OCXO Package Layout for Vacuum-Sealed Thermal Insulation
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Solution Overview
Problem
Conventional oven-controlled crystal oscillators (OCXOs) face a challenge in maintaining thermal insulation due to the encapsulation of components like capacitors, which can lead to gas generation and loss of vacuum when soldered, resulting in reduced thermal insulation.
Innovation Solution
The OCXO design includes a core section with an oscillation IC, piezoelectric resonator, and heater IC, hermetically encapsulated in a package. A circuit component, such as a capacitor, is attached to the package using a bonding material, but is disposed in a space outside the sealed vacuum space, preventing gas generation and maintaining vacuum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a capacitor is encapsulated in the package and soldered, then the component can be mounted and connected, but gas is generated due to re-melting of solder which results in loss of vacuum in the package
Solution Approach 1:
The package is divided into two distinct spaces: a sealed vacuum space containing the core section (piezoelectric resonator, oscillation IC, heater IC) and an unsealed space for mounting circuit components like capacitors. This segmentation allows the capacitor to be soldered in the unsealed space without generating gas that would compromise the vacuum in the sealed space, thus resolving the contradiction between ease of manufacture and vacuum preservation.
Solution Approach 2:
The capacitor is extracted from the sealed vacuum space and mounted on the outer surface of the package. This extraction removes the source of gas generation (soldering process) from the vacuum environment, allowing the capacitor to be easily mounted and connected without causing vacuum loss in the sealed space containing the core section.
2Loss of energy
If the package is vacuum-sealed to increase thermal insulation, then thermal insulation is improved, but components cannot be soldered inside the package
Solution Approach 1:
The package structure is segmented into a sealed vacuum space for thermal insulation and an unsealed external space for component mounting. The sealed space maintains vacuum to prevent heat transfer and improve thermal insulation, while the external space allows capacitors and other components to be soldered without compromising the vacuum seal, thus resolving the contradiction between thermal insulation and ease of manufacture.
Solution Approach 2:
The package body acts as an intermediary structure that separates the vacuum-sealed internal environment from the external mounting environment. This intermediary structure allows thermal insulation to be maintained within the sealed space while providing an external surface for soldering components, thus enabling both thermal insulation and ease of manufacture to coexist.
3Reliability
If the loss of vacuum in the package occurs, then the vacuum seal is broken, but thermal insulation of the OCXO is reduced
Solution Approach 1:
The package is segmented into a sealed vacuum space and an unsealed external space. Circuit components are mounted on the external surface rather than inside the sealed space. This segmentation ensures that the vacuum seal integrity is maintained in the sealed space, preventing thermal insulation degradation while still allowing component mounting and connection in the external space.
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 configuration effectively prevents loss of vacuum and maintains good thermal insulation in the OCXO, ensuring stable temperature control and oscillation frequency.
Implementation Method 1
The core section is vacuum-sealed in a sealed space of the package
Implementation Method 2
a heat insulation package in which the core section is hermetically encapsulated
Implementation Method 3
In a piezoelectric resonator such as a crystal resonator, the vibration frequency changes depending on the temperature
Implementation Method 4
a heater IC
Data Source
AI summary
An OCXO according to one or more embodiments may include a core section hermetically encapsulated in a heat insulation package. The core section includes: an oscillation IC; a crystal resonator; and a heater IC. The core section is supported by the package via a core substrate. The OCXO further includes a capacitor as an electronic component for adjustment, which is attached to the package by soldering. The core section is vacuum-sealed in a sealed space of the package, while the capacitor is disposed in a space other than the sealed space.