Inspection Socket Coaxial Structure for Low-Loss RF Contact

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Solution Overview

Problem

Existing inspection sockets face issues with signal attenuation, concentric accuracy, and warpage due to long plungers and uneven preload distribution, which can damage electronic devices with many contact terminals, especially when assembling high-frequency RF signal transmission paths.

Innovation Solution

The inspection socket design incorporates a flange section with a tapered portion and cut surface on the contact terminal, allowing for preloading through an alignment board that suppresses warpage and reduces signal attenuation, while maintaining high assemblability and concentric accuracy by using a coaxial structure with a dielectric layer for impedance matching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the plunger is made long to reach the solder ball, then the contact force is improved, but signal attenuation increases and concentric accuracy deteriorates

Engineering Contradiction:
Improvecontact forceVSAvoidsignal attenuation
Core Design Contradiction:
ForceVSLoss of energy

Solution Approach 1:

The contact terminal is divided into multiple sections: a barrel section, a plunger section, and an intermediate section with a flange. This segmentation allows the plunger to be shorter while maintaining contact force through the flange's preload function, thereby reducing signal attenuation and improving concentric accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The flange acts as an intermediary element between the barrel and the plunger. It receives the preload from the housing and transmits it to the plunger, enabling effective contact force without requiring a long plunger, thus reducing signal attenuation and improving concentric accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the plunger is made long to ensure contact, then the contact reliability is improved, but manufacturing precision and concentric accuracy worsen

Engineering Contradiction:
Improvecontact reliabilityVSAvoidconcentric accuracy
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The contact terminal is segmented with a flange section that provides a reference surface for positioning. This allows the plunger to be shorter while maintaining concentric accuracy through the flange's positioning function, thereby improving manufacturing precision without sacrificing contact reliability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The flange is designed to receive preload from the housing before the plunger makes contact with the solder ball. This preliminary action positions the plunger correctly, ensuring concentric accuracy and contact reliability simultaneously.

Inventive Principle:
Principle #10Preliminary action

3Force

If multiple housings are laminated to provide preload, then the contact force is improved, but the plunger length must be precisely adjusted and warpage may occur

Engineering Contradiction:
Improvepreload forceVSAvoidassembly complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The flange is designed with specific local features (tapered portion, cut surface) that concentrate the preload application area. This localized quality improvement allows effective preload transmission without requiring complex multi-housing structures or precise plunger length adjustments.

Inventive Principle:
Principle #3Local quality

4Stability of the object's composition

If the housing thickness is increased to suppress warpage, then the structural stability is improved, but the plunger becomes longer causing signal attenuation

Engineering Contradiction:
Improvestructural stabilityVSAvoidsignal attenuation
Core Design Contradiction:
Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The flange section with its tapered portion and cut surface provides localized structural reinforcement at the critical preload application area. This local quality improvement suppresses warpage without requiring increased overall housing thickness, thereby preventing plunger length increase and avoiding signal attenuation.

Inventive Principle:
Principle #3Local quality

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 design effectively reduces signal attenuation, improves concentric accuracy, and enhances assemblability by minimizing warpage and crosstalk, ensuring reliable high-frequency signal transmission in electronic devices.

Implementation Method 1

an air layer is formed between a contact terminal and a through-hole in a metal block into which the contact terminal is inserted, thereby forming a coaxial structure that has a signal contact terminal as a core conductor and an inner wall defining the through-hole as an outer conductor

Methodology Applied
Scientific EffectImpedance matching: Dielectric

Data Source

PatentEP3842811B1Inspection socket
Publication Date: 2024.01.17 YAMAICHI ELECTRONICS CO LTD
  • EP3842811B1 patent drawingFigure 1
  • EP3842811B1 patent drawingFigure 2
  • EP3842811B1 patent drawingFigure 3

AI summary

The inspection socket includes: a contact terminal 80 including a barrel 82 having a flange section 90, a device-side terminal 84, and a board-side terminal 86; housings 10, 30, and 50 having through holes 10c, 30c, and 50c into which the contact terminal 80 is inserted; and housings 20 and 40 having through holes 20c and 40c into which the contact terminal 80 is inserted, the through holes 20c and 40c being larger than the outer diameter of the contact terminal 80 excluding the flange section 90 and smaller than the outer diameter of the flange section 90. The housings 20 and 40 are sandwiched between the housings 10, 30, and 50, the flange section 90 is contained in the through hole 50c, and the through holes 10c, 30c, and 50c are designed to have, for impedance matching, a gap from the outer periphery of the contact terminal 80.