Sensor Unit Terminal Design Mitigating Resin Shrinkage Stress

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Solution Overview

Problem

Resin sealing type semiconductor devices face challenges in confirming electrical connections and experience stress due to resin expansion and shrinkage, leading to measurement accuracy deterioration and connection defects when embedded in sensor units.

Innovation Solution

A sensor unit design featuring terminal members with a thin wall lead portion and a protruding portion that functions as a branched filler, reducing resin shrinkage stress and improving connection reliability by providing additional connection points and insulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the sensor device is embedded inside the resin package with the external connection portion disposed inside the outer edge portion, then the resin sealing provides protection and integration, but it becomes difficult to confirm the presence or absence of connection problems and stress from resin expansion and shrinkage concentrates on the embedded sensor device

Engineering Contradiction:

Improveconnection reliabilityVSAvoiddifficulty to confirm connection status

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The external connection portion is extracted from the embedded position inside the resin package and repositioned to the outer edge portion where it can be easily accessed and inspected, while the sensor device remains embedded for protection. This separation allows the connection portion to be easily confirmed and tested without exposing the entire sensor device.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If the external connection portion is disposed inside the outer edge portion of the resin package, then the resin sealing provides integrated protection, but the stress from resin expansion and shrinkage concentrates on the embedded sensor device causing measurement accuracy deterioration

Engineering Contradiction:

Improveprotection from resin sealingVSAvoidsensor measurement accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The external connection portion is extracted from the embedded position and repositioned to the outer edge, separating it from the stress concentration zone. This allows the sensor device to remain protected by resin sealing while the connection portion is positioned where it can accommodate thermal expansion and shrinkage stresses without transmitting them to the sensitive sensor elements.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Different portions of the terminal member are given different functions: the external connection portion is positioned at the outer edge for stress accommodation and easy connection, while the lead portion connects to the embedded sensor device. This local differentiation allows each part to optimize its function - the connection portion handles mechanical stress while the lead portion ensures electrical connection stability.

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If the terminal member has a thin wall lead portion for flexibility, then the connection adapts to mounting variations, but the thin wall portion is more susceptible to stress damage from resin expansion and shrinkage

Engineering Contradiction:

Improveconnection adaptabilityVSAvoidresistance to stress damage

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The terminal member exhibits local quality variations: the external connection portion has larger dimensions for stress accommodation and easy connection, the lead portion has optimized thickness for both flexibility and strength, and the embedded connection portion adapts to the sensor device. This gradient structure allows each section to perform its specific function optimally while resisting stress damage.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The terminal member is designed with dimensional variations along its length, transitioning from a larger external connection portion to a thinner lead portion. This dimensional gradient provides flexibility in the thin section for adaptation while maintaining sufficient strength in the transition zone to resist stress from resin expansion and shrinkage.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS11262374B2Sensor unit, method of manufacturing sensor unit, inertial measurement device, electronic apparatus, and vehicle

Publication Date: 2022.03.01 SEIKO EPSON CORP

AI summary

A sensor unit includes a plurality of terminal members each of which includes a lead portion and an external terminal portion having an external connection end face, a sensor device connected to the lead portions, and a resin member that covers the sensor device and a part of the plurality of terminal members. The lead portion includes a thin wall portion having a thickness thinner than the external terminal portion and a protruding portion protruding from the thin wall portion to an external connection end face side. In a plan view from a direction where the terminal member and the sensor device overlap, the sensor device is disposed at a position overlapping the protruding portion and not overlapping the external terminal portion.