Ceramic Circuit Board Thermal Expansion Control
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Solution Overview
Problem
Ceramic circuit boards face challenges in achieving a low thermal expansion coefficient and high mechanical strength, particularly when used as interposer boards in semiconductor wafer inspection, where positional accuracy and thermal expansion matching with test heads and semiconductor wafers are critical across a wide temperature range.
Innovation Solution
A ceramic circuit board composition incorporating glass, willemite filler, and alumina filler, with specific mass percentage ranges and particle diameter ratios, is used to achieve a low thermal expansion coefficient and high mechanical strength, allowing for accurate semiconductor wafer inspection across varying temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a ceramic circuit board is formed using low-temperature fired ceramics containing glass, then the firing temperature is reduced, but the thermal expansion coefficient cannot be sufficiently lowered to match semiconductor wafer requirements
Solution Approach 1:
The patent employs a composite ceramic material system comprising glass matrix, willemite filler (Zn2SiO4), and alumina filler (Al2O3). This multi-component composite enables simultaneous achievement of low firing temperature (due to glass flux) and low thermal expansion coefficient (through willemite and alumina fillers with matched thermal expansion properties to semiconductor materials).
Solution Approach 2:
The patent systematically varies the composition ratios of glass, willemite filler, and alumina filler to optimize both thermal expansion coefficient and mechanical strength. By adjusting these compositional parameters, the ceramic board achieves thermal expansion coefficients matching semiconductor wafers while maintaining structural integrity at low firing temperatures.
2Reliability
If the thermal expansion coefficient of the interposer board is lowered to match the semiconductor wafer, then thermal expansion matching is improved, but the mechanical strength may be compromised
Solution Approach 1:
The ceramic board utilizes a composite structure where glass provides binding and flexibility, while willemite and alumina fillers provide structural strength and controlled thermal expansion. This composite architecture allows the material to simultaneously achieve low thermal expansion (for matching semiconductor wafers) and high mechanical strength (through the reinforcing filler network).
Solution Approach 2:
The patent distributes different filler materials (willemite and alumina) throughout the glass matrix to create localized regions with optimized properties. The fillers are dispersed to provide both thermal expansion control and mechanical reinforcement throughout the ceramic structure, ensuring uniform performance across the interposer board.
3Reliability
If the particle diameter of willemite filler is made larger than alumina filler, then thermal expansion control is improved, but manufacturing precision may be affected
Solution Approach 1:
The patent specifies controlled particle diameter ranges for willemite and alumina fillers, with willemite having larger average particle diameter than alumina. This parameter optimization ensures proper thermal expansion behavior while the controlled size distribution and mixing protocols maintain manufacturing precision for electrode pad positioning.
Solution Approach 2:
The patent creates a heterogeneous filler distribution where larger willemite particles and smaller alumina particles are strategically distributed within the glass matrix. This local quality variation optimizes thermal expansion control while the controlled particle size distribution prevents interference with precision manufacturing processes for electrode patterns.
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 ceramic circuit board achieves a thermal expansion coefficient of 4 ppm/°C or less and three-point bending strength of 100 MPa or more, ensuring accurate semiconductor wafer inspection and mechanical integrity within the temperature range of −40° C. to +125° C.
Implementation Method 1
it is preferable to make a thermal expansion coefficient of the interposer board approximate to a thermal expansion coefficient of the test head or the printed ceramic circuit board such that there is no difference between the distance between the electrode pads of the interposer board and the distance between the electrode pads of the test head or the printed ceramic circuit board when the inspection temperature changes
Data Source
AI summary
A ceramic circuit board includes: a ceramic board; and an internal conductor disposed in the ceramic board, in which the ceramic board contains glass, a willemite filler, and an alumina filler, and an average particle diameter of the willemite filler is larger than an average particle diameter of the alumina filler.