Sensor Lid Structure for Chemical-Free IC Package Protection

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Solution Overview

Problem

Integrated circuit packages with electronic sensors, such as pressure sensors, face challenges in maintaining sensor accuracy and performance under harsh environmental conditions while being protected from mechanical and chemical stresses, often requiring costly chemical protectants like gel and molding compounds.

Innovation Solution

A lid structure is placed over the transducer in the integrated circuit package, creating an air cavity around the sensor to protect it without using gel or molding compounds, allowing for pressure venting through a hole in the lead frame, thus reducing costs and maintaining sensor sensitivity and accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If chemical protectants like gel and molding compounds are used to protect the sensor, then the sensor is protected from mechanical and chemical stresses, but the package cost increases and sensor sensitivity may be compromised

Engineering Contradiction:

Improvesensor protection from harsh environmentsVSAvoidpackage cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent removes the chemical protectant (gel) from the package, extracting only the essential protective function. The lid structure provides mechanical protection while the open flag area allows direct environmental exposure to the transducer, eliminating the need for costly chemical protectants that would otherwise be required to protect the sensor in harsh environments.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The lid structure acts as a thin protective shell that provides mechanical protection to the transducer and internal components while allowing environmental pressure to be transmitted to the sensor through the open flag area. This thin-film approach replaces bulky chemical protectants with a streamlined protective structure.

Inventive Principle:

Principle #30Flexible shells and thin films

2Reliability

If chemical protectants are used to protect the sensor, then the sensor is protected from harsh environments, but sensor sensitivity and accuracy may be compromised

Engineering Contradiction:

Improvesensor protectionVSAvoidsensor accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent extracts the transducer from the chemical protectant environment by providing direct exposure through the open flag area. This allows the pressure sensor to directly sense environmental pressure without the interference or damping effects that gel or molding compounds would introduce, thereby maintaining measurement precision while still providing protection through the lid structure.

Inventive Principle:

Principle #2Taking out (Extraction)

3Ease of manufacture

If a lid structure is used to protect the transducer, then chemical protectants can be eliminated, but the transducer must be protected from environmental exposure

Engineering Contradiction:

Improvepackage cost reductionVSAvoidenvironmental exposure to transducer

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The lid structure provides localized protection with an open flag area that selectively exposes only the necessary portion of the transducer to the environment. This local quality approach allows the sensor to sense environmental pressure directly while the lid protects other components, eliminating the need for complete chemical encapsulation and reducing package cost.

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 solution effectively protects pressure sensors from harsh environments without the need for chemical protectants, reducing the package cost and ensuring sensor accuracy and performance, making them suitable for use in hostile conditions like automobile tires.

Implementation Method 1

The lid structure is placed over the transducer and is attached to the lead frame assembly on the backside surface. The lid can define an air cavity around the transducer, such that mold compound, gel, or other protective chemical material is not placed in contact with the transducer.

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Implementation Method 2

The lead frame is created such that there is a hole or opening at an exposed flag of the lead frame. The pressure sensor is placed under the opening at the backside of the lead frame, such that the opening provides a pressure vent for the pressure sensor.

Methodology Applied

Scientific EffectPressure equalization: Pressure Gradient

Data Source

PatentUS8890308B2Integrated circuit package and method of forming the same

Publication Date: 2014.11.18 CHIP PACKAGING TECH LLC

AI summary

An integrated circuit package includes an electronic sensor protected by a lid structure. The electronic sensor includes a transducer placed on a backside surface of a lead frame assembly. The lid structure is placed over the transducer and is attached to the lead frame assembly on the backside surface. The lid can define an air cavity around the transducer, such that mold compound, gel, or other protective chemical material is not placed in contact with the transducer. The transducer is therefore protected without a chemical protectant, lowering the cost of the integrated circuit package and maintaining the sensitivity and performance of the transducer.