BGA Package Layout Using Mixed-Height Solder Balls
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Solution Overview
Problem
Existing semiconductor devices using ball grid array (BGA) technology face challenges in achieving both high resistance to thermal fatigue and drop impacts, as taller solder balls enhance thermal fatigue resistance but compromise drop impact resistance, and shorter solder balls improve drop impact resistance but reduce thermal fatigue resistance.
Innovation Solution
The semiconductor device employs two types of solder balls with different heights, where each bonding pad is connected to at least one taller solder ball for enhanced thermal fatigue resistance and at least one shorter solder ball for improved drop impact resistance, allowing for signal transmission via either type of solder ball even if one type is damaged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If taller solder balls are used, then thermal fatigue resistance is improved, but drop impact resistance deteriorates
Solution Approach 1:
The invention divides the solder connection function into two distinct segments: taller solder balls (first solder balls) for thermal fatigue resistance and shorter solder balls (second solder balls) for drop impact resistance. This segmentation allows each type to optimize its performance for its specific function without compromising the other, resolving the contradiction between thermal fatigue resistance and drop impact resistance.
Solution Approach 2:
The invention applies local quality by assigning different heights (and thus different mechanical properties) to different solder balls based on their specific functional requirements. Taller solder balls are placed where thermal fatigue resistance is critical, while shorter solder balls are placed where drop impact resistance is prioritized, allowing each location to have the optimal solder ball characteristics for its specific demands.
2Strength
If shorter solder balls are used, then drop impact resistance is improved, but thermal fatigue resistance deteriorates
Solution Approach 1:
The invention segments the solder ball population into two groups with different heights, allowing the shorter solder balls to specifically address drop impact resistance while the taller solder balls handle thermal fatigue resistance, thus resolving the contradiction in favor of both requirements simultaneously.
Solution Approach 2:
By applying local quality, the invention ensures that shorter solder balls are strategically positioned where drop impact resistance is most critical, while taller solder balls are positioned where thermal fatigue resistance is prioritized, allowing each region to have the appropriate solder ball characteristics.
3Reliability
If multiple types of solder balls are used, then reliability is improved, but device complexity increases
Solution Approach 1:
While segmentation into two types of solder balls does increase configuration complexity, it dramatically improves overall reliability by ensuring both thermal fatigue and drop impact resistance requirements are met. The segmentation allows for specialized optimization that a single uniform solder ball type cannot achieve.
Solution Approach 2:
The invention achieves a form of multi-functionality where two types of solder balls serve different protective functions within the same package structure. This allows the system to handle multiple stress conditions (thermal cycling and mechanical impact) with a single integrated solution, improving reliability without requiring entirely separate systems for each function.
Data Source
AI summary
A packaged semiconductor device includes a wiring substrate with a bonding pad on a first surface, a wiring layer, a first conductive plug extending through the wiring substrate from the wiring layer to the first surface, a second conductive plug extending through the wiring substrate from the wiring layer to a second surface, and a third conductive plug extending through the wiring substrate from the wiring layer to the second surface. A semiconductor chip is mounted on the first surface and has a pad terminal electrically connected to the bonding pad. A first solder ball is on the second surface of the wiring substrate and electrically connected to the second conductive plug. A second solder ball is on the second surface of the wiring substrate and electrically connected to the third conductive plug.