Pressure Sensor Support Ring Segmentation and Gel Flow Control
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Solution Overview
Problem
Conventional pressure sensors face challenges in manufacturing cost, reliability, and assembly complexity, particularly in automotive applications, due to issues with support ring formation, gel flow management, and expensive contact assemblies.
Innovation Solution
A pressure sensor design featuring a support ring with interference fit slits and planar mounting tabs for improved alignment and welding, an oversized wire bond window for enhanced gel flow management, and a gel flow barrier with a moat to redirect gel, along with a contact spring assembly using symmetrical springs for cost-effective and reliable connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional support rings are used (metal soldered or plastic glued), then the sensor assembly can be manufactured, but the support ring lip is difficult to form uniformly, resulting in poor welds, excessive gaps, burn through, or laser welder missing the interface location
Solution Approach 1:
The support ring is segmented with interference fit slits that allow the ring to be divided into sections. This segmentation enables the support ring to flex and adapt during assembly, making the lip formation easier and more uniform while improving weld quality by allowing better alignment between the support ring and sense element port.
Solution Approach 2:
The support ring incorporates interference fit slits that change the mechanical parameters of the ring, allowing it to expand or contract slightly during assembly. This parameter change enables the lip to form more uniformly and consistently, improving weld quality without increasing manufacturing difficulty.
2Reliability
If conventional rectangular wire bond windows are used in PCBs, then the assembly can be manufactured, but the edge of the glass nearest the outer diameter of the diaphragm can be obscured by the PCB, leading to a lack of gel flow in this area and leaving the glass unprotected
Solution Approach 1:
The wire bond window transitions from a conventional rectangular shape to an annular (ring-shaped) design. This dimensional change creates a new geometric configuration that eliminates the obscuration problem, allowing gel to flow freely to all edges of the glass while maintaining a simple PCB layout without requiring complex irregular shapes.
3Reliability
If protective gel is dispensed over wire bonds and strain gauges, then corrosion and degradation are protected against, but bubbles or voids in the gel can allow corrosion, cause mechanical damage, or leave areas unprotected
Solution Approach 1:
The annular wire bond window is designed to facilitate gel flow before the gel is dispensed. The geometry of the annular window pre-establishes optimal gel flow paths, ensuring that gel can reach all necessary areas uniformly and completely, minimizing the formation of bubbles and voids during the dispensing process.
4Ease of manufacture
If conventional contact assemblies with pogo pins or asymmetrical springs are used, then electrical connections can be made, but the cost increases and manual handling is required during assembly
Solution Approach 1:
The spring is designed with asymmetrical features including a tapered end and an offset contact point. This asymmetry provides automatic orientation during assembly, allowing the spring to be inserted in only one correct orientation, which enables automated assembly while maintaining reliable electrical connections. The asymmetrical design eliminates the need for manual handling and orientation.
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 manufacturing costs, enhances reliability, and simplifies assembly by providing a larger process window for welding, minimizing gel-related issues, and eliminating the need for expensive pogo pins, while maintaining environmental protection and mechanical stability.
Implementation Method 1
strain gauge technology for converting changes in fluid pressure to related electrical signals
Implementation Method 2
the isolation of the sense element diaphragm from mechanical stresses in the electronics board (due to humidity, thermal expansion, and the like)
Data Source
AI summary
A pressure sensor includes a sense element port, a support ring and a plurality of interference fit slits to provide a flexible interference fit between the sense element port and the support ring to form a substantially flush lap joint. The sensor also includes an electronics board inside the support ring and attached to planar mounting tabs which provide a stable mounting. Gel flow barriers protect electronics board features from unwanted non-conductive gel. Double-ended symmetrical, tapered contact springs provide manufacturing cost savings and contribute to improved alignment of an interface connector of the sensor.