Semiconductor Corner Supports for Board Reliability
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Solution Overview
Problem
Conventional semiconductor devices experience mechanical stresses at solder ball junctions due to thermal expansion and impact, leading to board level reliability failures, particularly at corner bonds.
Innovation Solution
Incorporating reinforced corner supports, such as support billets with higher mass and contact area, or screws, to replace or supplement corner solder balls, providing increased structural integrity and stress dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solder balls are used at corner positions, then the device structure is simple and manufacturing is easy, but mechanical stresses from thermal expansion and impact cause solder ball cracking or detachment
Solution Approach 1:
The patent applies local quality by providing reinforced corner supports specifically at the corner positions where mechanical stresses are highest, while other positions use conventional solder balls. This targeted reinforcement improves reliability at critical locations without unnecessarily complicating the entire device structure.
Solution Approach 2:
The corner support structures are segmented into distinct components (support structures separate from regular solder balls) that can be independently designed and positioned at specific corner locations, allowing selective reinforcement where needed.
2Strength
If reinforced corner supports with higher mass are used, then structural integrity and stress dissipation are improved, but the weight of the device increases
Solution Approach 1:
Higher mass support structures are applied locally only at corner positions where mechanical stresses concentrate, rather than uniformly across all positions. This provides necessary structural integrity at critical points while minimizing overall weight increase.
Solution Approach 2:
The corner supports use excessive mass compared to regular solder balls, but only at the four corner positions. This partial application of excessive mass provides sufficient reinforcement where needed while keeping the overall device weight acceptable.
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
Enhances board level reliability by reducing the risk of solder ball cracking or detachment and allows for the omission of under-fill layers, improving thermal dissipation and simplifying the assembly process.
Implementation Method 1
corner structural supports at corners of the substrate, the corner structural supports having a higher strength than the solder balls
Implementation Method 2
these stresses can be generated as a result of different coefficients of thermal expansion of the semiconductor package and PCB, for example during thermal cycling tests
Data Source
AI summary
A semiconductor device is disclosed having reinforced supports at corners of the device. The semiconductor device may include solder balls on a lower surface of the device for soldering the device onto a printed circuit board. In one example, the solder balls at the corners of the semiconductor device may be replaced by support billets having more mass and more contact area between the semiconductor device and the PCB. In a further example, screws may be provided at the corners of the device (instead of the corner solder balls or in addition to the corner solder balls). These screws may be placed through the corners of the semiconductor device and into the printed circuit board.