Flow Sensor Package Recess Design for Turbulence Reduction
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Solution Overview
Problem
Conventional flow sensors are not small in size, which can lead to turbulence issues due to limited flow channel dimensions, and existing designs do not effectively manage fluid flow direction and turbulence within the sensor package.
Innovation Solution
A flow sensor package with a recess in the encapsulation that extends beyond the chip edges to define a longer flow channel, incorporating a thermo-electric arrangement with a heater and temperature sensors, and optionally a flow channel lid to guide fluid flow laminarly, while the encapsulation protects the chip and electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the flow channel is extended beyond the chip edges by forming a recess in the encapsulation, then the flow measurement accuracy is improved and turbulence is reduced, but the manufacturing complexity increases
Solution Approach 1:
The recess extends the flow channel from the chip surface into the encapsulation depth, utilizing the third dimension (depth) to increase the effective flow channel length without increasing the chip footprint. This allows laminar flow development while maintaining a compact overall package size.
Solution Approach 2:
The flow channel is nested within the encapsulation structure itself, using the encapsulation material to form the flow channel walls and bottom. This integrates the flow channel function into the protective encapsulation, eliminating the need for separate flow channel components.
2Length of moving object
If the recess extends beyond the chip edges into the encapsulation, then the flow channel length is increased for better flow guidance, but the chip size and package volume increase
Solution Approach 1:
The flow channel extension is achieved vertically into the encapsulation rather than horizontally, allowing increased flow channel length without increasing the lateral dimensions of the package. The recess depth provides the additional length while maintaining a compact footprint.
3Ease of operation
If a recess is formed in the encapsulation to expose the sensitive structure, then access to the sensitive structure is improved for fluid flow, but the structural protection of the chip is reduced
Solution Approach 1:
The encapsulation is selectively removed only in the region where fluid access to the sensitive structure is required, while the rest of the chip remains fully encapsulated and protected. The recess is precisely positioned to expose only the necessary portion of the chip surface.
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 design achieves a compact size with reduced turbulence and effective fluid flow guidance, ensuring accurate flow measurement by extending the flow channel beyond the chip edges and integrating a thermo-electric arrangement for precise temperature sensing.
Implementation Method 1
a heater and one or more temperature sensors, e.g. one temperature sensor arranged upstream and another temperature sensor arranged downstream of the heater, such that when a fluid passes this arrangement while the heater being turned on, the flow of the fluid may be derived from a difference in temperatures sensed by the two temperature sensors
Data Source
Figure 1a~1b
Figure 2a~2c
Figure 2b~2c
AI summary
A flow sensor package (100) comprises a chip (1) comprising a sensitive structure (12) for sensing the flow of a fluid and an encapsulation (2) at least partly encapsulating the chip (1). A recess (21) in the encapsulation (2) contributes to a flow channel (9) for guiding the fluid, which recess (21) exposes at least the sensitive structure (12) of the chip (1) from the encapsulation (2), and which recess (21) extends beyond an edge (Ex1, Ex2) of the chip (1).