Copper Bump IC Package with Nickel Layer for Glass Substrate Bonding
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Solution Overview
Problem
The existing metal bumps used for electrical transfer between IC chips and glass substrates, typically made of gold, are costly and have limitations in physical and electrical performance due to material and hardness restrictions, which affect their connectivity and longevity.
Innovation Solution
The use of copper (Cu) bumps in the packaging process, potentially covered by a non-conductive film (NCF), which reduces manufacturing costs and enhances physical and electrical performance by preventing oxidation and ion migration, and allows for a chip-on-glass structure with improved connectivity through conductive particles in a conductive film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gold (Au) metal bumps are used for electrical transfer, then reliable electrical connection is achieved, but manufacturing cost increases significantly
Solution Approach 1:
The patent replaces expensive gold bumps with cheaper copper bumps that can be formed using standard semiconductor manufacturing processes. The copper bumps are designed to be consumed during the bonding process to glass substrates, achieving reliable electrical connection at lower cost through material substitution and process integration.
2Ease of manufacture
If copper (Cu) bumps are used instead of gold, then manufacturing cost decreases, but oxidation and ion migration occur
Solution Approach 1:
The patent employs a multi-layer composite structure for the bumps: a copper core layer providing electrical conductivity and cost benefits, a nickel intermediate layer preventing oxidation and ion migration, and an optional gold cap layer for enhanced corrosion resistance. This composite structure combines the advantages of different materials while mitigating their individual disadvantages.
Solution Approach 2:
The patent utilizes an inert atmosphere (nitrogen or vacuum environment) during the bump formation and bonding processes to prevent copper oxidation. The inert environment protects the copper bumps from reacting with oxygen, maintaining their electrical properties and preventing harmful oxidation products.
3Productivity
If copper bumps are formed during packaging process, then manufacturing efficiency improves, but control over bump material properties becomes limited
Solution Approach 1:
The patent forms the copper bumps on the semiconductor wafer before dicing and packaging using standard semiconductor fabrication techniques such as electroplating or electroless plating. This preliminary formation allows precise control over bump dimensions, composition, and distribution using established process tools and methods, ensuring consistent material properties.
Solution Approach 2:
The patent optimizes various parameters including copper layer thickness, nickel layer thickness, plating time, plating temperature, and chemical composition to achieve the desired bump properties. By carefully controlling these parameters, the patent maintains manufacturing precision while integrating bump formation into the packaging process flow.
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
Cu bumps provide suitable physical and electrical performance in compression to glass substrates, reducing costs and extending storage life by inhibiting oxidation and ion migration, while enabling efficient electrical transfer and simplifying the conductive film structure, suitable for mass production.
Implementation Method 1
The conductive film, such as an anisotropic conductive film (ACF), contains a number of conductive particles and coves the Al electrodes. The top surfaces of the Cu bumps are electrically connected to the corresponding Al electrodes via a part of the conductive particles.
Implementation Method 2
Cu bumps provide suitable physical and electrical performance in compression to glass substrates, reducing costs and extending storage life by inhibiting oxidation and ion migration
Data Source
AI summary
An IC chip package and a chip-on-glass structure using the same are provided. The IC chip package includes an IC chip having a circuit surface, and plural copper (Cu) bumps formed on the circuit surface. Moreover, a non-conductive film (NCF) could be formed on the circuit surface to cover the Cu bumps. The chip-on-glass structure includes a glass substrate, plural electrodes such as aluminum (Al) electrodes formed on the glass substrate, and a conductive film formed on the electrodes. The conductive film contains a number of conductive particles. When the IC chip package is coupled to the glass substrate, the Cu bumps can be coupled to the corresponding electrodes via conductive particles.