Floating Pads for Underbump Metallization Testing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The placement and connection of electrical connectors on semiconductor dies using underbump metallization often suffer from misalignment, cracking, and delamination, leading to incomplete or partial electrical contact, which can result in the failure of semiconductor devices and necessitate remanufacturing.
Innovation Solution
The use of a post-passivation interconnect (PPI) and floating pads, which allow for flexible placement of underbump metallization and enable testing of electrical connections, ensuring reliable contact formation and reducing defects by analyzing current and voltage changes through multiple terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electrical connector placement is performed directly on underbump metallization, then manufacturing process is simple, but misalignment and connection defects occur frequently
Solution Approach 1:
The patent introduces a test structure with test pads and interconnects that are formed beforehand during the manufacturing process, before final electrical connector placement. This preliminary action allows alignment verification and connection testing to be performed in advance, preventing misalignment and connection defects while maintaining manufacturing simplicity.
Solution Approach 2:
The patent employs an intermediary test structure consisting of test pads and interconnects that mediate between the underbump metallization and the final electrical connectors. This intermediary layer enables precise alignment verification and connection quality assessment, resolving the contradiction between simple manufacturing and reliable connections.
2Device complexity
If electrical connector placement is performed directly on underbump metallization, then device structure is simple, but alignment precision is insufficient
Solution Approach 1:
The test pads and interconnects are formed in advance during manufacturing, creating a preliminary alignment reference structure. This allows precise positioning of electrical connectors to be verified before final assembly, improving alignment precision without significantly increasing overall device complexity.
Solution Approach 2:
The patent replaces direct mechanical placement of electrical connectors on underbump metallization with a test-based verification system. Electrical measurements through the test structure provide feedback on alignment quality, substituting mechanical precision requirements with electrical characterization.
3Productivity
If electrical connections are tested after manufacturing, then manufacturing process is fast, but defects are detected too late causing device failure
Solution Approach 1:
The test structure is integrated into the manufacturing process itself, with test pads and interconnects formed during fabrication. This enables electrical connection testing to be performed at an intermediate stage rather than after complete manufacturing, allowing early defect detection without significantly extending production time.
Solution Approach 2:
The patent implements a feedback mechanism where electrical measurements through the test structure provide real-time information about connection quality during manufacturing. This feedback allows for immediate identification and correction of defects, preventing device failure while maintaining manufacturing efficiency.
4Device complexity
If electrical connections are not monitored during manufacturing, then manufacturing process is simple, but connection defects go undetected
Solution Approach 1:
The test pads and interconnects serve as intermediary measurement access points that enable non-intrusive electrical characterization of underbump metallization and connector connections. This intermediary structure provides a simple yet effective means to detect connection defects without complicating the overall manufacturing process.
Solution Approach 2:
The test structure enables the manufacturing process to self-verify connection quality through electrical measurements. The underbump metallization and connectors themselves participate in the measurement process, eliminating the need for separate complex inspection equipment or procedures.
Data Source
AI summary
A system and method for testing electrical connections is provided. In an embodiment one or more floating pads may be manufactured in electrical connection with an underbump metallization structure. A test may then be performed to measure the electrical characteristics of the underbump metallization structure through the floating pad in order to test for defects. Alternatively, a conductive connection may be formed on the underbump metallization and the test may be performed on the conductive connection and the underbump metallization together.