Segmented Conductive Pads for Solder Crack Prevention

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Solution Overview

Problem

Existing semiconductor packages face issues with solder cracks due to the spreading of solder layers during the mounting process, which compromises the reliability and integrity of the package.

Innovation Solution

The use of elongated conductive pads with sub-bar patterns spaced apart on the package substrate inhibits the spreading of solder layers, preventing solder cracks by ensuring proper bonding and structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional continuous conductive pads are used, then electrical connectivity is ensured, but solder layers spread during mounting causing solder cracks

Engineering Contradiction:

Improvesolder crack preventionVSAvoidsolder layer control

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The conductive pad is divided into multiple sub-bar patterns spaced apart from each other in the first direction. This segmentation prevents solder layers from spreading continuously across the pad, thereby preventing solder cracks while maintaining electrical connectivity through the distributed sub-bars.

Inventive Principle:

Principle #1Segmentation

2Strength

If solder layers are allowed to spread for complete coverage, then bonding area is maximized, but solder cracks occur reducing package reliability

Engineering Contradiction:

Improvebonding strengthVSAvoidpackage reliability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The conductive pad is segmented into multiple sub-bar patterns that provide distributed bonding areas. This segmentation maintains adequate bonding strength through multiple contact points while preventing the continuous solder spread that causes cracks, thus improving overall package reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sub-bar patterns are strategically positioned to provide localized bonding strength where needed. Each sub-bar acts as an independent bonding zone, ensuring adequate mechanical strength while the spacing between them prevents harmful solder propagation.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If conductive pads are made continuous for electrical connectivity, then manufacturing is simpler, but solder cracks develop during mounting

Engineering Contradiction:

Improvepad structure fabricationVSAvoidsolder joint integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The conductive pad structure is segmented into multiple sub-bar patterns that can be fabricated using standard photolithography and metallization processes. While the pattern is more complex than a continuous pad, it remains compatible with conventional manufacturing techniques, achieving a balance between manufacturability and solder joint integrity.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10573588B2Package substrate and semiconductor package including the same

Publication Date: 2020.02.25 SAMSUNG ELECTRONICS CO LTD

AI summary

A package substrate and a semiconductor package are provided. The package substrate including a substrate body having a first surface on which a semiconductor chip is mounted and a second surface opposite to the first surface, and a conductive pad at the first surface, the conductive pad elongated in a first direction, the conductive pad including a plurality of sub-bar patterns spaced apart from each other in the first direction may be provided.