Semiconductor Package Recessed Land Structure for Thermal Stress Mitigation
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Solution Overview
Problem
Semiconductor packages face stress and potential breakage due to thermal expansion differences between the semiconductor chip and the printed circuit board, leading to solder bump detachment during temperature cycles.
Innovation Solution
Incorporating recessed portions on the lands of the semiconductor package, which increase the contact area with solder bumps and serve as an anchor point, reducing stress and preventing breakage by enhancing coupling strength between solder bumps and lands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder balls are used to mount the semiconductor package on the printed circuit board, then electrical connections are established, but the solder balls may be broken or detached due to thermal expansion stress
Solution Approach 1:
The land is divided into a flat portion and a recessed portion, creating a multi-level structure that segments the contact area. This segmentation allows the solder ball to be anchored in the recessed portion while maintaining contact with the flat portion, distributing the thermal stress and preventing complete detachment
Solution Approach 2:
The recessed portion is formed within the land structure, creating a nested configuration where the solder ball sits in the recessed area. This nested structure provides mechanical interlocking, enhancing the connection between the solder ball and the land without adding external components
2Strength
If the contact area between solder bumps and lands is increased, then coupling strength is enhanced, but the land structure becomes more complex
Solution Approach 1:
The recessed portion is strategically positioned at specific locations on the land where maximum stress concentration occurs. This local modification approach enhances coupling strength at critical points without unnecessarily complicating the entire land structure, maintaining simplicity while improving performance
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
The recessed portions effectively mitigate stress-induced breakage of solder bumps, ensuring reliable electrical connections and improved durability during temperature variations.
Implementation Method 1
the printed circuit board is mostly made of resin of relatively high thermal expansion. Consequently, while temperature causes the printed circuit board to expand and contract by a relatively large amount
Data Source
AI summary
According to one embodiment, a semiconductor device comprises a circuit board and a semiconductor package mounted on the circuit board. The semiconductor package comprises a semiconductor chip, a first connector on a bottom surface of the semiconductor package and electrically connected to the semiconductor chip, and a metal bump coupled to the first connector and electrically connected to a second connector on the circuit board. The first connector has a contact surface facing the second connector. The contact surface has a recessed portion into which the metal bump extends.