Copper Foil Carrier Interlayer for PCB Stability
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Solution Overview
Problem
In the manufacturing of multilayer printed wiring boards, the coreless build-up method faces challenges with unstable mechanical peel strength of carriers and peeling resistance during photoresist developing processes, particularly when using low thermal expansion materials like glass or ceramics, which can lead to warping and peeling issues.
Innovation Solution
A copper foil with a carrier is developed, featuring an interlayer composed of metals like Ti, Cr, Mo, Mn, W, or Ni between the carrier and a release layer, providing high peeling resistance and stability by ensuring secure adhesion and releasability, along with an extremely-thin copper layer and optional antireflective layers for improved wiring pattern formation and visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If low thermal expansion materials like glass or ceramics are used as carriers, then thermal stability is improved, but mechanical peel strength becomes unstable and warping occurs
Solution Approach 1:
An interlayer is introduced as an intermediary between the carrier and the release layer. This interlayer acts as a mediator that provides stable mechanical peel strength while allowing the carrier to maintain its low thermal expansion properties. The interlayer composition is specifically designed to bond well with both the carrier and the release layer, resolving the contradiction between thermal stability and mechanical peel strength.
Solution Approach 2:
The carrier structure is designed as a composite material system consisting of the carrier substrate, interlayer, and release layer. This composite structure allows each layer to contribute its specific properties: the carrier provides thermal stability, the interlayer provides mechanical peel strength, and the release layer provides releasability. The composite nature resolves the contradiction by distributing functions across multiple materials.
2Ease of operation
If carriers are designed for easy release, then separation between support and multilayer printed wiring board is facilitated, but peeling resistance during photoresist developing process deteriorates
Solution Approach 1:
The release mechanism is segmented into multiple functional layers: the interlayer provides strong bonding during processing (resisting peeling), while the release layer provides controlled release capability. This segmentation allows the system to exhibit both strong peeling resistance during photoresist developing and easy separation after processing, resolving the contradiction between these opposing requirements.
Solution Approach 2:
Different layers are assigned different local qualities: the interlayer has high bonding strength for peeling resistance, while the release layer has controlled adhesion for easy separation. This local differentiation of properties allows the overall structure to satisfy both contradictory requirements in different regions and at different stages of the process.
3Length of moving object
If extremely-thin copper layer is used, then miniaturization of embedded circuit is achieved, but adhesion stability deteriorates
Solution Approach 1:
The interlayer serves as an intermediary that enhances adhesion stability for the extremely-thin copper layer. By providing a robust bonding interface between the carrier and the copper layer, the interlayer compensates for the reduced adhesion inherent in extremely-thin copper structures, allowing miniaturization while maintaining adhesion stability.
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 copper foil with a carrier exhibits enhanced peeling resistance against developers and stable mechanical peel strength, preventing warping and peeling issues, while allowing for precise wiring pattern formation and efficient manufacturing of printed wiring boards.
Implementation Method 1
an interlayer disposed on the carrier, the interlayer having a first surface adjacent to the carrier and containing 1.0 atom % or more at least one metal selected from the group consisting of Ti, Cr, Mo, Mn, W and Ni
Implementation Method 2
providing high peeling resistance and stability by ensuring secure adhesion and releasability
Data Source
AI summary
There is provided a copper foil provided with a carrier exhibiting a high peeling resistance against the developer in the photoresist developing process and achieving high stability of mechanical peel strength of the carrier. The copper foil provided with a carrier comprises a carrier; an interlayer disposed on the carrier, the interlayer having a first surface adjacent to the carrier and containing 1.0 atom % or more of at least one metal selected from the group consisting of Ti, Cr, Mo, Mn, W and Ni and a second surface remote from the carrier and containing 30 atom % or more of Cu; a release layer disposed on the interlayer; and an extremely-thin copper layer disposed on the release layer.