Solder Ball Omission for Thermal Stress Relief in SiP
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Solution Overview
Problem
Semiconductor devices with soldering balls experience rupture when subjected to repeated temperature variations from high to low, leading to reliability issues due to stress caused by differences in thermal expansion coefficients between the semiconductor integrated circuit and the substrate.
Innovation Solution
The semiconductor device is designed with soldering balls omitted at the positions corresponding to the fringe of the semiconductor integrated circuit, where stress is highest, to prevent rupture and ensure reliable operation across varying temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If soldering balls are arranged at all positions including the fringe of the semiconductor integrated circuit, then electrical connection coverage is improved, but reliability deteriorates due to rupture under thermal stress
Solution Approach 1:
The patent extracts and removes soldering balls from specific high-stress positions (the fringe positions farthest from the center of the semiconductor integrated circuit). This selective removal eliminates the source of rupture while maintaining electrical connection functionality through remaining soldering balls at less stressful positions.
Solution Approach 2:
The patent applies different configurations of soldering balls to different regions of the substrate. Specifically, soldering balls are omitted at fringe positions farthest from the center where thermal stress concentrates, while maintaining soldering balls at other positions. This local differentiation optimizes both reliability and electrical connection.
2Reliability
If soldering balls are positioned at the fringe of the semiconductor integrated circuit, then electrical connection coverage is improved, but manufacturing precision deteriorates due to rupture under repeated temperature cycling
Solution Approach 1:
The patent removes soldering balls from specific fringe positions that are farthest from the center of the semiconductor integrated circuit. This extraction eliminates the manufacturing defect (rupture under thermal cycling) while maintaining adequate electrical connection coverage through remaining soldering balls at other positions.
3Reliability
If soldering balls are arranged in a complete grid pattern, then electrical connection coverage is improved, but device complexity increases due to stress management requirements
Solution Approach 1:
The patent simplifies the soldering ball arrangement by removing balls from specific fringe positions farthest from the center. This creates a less complex configuration that inherently resists open failures by eliminating the most vulnerable connection points under thermal stress.
Solution Approach 2:
The patent applies a non-uniform soldering ball distribution pattern where fringe positions farthest from the center have no soldering balls, while other positions maintain them. This local differentiation reduces overall device complexity by eliminating stress-prone connections while maintaining necessary electrical pathways.
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 configuration effectively suppresses open failures and contact failures, enhancing the reliability of the semiconductor device by reducing stress on soldering balls, particularly at the farthest positions from the center, thereby maintaining normal operation over a wide temperature range.
Implementation Method 1
differences in thermal expansion coefficients between the semiconductor integrated circuit and the substrate
Data Source
Figure 1~2
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Figure 4
AI summary
The object is to suppress rupture of the soldering balls when an atmosphere varying from a high temperature to a low temperature is repeated. A semiconductor device includes a semiconductor integrated circuit and a substrate. The semiconductor integrated circuit is, for example, a semiconductor chip. The coefficient of thermal expansion is different between the semiconductor integrated circuit and the substrate. The substrate includes a plurality of soldering balls on the opposite surface to the surface where the semiconductor integrated circuit is mounted. The substrate does not have the soldering balls at a position corresponding to at least one side of the fringe of the semiconductor integrated circuit.