Wafer Placement Table Plug Joint for Secure Gas-Permeable Retention

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Solution Overview

Problem

Existing wafer placement tables face challenges in preventing gas-permeable plugs from slipping out of their placement holes due to the difficulty in forming protrusions or similar structures on the vent path inner walls.

Innovation Solution

A wafer placement table design featuring a plug joint that covers the outer edge of the plug and the plug placement hole opening edge, either through thermal spraying or laser welding, to secure the plug in place.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If protrusions are formed on the inner wall of the vent path to prevent the gas-permeable member from moving, then the plug can be secured in place, but the manufacturing complexity and difficulty increase significantly

Engineering Contradiction:

Improveplug retentionVSAvoidmanufacturing difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of forming protrusions on the inner wall of the vent path (inside the ceramic plate), the invention forms protrusions on the outer surface of the plug. This inversion of where the retaining feature is located simplifies manufacturing since the plug can be independently formed with external protrusions that then engage with the vent path structure during assembly, avoiding the need to create complex internal features in the ceramic plate

Inventive Principle:

Principle #13The other way round (Inversion)

2Strength

If the plug joint covers the entire circumference of the plug, then the joint strength is maximized, but the device complexity and material usage increase

Engineering Contradiction:

Improvejoint strengthVSAvoidstructure complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The plug joint is segmented into discrete positioning points arranged circumferentially around the plug rather than forming a continuous circumferential joint. This segmentation provides sufficient retention strength through multiple distributed contact points while simplifying the overall structure and reducing material requirements compared to a full circumferential joint

Inventive Principle:

Principle #1Segmentation

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 plug joint effectively prevents the plug from slipping out of the placement hole, ensuring stable operation and facilitating easy replacement when needed.

Implementation Method 1

either through thermal spraying or laser welding

Methodology Applied

Scientific EffectThermal spraying: Plasma Spray

Implementation Method 2

either through thermal spraying or laser welding

Methodology Applied

Scientific EffectLaser welding: Laser Beam Welding

Data Source

PatentUS12451385B2Wafer placement table

Publication Date: 2025.10.21 NGK INSULATORS LTD

AI summary

A wafer placement table includes: a ceramic plate having a wafer placement surface on an upper surface and a built-in electrode; a plug placement hole extending through the ceramic plate from a lower surface to the upper surface; a plug placed in the plug placement hole and allowing gas to pass therethrough; and a plug joint joining an outer edge of an upper surface of the plug and an upper opening edge of the plug placement hole and covering the outer edge of the upper surface of the plug from above.