Image Sensor Packaging With Opaque Wire-Bond Shielding

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Solution Overview

Problem

Semiconductor packages with visible wire bonds cause reflectance, negatively impacting the performance of image sensors and leading to yield loss.

Innovation Solution

A semiconductor package design featuring a transparent cover over the sensor region with an opaque layer on the package encapsulation surface, obscuring the wire bonds to reduce reflectance and improve sensor performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If wire bonds are used to connect die bond pads to package bond pads, then electrical connectivity is achieved, but reflectance occurs that negatively impacts sensor performance

Engineering Contradiction:

Improvesensor performanceVSAvoidreflectance from wire bonds

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

An opaque coating layer is introduced as an intermediary between the wire bonds and the external environment. This coating layer blocks light from reaching the wire bonds, preventing reflectance while maintaining the electrical connectivity function of the wire bonds underneath.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The package encapsulation surface is modified with an opaque coating that changes the optical properties by absorbing or blocking light. This coating creates a non-reflective surface that prevents light from interacting with the wire bonds, thereby eliminating the harmful reflectance effect.

Inventive Principle:

Principle #32Color changes

2Strength

If wire bonds are encased in package encapsulation, then protection is provided, but wire bonds remain visible and cause reflectance

Engineering Contradiction:

Improveprotection of wire bondsVSAvoidvisibility and reflectance of wire bonds

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The package encapsulation is provided with an opaque coating layer that changes its optical appearance from transparent/visible to opaque/non-visible. This coating maintains the physical protection function while eliminating the visual visibility and reflectance of the underlying wire bonds.

Inventive Principle:

Principle #32Color changes

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

The solution effectively minimizes reflectance from wire bonds, enhancing the performance and reliability of semiconductor sensor packages by preventing light flaring and scattering, thereby improving image sensor functionality.

Implementation Method 1

an opaque layer disposed on a top surface of the package encapsulation. The opaque layer obscures the wire bonds within the encapsulation to reduce reflectance to improve sensor performance

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS20240186346A1Semiconductor packaging for image sensors

Publication Date: 2024.06.06 UTAC HEADQUARTERS PTE LTD

AI summary

A semiconductor package for a sensor is disclosed. The package includes an opaque layer on the encapsulation to prevent the wire bonds encased by the encapsulation from being visible to the naked eye. This reduces or prevents reflectance which improves the performance of the sensor. In some cases, the opaque layer extends beyond the encapsulation to cover a peripheral portion of the cover to form a cover opaque region. The cover opaque region reduces or prevents flaring and scattering of light, further enhancing the performance of the sensor.