Flow Sensor Resin Sealing for Airflow Stabilization
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Solution Overview
Problem
Existing flow sensors experience performance variations due to shifting semiconductor chips during the manufacturing process, leading to decreased detection accuracy and increased costs, as the potting resin's low dimensional accuracy and slow curing time hinder precise mounting and sealing.
Innovation Solution
A flow sensor design where the semiconductor chip and control circuit are sealed with resin, exposing the flow sensing unit, and using air current control units integrated with the resin to stabilize airflow, while also employing a polyimide film for enhanced bonding properties, improves the chip's positioning accuracy and reduces curing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If potting resin is used to seal the semiconductor chip, then the chip is protected and sealed, but the dimensional accuracy is low and curing time is slow
Solution Approach 1:
The patent divides the sealing structure into two parts: a precision-molded resin seal that provides dimensional accuracy and positioning, and a potting resin that provides protective sealing. The precision-molded resin seal is formed first with high dimensional accuracy to position the semiconductor chip, then the potting resin is applied for additional protection without compromising the positioning precision achieved by the first seal.
2Reliability
If potting resin is used to seal the semiconductor chip, then the chip is protected and sealed, but the curing time is extended
Solution Approach 1:
The sealing process is segmented into two stages with different curing characteristics. The precision-molded resin seal is formed with controlled curing parameters to achieve rapid setting and dimensional stability. The potting resin is then applied in a thinner layer that cures faster due to reduced thickness and improved heat/UV penetration, thereby reducing total curing time while maintaining protective sealing.
3Reliability
If the semiconductor chip is sealed completely with resin, then the chip is protected, but the flow sensing unit cannot be exposed for airflow measurement
Solution Approach 1:
The patent applies different sealing qualities to different regions of the semiconductor chip. The precision-molded resin seal and potting resin provide complete protection to the chip body, connection terminals, and wiring. However, the flow sensing unit area is deliberately left exposed or selectively sealed to allow airflow contact, ensuring the sensing elements can detect flow conditions accurately while the rest of the chip remains protected.
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 stabilizes the semiconductor chip's position, enhances detection accuracy, and reduces manufacturing costs by minimizing performance variations and accelerating the curing process.
Implementation Method 1
employing a polyimide film for enhanced bonding properties
Implementation Method 2
the semiconductor chip and control circuit are sealed with resin, exposing the flow sensing unit
Implementation Method 3
using air current control units integrated with the resin to stabilize airflow
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Technique of suppressing performance variations for each flow sensor is provided. In a flow sensor FS1 of the present invention, a part of a semiconductor chip CHP1 is configured to be covered with resin (MR) in a state in which a flow sensing unit (FDU) formed on a semiconductor chip CHP1 is exposed. Since an upper surface SUR (MR) of the resin (MR) is higher than an upper surface SUR(CHP) of the semiconductor chip (CHP1) by sealing the resin (MR) on a part of the upper surface SUR(CHP) of the semiconductor chip CHP1 in a direction parallel to an air flow direction, the air flow around the flow sensing unit (FDU) can be stabilized. Further, interface peeling between the semiconductor chip (CHP1) and the resin (MR) can be prevented by an increase of contact area between the semiconductor chip (CHP1) and the resin (MR).