Shield Layer Adhesion and Scratch Resistance in Sealed Modules
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Solution Overview
Problem
Existing shield layers in portable terminal modules have low adhesion strength with resin and insufficient corrosion resistance, and they are prone to scratches due to low hardness, which affects their durability during manufacturing and usage processes.
Innovation Solution
A shield layer structure comprising a first adhesion film of Ti, Cr, Ni, or their alloys, a conductive layer, and a protective layer of nitride, oxide, or oxynitride of these metals, which enhances adhesion strength and scratch resistance by using a sputtering system for deposition, allowing for improved hardness and reduced cost through shared targets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive film of Cu, Al, or Ag is used for electromagnetic shielding, then the shielding function is achieved, but the adhesion strength with mold resin is low and corrosion resistance is insufficient
Solution Approach 1:
The patent applies composite material structure by combining multiple metal films with different functions: SUS304 provides adhesion and corrosion resistance, Cu provides electrical conductivity for shielding, and another SUS layer provides protective coverage. This composite approach resolves the contradiction by assigning different properties to different layers rather than relying on a single material.
Solution Approach 2:
The shield layer is segmented into multiple functional sub-layers: an adhesion layer (SUS304), a conductive layer (Cu), and a protective layer (SUS). Each segment performs a specific function, allowing the overall structure to achieve both strong adhesion and good corrosion resistance while maintaining shielding effectiveness.
2Reliability
If SUS is used for the protective film to improve corrosion resistance, then corrosion resistance is enhanced, but the hardness is low and scratches are likely to occur
Solution Approach 1:
The protective structure uses a composite of SUS304 and Cu layers where the SUS304 provides corrosion resistance through chromium oxide formation, while the Cu layer provides ductility and toughness. This composite approach allows the protective film to resist both corrosion and mechanical scratching by combining materials with complementary properties.
Solution Approach 2:
Different regions of the protective film have different compositions optimized for different functions: the SUS304 layer is optimized for corrosion resistance with its chromium-rich passive film, while the Cu layer provides mechanical flexibility and scratch resistance. This local differentiation of material properties resolves the contradiction between hardness and corrosion resistance.
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 proposed shield layer structure achieves excellent adhesion strength and scratch resistance, improving the durability and manufacturing efficiency of modules by using metals like TiAl for the adhesion and protective films, which have higher hardness and adhesion properties than traditional Cu or Ag layers.
Implementation Method 1
a shield layer provided so as to cover a surface of the sealing resin layer, wherein the shield layer includes an adhesion layer which is stacked on the surface of the sealing resin layer... a conductive layer which is stacked on the adhesion layer... and a protective layer which is stacked on the conductive layer
Data Source
AI summary
A module includes a wiring board, a plurality of components mounted on an upper surface of the wiring board, a sealing resin layer which seals the components provided on the upper surface of the wiring board, and a shield layer provided so as to cover a surface of the sealing resin layer. The shield layer includes an adhesion layer which is stacked on the surface of the sealing resin layer and includes a first adhesion film composed of a metal selected from the group consisting of Ti, Cr, Ni, TiCr, TiAl, NiAl, CrAl, and CrNiAl, a conductive layer which is stacked on the adhesion layer, and a protective layer which is stacked on the conductive layer and includes a protective film composed of a nitride, oxide, or oxynitride of a metal selected from the group consisting of Ti, Cr, Ni, TiCr, TiAl, NiAl, CrAl, and CrNiAl.