Microfabricated Probe Card Needles for High-Density Semiconductor Testing
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Solution Overview
Problem
Existing probe card needles struggle with miniaturization and high-density integration of semiconductor chips due to limitations in pad pitch, increased failure rates during manual mounting, and inability to achieve fast signal response, especially when the number of devices to be tested exceeds 64, as they adhere to each other and fail to match impedance with printed circuit boards.
Innovation Solution
The development of probe card needles formed on a ceramic circuit board using microfabrication technology, incorporating a conductive metal layer and a polymeric elastomer layer, which allows for precise formation of probe tips and improved elasticity, enabling reduced pad pitch and increased number of needles without manual mounting failures, and supporting high-speed signal response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If tungsten probe needles with diameter of 100±10 microns are used, then mechanical contact with electrode pads is achieved, but probe needles adhere to each other when pad pitch is less than 100 microns
Solution Approach 1:
The patent changes the material parameter from tungsten to copper, which has different physical properties including lower adhesion tendency. It also changes the dimensional parameter by reducing probe needle diameter to 50 microns, enabling operation at pad pitches less than 100 microns without adhesion problems
Solution Approach 2:
The patent uses copper as a composite material alternative to tungsten, leveraging copper's superior electrical conductivity and reduced adhesion characteristics to solve both the precision and reliability issues simultaneously
2Ease of operation
If manual mounting of probe needles is performed, then individual needle placement is possible, but failure rate increases greatly when number of devices tested exceeds 64
Solution Approach 1:
The patent replaces the manual mechanical mounting system with an automated lamination process using heat and pressure. This substitution eliminates human error and enables consistent, high-volume production without increasing failure rates, even when testing more than 64 devices simultaneously
Solution Approach 2:
The patent applies a resin layer that undergoes thermal curing, changing from a soft state during placement to a hardened state after lamination. This phase change enables precise needle positioning followed by secure fixation, achieving both ease of operation and high reliability
3Reliability
If wires and probe needles are exposed, then electrical connection is achieved, but impedance does not coincide with printed circuit board causing slow signal response
Solution Approach 1:
The patent creates a homogeneous impedance environment by covering exposed wires and probe needles with resin, eliminating impedance discontinuities. This homogenization maintains constant impedance throughout the signal path, enabling fast signal response speeds while preserving reliable electrical connections
4Manufacturing precision
If microfabrication technology is used to form probe needles, then miniaturization is achieved, but strength and elasticity are insufficient
Solution Approach 1:
The patent creates a composite structure where copper probe needles (providing strength and conductivity) are embedded in a resin matrix (providing elasticity and support). This composite approach enables miniaturization to 50-micron diameters while maintaining sufficient mechanical strength and elastic recovery for reliable contact
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 solution enhances the reliability and accuracy of probe card needles by preventing plastic deformation, ensuring sufficient strength and elasticity, enabling testing of 256 chips simultaneously with a pad pitch of 50 microns and signal response at 2-GHz speeds, while reducing failure rates and maintaining contact force.
Implementation Method 1
forming, on a ceramic board, probe needle bases made of conductive metal and having an island seed layer, using photolithography and a photoresist
Implementation Method 2
a polymeric elastomer layer formed just below the conductive metal layer
Data Source
AI summary
Disclosed are probe card needles manufactured using microfabrication technology, a method for manufacturing the probe card needles, and a probe card having the probe card needles. The probe needles are manufactured by forming, on a ceramic board, probe needle bases made of conductive metal, and a polymeric elastomer layer, by using photolithography and a photoresist, and continuously depositing conductive metal layers on the probe needle bases in such a manner as to be supported by the polymeric elastomer layer. The probe card comprises: a printed circuit board (PCB) which is connected to a test head for transmitting an electrical signal from a tester; a ceramic board located below the PCB and electrically connected to the PCB by a plurality of interface pins; a jig for mechanically holding the interface pins and the multilayer ceramic board to the PCB; and a plurality of probe needles attached to the lower surface of the multilayer ceramic board and making contact with electrical/electronic devices.