provided. At least one pad and an insulating layer are formed on the driving base. The pad is formed on an arrangement surface of the driving base and has an upper surface. The insulating layer covers the arrangement surface of the driving base and the pad, and exposes a part of the upper surface of the pad. A patterned metal layer is formed on the upper surface of the pad exposed by the insulating layer, and extends to cover a part of the insulating layer. An electro-less plating process is performed to form at least one metal bump on the patterned metal layer. A first extension direction of the metal bump is perpendicular to a second extension direction of the driving base.