Dummy Tie Bar in IC Package Lead Structures

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Solution Overview

Problem

Integrated circuit package systems face manufacturing defects such as cracking and chip-outs during singulation, leading to environmental protection failure and increased costs due to the limitations of existing semiconductor packaging technologies.

Innovation Solution

The introduction of dummy tie bars that intersect with the outer edge of the integrated circuit package system, providing structural integrity and connecting the integrated circuit die to lead structures, thereby preventing chip-outs and cracks during the singulation process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If mechanical sawing or scribing techniques are used for singulation, then individual semiconductor packages can be separated, but cracks or chipouts occur during the process

Engineering Contradiction:

Improvesingulation capabilityVSAvoidpackage integrity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The dummy tie bar is designed and positioned in advance during the leadframe manufacturing process, before singulation occurs. This preliminary structural reinforcement is already in place when the singulation process begins, preventing cracks and chipouts during separation of individual packages from the strip.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If the leadframe structure is simplified for manufacturing, then production costs decrease, but configurability for different terminal pad layouts is reduced

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidterminal pad configuration flexibility

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The dummy tie bar serves multiple functions: it reinforces the leadframe structure to prevent manufacturing defects, provides mechanical support during singulation, and can be positioned to accommodate different terminal pad configurations. This single structural element addresses both structural integrity and configurability needs.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The leadframe is divided into functional segments including the dummy tie bar, inner terminal tie bars, and outer terminal pads. This segmentation allows each component to be optimized independently - the dummy tie bar for structural support and the terminal pads for electrical connectivity in various configurations.

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If more terminal pads are added to increase connectivity options, then adaptability increases, but manufacturing complexity and defect risk increase

Engineering Contradiction:

Improveterminal pad connectivity optionsVSAvoidleadframe structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The dummy tie bar acts as an intermediary structural element between the inner terminal tie bars and outer terminal pads. It provides mechanical support and stress distribution that enables the addition of more terminal pads without proportionally increasing the risk of manufacturing defects, as the dummy tie bar reinforces the overall structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS7936053B2Integrated circuit package system with lead structures including a dummy tie bar

Publication Date: 2011.05.03 STATS CHIPPAC LTD

AI summary

An integrated circuit package system includes forming lead structures including a dummy tie bar having an intersection with an outer edge of the integrated circuit package system, and connecting an integrated circuit die to the lead structures.