Semiconductor Package Structure for Thermal Stress Buffering

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Solution Overview

Problem

Semiconductor packages face reliability issues due to thermal stress caused by mismatched coefficients of thermal expansion (CTEs) between substrate and semiconductor die materials, leading to warping or cracking and potential damage to electrical connections.

Innovation Solution

The semiconductor package structure incorporates a substrate with strategically formed holes and a stress buffer layer to alleviate thermal stress, along with a frame and molding material to enhance structural strength and heat dissipation, and uses multiple small substrates instead of a single large one to improve reliability and design flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If a single large substrate is used, then the package area is increased, but the thermal stress and warping risk are exacerbated

Engineering Contradiction:
Improvepackage areaVSAvoidthermal stress resistance
Core Design Contradiction:
Area of stationary objectVSReliability

Solution Approach 1:

The substrate is divided into multiple separate substrate partitions instead of using a single large substrate. Each partition is independently supported by the frame structure, which segments the thermal stress and prevents warping across the entire package area while maintaining overall structural integrity.

Inventive Principle:
Principle #1Segmentation

2Reliability

If substrate partitions are added, then the thermal stress is reduced, but the device complexity is increased

Engineering Contradiction:
Improvethermal stress resistanceVSAvoidsubstrate structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The frame structure serves multiple functions simultaneously: it provides mechanical support for the substrate partitions, acts as a heat spreader, and serves as a structural reinforcement element. This merging of functions reduces the need for additional separate components, thereby limiting the increase in device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The frame is designed as a multi-functional component that provides both structural support for the substrate partitions and thermal management through heat spreading. This universal component eliminates the need for separate support structures and heat sinks, balancing reliability improvement with controlled complexity.

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

3Strength

If a frame structure is added, then the structural strength is enhanced, but the device complexity is increased

Engineering Contradiction:
Improvestructural strengthVSAvoidpackage structure complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The frame structure combines mechanical support and thermal management functions into a single integrated component. By merging the support structure and heat spreader functions, the design enhances structural strength without proportionally increasing device complexity.

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If holes are formed in the substrate, then the stress buffer is improved, but the manufacturing precision requirements are increased

Engineering Contradiction:
Improvestress buffer capacityVSAvoidhole formation precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

Holes are strategically formed only in specific regions of the substrate partitions where stress concentration is most likely to occur. This localized approach provides effective stress buffering while minimizing the overall number of holes required, thereby reducing the cumulative manufacturing precision requirements.

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 reduces the risk of warping or cracking, maintains the integrity of electrical connections, and enhances the overall reliability and lifespan of the semiconductor package by managing thermal expansion mismatch and providing structural reinforcement.

Implementation Method 1

The semiconductor package may be highly stressed due to the different coefficients of thermal expansion (CTEs) of the various substrate and semiconductor die materials

Methodology Applied
Scientific EffectThermal stress: Thermal Expansion

Implementation Method 2

A lower portion of the heat spreader is arranged on a substrate

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Data Source

PatentEP3754698B1Semiconductor package structure
Publication Date: 2024.02.28 MEDIATEK INC
  • EP3754698B1 patent drawingFigure 1A
  • EP3754698B1 patent drawingFigure 1B
  • EP3754698B1 patent drawingFigure 1C

AI summary

A semiconductor package structure is provided. The semiconductor package structure includes a substrate, a frame, a redistribution layer, and a first semiconductor die. The substrate has a wiring structure and is surrounded by a molding material. The frame is disposed in the molding material and surrounds the substrate. The redistribution layer is disposed over the substrate and electrically coupled to the wiring structure. The first semiconductor die is disposed over the redistribution layer.