Multi-die IC Package with Internal Leadframe Segmentation

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Solution Overview

Problem

Current integrated circuit packaging methods face challenges in efficiently integrating multiple semiconductor dies into a single package without increasing the overall footprint, particularly in mounting dies on both sides of a leadframe due to difficulties in connecting wire bonds and manufacturing flat no-leads packages like QFN and DFN.

Innovation Solution

The solution involves using an internal leadframe positioned between two dies, with one die on each side, and a separate external leadframe with exposed leads on the bottom surface, allowing for wire bonding between the dies and the internal leadframe, and encapsulating the assembly to maintain the QFN structure while ensuring no portion of the internal leadframe is exposed externally.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple dies are integrated into a single package, then the functional complexity and integration density are improved, but the manufacturing difficulty and wire bonding complexity increase

Engineering Contradiction:

Improveintegration densityVSAvoidwire bonding complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The leadframe is divided into multiple isolated sections, each capable of supporting a die independently. This segmentation allows wire bonds to be confined to specific regions rather than spanning the entire leadframe, reducing wire bonding complexity while enabling integration of multiple dies

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the leadframe are designed with different properties - some regions have isolated sections for individual die mounting with localized wire bonding, while other regions maintain continuous structure. This local differentiation optimizes the structure for multi-die integration without uniformly increasing complexity

Inventive Principle:

Principle #3Local quality

2Area of stationary object

If dies are mounted on both sides of the leadframe, then the package footprint is reduced, but the manufacturing difficulty increases

Engineering Contradiction:

Improvepackage footprintVSAvoidmanufacturing difficulty

Core Design Contradiction:

Area of stationary objectVSEase of manufacture

Solution Approach 1:

Instead of mounting all dies on one side of the leadframe (conventional approach), the invention inverts the approach by mounting dies on both sides of the leadframe. This allows the package footprint to be reduced while the isolated leadframe sections simplify the manufacturing process by providing clear separation between dies

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If the leadframe is fully encapsulated, then the protection against corrosion and environmental damage is improved, but the visibility and accessibility of leads decrease

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidlead accessibility

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The leads are extracted from the encapsulated region and extended outward from the housing. This allows the housing to provide full encapsulation and corrosion protection for the internal components, while the leads remain accessible for electrical connections by extending beyond the protected region

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS11328984B2Multi-die integrated circuit packages and methods of manufacturing the same

Publication Date: 2022.05.10 TEXAS INSTRUMENTS INC

AI summary

Multi-die integrated circuit packages and methods of manufacturing the same are disclosed. An example integrated circuit package includes a first leadframe, a first die on a first side of the first leadframe, and a second die on a second side of the first leadframe opposite the first side. The example integrated circuit package further includes external second leadframe separate from the first leadframe.