IC Probing Device With Nano-Contactor For Fine-Pitch Testing
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Solution Overview
Problem
Current electrical testing of ICs with fine-pitch contact pads or micro-bumps faces challenges such as constructing probes that match shrinking sizes, alignment accuracy, potential damage from probing, and durability of fine-pitch probes, especially with conventional cantilever and vertical probe cards being limited in flexibility and accuracy.
Innovation Solution
A semiconductor substrate with an anisotropically conducting contactor comprising nano-scaled conductors embedded in an insulating matrix, allowing for a probing device with probes that can be precisely aligned and selected for contact with IC pads, enabling electrical testing of ICs with pitches as low as 20 micrometers without requiring specific tester input boards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional cantilever probe technology is used, then the probe array can be constructed with simple structure, but the pitch is limited to minimum 20 μm and configuration is restricted to two rows or four staggered rows
Solution Approach 1:
The probe card is divided into multiple independently controllable probe groups, where each group can be selectively activated or deactivated. This segmentation allows flexible configuration of probe arrays while maintaining structural simplicity, resolving the contradiction between device complexity and adaptability.
Solution Approach 2:
The probe card incorporates dynamic control mechanisms that allow the probe configuration to be changed during operation. By enabling selective activation of different probe groups, the system transitions from a static fixed configuration to a dynamic reconfigurable system, achieving versatility without proportionally increasing complexity.
2Adaptability or versatility
If vertical probe cards are used, then arbitrary arrays of probes can be constructed, but the minimum pitch is limited to 40 μm
Solution Approach 1:
Different regions of the probe card are designed with locally optimized characteristics. By varying the probe density and spacing in different areas according to specific testing requirements, the system achieves arbitrary array configurations with fine pitch in critical regions while maintaining overall structural feasibility.
Solution Approach 2:
The probe card design transitions from a two-dimensional planar arrangement to a three-dimensional structure with multiple layers or height variations. This dimensional change enables arbitrary probe arrays with fine pitch by utilizing vertical space and angular orientations, overcoming the 40 μm pitch limitation of conventional vertical probe cards.
3Measurement precision
If probe-to-pad alignment accuracy is maintained at +/- 1.8 μm, then conventional probe stations can be used, but this becomes a bottleneck when micro-bump pitch is 20 μm and bump diameter is about 10 μm
Solution Approach 1:
The probe card incorporates self-alignment features and compensation mechanisms that automatically correct for misalignment without requiring high-precision external alignment equipment. This self-service capability maintains effective measurement precision at the probe-bump interface while allowing the use of less precise (and more productive) probe stations.
Solution Approach 2:
The system changes the alignment parameter from requiring high precision (±1.8 μm) to accepting lower precision by incorporating tolerance compensation in the probe card design. By modifying the alignment approach and using parameters such as probe group selection and local positioning, the system maintains testing accuracy while significantly improving productivity with coarser alignment capabilities.
4Reliability
If the pitch of probes is made smaller than the pitch of bumps, then each bump can be contacted by a plurality of probes, but the contactor requires a specific tester input board for each IC under test
Solution Approach 1:
The probe card is designed with universal interfaces and standardized connection protocols that allow a single probe card design to work with multiple different IC types and tester input boards. By incorporating multi-functionality and adaptability in the connection interface, the system achieves reliable multi-probe contact without requiring custom-specific input boards for each IC type, thereby reducing device complexity.
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
The solution allows for accurate and durable electrical testing of ICs with fine-pitch contact structures, enabling precise alignment and connection of probes to pads with reduced risk of damage, and facilitates fan-out routing to test equipment, improving testing efficiency and accuracy.
Implementation Method 1
the anisotropically conducting contactor comprises a multitude of nano-scaled conductors embedded in an insulating matrix, so that each probe is formed by a plurality of nano-scaled conductors
Data Source
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Figure 3a~3b
AI summary
The present invention is related to a probing device for electrical testing of ICs, comprising a semiconductor substrate and an anisotropically conducting contactor attached to the substrate. The substrate comprises an integrated circuit portion comprising an array of contact pads on the surface of the substrate. The contactor is attached to the array of pads and comprises an array of probes, each probe being in contact with one pad. The IC portion comprises circuitry for selecting a number of probes and connecting the selected probes to an I/O terminal of the device, for connection to test equipment. According to a particular embodiment, the anisotropically conducting contactor comprises a multitude of nano-scaled conductors embedded in an insulating matrix, so that each probe is formed by a plurality of nano-scaled conductors.