Semiconductor Device Side Wall Solder Inspection
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Solution Overview
Problem
Conventional semiconductor devices with leadless packages, such as QFN, are difficult to inspect using automated optical systems due to hidden Input/Output terminals, which limits the ability to check solder quality effectively.
Innovation Solution
The semiconductor device is designed with solderable/glueable contacts on both sides and an isolating layer on four sidewalls, allowing for automatic optical inspection by moving the solder pad to the sidewall, enabling visual inspection of connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the semiconductor device uses a leadless package with terminals on the bottom surface, then the device achieves a compact structure and improved electrical performance, but the solder connections become hidden and inaccessible for visual inspection
Solution Approach 1:
The patent transitions the solder connection location from the bottom surface (2D plane) to the side surface (vertical dimension) of the semiconductor device. This dimensional change allows the solder connections to be visually accessible from the side while maintaining the leadless package structure, resolving the contradiction between compact design and inspection accessibility.
2Difficulty of detecting and measuring
If the semiconductor device exposes all surfaces for soldering, then inspection accessibility is improved, but the device becomes vulnerable to environmental damage and oxidation
Solution Approach 1:
The patent applies different surface properties to different regions: the side surface containing solder balls is left exposed for inspection and connection, while the top and bottom surfaces are covered with passivation layers for protection. This local differentiation resolves the contradiction between inspection accessibility and environmental protection.
Solution Approach 2:
The solder balls act as intermediaries that connect the semiconductor device to the PCB while being positioned on the side surface. This allows the solder connections to be visible for inspection without requiring the entire device surface to be exposed, thus protecting the device from environmental damage while maintaining inspection accessibility.
3Reliability
If the semiconductor device maintains vertical current flow through the chip, then electrical performance is optimized, but the solder pads must be located on the bottom surface making them invisible for inspection
Solution Approach 1:
The patent relocates the solder connections from the bottom surface to the side surface of the device, creating a vertical profile that exposes the solder balls. This allows the current to flow vertically through the chip while the connection points remain visible on the side, resolving the contradiction between electrical performance optimization and inspection visibility.
Data Source
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AI summary
A semiconductor device (200) comprising a frontside and a backside, four sidewalls, a first solder/glue connection (210) on the frontside and a second solder/glue connection (212) on the backside. The semiconductor device (200) connected as a chip scale package to a printed circuit board (202) so that the first solder/glue connection (210) and the second solder/glue connection (212) are visible for a visual solder/glue inspection.