Image Sensor Package Structure for Bonding Wire Stress Relief

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Solution Overview

Problem

Existing image sensor packages face challenges in reliability due to stress applied to bonding wires, which can lead to cracks and reduced package performance.

Innovation Solution

The image sensor package incorporates a dam on the image sensor chip to cover the bonding wire ends and a stress reducing layer made of the same material as the dam, covering the substrate pad end of the bonding wire, to mitigate stress and prevent cracks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If bonding wires are used to electrically connect the image sensor chip to the substrate, then electrical connectivity is achieved, but stress is applied to the bonding wires which can lead to cracks and reduced reliability

Engineering Contradiction:

Improvebonding wire reliabilityVSAvoidstress on bonding wire

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

A stress reducing layer is formed on the substrate to cover and protect the bonding wire before stress can cause damage. This layer acts as a cushion that absorbs and distributes the stress away from the bonding wire, preventing cracks and enhancing reliability before failures can occur.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The stress reducing layer serves as an intermediary element between the substrate and the bonding wire. It mediates the stress transmission by providing a compliant interface that reduces the direct stress concentration on the bonding wire, thereby protecting the electrical connection.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a dam structure is added to cover the bonding wire ends, then stress protection is improved, but device complexity increases

Engineering Contradiction:

Improvebonding wire protectionVSAvoidpackage structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The dam structure and the stress reducing layer are merged into a single integrated component. The dam is formed using the same material as the stress reducing layer and serves dual functions: containing the encapsulant material during fabrication and providing ongoing stress protection to the bonding wire ends, thereby reducing overall device complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The dam structure is designed to perform multiple functions: it acts as a barrier to contain encapsulant material during the encapsulation process and simultaneously serves as a stress reducing structure that protects the bonding wire ends throughout the device lifetime, eliminating the need for separate protective components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12278248B2Image sensor package and method of fabricating the same

Publication Date: 2025.04.15 SAMSUNG ELECTRONICS CO LTD

AI summary

Provided are an image sensor package with improved reliability and a method of fabricating the same. The image sensor package includes a package substrate, an image sensor chip mounted on the package substrate, a transparent cover on the image sensor chip, an encapsulant encapsulating the image sensor chip and covering a side surface of the transparent cover, a dam on a surface of the image sensor chip and surrounding a portion of the upper surface of the image sensor, the transparent cover on the dam, a bonding wire connecting a chip pad of the image sensor chip to a substrate pad of the package substrate, the dam covering a first end of the bonding wire connected to the chip pad, and a stress reducing layer covering a second end of the bonding wire connected to the substrate pad, the stress reducing layer including substantially the same material as the dam.