Crystal Unit Package Venting for Accurate Temperature Sensing
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Solution Overview
Problem
In crystal units, the temperature difference between the crystal element and the thermosensitive element is exacerbated by heat transfer from other electronic components, leading to inaccuracies in voltage conversion temperature readings.
Innovation Solution
A crystal unit design featuring a rectangular substrate with a frame on the upper surface and a mounting frame on the lower surface, creating a clearance portion that allows heated air to escape and external air to enter, thereby mitigating heat influence on the thermosensitive element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the thermosensitivel element is mounted in the second concave portion on the lower surface of the substrate, then the temperature around the thermosensitivel element can be measured, but heat from other electronic parts accumulates in the second concave portion causing temperature measurement inaccuracy
Solution Approach 1:
The harmful hot air is extracted from the second concave portion through the clearance portion formed between the mounting frame and the substrate. This allows the accumulated heat to be removed from the measurement environment, resolving the contradiction between having a covered structure for protection and preventing heat accumulation that affects measurement accuracy.
Solution Approach 2:
The clearance portion is strategically positioned only in specific regions where heat accumulation occurs, while other areas maintain their sealed structure. This localized opening allows heat removal without compromising the overall protective enclosure, addressing the measurement accuracy issue without sacrificing structural integrity.
2Reliability
If a sealed package structure is used to protect the crystal element and thermosensitivel element, then environmental protection is improved, but heat from surrounding electronic parts transfers to the interior causing temperature differences
Solution Approach 1:
The clearance portion acts as an intermediary channel between the sealed interior and the external environment. It allows thermal exchange without requiring a fully open structure, thus maintaining environmental protection while enabling heat dissipation to reduce temperature differences between the crystal element and thermosensitivel element.
Solution Approach 2:
The package structure is segmented into sealed regions for protection and a specific clearance region for thermal management. This segmentation allows different parts of the package to serve different functions - most areas remain sealed for environmental protection while the clearance portion enables heat removal.
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 reduces the temperature difference between the thermosensitive element's output voltage and the actual temperature around the crystal element, improving accuracy and stability.
Implementation Method 1
A crystal unit utilizes a piezoelectric effect of a crystal element to generate a specific frequency
Implementation Method 2
air which is heated up by that heat is not accumulated in the second concave portion. Rather, the heated air is discharged to the outside through the clearance portion, and external air enters the second concave portion through the clearance portion
Data Source
AI summary
A crystal unit is provided with a rectangular substrate, a frame which is provided on an upper surface of the substrate, a mounting frame which has joining pads which are provided along the outer circumferential edge of the upper surface and which is provided on the lower surface of the substrate by joining joining terminals provided along the outer circumferential edge of the lower surface of the substrate and its joining pads, a crystal element which is mounted on electrode pads which are provided on the upper surface of the substrate in a region surrounded by the frame, a thermosensitive element which is mounted on connection pads which are provided on the lower surface of the substrate in a region surrounded by the mounting frame, and a lid which is joined to the upper surface of the frame.