Metal Tab Die Attach Paddle for Power Device Packages

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional power device packages experience stress and deformation due to the difference in thermal expansion coefficients between semiconductor dies and lead frames, leading to performance deterioration, cracking, and penetration of foreign substances.

Innovation Solution

A power device package is designed with a metal tab die attach paddle (DAP) attached to the lead frame, using conductive adhesive materials with varying melting points and CTEs to minimize stress, and a sealant with an extended surface creepage distance to prevent impurities from entering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the semiconductor die is directly bonded to the lead frame, then the bonding process is simple, but the semiconductor die is stressed and deformed due to the difference in coefficient of thermal expansion (CTE) between the die and lead frame

Engineering Contradiction:

Improvebonding process complexityVSAvoidsemiconductor die performance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

A metal tab die attach paddle (DAP) is introduced as an intermediary component between the semiconductor die and the lead frame. This DAP serves as a stress buffer that compensates for the CTE mismatch, preventing stress and deformation of the semiconductor die while maintaining bonding simplicity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the thermal expansion parameter by selecting a metal tab material whose CTE is between that of the semiconductor die and the lead frame. This intermediate CTE value allows the metal tab to act as a gradient transition, reducing thermal stress on the die during temperature changes.

Inventive Principle:

Principle #35Parameter changes

2Volume of moving object

If the semiconductor die is directly bonded to the lead frame, then the package structure is compact, but the stress causes cracking and foreign substance penetration

Engineering Contradiction:

Improvepackage sizeVSAvoidcracking and foreign substance penetration

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The metal tab DAP acts as a protective intermediary that prevents stress-induced cracking. By absorbing and distributing thermal stress, it protects the semiconductor die and bonding interfaces from cracking, thereby preventing foreign substance penetration through cracks.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The metal tab DAP provides beforehand cushioning by pre-absorbing thermal expansion stresses before they can propagate to the semiconductor die and bonding interfaces. This preventive cushioning eliminates the root cause of cracking and subsequent contamination.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If the semiconductor die size is limited to the lead frame size, then the lead frame can be used directly, but larger semiconductor dies cannot be accommodated

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoiddie size adaptability

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The metal tab DAP serves as a flexible intermediary platform that can be manufactured in various sizes independent of the lead frame constraints. This allows semiconductor dies larger than the lead frame to be accommodated, as the DAP can be sized to match the die while still attaching to the lead frame.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The bonding structure is segmented into three independent components: the lead frame, the metal tab DAP, and the semiconductor die. This segmentation allows each component to be optimized independently, enabling the die size to exceed lead frame dimensions while maintaining manufacturing simplicity.

Inventive Principle:

Principle #1Segmentation

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 solution significantly reduces stress on the semiconductor die, enhances sealant bonding, and allows for larger semiconductor dies by compensating for thermal expansion differences, thereby improving package reliability and preventing impurity penetration.

Implementation Method 1

the stress is caused by the difference between a coefficient of thermal expansion (CTE) of the semiconductor die and that of a lead frame

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

The metal tab DAP may be attached to the lead frame using a first conductive adhesive material, the power device die may be bonded to the metal tab DAP using a second conductive adhesive material

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS8945992B2Power device package comprising metal tab die attach paddle (DAP) and method of fabricating the package

Publication Date: 2015.02.03 SEMICON COMPONENTS IND LLC

AI summary

A metal tab die attach paddle (DAP) disposed between the lead frame and a power device die in a power device package reduces the stress exerted on the semiconductor power device die caused by the different coefficients of thermal expansion (CTE) of the semiconductor power device die and the lead frame. In addition the power device package substantially prevents impurities from penetrating into the power device package by increasing the surface creepage distance of a sealant resulting from the metal tab DAP and an optional swaging of the lead frame.