Multilayer PCB Carrier Foil Thickness Inversion for Residue-Free Separation
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Solution Overview
Problem
In the coreless build-up method for multilayer printed wiring boards, a thick heat-resistant metal layer often remains on the surface after separation, necessitating an additional step for removal, which is undesirable.
Innovation Solution
A copper foil with carrier foil is structured into at least four layers: a copper foil layer, a release layer, a heat-resistant metal layer, and a carrier foil, where the carrier foil is thicker than the copper foil layer, and the heat-resistant metal layer is formed using nickel or nickel alloys, with a release layer composed of organic substances to facilitate easy separation without leaving residue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick heat-resistant metal layer is used between the copper foil layer and releasing layer, then the release strength stability is improved, but the heat-resistant metal layer remains on the surface after separation requiring additional removal steps
Solution Approach 1:
The invention extracts the heat-resistant metal layer from the surface of the build-up layer by optimizing the carrier foil thickness to be greater than the copper foil layer thickness. This allows the heat-resistant metal layer to remain on the carrier foil after separation, eliminating the need for additional removal steps while maintaining release strength stability throughout the manufacturing process.
Solution Approach 2:
The invention segments the copper foil with carrier foil into distinct layers with specific thickness relationships. The carrier foil thickness is designed to be greater than the copper foil layer thickness, creating a clear separation boundary that enables clean detachment of the build-up layer from the carrier foil, leaving no residual metal on the build-up layer surface.
2Object-affected harmful factors
If a thick heat-resistant metal layer is used to prevent copper diffusion, then the thermal diffusion prevention is improved, but an additional removal step is required after separation
Solution Approach 1:
The heat-resistant metal layer is effectively extracted from the build-up layer surface through the designed thickness relationship. The carrier foil, being thicker than the copper foil layer, retains the heat-resistant metal layer after separation, removing the harmful residual metal effect without requiring additional productivity-consuming removal steps.
Solution Approach 2:
The invention performs preliminary action by designing the layer thickness relationship before separation occurs. The carrier foil thickness is predetermined to be greater than the copper foil layer thickness, ensuring that the heat-resistant metal layer remains on the carrier foil after separation, thus preventing copper diffusion while maintaining manufacturing efficiency.
3Ease of manufacture
If the carrier foil thickness is made greater than the copper foil layer thickness, then the heat-resistant metal layer remains on the carrier foil after separation, but the structural design becomes more constrained
Solution Approach 1:
The invention applies segmentation by dividing the copper foil with carrier foil into distinct layers with a specific thickness hierarchy. The carrier foil thickness is segmented to be greater than the copper foil layer thickness, creating a clear separation boundary that simplifies the separation process while establishing a straightforward structural design rule.
Solution Approach 2:
Instead of making the copper foil layer thicker than the carrier foil (conventional approach), the invention inverts the thickness relationship by making the carrier foil thicker. This inversion ensures that the heat-resistant metal layer remains on the carrier foil after separation, improving ease of manufacture without complex structural constraints.
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 allows for the dispensability of the heat-resistant metal layer removal step, enhancing the manufacturing efficiency and cost-effectiveness of multilayer printed wiring boards by preventing residue on the build-up layer surface.
Implementation Method 1
a release layer which mechanically separates the support copper foil and the ultra-thin copper foil provided between the support copper foil and the ultra-thin copper foil
Implementation Method 2
a thermal diffusion preventing layer which hinders the diffusion of copper between the support copper foil and an ultra-thin copper foil due to heat
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 copper foil layer/a release layer/a heat-resistant metal layer/a carrier foil is used; a supporting substrate is manufactured by laminating an insulating layer constituting material to the surface of the carrier foil 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 copper foil layer 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.