Carrier-Attached Metal Foil Side-Face Anchoring Against Release
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Solution Overview
Problem
Existing carrier-attached metal foils experience unintended release of the metal layer due to chemical solution infiltration during the formation of redistribution layers, leading to incomplete circuit patterns and hindered processing steps.
Innovation Solution
The carrier-attached metal foil design extends the metal layer from the surface to the side face of the carrier, incorporating an uneven region with a controlled developed interfacial area ratio (Sdr) to prevent chemical solution infiltration and maintain adhesion, thereby suppressing unintended release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the metal layer is made thinner to achieve finer wiring patterns, then the wiring precision is improved, but the metal layer becomes more susceptible to unintended release during handling and processing
Solution Approach 1:
The invention extends the metal layer from a two-dimensional surface layer to a three-dimensional structure that wraps around the side face of the carrier. This dimensional extension creates additional adhesion interfaces and prevents release by anchoring the metal layer at multiple locations, thereby maintaining reliability while enabling thinner metal layers for finer wiring patterns.
Solution Approach 2:
The metal layer is designed to extend onto the side face of the carrier before any processing or handling occurs. This preliminary structural configuration ensures that the metal layer is pre-secured against unintended release during subsequent handling, conveyance, and processing steps, allowing thinner layers to be used without compromising adhesion stability.
2Reliability
If the metal layer is extended to the side face to prevent release, then the adhesion stability is improved, but the amount of metal material required increases
Solution Approach 1:
The metal layer is formed as an extremely thin film that conformally coats the side face of the carrier. This thin-film approach provides sufficient adhesion stability to prevent release while minimizing metal material consumption. The film follows the contour of the side face, ensuring coverage where needed without excessive material use.
Solution Approach 2:
The metal layer thickness and coverage are optimized locally: it extends onto the side face only to the extent necessary to prevent release, and its thickness on the side face can be thinner than on the surface where wiring patterns are formed. This local optimization maintains adhesion stability while reducing overall metal material consumption.
3Manufacturing precision
If the carrier surface is made ultrasmooth to reduce metal layer roughness, then the wiring precision is improved, but the adhesion between carrier and metal layer is reduced, increasing release risk
Solution Approach 1:
The invention compensates for the adhesion deficiency caused by ultrasmooth surfaces by extending the metal layer into the third dimension onto the side face of the carrier. This creates additional adhesion zones that make up for the weak adhesion on the smooth surface, thereby maintaining reliability while allowing the use of ultrasmooth carriers for high-precision wiring patterns.
Solution Approach 2:
The metal layer is designed to extend onto the side face as a preliminary structural feature before processing. This pre-configured extension ensures that even though adhesion on the smooth surface is weak, the metal layer is pre-secured at the side face interface, preventing unintended release during handling and 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 design effectively prevents chemical solution infiltration, ensuring the integrity of the metal layer and enabling successful formation of redistribution layers, enhancing the reliability of the manufacturing process.
Implementation Method 1
a metal layer having a thickness of 0.01 μm or more and 4.0 μm or less provided on the release layer, wherein the metal layer extends from the first surface to the side face of the carrier so that at least a portion of the side face is covered by the metal layer
Implementation Method 2
the carrier has an uneven region having a developed interfacial area ratio Sdr of 3% or more and 39% or less as measured in accordance with ISO 25178 on the side face or the side face and the first surface, and wherein the uneven region encompasses a region of the side face covered by the metal layer
Data Source
AI summary
There is provided a carrier-attached metal foil including a carrier having a first surface and a second surface facing each other, and a side face connected to the first surface and the second surface; a release layer provided on the first surface of the carrier; and a metal layer having a thickness of 0.01 μm or more and 4.0 μm or less provided on the release layer. The metal layer extends from the first surface to the side face of the carrier so that at least a portion of the side face is covered by the metal layer. The carrier has an uneven region having a developed interfacial area ratio Sdr of 3% or more and 39% or less on the side face or the side face and the first surface, and the uneven region encompasses a region of the side face covered by the metal layer.