Multi-Chip Package Shield Bump Layout for Wire Crack Prevention

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Solution Overview

Problem

Forming a reliable chip package structure with multiple chips is challenging due to thermal stress and mechanical stress issues, particularly in wafer-level packaging, where the mismatch of thermal expansion coefficients between chip structures and the wiring substrate can lead to cracks in wires.

Innovation Solution

A chip package structure is developed with a shield bump structure and shield pad design that includes a mesh-shaped shield pad with outgassing holes and a misaligned shield bump structure, which provides enhanced stress shielding by increasing the stress transmitting path length and allowing outgassing, thereby improving the reliability of the package.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a conventional chip package structure is used with multiple chips, then the package can accommodate multiple functional chips, but thermal stress and mechanical stress cause cracks in wires due to mismatch of thermal expansion coefficients

Engineering Contradiction:

Improvemultiple functional chipsVSAvoidwire cracks

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

A stress shielding structure comprising a shield pad and shield bump is introduced as an intermediary element between the wiring substrate and chip structures. The shield pad (218') made of stress shielding material and the shield bump (219) work together to intercept and dissipate stress before it reaches the wires, preventing wire cracks while allowing multiple chips to be packaged

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a shield bump structure is added to provide stress shielding, then wire reliability is improved, but device complexity increases

Engineering Contradiction:

Improvewire crack preventionVSAvoidpackage structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The stress shielding function is divided into two segmented components: a shield pad (218') located on the wiring substrate and a shield bump (219) positioned between chip structures. This segmentation allows each component to perform its specific stress shielding function independently, making the overall structure more manageable and manufacturable despite the added complexity

Inventive Principle:

Principle #1Segmentation

3Reliability

If the shield pad is made mesh-shaped with outgassing holes, then stress distribution is improved and outgassing is allowed, but manufacturing precision requirements increase

Engineering Contradiction:

Improvestress distributionVSAvoidmesh structure alignment

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The shield pad (218') is designed with a mesh shape including outgassing holes (218h), transforming it from a solid structure to a porous one. This allows trapped gases to escape during packaging processes while the mesh pattern distributes stress more effectively across the pad area, reducing stress concentration points

Inventive Principle:

Principle #31Porous materials

4Reliability

If the shield bump structure is misaligned, then stress transmitting path length is increased providing enhanced stress shielding, but manufacturing complexity increases

Engineering Contradiction:

Improvestress shieldingVSAvoidalignment process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The shield bump (219) is intentionally designed with a misaligned configuration rather than being perfectly centered or aligned with the shield pad. This asymmetric positioning increases the stress transmitting path length, forcing stress to travel a longer route and be distributed over a larger area, thereby enhancing stress shielding effectiveness

Inventive Principle:

Principle #4Asymmetry

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 shield bump and pad design effectively shields thermal and mechanical stress, preventing cracks in wires and enhancing the reliability of the chip package structure by allowing outgassing and distributing stress more effectively.

Implementation Method 1

the shield bump structure and mesh-shaped shield pad with outgassing holes, which provides enhanced stress shielding by increasing the stress transmitting path length

Methodology Applied

Scientific EffectStress shielding:

Implementation Method 2

allowing outgassing, thereby improving the reliability of the package

Methodology Applied

Scientific EffectOutgassing:

Data Source

PatentUS12113033B2Chip package structure

Publication Date: 2024.10.08 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A chip package structure is provided. The chip package structure includes a redistribution structure including a dielectric structure and a plurality of wiring layers in or over the dielectric structure. The chip package structure includes a shield bump structure over the redistribution structure and electrically insulated from the wiring layers. The chip package structure includes a first chip structure bonded to the redistribution structure. The first chip structure is electrically insulated from the shield bump structure, and the first chip structure partially overlaps the shield bump structure. The chip package structure includes a second chip structure bonded to the redistribution structure.