Electrical Connector Structure Fine Pitch Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The conventional electroplating process for forming conductive bumps on semiconductor chip packaging faces challenges with fine pitch alignment accuracy, leading to increased complexity, fabrication time, and uneven bump heights, which affect the reliability of electrical connections.
Innovation Solution
A method involving the formation of conductive layers and resist layers on a circuit board, with specific opening patterns and an adhesive layer to facilitate the formation of metal bumps and an insulating protective layer, allowing for reduced exposure processes and controlled bump heights, enabling fine pitch connections with improved alignment accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If stencil printing technology is used to form soldering material on electrical connection pads, then the process is simple and cost-effective, but the smaller openings in the stencil increase production cost and hamper the production process due to difficulty in stencil production and cleaning
Solution Approach 1:
The patent extracts the soldering material formation process from the stencil printing process by directly forming conductive bumps through electroplating on the electrical connection pads, eliminating the need for a stencil and its associated production and cleaning complexities
Solution Approach 2:
The patent introduces a resist layer as an intermediary to define the pattern of electrical connection pads before forming the conductive bumps, replacing the stencil's patterning function with a more manageable photoresist-based approach
2Quantity of substance
If the size and pitch of electrical connection pads are shrunk to accommodate more input and output terminals, then the packaging density is elevated, but the openings on the stencil become smaller which increases stencil production cost and makes the stencil impervious to soldering material
Solution Approach 1:
The patent replaces the mechanical stencil system with an electrochemical electroplating system that can achieve finer feature sizes and better material distribution without the physical constraints of stencil openings
Solution Approach 2:
The patent changes the formation mechanism of soldering material from screen-based printing to electrochemical deposition, enabling control of bump dimensions through electroplating parameters rather than stencil opening dimensions
3Productivity
If the stencil is used multiple times without cleaning, then the production efficiency is maintained, but the soldering material accumulates on the inner wall of openings causing incorrect quantity and shape of soldering material
Solution Approach 1:
The patent removes the stencil from the process entirely, eliminating the accumulation problem and the need for repeated cleaning, while maintaining the ability to form precise conductive bumps through electroplating
4Quantity of substance
If conventional electroplating process is used to form conductive bumps, then the soldering material can be formed on electrical connection pads, but the fine pitch alignment accuracy is difficult to achieve leading to increased complexity and fabrication time
Solution Approach 1:
The patent performs preliminary patterning of the resist layer to define the electrical connection pad locations before electroplating, establishing the alignment framework in advance to guide subsequent bump formation with fine pitch accuracy
5Reliability
If conventional electroplating process is used to form conductive bumps, then the electrical connection can be established, but the bump heights become uneven affecting the reliability of electrical connections
Solution Approach 1:
The patent employs a controlled electroplating process with monitoring to ensure uniform current distribution and consistent bump height across all electrical connection pads, maintaining reliability through precise process control
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 simplifies the fabrication process, allows for precise formation of conductive bumps at fine pitches, and ensures even bump heights, enhancing the reliability of electrical connections between circuit boards and external devices.
Implementation Method 1
forming electrical connection pads in the first openings
Implementation Method 2
forming an adhesive layer to cover the exposed surfaces of the electrical connection pads and the metal bumps
Data Source
AI summary
An electrical connector structure of circuit board and a method for fabricating the same are proposed. A circuit board having a conductive layer is formed with a first resist layer and a second resist layer thereon, so as to form electrical connection pads and metal bumps on the electrical connection pads. The first and second resist layers are formed with openings therein at positions corresponding to the electrical connection pads and metal bumps, and the exposed conductive layer is removed. An adhesive layer is formed to cover the exposed surfaces of the electrical connection pads and the metal bumps. Then, the second resist layer, the first resist layer and the conductive layer covered by the first resist layer are removed. Later, an insulating protective layer is formed on a surface of the circuit board, and thinned to expose a portion of the adhesive layer, such that electrical connectors of the circuit board are fabricated.