Probe Base Plate Local Quality Design for Contact Height Uniformity
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Solution Overview
Problem
Large-sized probe base plates with numerous contacts used for testing integrated circuits face bending issues due to uneven pressing forces, leading to inconsistent contact heights and inaccurate electrical connections during testing.
Innovation Solution
The electrical connecting apparatus features a probe base plate with contacts arranged in concentric regions, where the distance from an imaginary plane to the tips increases towards the center, and thicker probe lands near the center, ensuring consistent tip positioning and reduced bending, thereby maintaining uniform contact pressure and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the probe base plate is made larger to accommodate more contacts for testing larger wafers, then the number of integrated circuits that can be tested simultaneously increases, but the probe base plate becomes more prone to bending and deflection under pressing force
Solution Approach 1:
The patent applies local quality by making the probe lands in the central region thicker than those in the outer regions. This non-uniform thickness distribution provides additional structural support where the pressing force causes the most deflection (center region), while maintaining thinner lands at the periphery where less support is needed. This resolves the contradiction by locally reinforcing the probe base plate structure to prevent bending while maintaining the large overall size needed for high productivity.
2Reliability
If the pressing force per contact is increased to improve electrical contact quality, then the electrical connection reliability improves, but the total pressing force on the probe base plate increases causing greater bending and height variations
Solution Approach 1:
The patent makes the probe lands thicker in the central region to provide additional support against bending when pressing force is applied. This local reinforcement compensates for the deflection that would otherwise cause height variations, allowing high pressing forces to be applied without sacrificing tip height uniformity. This resolves the contradiction by enabling reliable electrical contact while maintaining manufacturing precision through localized structural enhancement.
3Manufacturing precision
If the probe base plate is flattened to make uniform the heights of contact tips, then the electrical connection consistency improves, but the structural complexity and manufacturing difficulty increase
Solution Approach 1:
The patent achieves tip height uniformity by varying the thickness of probe lands locally - thicker in the center and thinner at the periphery. This approach is simpler than attempting to flatten the entire probe base plate, as it only requires local thickness variation rather than global flattening. The non-uniform land thickness compensates for deflection under load, maintaining tip height consistency while avoiding the complexity of a completely flattened structure.
4Productivity
If the number of contacts on the probe base plate is increased to test more integrated circuits, then the productivity increases, but the total pressing force increases causing greater deflection of the probe base plate
Solution Approach 1:
The patent handles the increased total pressing force from numerous contacts by providing localized reinforcement through thicker probe lands in the central region. This distributed reinforcement strategy allows the probe base plate to support the cumulative pressing force from many contacts without excessive deflection, enabling high contact counts for improved productivity while maintaining structural integrity.
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 ensures better contact pressure and reduces distance variations between contacts and the device under test, enabling more accurate testing by minimizing differences in slide and scrape marks, thus improving the reliability of electrical connections.
Implementation Method 1
the tip of each contact is pressed against an electrode of the integrated circuit to be elastically deformed
Data Source
AI summary
An embodiment of an electrical connecting apparatus comprises a probe base plate and a plurality of contacts provided with tips to be pressed against electrodes of a device under test and arranged on the underside of the probe base plate. The distance dimensions from an imaginary plane parallel to the probe base plate to the tips of the contacts are made the greater toward the center of the probe base plate.