Ball Grid Array Test Clusters for Probe Alignment Tolerance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-density C4 arrays in semiconductor dies face challenges such as missing electrical contact and electrical shorting due to tolerances in C4 ball size, probe tip size, and alignment tolerance during testing, which limit grid density and increase the risk of testing errors.
Innovation Solution
The formation of test clusters where multiple I/O pads carry the same data signal, allowing a single probe tip to safely contact multiple pads without causing shorts, and the use of self-centering probe tips and clusters to enhance alignment tolerance and reduce misalignment issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the C4 ball size is reduced to increase grid density, then the grid density is improved, but the alignment tolerance deteriorates and electrical contact reliability worsens
Solution Approach 1:
Multiple I/O pads carrying the same data signal are merged into a single testable unit. Instead of requiring separate probe contacts for each pad, the invention groups pads with identical signals together, allowing a single probe tip to test multiple pads simultaneously. This merging approach increases grid density while maintaining alignment tolerance because the probe has a larger effective contact area that can accommodate variations in positioning.
Solution Approach 2:
The test structure is segmented into multiple clusters, where each cluster contains multiple I/O pads with the same data signal. This segmentation allows the testing system to handle high-density grids by dividing the contact requirements into manageable clusters, where each cluster can be contacted by a single probe tip with appropriate tolerance margins.
2Measurement precision
If the probe tip size is reduced to contact smaller C4 balls, then the contact precision is improved, but the alignment tolerance deteriorates and misalignment risk increases
Solution Approach 1:
The invention combines multiple I/O pads into clusters that can be contacted by a single probe tip. This merging creates a larger effective contact target that maintains electrical contact reliability even when the probe tip is relatively large, while still achieving the necessary contact precision for testing.
3Device complexity
If conventional probe tips are used to contact high-density C4 arrays, then the device complexity is kept simple, but electrical shorting between adjacent pads increases
Solution Approach 1:
By merging multiple I/O pads with the same data signal into single testable clusters, the invention eliminates the harmful effect of electrical shorting between adjacent pads. The probe tip contacts a cluster rather than individual pads, ensuring that only pads with identical signals are contacted simultaneously, thus preventing shorting between different signal lines while maintaining simple probe structure.
4Measurement precision
If each I/O pad is contacted by a separate probe tip, then the testing accuracy is improved, but the device complexity and alignment requirements increase
Solution Approach 1:
The invention merges multiple I/O pad contacts into single probe tip contacts by creating clusters of pads with identical data signals. This reduces the number of probe tips required from one per pad to one per cluster, significantly reducing probe card complexity and alignment requirements while maintaining testing accuracy through the clustered configuration.
Data Source
AI summary
A semiconductor die with an array of contacts, where at least two contacts in adjacent positions have the same data signal during testing operations with a test probe. The adjacent contacts of the cluster allow the use of a larger test probe tip and/or greater tolerance on test probe tip alignment during testing operations.