Power Module Lead Frame Layout for Larger Heat Sink Coupling

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Solution Overview

Problem

Integrated power modules face challenges in dissipating heat and providing complex circuitry while minimizing package size, as existing packaging techniques restrict heat sink design and lead frame configurations.

Innovation Solution

The power module design features a lead frame with a paddle attached to power leads, where the leads extend in different directions to allow for a larger heat sink and includes recessed portions for secure locking, enabling improved heat removal and reduced stress on the package.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If conventional packaging techniques are used, then package size is reduced, but heat dissipation capability deteriorates

Engineering Contradiction:
Improvepackage sizeVSAvoidheat dissipation capability
Core Design Contradiction:
Volume of moving objectVSTemperature

Solution Approach 1:

The lead frame structure utilizes three-dimensional spatial arrangement by extending leads in different directions (first direction and second direction perpendicular to each other) and positioning the paddle below the mold material. This dimensional optimization allows the heat sink to extend beyond the mold material surface without increasing the overall package footprint, effectively resolving the contradiction between compact package size and heat dissipation capability.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Temperature

If leads are extended in different directions for larger heat sink, then heat dissipation is improved, but lead frame complexity increases

Engineering Contradiction:
Improveheat dissipation capabilityVSAvoidlead frame complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The lead frame structure serves multiple functions simultaneously: the leads provide both electrical connection and structural support for heat dissipation, the paddle provides both mechanical anchoring and thermal conduction path, and the extension beyond mold material surface serves both heat sink attachment and stress relief. This multi-functionality reduces the need for separate components, thereby managing complexity while achieving improved heat dissipation.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Strength

If paddle is attached to power leads and signal leads, then structural integrity is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvestructural integrityVSAvoidmanufacturing complexity
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The paddle is pre-positioned and attached to the leads before the leads are inserted into the mold material. This preliminary assembly allows for precise alignment and secure attachment in a single manufacturing step, rather than requiring complex post-assembly operations. The pre-attached paddle configuration simplifies the overall manufacturing process while ensuring strong structural integrity for heat sink mounting.

Inventive Principle:
Principle #10Preliminary action

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

This design enhances heat dissipation by allowing a larger heat sink and secure lead retention, addressing the limitations of conventional configurations and improving the module's thermal management and structural integrity.

Implementation Method 1

The exposed surface of the paddle is configured to couple to a heatsink configured to extend beyond a surface of the mold material

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

allowing a larger heat sink and secure lead retention, addressing the limitations of conventional configurations and improving the module's thermal management

Methodology Applied
Scientific EffectHeat dissipation: Heat Sink

Data Source

PatentEP4062446B1Power module package
Publication Date: 2024.12.11 ALLEGRO MICROSYSTEMS LLC
  • EP4062446B1 patent drawingFigure 1A
  • EP4062446B1 patent drawingFigure 1B
  • EP4062446B1 patent drawingFigure 1C

AI summary

A power integrated circuit (IC) includes a lead frame comprising a signal lead, a power lead, and a paddle attached to one or more of the signal lead and the power lead, an electrical component supported by the paddle, and a mold material enclosing a portion of the lead frame and exposing a surface of the paddle. The power lead has a first portion extending from an edge of the mold material outside of the mold material in a first direction and a second portion enclosed by the mold material and extending from the edge of the mold material inside the mold material in a second direction to the paddle. The paddle can be only attached to the second portion of the power lead. The first and second portions of the power lead meet at a junction between first and second portions of the mold material.