Rigid Probe Head for 3D IC Wafer Testing
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Solution Overview
Problem
Existing probe card designs and assembly techniques struggle with testing small pitch micro bump arrays on 3D IC chip packages due to limitations in guide plate manufacturing, probe handling, and the fragility of flexible probes, leading to inaccurate alignments and frequent damage during wafer level testing.
Innovation Solution
A probe card design featuring a testing probe head with rigid metallic probes and a guide plate assembly that includes stoppers to prevent lateral deformation and breakage, combined with a fabrication method using reverse wire electrical discharge machining (R-WEDM) to produce probes with precise pitch and strength, allowing for accurate and reliable connections with microbump arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If flexible needle-like metal testing probes are used to test small pitch micro bump arrays, then the probes can be inserted through small diameter probe holes, but the probes are easily bent and damaged during handling and assembly
Solution Approach 1:
The patent changes the fundamental parameter of probe rigidity from flexible to rigid. The rigid metallic probes maintain structural strength while still being able to insert through small diameter probe holes due to their precise manufacturing and controlled insertion process using R-WEDM technology.
Solution Approach 2:
The probe holes in the guide plate are pre-formed with precise dimensions and positions using R-WEDM before probe insertion. This preliminary preparation ensures that rigid probes can be accurately inserted without bending, as the insertion path and positioning are predetermined and precisely controlled.
2Ease of manufacture
If manual insertion techniques are used to insert slender probes through small diameter probe holes, then probe placement can be performed, but the operation is time-consuming and results in frequent damage to the structurally thin and weak probes
Solution Approach 1:
The patent replaces manual mechanical insertion operations with an automated R-WEDM (Reverse Wire Electrical Discharge Machining) process. This automated system precisely machines the probe holes and positions the rigid probes without manual handling, dramatically increasing assembly speed while eliminating probe damage associated with manual insertion of flexible probes.
Solution Approach 2:
The R-WEDM system performs both the machining of probe holes and the positioning/insertion of probes in an integrated automated process. The system serves itself by automatically completing the entire probe assembly operation without manual intervention, thereby increasing productivity and eliminating handling damage.
3Ease of manufacture
If existing guide plate manufacturing techniques are used to create closely spaced holes for small pitch probes, then probe placement is possible, but manufacturing precision and alignment accuracy are insufficient for fine pitch arrays
Solution Approach 1:
The patent replaces conventional mechanical drilling or punching methods for creating probe holes with R-WEDM (Reverse Wire Electrical Discharge Machining). This electrical discharge process achieves superior manufacturing precision for closely spaced holes, enabling accurate positioning for fine pitch probe arrays while maintaining ease of manufacture through automated processing.
4Strength
If rigid metallic probes are used instead of flexible probes, then probe strength and durability are improved, but the probes require more precise alignment and positioning during assembly
Solution Approach 1:
The patent uses R-WEDM to automatically machine both the probe holes in the guide plate and the corresponding positions on the substrate with high precision. This automated electrical discharge machining system ensures that rigid probes align perfectly with their target positions, eliminating the alignment difficulties that would otherwise arise from using rigid materials.
Solution Approach 2:
The guide plate serves as an intermediary component with precisely machined holes that guide and position the rigid probes during insertion. The R-WEDM process ensures the guide plate holes are precisely positioned, thereby facilitating accurate alignment of rigid probes without requiring direct high-precision positioning during the insertion operation itself.
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 enables precise and durable probe connections for wafer level testing, reducing assembly time and reject rates, and supporting high probe counts with fine pitch spacing suitable for 3D IC packages, while minimizing manual handling and damage to probes.
Implementation Method 1
cutting a plurality of first channels in the workpiece in a first axial direction using an electric discharge wire; cutting a plurality of second channels in the workpiece in a second axial direction using the electric discharge wire
Data Source
AI summary
A testing probe card for wafer level testing semiconductor IC packaged devices. The card includes a circuit board including testing circuitry and a testing probe head. The probe head includes a probe array having a plurality of metallic testing probes attached to a substrate including a plurality of conductive vias. In one embodiment, the probes have a relatively rigid construction and have one end that may be electrically coupled to the vias using a flip chip assembly solder reflow process. In one embodiment, the probes may be formed from a monolithic block of conductive material using reverse wire electric discharge machining.