Shielded Semiconductor Module Step Structure for Eddy Current Control
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Solution Overview
Problem
Conventional semiconductor modules with shield films in grids suffer from defective connections between shield films due to adhesive drip during substrate division, leading to increased eddy currents and reduced electrical characteristics of inductors, especially when the module profile is reduced.
Innovation Solution
A module design featuring a substrate with a first shield film covering the upper surface and a second shield film covering the side surface, where a step portion is provided on the outer periphery of the sealing resin, ensuring electrical connection between the shield films below the step portion, preventing adhesive drip-induced defective connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shield film is formed in grids to cover the sealing resin, then electromagnetic shielding is provided, but eddy currents are generated that lower electrical characteristics of the inductor
Solution Approach 1:
The shield film is divided into multiple strips arranged in a grid pattern rather than forming continuous loops. This segmentation breaks the eddy current paths into smaller segments, reducing the magnitude of eddy currents while maintaining electromagnetic shielding effectiveness.
Solution Approach 2:
The shield film structure is optimized locally by creating strips with specific widths, spacing, and orientations. The grid pattern provides different shielding characteristics in different directions, allowing tailored electromagnetic interference protection while controlling eddy current generation in specific regions.
2Volume of moving object
If the module profile is reduced to make it more compact, then miniaturization is achieved, but the distance between the inductor and shield layer decreases causing increased eddy current influence
Solution Approach 1:
The segmented strip pattern allows the shield film to maintain effective shielding at smaller distances from the inductor. The broken grid structure reduces eddy current loops, enabling compact module design without excessive eddy current interference even when the profile is reduced.
3Reliability
If a sheet is bonded onto the shield film with adhesive to prevent exposure during division, then shield film coverage is maintained, but adhesive drips down the side surface causing defective connection between shield films
Solution Approach 1:
The sheet is bonded to the shield film in advance before the division process. This preliminary action ensures the shield film remains covered and protected during subsequent division operations, preventing exposure and maintaining connection integrity despite adhesive drip.
Solution Approach 2:
The sheet acts as an intermediary protective layer between the shield film and the division process. It prevents direct contact between the shield film and potential contaminants or damage during division, while the adhesive bonds the sheet to the shield film structure.
4Productivity
If the integrated substrate is divided into individual modules, then module production is enabled, but the side surface becomes exposed requiring additional shield film formation
Solution Approach 1:
The shield film is formed on the integrated substrate before division into individual modules. This preliminary formation ensures continuous shield film coverage across module boundaries, eliminating the need for additional shield film formation after division and reducing overall process complexity.
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 suppresses the generation of eddy currents, maintaining the electrical characteristics of the inductor and preventing defective connections between shield films, even when adhesive drips during substrate division.
Implementation Method 1
a shield layer is formed in grids to cover a part of the sealing resin... when a current flows through the inductor, magnetic lines of force are generated and reach a shield film
Implementation Method 2
An eddy current flows through the shield film with the magnetic lines of force being defined as a central axis. The eddy current generates magnetic field to cancel magnetic field generated by the magnetic lines of force
Data Source
AI summary
A module includes a substrate including a first main surface, a first component mounted on the first main surface, a first sealing resin including a first upper surface, the first component being sealed with the first sealing resin, a first shield film that covers at least a part of the first upper surface of the first sealing resin, and a second shield film that covers a side surface of the first sealing resin and a side surface of the substrate. A step portion lower than the first upper surface of the first sealing resin is provided on an outer periphery of the first sealing resin. The first shield film and the second shield film are electrically connected to each other on a side surface below the step portion.