Segmented Adhesive Sheet for Thermal Airflow Sensor Ventilation

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Solution Overview

Problem

The existing methods for bonding semiconductor elements with diaphragm portions using adhesive sheets often result in an airtight state, leading to measurement errors due to air expansion and contraction, which is not addressed by current techniques that do not consider ventilation openings for physical quantity sensors.

Innovation Solution

The adhesive sheet is divided into multiple thin sections with slits to match the shape of the semiconductor element, and external energy is used to increase adhesion, forming ventilation openings to prevent airtight conditions and improve measurement accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If an adhesive sheet is used to bond the semiconductor element to the support substrate, then the bonding strength is improved, but the back surface area becomes airtight causing measurement errors

Engineering Contradiction:
Improvebonding strengthVSAvoidairflow volume measurement accuracy
Core Design Contradiction:
StrengthVSMeasurement precision

Solution Approach 1:

The adhesive sheet is divided into multiple independent adhesive regions corresponding to different chip positions, with non-adhesive gaps between them. This segmentation allows air to pass through the gaps while maintaining bonding strength at each chip location, resolving the contradiction between bonding strength and measurement precision.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If the adhesive sheet is made thin to reduce interference, then the measurement accuracy is improved, but the bonding reliability deteriorates

Engineering Contradiction:
Improvediaphragm deformation controlVSAvoidbonding reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The adhesive sheet exhibits different properties in different regions: thin adhesive regions for bonding reliability and non-adhesive gaps for air passage. This local quality differentiation allows the adhesive sheet to simultaneously achieve sufficient bonding strength and maintain measurement accuracy by preventing diaphragm deformation.

Inventive Principle:
Principle #3Local quality

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 enhances the accuracy of airflow volume measurement by allowing air to escape and preventing deformation of the diaphragm, reducing errors and improving the durability of the semiconductor device.

Implementation Method 1

an adhesive sheet is divided into at least two or more per adherend and having a thickness of approximately 0.1 mm or less, the adhesive sheet is divided to correspond to a shape of the adherend, and adhesion or stickiness is generated or increased by external energy

Methodology Applied
Scientific EffectExternal energy activation of adhesive: Adhesive

Data Source

PatentEP3009486B1Method for manufacturing a semiconductor device, method for manufacturing a thermal type airflow sensor, and thermal type airflow sensor
Publication Date: 2018.01.31 HITACHI AUTOMOTIVE SYST LTD
  • EP3009486B1 patent drawingFigure 1(a)~1(d)
  • EP3009486B1 patent drawingFigure 2(a)~2(b)
  • EP3009486B1 patent drawingFigure 3(a)~4

AI summary

Provided is a thermal type airflow volume meter improving measurement accuracy, a method for manufacturing the same, and an adhesive sheet for use therein, the adhesive sheet divided into at least two or more per adherend and having a thickness of approximately 0.1 mm or less is divided to correspond to a shape of the adherend and generates or increases adhesion or stickiness by external energy.