Shadow Pad Material for Post-Passivation Interconnect Stress Relief

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current semiconductor packaging technologies face challenges in reducing stress and improving signal design flexibility, particularly in interconnect structures, which can affect the reliability and performance of packaged semiconductor devices.

Innovation Solution

The introduction of a shadow pad material proximate to the landing pads and post-passivation interconnect (PPI) pads in the interconnect structure, which is disposed beneath and coupled to the PPI pad, helps in reducing stress and enhancing signal design flexibility by providing a larger conductive area and improved chip-package interaction (CPI) windows.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional interconnect structures are used without shadow pad material, then the structure is simpler and manufacturing is easier, but stress accumulation occurs and signal design flexibility is reduced

Engineering Contradiction:

Improvestress reductionVSAvoidinterconnect structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A shadow pad material is introduced as an intermediary element between the landing pad and the PPI pad. This shadow pad material serves as a stress-relief layer that mediates the mechanical stress transmitted through the interconnect structure, preventing stress accumulation while maintaining electrical connectivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The interconnect structure is segmented into distinct functional layers: the landing pad, the shadow pad material layer, and the PPI pad. This segmentation allows each layer to perform its specific function - the shadow pad material specifically addresses stress management while the other layers handle electrical connectivity.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If conventional interconnect structures are used without shadow pad material, then manufacturing processes are simpler, but signal design flexibility and CPI window optimization are limited

Engineering Contradiction:

Improvesignal design flexibilityVSAvoidmanufacturing process simplicity

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The shadow pad material enables changes in key design parameters including CPI window dimensions, signal trace routing flexibility, and impedance control. By adjusting the shadow pad material properties and geometry, designers can optimize signal integrity and adaptability without fundamentally changing the manufacturing process flow.

Inventive Principle:

Principle #35Parameter changes

3Stress or pressure

If larger conductive area is provided for stress reduction, then stress is better distributed, but the package area increases

Engineering Contradiction:

Improvestress distributionVSAvoidpackage area

Core Design Contradiction:

Stress or pressureVSArea of stationary object

Solution Approach 1:

The shadow pad material is strategically positioned only in specific locations where stress concentration occurs - specifically between the landing pad and PPI pad. This localized approach provides stress distribution benefits without requiring the entire package area to be enlarged, maintaining compact form factor.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS9748212B2Shadow pad for post-passivation interconnect structures

Publication Date: 2017.08.29 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Interconnect structures, packaged semiconductor devices, and methods of packaging semiconductor devices are disclosed. In some embodiments, an interconnect structure includes a first post-passivation interconnect (PPI) layer. The first PPI layer includes a landing pad and a shadow pad material proximate the landing pad. A polymer layer is over the first PPI layer, and a second PPI layer is over the polymer layer. The second PPI layer includes a PPI pad. The PPI pad is coupled to the landing pad by a via in the polymer layer. The shadow pad material is proximate the PPI pad and comprises a greater dimension than a dimension of the PPI pad. The shadow pad material is disposed laterally around the PPI pad.