Combined Pressure Humidity Sensor Package Design

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Solution Overview

Problem

The challenge lies in combining MEMS pressure and humidity sensors into a single package while minimizing light exposure for sensitive semiconductor components and ensuring effective gas exchange, which is difficult due to competing requirements for smaller openings and limited light exposure for pressure sensors and larger openings for humidity sensors, respectively.

Innovation Solution

The solution involves strategically positioning media openings and integrating sensor components on a shared substrate with light-blocking materials and an opaque gel to protect pressure sensors from light, allowing for combined MEMS pressure and humidity sensors with a single evaluation circuit, enabling smaller device sizes and cost-effective production.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If smaller openings are provided in the sensor housing to minimize light exposure for pressure sensors and ASICs, then light protection for semiconductor components is improved, but gas exchange between the interior volume and exterior atmosphere is reduced, affecting humidity sensor performance

Engineering Contradiction:
Improvelight exposure to semiconductor componentsVSAvoidgas exchange rate for humidity sensing
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The sensor housing is segmented into multiple openings with different functions: smaller openings (first openings) for pressure sensing with light protection, and larger openings (second openings) for humidity sensing without light protection. This segmentation allows each opening to be optimized for its specific sensor type, resolving the contradiction between light protection and gas exchange requirements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the sensor housing are provided with different opening characteristics: regions associated with pressure sensors and ASICs have smaller, light-protective openings, while regions associated with humidity sensors have larger, light-exposed openings. This local differentiation allows each sensor type to operate under its optimal conditions simultaneously within the same housing.

Inventive Principle:
Principle #3Local quality

2Speed

If larger openings are provided in the sensor housing to enable rapid response times for humidity sensors, then gas exchange and response time are improved, but light exposure to pressure sensors and ASICs increases, corrupting measurement signals

Engineering Contradiction:
Improveresponse time of humidity sensorVSAvoidlight exposure to semiconductor components
Core Design Contradiction:
SpeedVSObject-affected harmful factors

Solution Approach 1:

The sensor housing is segmented into multiple openings with different functions: smaller openings (first openings) for pressure sensing with light protection, and larger openings (second openings) for humidity sensing without light protection. This segmentation allows each opening to be optimized for its specific sensor type, resolving the contradiction between light protection and gas exchange requirements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the sensor housing are provided with different opening characteristics: regions associated with pressure sensors and ASICs have smaller, light-protective openings, while regions associated with humidity sensors have larger, light-exposed openings. This local differentiation allows each sensor type to operate under its optimal conditions simultaneously within the same housing.

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If multiple separate packages are used for pressure sensors and humidity sensors, then each sensor can be optimized independently, but device size and manufacturing cost increase

Engineering Contradiction:
Improvesensor optimizationVSAvoidpackage size
Core Design Contradiction:
Manufacturing precisionVSVolume of moving object

Solution Approach 1:

Multiple sensor types (pressure sensors, humidity sensors, and ASICs) that would traditionally require separate packages are merged into a single integrated sensor housing. The housing contains multiple openings and internal structures that accommodate different sensor types with their respective optimization requirements, achieving both integration and individual optimization.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The sensor housing is designed as a universal platform that can accommodate multiple types of sensors with different requirements. By providing different opening types and configurations within the same housing, the design achieves multi-functionality, allowing pressure sensing, humidity sensing, and signal evaluation to coexist in a single package.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 allows for the integration of combined pressure and humidity sensors in smaller packages with reduced openings, improved light protection, and faster response times, while using a single evaluation circuit, enhancing cost-effectiveness and electromagnetic radiation shielding.

Implementation Method 1

Sensing elements based on piezoresistive technology and capacitive sensing technology are typically used

Methodology Applied
Scientific EffectPiezoresistive effect: Piezoresistive Effect

Implementation Method 2

Sensing elements based on piezoresistive technology and capacitive sensing technology are typically used

Methodology Applied
Scientific EffectCapacitive sensing: Capacitance

Implementation Method 3

The dielectric layer is formed of a material, such as polymer that is configured to absorb and retain water molecules at concentrations that are proportional to the ambient humidity

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 4

The water molecules alter the dielectric constant of the polymer resulting in a change in capacitance between the two electrodes

Methodology Applied
Scientific EffectCapacitance change: Capacitance

Data Source

PatentEP2912426B1Combined pressure and humidity sensor
Publication Date: 2019.08.07 ROBERT BOSCH GMBH
  • EP2912426B1 patent drawingFigure 1~2
  • EP2912426B1 patent drawingFigure 3~4
  • EP2912426B1 patent drawingFigure 5~6

AI summary

A sensor device package includes a pressure sensor and a humidity sensor mounted on the same substrate and in the same housing with light protection for the pressure sensor a media opening for gas exchange for the humidity sensor. Light protection and rapid response times are provided through strategic positioning of the media opening, strategic arrangement of the pressure sensor, humidity sensor, and the media opening, and/or the use of opaque materials.