Flow Sensor Mold Ejection Pin Configuration
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Solution Overview
Problem
The existing manufacturing methods for flow sensors result in performance variations due to positional shifts of semiconductor chips and inaccuracies in resin sealing, leading to increased costs and decreased throughput, as the potting resin does not effectively fix the gold wire and lacks accelerated hardening, causing reliability issues.
Innovation Solution
A method for manufacturing flow sensors that involves using a resin-sealing technique where the semiconductor chip is fixed by a mold, with an elastic body film to absorb dimensional variations, and an ejection pin configuration that thrusts the sealing body peripherally to minimize deformation and prevent breakage, allowing for consistent positioning and improved resin hardening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the gold wire is fixed by potting resin without mold fixation, then the manufacturing process is simple, but the position of the semiconductor chip shifts due to resin shrinkage causing performance variation
Solution Approach 1:
The semiconductor chip is fixed to the substrate by the mold before potting resin is applied. This preliminary fixation prevents the chip from shifting during resin shrinkage, ensuring consistent positioning while maintaining manufacturing simplicity
Solution Approach 2:
The mold acts as an intermediary tool that temporarily holds the semiconductor chip in the correct position during the potting process. The mold releases after hardening, leaving the chip securely positioned without requiring complex fixation mechanisms
2Ease of manufacture
If the potting resin is formed by dropping, then the manufacturing process is simple, but the dimension accuracy of the resin is low causing variation in detection performance
Solution Approach 1:
The manual dropping method is replaced with a mold-based casting system. The mold cavity defines the exact dimensions and position of the potting resin, eliminating the dimensional variability inherent in dropping methods while maintaining ease of manufacture through automated molding
Solution Approach 2:
The resin forming method changes from uncontrolled dropping to controlled mold casting. The mold parameters (cavity size, shape, position) precisely control the resin dimensions, ensuring consistent detection performance across all sensors
3Ease of manufacture
If the potting resin is not subjected to accelerated hardening by heating, then the process is simple, but the hardening time is long decreasing throughput
Solution Approach 1:
The potting resin undergoes phase transition from liquid to solid through controlled hardening. By applying heat, the transition occurs faster, reducing hardening time and increasing throughput while maintaining process simplicity through standard thermal treatment
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 approach reduces performance variations, enhances reliability, and increases manufacturing efficiency by maintaining consistent chip positions and reducing the risk of breakage, thereby improving yield and reducing costs.
Implementation Method 1
an elastic body film interposed between the semiconductor chip and the sealing body
Implementation Method 2
the potting resin is subjected to the acceleration of the hardening by heating
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A technique capable of suppressing performance variation of every flow sensor and achieving performance improvement is provided. For example, in an arbitrary cross-sectional surface in parallel to a moving direction of a gas flowing on an exposed flow detecting unit FDU which is formed in a semiconductor chip CHP1, a sealing body is released from the lower mold BM by thrusting up, from a lower mold BM, an ejection pin EJPN arranged in an outer region of the semiconductor chip CHP1 so as not to overlap with the semiconductor chip CHP1 arranged in the vicinity of the center part. Thus, according to the first embodiment, the deformation applied to the sealing body at the time of mold releasing can be smaller than that in a case in which the sealing body is released from the lower mold BM by arranging the ejection pin EJPN in a region overlapping with the semiconductor chip CHP1.