Selective EMI Shielding Mask for Exposed Pads and Antennas
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Solution Overview
Problem
Existing semiconductor devices face challenges in applying selective EMI shielding, particularly in leaving contact pads or antennas exposed, as current masking techniques are technically challenging, prone to shifting, and difficult to use with unconventional package shapes.
Innovation Solution
A reusable mask is applied using a pick-and-place process, allowing selective EMI shielding by forming a conductive layer over semiconductor packages, with openings and legs that conform to the package shape, enabling precise exposure of contact pads and antennas, and grounded for enhanced interference reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a mask is applied prior to forming the shielding layer, then selective EMI shielding can be achieved, but the process becomes technically challenging and prone to shifting
Solution Approach 1:
The patent introduces a sacrificial layer as an intermediary between the substrate and the shielding layer. This sacrificial layer acts as a temporary placeholder that defines the unshielded regions, allowing the shielding layer to be deposited uniformly over the entire structure. After deposition, the sacrificial layer is removed, leaving precisely defined unshielded areas without requiring complex masking operations during the shielding deposition process itself.
2Ease of operation
If a mask is used for selective shielding, then contact pads or antennas can be exposed, but the mask is difficult to remove and may shift during processing
Solution Approach 1:
The sacrificial layer is designed as a temporary, disposable structure that serves its purpose during the shielding deposition process and is then completely removed. It does not need to withstand prolonged processing or complex removal procedures; instead, it is engineered to be easily removable after it has fulfilled its function of defining the unshielded regions during deposition.
3Adaptability or versatility
If traditional masking is used, then selective shielding can be achieved, but it is difficult to use with unconventionally shaped packages
Solution Approach 1:
The sacrificial layer is segmented into multiple discrete elements positioned at specific locations where unshielded areas are required. Rather than using a continuous mask that must conform to complex package shapes, the sacrificial layer is divided into separate, simple geometric forms that are easier to manufacture and position, yet collectively achieve the desired selective shielding pattern for any package shape.
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 facilitates cost-effective, high-throughput manufacturing of selectively shielded semiconductor packages with reduced defects, ensuring effective EMI reduction while maintaining functional areas like antennas and contact pads unobstructed.
Implementation Method 1
EMI shielding is typically formed over and around semiconductor packages to block inter-device interference
Implementation Method 2
A reusable mask is applied using a pick-and-place process
Data Source
AI summary
A semiconductor device is made by providing a strip substrate including a plurality of units. A hole is formed in the strip substrate. An encapsulant is deposited over the strip substrate. A mask is disposed over the strip substrate and encapsulant with a leg of the mask disposed in the hole. A shielding layer is formed over the mask and strip substrate. The mask is removed after forming the shielding layer. The strip substrate is singulated to separate the plurality of units from each other after forming the shielding layer.