Pressure Sensor Package Sealing Ring Elastic Modulus
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Solution Overview
Problem
Conventional molded pressure sensor packages require significant effort to form a proper flexible seal with module housings, as the existing molding compounds are hard and can impair the electrical functionality of the pressure sensor die if excessive force is applied.
Innovation Solution
Incorporating a sealing ring with a lower elastic modulus than the molding compound, either as a separate ring or a ridge, to surround a cavity in the molding compound, ensuring a reliable and unrelenting pressure redirection to the diaphragm without exerting excessive force on the package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a molding compound with high elastic modulus is used to encase the pressure sensor die, then the mechanical strength and protection of the package is improved, but the ability to form a flexible seal without exerting excessive force on the die deteriorates
Solution Approach 1:
The package is segmented into two distinct sealing structures: a rigid molding compound for structural strength and a separate flexible sealing ring for sealing operations. This allows each component to perform its specialized function without compromise
Solution Approach 2:
The sealing ring acts as an intermediary element between the rigid molding compound and the module housing. It mediates the sealing function by providing flexibility where needed while allowing the rigid molding compound to maintain its protective strength
2Adaptability or versatility
If a separate flexible seal is formed after the pressure sensor package is placed in the module housing, then the sealing flexibility is improved, but the manufacturing complexity and integration effort increase
Solution Approach 1:
The sealing ring is merged with the molding compound to form an integrated sealing structure. This combination is achieved by either embedding the sealing ring within the molding compound or forming the sealing ring as an integral part of the molding process, thereby eliminating separate sealing steps
Solution Approach 2:
The sealing ring is pre-positioned and integrated into the molding compound before the pressure sensor die is installed in the module housing. This preliminary integration simplifies subsequent assembly operations and eliminates the need for complex post-assembly sealing procedures
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 integrated sealing ring facilitates a proper seal during assembly, ensuring full pressure redirection to the pressure sensor die while protecting the electrical functionality, reducing the effort required for module integration and ensuring reliable operation.
Implementation Method 1
The sealing ring surrounds the cavity and has a lower elastic modulus than the molding compound
Implementation Method 2
Pressure sensor semiconductor dies include a diaphragm for sensing pressure. The sensed pressure is converted to an electrical parameter such as change in resistivity
Data Source
AI summary
A pressure sensor package includes a lead and a semiconductor die spaced apart from the lead and including a terminal and a diaphragm disposed at a first side of the die. The die is configured to change an electrical parameter responsive to a pressure difference across the diaphragm. The package further includes an electrical conductor connecting the terminal to the lead, a molding compound encasing the electrical conductor, the die and part of the lead, a cavity in the molding compound exposing the diaphragm, and a sealing ring disposed on a side of the molding compound with the cavity. The sealing ring surrounds the cavity and has a lower elastic modulus than the molding compound. Alternatively, the sealing ring can be a ridge of the molding compound that protrudes from the side of the molding compound with the cavity and surrounds the cavity. A package manufacturing method is also provided.