Pressure Sensor Bubble Discharge Opening Design
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Solution Overview
Problem
In pressure sensors, bubbles trapped in the adhesive between the substrate and the chip mounting member can lead to reduced electrostatic strength and aesthetic defects due to the inferior dielectric strength of air compared to the adhesive, and the bubbles may not be easily discharged during the solidification process.
Innovation Solution
Incorporating bubble discharge openings on the substrate adjacent to the input-output terminals, allowing bubbles to be easily discharged into the internal space of the sensor unit accommodating portion and outside, preventing their entrapment in the adhesive and maintaining electrostatic strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive is charged into the space between substrate and chip mounting member, then the substrate and components are hermetically sealed and protected from moisture, but bubbles contained in the adhesive may stick to and remain around the lead pins, deteriorating electrostatic strength and causing appearance defects
Solution Approach 1:
The patent extracts the harmful bubbles from the adhesive by providing a dedicated discharge path. The substrate includes a through-hole that serves as an escape route for bubbles during adhesive charging, allowing them to be removed from the sealing space before the adhesive solidifies, thus preventing bubble entrapment around the lead pins while maintaining hermetic sealing
2Reliability
If adhesive is solidified with bubbles trapped around lead pins, then the hermetic sealing is maintained, but the dielectric strength between lead pins and housing is reduced due to inferior dielectric strength of air
Solution Approach 1:
The patent applies preliminary action by providing a bubble discharge path before the adhesive solidifies. The through-hole in the substrate is pre-configured to allow bubbles to escape during the adhesive charging and solidification process, preventing bubble entrapment that would otherwise occur and compromise the dielectric strength between lead pins and housing
3Ease of manufacture
If adhesive is charged without bubble discharge openings, then the hermetic sealing process is simple, but bubbles may emerge on the uppermost surface of adhesive and cause appearance defects
Solution Approach 1:
The patent extracts bubbles from the adhesive charging process by incorporating a through-hole in the substrate that serves as a dedicated discharge path. This allows bubbles to be removed through the substrate rather than emerging on the uppermost surface of the adhesive, preventing appearance defects while maintaining ease of manufacture
Data Source
AI summary
In a pressure sensor including a substrate supported by input-output terminals, the substrate is provided with a circular hole located substantially at its central part, and an arc-shaped communication hole formed adjacent to three through-holes to which three of lead pins are inserted and fixed, respectively.