Shielded Module Surface Layout to Prevent Film Peeling
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Solution Overview
Problem
The existing method of grinding the upper surface of chip-shaped components to expose them from sealing resin results in large grinding scratches, which can cause the shield film to peel off due to stress, leading to a deterioration in the shielding properties of the module.
Innovation Solution
A module design where a strip-shaped portion with reduced surface roughness is created on the exposed surface of the component using laser processing, dividing the grinding scratches into shorter pieces, thereby reducing the stress causing peeling off of the shield film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the upper surface of the chip-shaped component is ground to expose it from the sealing resin, then the component surface is exposed on the same plane as the sealing resin, but grinding scratches are created that cause stress concentration and lead to shield film peeling
Solution Approach 1:
The patent applies segmentation by introducing multiple linear reduced-roughness portions that divide and segment the grinding scratches into shorter sections. These linear portions act as stress relief zones that break up the continuous stress concentration along long grinding scratches, preventing shield film peeling while maintaining the exposed surface configuration.
Solution Approach 2:
The patent applies local quality by creating linear portions with locally reduced surface roughness on the exposed surface of the chip-shaped component. These specific local regions have different surface properties (lower roughness) compared to the surrounding ground surface, providing stress relief zones that prevent shield film peeling without affecting the overall surface flatness.
2Reliability
If a shield film is formed by sputtering to cover the upper surfaces, then electromagnetic shielding is provided, but the shield film peels off when grinding scratches are present due to stress concentration
Solution Approach 1:
The linear reduced-roughness portions segment the grinding scratches into shorter pieces, breaking the continuous stress concentration path that would cause shield film peeling. This segmentation maintains shielding property while preventing integrity failure of the shield film.
Solution Approach 2:
The reduced-roughness linear portions are created beforehand as cushioning zones that reduce stress concentration before the shield film is formed. These pre-prepared low-stress regions prevent stress-induced peeling, cushioning against potential shield film failure.
3Reliability
If the shield film is to shrink due to temperature change, then shielding function is maintained, but peeling off starts from grinding scratches due to increased stress
Solution Approach 1:
The linear reduced-roughness portions segment long grinding scratches into shorter sections, reducing the cumulative stress that develops during thermal shrinkage of the shield film. This prevents peeling initiation at scratch locations while maintaining shielding function.
Solution Approach 2:
The local reduced-roughness portions create zones with lower stress concentration factors, providing localized relief from thermal shrinkage stress. These quality-differentiated regions prevent peeling initiation while the rest of the shield film maintains its shielding function.
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 minimizes the likelihood of shield film peeling off due to grinding scratches, maintaining the shielding properties of the module.
Implementation Method 1
A surface of the first component on a side farther from the substrate is exposed from the first sealing resin. When the surface of the first component that is exposed from the first sealing resin is defined as a first exposed surface, the first exposed surface has a region covered with the shield film, the region including a strip-shaped portion that is locally reduced in surface roughness.
Data Source
AI summary
A module includes: a substrate having a first surface; a first component mounted on the first surface; a first sealing resin that seals at least a part of the first surface and at least a side surface of the first component; and a shield film that is grounded and covers a surface of the first sealing resin on a side farther from the substrate. A surface of the first component on a side farther from the substrate is exposed from the first sealing resin. When the surface of the first component that is exposed from the first sealing resin is defined as a first exposed surface, the first exposed surface has a region covered with the shield film, the region including a strip-shaped portion that is locally reduced in surface roughness.