Perforated Metal Plate Space Transformer for Probe Pin Support
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Solution Overview
Problem
The challenge in the integrated circuit industry is performing comprehensive electrical testing on unpackaged die, which is complicated due to their small dimensions and numerous testable points, requiring a robust space transformer that can withstand thermal stress and ensure accurate testing without damaging the die.
Innovation Solution
A space transformer is designed with a substrate and a perforated metal sheet cover plate, where the substrate has conductive traces and probe pins, and the perforated plate provides lateral support and protection, featuring a higher Young's modulus and coefficient of thermal expansion matching the substrate to reduce wear and thermal stress, with a polymeric material insulating the metal sheet from the pins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a space transformer is used for electrical testing of unpackaged die, then testing accuracy is improved, but wear and misalignment occur due to repetitive interfacing
Solution Approach 1:
The patent changes the physical parameters of the space transformer by incorporating a metallic plate with high Young's modulus and matching coefficient of thermal expansion (CTE) to the substrate. This parameter optimization reduces wear and misalignment during repetitive die interfacing while maintaining testing accuracy. The metallic plate's mechanical properties are specifically selected to minimize degradation over time.
Solution Approach 2:
The space transformer employs a composite structure combining a substrate with a metallic plate layer. This composite material approach integrates the electrical properties of the substrate with the mechanical strength and thermal stability of the metal, creating a robust component that resists wear and maintains alignment precision during repeated testing operations.
2Adaptability or versatility
If testing is performed at high temperatures (200°C or more), then comprehensive electrical testing capability is improved, but thermal stress damages the space transformer
Solution Approach 1:
The patent applies thermal expansion principles by selecting a metallic plate with a coefficient of thermal expansion (CTE) that matches the substrate material. This CTE matching ensures that both materials expand and contract at the same rate during thermal cycling, preventing differential expansion stresses that would otherwise damage the space transformer structure during high-temperature testing.
Solution Approach 2:
The composite structure of substrate plus metallic plate creates a thermally stable assembly. The metal layer's thermal properties are engineered to complement the substrate, forming a composite material system that can withstand repeated thermal cycling at 200°C or higher without structural degradation, thereby enabling comprehensive high-temperature electrical testing.
3Measurement precision
If probe pin dimensions are reduced for accurate alignment with scaled interconnect geometries, then measurement precision is improved, but pin strength and durability worsen
Solution Approach 1:
The metallic plate integrated with the substrate provides enhanced mechanical support to the probe pins. This composite construction allows the pins to be made smaller for better alignment accuracy with scaled interconnect geometries while the surrounding metal structure compensates for the reduced pin strength, maintaining durability despite the smaller dimensions.
Solution Approach 2:
The space transformer structure segments the mechanical support function from the pin itself by introducing a metallic plate framework. This segmentation allows the pins to be optimized for electrical contact precision while the separate metal plate provides the structural strength and rigidity, enabling smaller pin dimensions without sacrificing durability.
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 configuration enhances the durability and accuracy of electrical testing by reducing wear and misalignment, ensuring high uptime and reliable electrical connections during thermal cycling, thereby improving the efficiency of unpackaged die testing.
Implementation Method 1
the perforated plate comprises a metal sheet insulated from the conductive pins by an insulative material disposed on a sidewall of the perforations
Implementation Method 2
the perforated plate provides lateral pin support
Implementation Method 3
the perforated plate features a higher Young's modulus and coefficient of thermal expansion matching the substrate to reduce wear and thermal stress
Data Source
AI summary
Space transformer including a substrate and a perforated plate disposed on the substrate. The substrate includes conductive traces and an array of conductive probe pins extend outwardly from anchor points on the substrate. The pins are electrically coupled to at least one of the conductive traces on the substrate as an interface between an E-testing apparatus and a DUT. The perforated plate may be affixed to a surface of the substrate and includes an array of perforations through which the conductive pins may pass. The perforated plate may provide one or more of lateral pin support and protection to the underlying substrate and/or traces. The perforated plate may include a metal sheet. A polymeric material may be disposed on at least a sidewall of the perforations to electrically isolate the metal sheet from the conductive probe pins.