Semiconductor Flow Sensor Chip with Integrated Channel
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Solution Overview
Problem
Variations in sensor performance due to misalignment and unit-to-unit variability in the manufacturing process of flow sensor packaging components, which affect the formation of the flow channel and subsequently the accuracy of flow measurements.
Innovation Solution
A flow sensing device with a semiconductor chip having an integrated flow channel between its base and cap, featuring passage-openings for access from opposite sides of the package base, allowing for simplified packaging and precise control of channel dimensions and alignment through wafer bonding techniques, thereby reducing the impact of packaging processes on performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the flow channel is formed by mating the sensor chip with package components during assembly, then the flow channel can be created after sensor chip mounting, but misalignment and unit-to-unit variability occur affecting sensor performance
Solution Approach 1:
The flow channel is pre-formed in the sensor chip before packaging assembly. The chip is designed with an integrated flow channel structure that is created during chip fabrication rather than during package assembly, eliminating alignment issues between separate components
Solution Approach 2:
The flow channel structure is merged with the sensor chip as an integrated unit. The channel is formed within the chip substrate itself, combining the sensing element mounting area with the fluid flow path in a single monolithic structure
2Manufacturing precision
If the flow channel is formed by pre-molded cavities in the package cover, then the flow channel structure is defined early, but alignment variability and manufacturing tolerances affect performance
Solution Approach 1:
The flow channel formation process is extracted from the package assembly operations and transferred to the chip fabrication process. The channel is created using standard semiconductor manufacturing techniques before the chip is packaged, separating channel formation from package component assembly
Solution Approach 2:
Mechanical alignment and mating of separate package components is replaced by integrated chip fabrication processes. Instead of physically aligning and assembling separate pieces to form the channel, the channel is created through planar semiconductor manufacturing techniques directly in the chip substrate
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 provides high pneumatic impedance and reproducible flow channel characteristics, minimizing performance variations and enhancing the accuracy of flow measurements by ensuring accurate alignment and dimension control of the flow channel.
Implementation Method 1
Typically the flow channel maintains laminar flow which is directly proportional to the pressure difference between the two ports (ends) of the flow channel
Implementation Method 2
Gas or liquid (fluid) flow passing over the sensing element disturbs the temperature distribution in the fluid in the vicinity of the heater, causing a temperature difference between two temperature-sensitive entities
Data Source
Figure 1
Figure 2a~2e
Figure 3a~3f
AI summary
There is described a flow sensing device having a semiconductor chip with a flow channel integrated therein and a sensing element positioned in the flow channel, and a package base attached to the semiconductor chip and allowing access to the two passage-openings of the flow channel from opposite sides of the package base.