Probe Card Assembly Thermal Warping Decoupling
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Solution Overview
Problem
Probe card assemblies experience significant warping due to temperature changes, leading to unstable probe contact pressures and prolonged preheating times, which result in defective measurements and low throughput during wafer testing.
Innovation Solution
A probe card assembly with a loosely decoupled PCB support mechanism using spacers or elastic elements to absorb thermal expansion, allowing for minimal warping of the stiffener and maintaining consistent probe contact pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the PCB is tightly attached to the stiffener, then structural stability is improved, but warping due to temperature changes increases
Solution Approach 1:
The stiffener is divided into a first stiffener portion and a second stiffener portion that are movable relative to each other along a first direction. This segmentation allows the structure to accommodate thermal expansion and contraction, reducing warping while maintaining overall stability.
Solution Approach 2:
The patent introduces a play or gap between the PCB and the stiffener, and between the first and second stiffener portions. This parameter change allows the structure to flex and adjust during thermal cycles, preventing rigid warping while maintaining structural integrity.
2Strength
If the PCB is tightly attached to the stiffener, then structural support is improved, but probe contact pressure stability deteriorates
Solution Approach 1:
The stiffener is segmented into movable portions that can adjust independently. This allows the structure to maintain support strength while accommodating dimensional changes that would otherwise affect probe contact pressure.
Solution Approach 2:
The stiffener portions are designed to move dynamically in response to thermal changes. This dynamic adjustment maintains stable probe contact pressure despite temperature variations, while the overall structural support remains intact.
3Measurement precision
If preheating time is extended, then measurement accuracy is improved, but productivity deteriorates
Solution Approach 1:
The wafer receptacle is preheated or pre-cooled to the target test temperature before the wafer is introduced. This preliminary thermal conditioning eliminates the need for extended preheating after wafer loading, maintaining measurement accuracy while significantly reducing cycle time and improving throughput.
Solution Approach 2:
The patent prepares the thermal environment in advance by conditioning the wafer receptacle before wafer insertion. This beforehand preparation cushions against the need for lengthy post-loading thermal equilibration, ensuring accurate measurements without sacrificing productivity.
4Productivity
If the wafer receptacle is heated quickly, then productivity is improved, but measurement accuracy deteriorates due to warping
Solution Approach 1:
The segmented stiffener structure allows for rapid thermal equilibration without inducing excessive warping. Each segment can adjust independently to thermal changes, enabling faster heating cycles while maintaining measurement accuracy.
Solution Approach 2:
The dynamic, movable stiffener portions respond flexibly to rapid temperature changes. This dynamic adaptability allows quick heating for improved productivity while preventing the rigid warping that would compromise measurement accuracy.
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 effectively reduces warping and maintains consistent probe contact pressures, enhancing measurement accuracy and reducing cycle times by decoupling the PCB from the stiffener, thereby improving the overall efficiency of the wafer testing process.
Implementation Method 1
multiple screws with spacers are inserted between the PCB and the stiffener. The spacers are preferably designed as spacer sleeves that function like a shoulder screw.
Data Source
AI summary
The invention relates to a probe card assembly comprising a stiffener (1), comprising a PCB (2) disposed in the stiffener (1), and comprising a spider (3) supported by the stiffener and the PCB (2), said spider comprising at least one probe (30) to test a wafer (5). This probe card assembly of the PCB (2) is supported in a loosely decoupled manner in the stiffener (1) to prevent transmission of high thermally-induced warping effects.