Piezoelectric Device Frame Composite Material Welding
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Solution Overview
Problem
Quartz crystal oscillators with ceramic and metal components experience cracking due to significant differences in thermal expansion coefficients during welding, leading to operational issues.
Innovation Solution
A piezoelectric device with a frame composed of a composite material containing metal and metal oxide, allowing for electroplating and reducing thermal shock during welding, thereby preventing crack generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal sealing conductor is arranged on the frame-shaped ceramic layer and joined to the metal lid by resistance welding, then the space for the quartz resonator is formed, but the frame-shaped ceramic layer cracks around the sealing conductor region due to significant difference in thermal expansion coefficients between the ceramic and metal
Solution Approach 1:
The patent applies composite materials by forming a composite portion containing both metal and metal oxide within the frame-shaped ceramic layer. This composite structure has a thermal expansion coefficient that is closer to that of the metal sealing conductor than pure ceramic, reducing thermal shock during resistance welding and preventing crack generation while maintaining sealing performance
Solution Approach 2:
The patent changes the physical parameter of thermal expansion coefficient by incorporating metal particles into the metal oxide matrix. The composite portion's thermal expansion coefficient is adjusted to an intermediate value between pure ceramic and pure metal, specifically designed to match the metal sealing conductor better, thereby reducing thermal stress during welding operations
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 use of a composite frame with a metal and metal oxide composite portion enhances electrical conductivity, prevents peeling of the metal layer, and reduces thermal shock, effectively suppressing crack formation and improving sealing performance.
Implementation Method 1
the metal layer and the metal lid being joined to each other by resistance welding
Implementation Method 2
The coefficient of thermal expansion of the composite portion becomes a value closer to that of the metal than that of a ceramic consisting of the pure metal oxide. This relieves thermal shock caused in the composite portion during the resistance welding
Implementation Method 3
the composite portion has electric conductivity and thus can be subjected to electroplating
Data Source
AI summary
A piezoelectric device has: a ceramic substrate having a first principal surface and a second principal surface opposed to each other; a piezoelectric element arranged on the first principal surface; a frame having a first face and a second face opposed to each other and arranged on the ceramic substrate so as to surround the piezoelectric element; a metal layer arranged on the second face of the frame; and a metal lid arranged on the metal layer so as to close a space surrounded by the frame. The first face of the frame is in contact with the first principal surface of the ceramic substrate. The metal layer and the metal lid are joined to each other by resistance welding. The frame has a composite portion containing a metal and a metal oxide and the composite portion includes the second face and is in contact with the metal layer.