Intelligent Power Module Lead Frame Layout for Flat Thermal Contact

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Solution Overview

Problem

Existing intelligent power modules face issues with surface flatness of the lead frame, leading to poor thermal contact between the heat dissipation structure and the lead frame, residual stress at chip connections, and complex manufacturing processes.

Innovation Solution

The intelligent power module features a lead frame with all portions encapsulated inside an encapsulating material structure at the same planar level, eliminating downsets and deformations, and using a reusable fixture for consistent surface flatness and simplified manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a bending part is formed in the lead frame to create a downset for chip placement, then chip mounting capability is improved, but surface flatness deteriorates causing poor thermal contact and residual stress

Engineering Contradiction:

Improvechip mounting capabilityVSAvoidsurface flatness

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The lead frame is divided into two distinct regions: a flat mounting surface for chip placement and a separate bending part for electrical connection. This segmentation allows each region to optimize its function independently - the flat surface ensures good thermal contact while the bending part provides mechanical attachment capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A dedicated bending part acts as an intermediary element between the flat lead frame surface and the chip mounting structure. This intermediary component handles the mechanical deformation and connection functions, preserving the flatness of the main mounting surface while still enabling chip attachment.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If multiple height levels are introduced for chip placement on the lead frame, then chip arrangement flexibility is improved, but positioning accuracy of bonding wires deteriorates

Engineering Contradiction:

Improvechip arrangement flexibilityVSAvoidbonding wire positioning accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The lead frame mounting surface is designed to be at a uniform height level, creating an equipotential surface for chip placement. This ensures that all chips mounted on the surface have the same reference plane, which maintains positioning accuracy for bonding wires while still allowing flexible chip arrangement through proper layout design.

Inventive Principle:

Principle #12Equipotentiality

3Adaptability or versatility

If a downset is formed in the lead frame to accommodate chips, then chip accommodation capability is improved, but thermal contact between heat dissipation structure and lead frame deteriorates

Engineering Contradiction:

Improvechip accommodation capabilityVSAvoidthermal contact quality

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The lead frame structure is segmented into a flat thermal contact surface and a separate chip accommodation region. This segmentation ensures that the heat dissipation structure maintains full contact with the flat lead frame surface while chips are accommodated through the dedicated bending part, preventing any compromise in thermal contact quality.

Inventive Principle:

Principle #1Segmentation

4Adaptability or versatility

If bending tools are used to form the downset, then chip mounting structure is created, but surface damage on the lead frame occurs due to long-term tool use

Engineering Contradiction:

Improvechip mounting structureVSAvoidsurface damage

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The bending part is pre-formed or designed in a way that minimizes the need for repeated tooling operations. By incorporating the bending structure as an integral part of the lead frame design, the number of times bending tools need to contact the surface is reduced, thereby minimizing cumulative surface damage from long-term tool use.

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 achieves better surface flatness, improved thermal conductivity, reduced residual stress, and a simpler manufacturing process, resulting in enhanced heat dissipation performance and increased yield.

Implementation Method 1

an encapsulating material structure; a lead frame at least partially encapsulated inside the encapsulating material structure

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Implementation Method 2

a heat dissipation structure, connected to the lead frame

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS20250201680A1Intelligent power module

Publication Date: 2025.06.19 RICHTEK TECH

AI summary

An intelligent power module includes: an encapsulating material structure; a lead frame which is at least partially encapsulated inside the encapsulating material structure, wherein all portions of the lead frame encapsulated inside the encapsulating material structure are at a same planar level; and a heat dissipation structure, which is connected to the lead frame.