Multi-Layered Water-Soluble Resin Entry Sheet for Drilling
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Solution Overview
Problem
Conventional methods for forming a water-soluble resin composition layer on a metal foil for drilling copper-clad laminates or multi-layer boards face issues with foaming and air bubbles, leading to decreased hole registration accuracy and surface smoothness, especially when trying to achieve a thickness of at least 50 μm.
Innovation Solution
A multi-layered water-soluble resin composition layer is formed by repeatedly applying and solidifying a water-soluble resin composition solution on a metal foil, with each layer having a thickness of 10 μm to 50 μm, reducing internal air bubbles and preventing re-melting, thus achieving a smooth surface and accurate hole registration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a thick water-soluble resin composition layer (at least 50 μm) is formed by applying a water-soluble resin composition solution thickly and drying and solidifying it, then the hole registration accuracy is improved, but air bubbles are generated in the layer and the surface smoothness decreases
Solution Approach 1:
The patent divides a single thick resin layer into multiple thin layers by repeatedly applying and drying the resin composition solution. Each application forms a layer of 1-10 μm thickness, and multiple such layers are stacked to achieve the total thickness of at least 50 μm. This segmentation prevents air bubble generation during drying while maintaining surface smoothness and improving hole registration accuracy.
2Length of stationary object
If a thick water-soluble resin composition layer is formed by applying a low viscosity solution thickly, then the layer thickness is sufficient for high-quality drilling, but the solution drips during application and foaming occurs during drying and solidification
Solution Approach 1:
Instead of applying a thick layer in one go which causes dripping and foaming, the patent segments the application process into multiple steps. Each step applies a thin layer (1-10 μm) that dries completely before the next application. This eliminates dripping during application and foaming during drying, making production feasible while achieving the required total thickness of at least 50 μm.
Solution Approach 2:
The patent applies preliminary drying and solidification of each thin resin layer before applying the next layer. This preliminary action ensures that each layer is fully set before subsequent processing, preventing defects like foaming and ensuring proper adhesion between layers, thereby facilitating smooth production.
3Length of stationary object
If two water-soluble resin composition layers are successively formed from two applied coating portions, then a thicker layer is achieved, but air bubbles exist in the layer and the smoothness of the surface decreases
Solution Approach 1:
The patent further segments each coating portion into multiple thin sub-layers of 1-10 μm thickness. By repeatedly applying and drying the resin composition solution multiple times, each 'layer' becomes a stack of ultra-thin sub-layers. This fine segmentation eliminates air bubbles within layers and maintains excellent surface smoothness, achieving both increased thickness and high manufacturing precision.
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 process results in an entry sheet with improved hole registration accuracy and reduced inner hole wall roughness, eliminating the need for auxiliary materials like PET films, making it an industrially advantageous production method.
Implementation Method 1
drying and solidifying the applied solution
Implementation Method 2
forming a multi-layered water-soluble resin composition layer
Data Source
AI summary
A process for the production of an entry sheet for drilling a printed wiring board material, which process comprises forming a multi-layered water-soluble resin composition layer on at least one surface of a metal foil, wherein an aqueous solution of a water-soluble resin composition is applied to the metal foil, dried and solidified to form one water-soluble resin composition layer, the application, drying and solidification of the aqueous solution of the water-soluble resin composition are repeated at least once to form at least one water-soluble resin composition layer on the above one water-soluble resin composition layer, the multi-layered water-soluble resin composition layer is composed of these water-soluble resin composition layers, the multi-layered water-soluble resin composition layer has a thickness of at least 50 μm and is almost free from air bubbles, and an entry sheet for drilling a printed wiring board material obtained by the above process.