Multilayer Carrier Foil for Consistent Peeling and Pinhole Prevention
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Solution Overview
Problem
Conventional electrodeposited copper foils with carrier layers face issues such as varying peel strength, surface roughness, and pinholes, which affect the quality of ultra-thin copper foils used in printed circuit boards, leading to energy inefficiencies and inconsistent bonding during the manufacturing of miniaturized electronic components.
Innovation Solution
A multilayer carrier foil design comprising a copper carrier layer with a chromium release layer, an intermediate copper layer, an anti-migration layer, and an ultra-thin copper layer, which improves peeling consistency and prevents pinholes, enabling the production of high-quality printed circuit boards for miniaturized electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional carrier foil with release layer is used, then the ultra-thin copper foil can be formed, but the peeling strength varies widely and peeling consistency is poor
Solution Approach 1:
The patent divides the carrier foil into multiple functional layers: a support layer (aluminum or copper), a release layer (metal oxide), and an intermediate layer (copper or alloy). This segmentation allows each layer to perform its specific function optimally, with the intermediate layer acting as a buffer to control peeling behavior and improve consistency.
Solution Approach 2:
The patent uses composite material structures combining different metals and metal oxides in specific sequences. The combination of aluminum/copper support layer with metal oxide release layer and copper intermediate layer creates a composite structure that balances peeling performance with structural integrity.
2Manufacturing precision
If the carrier foil surface roughness is high, then the ultra-thin copper foil can be formed, but the surface roughness of the copper foil increases affecting etching quality
Solution Approach 1:
The intermediate layer acts as an intermediary between the carrier foil surface and the ultra-thin copper layer. It transfers the mechanical support function while providing a controlled surface that prevents direct transmission of carrier foil roughness to the copper layer, ensuring high surface quality for etching.
3Use of energy by moving object
If laser drilling is used on shiny ultra-thin copper foil, then microvias can be created, but more energy is consumed due to laser reflection
Solution Approach 1:
The patent modifies the surface optical properties of the ultra-thin copper foil through the release layer and surface treatment, changing its reflectivity characteristics. This reduces laser ray reflection and improves laser drilling efficiency by allowing better energy absorption.
4Productivity
If the ultra-thin copper foil is made thinner to achieve micro-thin circuit patterns, then higher wiring density is achieved, but the foil becomes more susceptible to pinholes
Solution Approach 1:
The patent applies different material compositions and thicknesses to different layers based on their specific functions. The intermediate layer uses specific copper alloys or compositions that provide pinhole resistance locally, while the ultra-thin copper layer maintains minimal thickness for high wiring density.
5Strength
If high temperature compression is applied during lamination, then bonding is achieved, but the peeling strength becomes inconsistent due to oxidation-reduction reactions
Solution Approach 1:
The patent performs preliminary surface treatment of the carrier foil and release layer before lamination to create stable surface conditions. This preliminary preparation prevents unwanted oxidation-reduction reactions during the high-temperature compression process, ensuring consistent peeling strength.
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 multilayer carrier foil enhances the peeling process, reduces energy consumption, and ensures consistent bonding, facilitating the manufacture of high-density, precise circuitry in miniaturized electronic devices.
Implementation Method 1
a chromium release layer applied to the release side of the copper carrier layer
Implementation Method 2
an intermediate copper layer applied to the chromium release layer
Implementation Method 3
an anti-migration layer applied to the intermediate copper layer
Implementation Method 4
an ultra-thin copper layer applied to the anti-migration layer
Data Source
AI summary
The present disclosure relates to a multilayer carrier foil, a core structure formed using the multilayer carrier foil, printed circuit boards, and electronic devices. The multilayer carrier foil comprises: (a) a copper carrier layer having a release side and a laminate side, the laminate side of carrier layer optionally having nodules; (b) a chromium release layer applied to the copper carrier layer; (c) an intermediate copper layer applied to the chromium release layer; (d) an anti-migration layer applied to the intermediate copper layer of (c); and (e) an ultra-thin copper layer applied to the anti-migration layer of (d). The disclosure further relates to methods of making the multi-layer carrier foil, the core structure, and printed circuit boards.