Semiconductor Bump Pillar Adjacent to Pad
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Solution Overview
Problem
In semiconductor devices, the miniaturization and increased signal processing speed lead to stress on pads due to the placement of circuit units underneath, making them vulnerable to lifting and poor coupling with substrates during thermal processes.
Innovation Solution
A semiconductor device design featuring a bump pillar adjacent to the pad but not overlapping with it, with a solder layer including a solder bump and fillet portion that covers only a portion of the pad, reducing stress and ensuring stable electrical coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If circuit units are placed underneath pads to achieve miniaturization, then device size is reduced, but pad stress increases causing lifting and poor coupling
Solution Approach 1:
The bump structure is extracted from directly over the pad and repositioned to the side, removing the source of stress concentration on the pad while maintaining the electrical connection function through the solder fillet portion
Solution Approach 2:
The solder fillet portion acts as an intermediary element that provides both mechanical support and electrical coupling between the bump pillar and the pad, distributing stress away from the pad while ensuring reliable connection
2Reliability
If solder covers the entire pad to ensure electrical coupling, then coupling reliability improves, but pad lifting increases due to stress concentration
Solution Approach 1:
The solder layer is applied locally rather than uniformly across the entire pad. The solder bump portion is concentrated on the bump pillar while the solder fillet portion selectively covers only the necessary area for electrical coupling, creating local quality variations that optimize both coupling and stress distribution
Solution Approach 2:
Instead of covering the entire pad with solder, only the necessary portion is covered - the solder fillet portion that bridges the bump pillar and pad. This partial action is sufficient to achieve electrical coupling while avoiding the harmful effects of full pad coverage
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 design reduces the likelihood of pad lifting and enhances coupling reliability by distributing stress away from the pad and maintaining sufficient solder height for stable bonding with the substrate.
Implementation Method 1
reflowing the solder layer, thereby forming a solder bump portion over the bump pillar and forming a solder fillet portion at one side of the bump pillar facing the pad to cover the pad and electrically couple the bump pillar and the pad
Data Source
AI summary
A semiconductor device includes a semiconductor chip having a pad which is exposed through a passivation layer, a bump pillar formed over the passivation layer adjacent to the pad, but not overlapping with the pad. The semiconductor chip also has a solder layer including a solder bump portion which is formed over the bump pillar and a solder fillet portion which is formed at one side of the bump pillar facing the pad to cover the pad and electrically couples the bump pillar and the pad.