Protective Conductor Structure for Sn Bump Leakage Control
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Solution Overview
Problem
In conventional acoustic wave devices, the absence of a protective layer over metal lines like Al, Au, or Cu leads to Sn bump leakage during the reflow process, resulting in insufficient thickness for flip-chip bonding.
Innovation Solution
An electronic structure with a protective layer covering the second conductor's top surface and exposing its side surface, while the bump structure is disposed on the conductor, using a metal or dielectric material to prevent Sn leakage and maintain sufficient thickness for flip-chip bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If no protective layer is used over metal lines, then the structure is simpler and manufacturing is easier, but Sn bump leakage occurs during reflow process
Solution Approach 1:
A protective layer is introduced as an intermediary element between the metal line and the bump structure. This protective layer prevents direct interaction between the metal line and molten solder during reflow, thereby preventing Sn bump leakage while maintaining manufacturing simplicity
Solution Approach 2:
The protective layer is formed on the metal line before the bump structure is created. This preliminary protective action prevents the harmful leakage effect from occurring in the first place, rather than attempting to correct it after the fact
2Device complexity
If no protective layer is used over metal lines, then the manufacturing process is simpler, but the Sn bump becomes too thin for flip-chip bonding
Solution Approach 1:
The protective layer serves as a mediator that prevents molten solder from leaking onto the metal line during reflow. This ensures that the bump structure maintains its intended thickness and geometry, achieving the required manufacturing precision for flip-chip bonding without significantly increasing device complexity
Solution Approach 2:
The protective layer is applied in advance to the metal line before bump formation. This preliminary action ensures that when reflow occurs, the bump material is contained and maintains proper thickness, thereby achieving manufacturing precision requirements
3Reliability
If a protective layer is added over the conductor, then Sn bump leakage is prevented, but the side surface of the conductor should remain exposed
Solution Approach 1:
The protective layer is applied selectively only to the top surface of the conductor, while the side surface remains exposed. This local application provides the necessary protection against Sn bump leakage on the top surface while maintaining conductor accessibility and electrical functionality on the exposed side surface, without unnecessarily increasing device complexity
Data Source
AI summary
An electronic structure is provided. The electronic structure includes a substrate, a plurality of conductors, a bump structure, and a protective layer. The conductors are disposed on the substrate. The bump structure is disposed on at least one of the conductors. The protective layer is disposed on the conductors. A region is exposed between the conductors. A method of manufacturing the electronic structure is also provided.