Metal Shield Case Bottom Attachment for Resin Sealing
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Solution Overview
Problem
Conventional packages with shield cases face challenges in sealing electronic components mounted on one surface of a substrate with resin due to the need for recesses in the substrate's side surfaces, limiting downsizing and requiring flip chip bonding instead of bonding wires for electrical connections.
Innovation Solution
A package design featuring a metallic shield case with an inverted U-shape and bent parts that attach to the substrate's opposite surface, allowing for resin sealing and bonding wire connections without direct contact with the shield case, eliminating the need for side surface attachment and space between components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If recesses are formed in the side surfaces of the substrate to attach the shield case, then the shield case can be securely attached, but the electronic components cannot be sealed with resin
Solution Approach 1:
The attachment structure transitions from side-surface attachment (conventional) to bottom-surface attachment. The shield case is attached to the bottom surface of the substrate through protrusions that fit into recesses formed in the bottom surface, eliminating the need for side surface recesses and enabling complete resin sealing of electronic components.
Solution Approach 2:
Instead of attaching the shield case to the side surfaces of the substrate as in conventional designs, the invention inverts the attachment approach by attaching the shield case to the bottom surface of the substrate. This inversion allows the side surfaces to remain intact for resin sealing while maintaining secure attachment through the inverted protrusion-recess mechanism.
2Object-affected harmful factors
If space is ensured between the shield case and electronic components to prevent contact, then contact prevention is achieved, but package downsizing is limited
Solution Approach 1:
A resin layer is introduced as an intermediary substance between the shield case and the electronic components. This resin layer serves as both the sealing material for the electronic components and the insulating barrier that prevents contact between the metallic shield case and the components, eliminating the need for additional spacing.
Solution Approach 2:
The sealing function and the insulation function are merged into a single resin layer. This resin layer simultaneously seals the electronic components and provides electrical insulation between the shield case and the components, reducing the overall package size by eliminating the need for separate insulation structures or spacing.
3Reliability
If flip chip bonding is used for electrical connection, then connection reliability is improved, but manufacturing flexibility is reduced
Solution Approach 1:
The constraint that forced the use of flip chip bonding (the side surface recesses) is extracted and removed by changing the attachment structure to bottom surface attachment. This extraction of the constraining feature restores the flexibility to choose different bonding methods, including wire bonding, while maintaining connection reliability.
Data Source
AI summary
A package includes: a package body including a substrate, an electronic component mounted on a first surface of the substrate, and a sealing resin layer for sealing the electronic component; and a shield case for covering the sealing resin layer, the shield case being made of metal and having an inverted U-shape in a cross-sectional view, wherein a bent part of the shield case is formed in such a manner that at least a part of an end of the shield case is bent toward a second surface of the substrate opposite to the first surface, and the bent part abuts on the second surface so that the shield case is attached to the substrate.