Pressure Sensor Recessed Port Adhesive Bonding
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Solution Overview
Problem
Pressure sensors face reliability issues due to unreliable cemented joints under high pressures and pressure differentials, especially when using lead-free materials, which are difficult to produce and maintain over varying temperature ranges.
Innovation Solution
The pressure sensor employs a capillary effect to ensure void-free and durable cemented joints by using recesses to hold adhesive substances, allowing precise distribution and filling of the intermediate space between components, combined with surface roughness and passivation layers to enhance adhesion and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead-free materials are used for cemented joints, then environmental compliance is improved, but joint reliability under high pressure deteriorates
Solution Approach 1:
The patent changes the physical-chemical parameters of the adhesive substance by heating it above its melting point during the cementing process. This parameter change allows the adhesive to flow into the intermediate space and form reliable joints with lead-free materials, resolving the contradiction between environmental compliance and joint reliability
Solution Approach 2:
The patent creates a recess in one of the components before assembly, which serves as a reservoir for the adhesive substance. This preliminary action ensures that the adhesive is properly positioned and distributed in the intermediate space, enabling reliable bonding without lead-containing materials
2Ease of operation
If cemented joints are used to connect pressure port and housing, then assembly ease is improved, but connection reliability under high pressure deteriorates
Solution Approach 1:
The recess is prepared in advance in one component, serving as a reservoir for the adhesive. This preliminary preparation allows the adhesive to be easily applied and distributed during assembly, maintaining ease of operation while ensuring reliable pressure-tight connections
Solution Approach 2:
Heating the adhesive above its melting point changes its physical state to a flowing liquid, enabling it to completely fill the intermediate space and eliminate voids. This parameter change transforms the cementing process into a more reliable operation that maintains ease of assembly while achieving high connection reliability
3Strength
If adhesive is applied to fill intermediate space, then bond strength is improved, but void formation deteriorates
Solution Approach 1:
The adhesive is heated above its melting point to change its physical state, increasing its fluidity and ability to flow into and completely fill the intermediate space. This parameter change ensures void-free filling while maintaining strong bonds, resolving the contradiction between bond strength and manufacturing precision
Solution Approach 2:
The recess is pre-formed to serve as an adhesive reservoir, ensuring proper positioning and distribution of the adhesive material. This preliminary action prevents air entrapment and void formation while ensuring complete filling of the intermediate space, achieving both strong bonds and void-free joints
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 solution results in reliable, pressure-tight connections capable of withstanding up to 40 bar operating pressure and maintaining stability across a wide temperature range, from -40°C to 150°C, while adhering to lead-free material requirements.
Implementation Method 1
the intermediate space is set so short that the intermediate space acts as the capillary on the adhesive in its liquid state
Data Source
AI summary
A pressure sensor comprises a housing, a housing plug and a pressure port, which projects into the housing. The pressure sensor has a pressure-sensing element adhesively cemented on the pressure port, so that a passage, located in the pressure port, is sealed. To produce an adhesive film between the pressure port and the housing, the pressure port or the housing or both exhibit a recess in a region, which borders at least section by section on the adhesive film. The volume of recess is equal to the volume of the adhesive film. To produce the adhesive film, the intermediate space between the pressure port and the housing is filled with the adhesive, which was introduced into the recess, while utilizing a capillary effect.