Ceramic Heater Radial Interval Optimization
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Solution Overview
Problem
The existing wafer heating devices suffer from thermal non-uniformity due to the formation of hot and cold spots on the ceramic substrate, where the distance between folded-back heater patterns is too short, leading to temperature singularities, especially on the outer circumferential portions.
Innovation Solution
A ceramic heater with a plate-shaped design featuring embedded heat generating lines arranged concentrically, where the interval between folded-back portions is narrower at the ends to prevent cold spots and wider at the middle to prevent hot spots, ensuring improved thermal uniformity by optimizing heat distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the heater pattern is folded back with short distance between centers, then the heater pattern can be compactly arranged, but hot spots are generated and thermal uniformity deteriorates
Solution Approach 1:
The patent applies local quality by varying the interval between folded-back portions along the radial direction. Specifically, the interval is set to be narrower at the ends in the radial direction and wider at the middle portions. This non-uniform interval distribution creates different thermal characteristics in different regions, preventing both hot spots (by increasing spacing at middles) and cold spots (by decreasing spacing at ends), thereby resolving the thermal uniformity problem while maintaining compact heater arrangement.
2Temperature
If the heater pattern is folded back with narrow interval at ends, then cold spots are prevented in radial end regions, but the overall heater pattern complexity increases
Solution Approach 1:
The patent employs asymmetry by creating an non-uniform interval distribution between folded-back portions. Instead of using a constant interval throughout, the interval is deliberately made asymmetric with narrower spacing at the radial ends and wider spacing at the middle portions. This asymmetric configuration optimizes temperature distribution by addressing the different thermal needs of different regions, preventing both hot and cold spots while maintaining a relatively simple overall heater structure.
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 enhances thermal uniformity on the ceramic heater's surface by increasing heat quantity at the ends to prevent cold spots and reducing heat quantity at the middle to prevent hot spots, effectively addressing the temperature distribution issues.
Implementation Method 1
a heat generating element that is embedded in the ceramic substrate and in which linear heat generating lines are arranged substantially concentrically
Data Source
AI summary
This heat generating element of a ceramic heater, if viewed from the thickness direction of the ceramic heater, comprises: as a pair of heat generating lines formed from two heat generating lines adjacent to each other of the heat generating element in the radial direction, a pair of first heat generating lines and a pair of a second heat generating lines disposed apart from each other by sandwiching a prescribed separation region therebetween in the circumferential direction of the heating element; a first folded back portion connecting both ends on the separation region side of two of the heat generating lines forming the pair of first heat generating lines; and a second folded back portion connecting both ends on the separation region side of two of the heat generating lines forming the pair of second heat generating lines. At a pair of folded back portions formed from the first folded back portion and the second folded back portion, the spacing of the pair of folded back portions between the first folded back portion and the second folded back portion at the end on one side of the beat generating element in the radial direction is narrower than the spacing of the pair of folded back portions between the first folded back portion and the second folded back portion in the center of the heat generating element in the radial direction.