RF Module Shield Structure With Barrier Metal Against Diffusion
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Solution Overview
Problem
In radio frequency modules, metal diffusion from a metal film into electronic components, such as surface acoustic wave filters, can deteriorate the characteristics of these components by mixing as impurities into their circuit portions, leading to performance degradation.
Innovation Solution
A radio frequency module design that includes a barrier metal layer made of titanium, tantalum, cobalt, or tungsten between the metal shield layer and the electronic component's circuit portion, which reduces metal diffusion and maintains the component's characteristics by acting as a barrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal film is formed on the surface of the resin layer and directly contacts the electronic component, then electrical conductivity and grounding are improved, but metal diffuses into the circuit portion causing characteristic deterioration
Solution Approach 1:
The patent introduces a barrier metal layer as an intermediary substance between the copper metal film and the electronic component. This barrier layer (made of titanium, tantalum, cobalt, or tungsten) mediates the interaction by preventing direct contact and metal diffusion into the circuit portion, while still allowing the copper layer to provide electrical conductivity and grounding functionality.
Solution Approach 2:
The patent creates a composite metal layer structure consisting of multiple materials: a copper-based metal film layer for conductivity, a barrier metal layer for diffusion prevention, and optionally a resin layer for protection. This composite structure combines the beneficial properties of different materials while mitigating their individual drawbacks.
2Ease of manufacture
If the metal film is in direct contact with the electronic component, then manufacturing process is simplified, but metal diffusion deteriorates component characteristics
Solution Approach 1:
The barrier metal layer serves as an intermediary that is easily deposited using standard sputtering or evaporation techniques. This intermediate layer does not significantly complicate the manufacturing process while effectively preventing metal diffusion and preserving component characteristics.
Solution Approach 2:
The patent changes the material parameter of the metal layer by introducing a barrier metal with specific properties (high diffusion barrier capability) between the copper layer and the electronic component. This parameter change maintains ease of manufacture while improving 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 barrier metal layer effectively suppresses metal diffusion, thereby preventing characteristic deterioration of electronic components and enhancing the reliability of the radio frequency module's performance.
Implementation Method 1
a second metal layer formed between the first metal layer and the circuit portion. The second metal layer is a barrier metal
Data Source
AI summary
The radio frequency module includes a module substrate, an electronic component disposed on a main surface, a resin member covering at least part of the main surface and at least part of a side surface of the electronic component, and a metal shield layer that is formed on a surface of the resin member and is set to a ground potential. The electronic component has a top surface in contact with the metal shield layer, a bottom surface facing the main surface, a circuit portion formed at a position closer to the bottom surface than to the top surface, and a metal layer formed between the metal shield layer and the circuit portion. The metal layer is a barrier metal.