Coreless Build-up PCB via Sacrificial Copper Layer
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Solution Overview
Problem
In the coreless build-up method for multilayer printed wiring boards, the heat-resistant metal layer remains on the surface of the build-up layer after separation, necessitating its removal, which is undesirable.
Innovation Solution
A copper foil with carrier foil structure comprising at least four layers, including a carrier foil, a release layer, a heat-resistant metal layer, and a copper foil layer, where the heat-resistant metal layer is formed using nickel or nickel alloys, and the release layer is formed using organic substances, allowing for easy separation without leaving residual metal on the surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heat-resistant metal layer is used to prevent diffusion during high temperature lamination, then the separation between supporting substrate and build-up layer is ensured, but the heat-resistant metal layer remains on the surface of the build-up layer after separation, necessitating additional removal steps
Solution Approach 1:
The invention extracts the heat-resistant metal layer from the final product by designing a specific layer structure where the copper foil layer is positioned between the heat-resistant metal layer and the build-up wiring layer. During the lamination and separation process, the copper foil layer is selectively removed along with the supporting substrate, leaving only the build-up layer without residual heat-resistant metal layer.
Solution Approach 2:
The invention segments the functional layers into distinct components: the heat-resistant metal layer serves its protective function during processing, while the copper foil layer acts as a sacrificial barrier that prevents heat-resistant metal layer contamination of the final product. This segmentation allows each layer to fulfill its specific function without causing unwanted residues.
2Reliability
If the heat-resistant metal layer is used to ensure separation at the release layer, then separation is achieved even after high temperature lamination, but additional etching steps are required to remove the remaining heat-resistant metal layer
Solution Approach 1:
The copper foil layer is designed as a sacrificial element that is removed during the separation process. This extraction approach ensures that the heat-resistant metal layer performs its protective function during lamination but does not remain as unwanted residue on the final product, eliminating the need for additional etching steps.
Solution Approach 2:
The copper foil layer is pre-positioned between the heat-resistant metal layer and the build-up wiring layer before lamination. This preliminary arrangement ensures that during the high temperature lamination process, the copper foil layer will be selectively removed along with the supporting substrate, preventing heat-resistant metal layer contamination in advance.
3Ease of operation
If a copper foil with carrier structure is used in coreless build-up method, then easy separation from supporting substrate is achieved, but the heat-resistant metal layer remains on the build-up layer surface after separation
Solution Approach 1:
The copper foil layer serves as a removable intermediary that is extracted during the separation process. This allows the heat-resistant metal layer to fulfill its protective function during lamination while being completely removed from the final product through the selective removal of the copper foil layer along with the supporting substrate.
Solution Approach 2:
The copper foil layer acts as an intermediary between the heat-resistant metal layer and the build-up wiring layer. During separation, this intermediary layer is selectively removed, facilitating clean separation without leaving the heat-resistant metal layer on the build-up layer surface, thus simplifying post-separation processing.
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 method eliminates the need for removing the heat-resistant metal layer, simplifying the manufacturing process and reducing costs by ensuring it does not remain on the multilayered laminate, thus enhancing the efficiency and cost-effectiveness of producing multilayer printed wiring boards.
Implementation Method 1
an ultra-thin copper foil with carrier having a layer structure consists of 'a carrier foil, a diffusion prevention layer, a release layer and an ultra-thin copper foil' is used to achieve the objects; to provide an ultra-thin copper foil with carrier without blister in the releasing interface, low carrier peel
Implementation Method 2
the diffusion prevention layer (heat-resistant metal layer) which prevents diffusion of the release layer components exists on the carrier side to ensure the separation at the release layer even after loading a high temperature in lamination
Data Source
AI summary
A manufacturing method of a multilayer printed wiring board in which a copper foil with carrier foil consists of at least four layers, a carrier foil/a release layer/a heat-resistant metal layer/a copper foil layer is used; a supporting substrate is manufactured by laminating an insulating layer constituting material on the surface of the copper foil layer constituting the copper foil with carrier foil; a supporting substrate with build-up wiring layer is manufactured by forming a build-up wiring layer on the surface of the carrier foil constituting the copper foil with carrier foil in the supporting substrate; the resulted supporting substrate with build-up wiring layer is separated at the release layer to manufacture a multilayered laminate; the resulted multilayered laminate is processed a necessary procedures to manufacture a multilayer printed wiring board.