High-Density Fine Line Structure Using Electroplating
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Solution Overview
Problem
Conventional fine line manufacturing techniques, such as etching, fail to achieve high-density, thin pitch line circuits due to surface roughness issues and poor adhesion, leading to reduced wiring density and reliability in electronic devices.
Innovation Solution
The method employs electroplating with a removable carrier and metal barrier layer to form fine line circuits without etching, using a patterned photoresist layer to define the circuit location, and removing the carrier and metal barrier layer to increase wiring density, eliminating the need for semi-additive processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If etching is used to form fine line circuits on thin copper layers, then the circuit pattern can be defined, but the wire width is damaged and wiring density decreases
Solution Approach 1:
The patent extracts and removes the harmful etching process from the manufacturing flow. Instead of using etching to define circuit patterns, the invention uses a plating process on a removable carrier, eliminating the need for etching and thus preventing wire width damage while achieving precise pattern definition.
Solution Approach 2:
The patent performs preliminary actions by first forming the circuit pattern on a removable carrier through plating before transferring it to the final substrate. This preliminary pattern formation avoids direct etching of the thin copper layer, preserving wire width while establishing the circuit geometry in advance.
2Reliability
If conductor trace lines are retained in the printed circuit board after plating, then the fine line circuit layer can be fully covered, but the wiring density is occupied and decreased
Solution Approach 1:
The patent extracts and removes the conductor trace lines from the final product structure. By forming circuits on a removable carrier that is subsequently removed, the method achieves full coverage of the fine line circuit layer without leaving occupying trace lines, thus maximizing wiring density while maintaining reliability.
Solution Approach 2:
The removable carrier serves as an intermediary during the manufacturing process. It enables complete coverage and reliable plating of the fine line circuit layer, then is removed to free up wiring density. The carrier mediates between the need for full coverage and the need for high wiring density.
3Productivity
If the width of conductor trace lines is narrowed to decrease wiring density, then space is freed for higher density, but the plated nickel layer thickness becomes non-uniform
Solution Approach 1:
The patent removes the problematic conductor trace lines entirely by using a removable carrier approach. This eliminates the need to narrow trace widths, allowing uniform plated nickel layer thickness to be maintained while still achieving high wiring density through the removal of the carrier and its associated trace structures.
4Manufacturing precision
If etching is used on thin copper layers with thickness of 1.5-5.0 μm, then the copper layer can be patterned, but the rough surface structure requires increased etching depth causing wire width damage
Solution Approach 1:
The patent extracts and eliminates the etching process entirely from the manufacturing sequence. By using plating on a removable carrier instead of etching patterned copper, the method achieves precise patterning without requiring deep etching, thus preserving wire width even when working with thin copper layers.
Solution Approach 2:
The patent performs preliminary pattern formation on the carrier before final assembly. This preliminary action allows precise circuit definition through plating without subsequent etching steps that would damage wire width, effectively separating the patterning function from the potentially harmful etching process.
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 enables the fabrication of high-density fine line structures with improved wiring density and reliability, meeting the demands of thinner and lighter electronic devices by avoiding etching-related limitations and enhancing adhesion.
Implementation Method 1
electroplating with a removable carrier and metal barrier layer to form fine line circuits without etching
Data Source
AI summary
A high-density fine line structure mainly includes: two boards with similar structures and a dielectric film for combing the two boards. Semiconductor devices respectively in two boards are opposite to each other after the two boards are combined. The two boards each include a fine line circuit, an insulated layer on the same surface, and the semiconductor device installed above the fine line circuit. The surface of the circuit, which is not covered by a solder mask, is made into a pad. The pad is filled with the tin balls for electrically connecting with another semiconductor device. Electroplating rather than the etching method is used for forming the fine line circuit layer, and a carrier and a metal barrier layer, which are needed during or at the end of the manufacturing process, are removed to increase the wiring density for realizing the object of high-density.