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LEADFRAME SOLUTION FOR HALF-BRIDGE POWER MODULE

IP.com Disclosure Number: IPCOM000005940D
Original Publication Date: 2001-Nov-16
Included in the Prior Art Database: 2001-Nov-16
Document File: 4 page(s) / 155K

Publishing Venue

Motorola

Related People

Frank Rehme: AUTHOR [+2]

Abstract

A leadframe solution has been developed in the design of half-bridge module for high power applications. This solution provides answers to requirements associated to high volume productions such as cost effectiveness, reliability, compactness and modularity.

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LEADFRAME SOLUTION

FOR

HALF-BRIDGE POWER MODULE

by Frank Rehme and Fabien Malacarne

 

ABSTRACT

A leadframe solution has been developed in the design of half-bridge module for high power applications. This solution provides answers to requirements associated to high volume productions such as cost effectiveness, reliability, compactness and modularity.

The proposed design includes a solution to optimise the heat capacity of the copper section under the dies by attaching thick copper heatsinks on a core leadframe and forming them to run under this core leadframe.

Other original features related to transfer moulding have also been tested on that large power module package such as stress relief grooves.

PROBLEM

The packaging of high power electronics is facing very challenging times, in particular when it is driven by typical high volume requirements such as:

-          Cost effectiveness.

-          Reliability.

-          Compactness.

-          Power modularity.

That applies in particular to half-bridge power modules switching high currents in the windings of an electrical motor. A half-bridge module is a well known architecture, and power MosFet’s and diodes are typically used to provide the high-end and low-end switches.

But the current solutions on the market are based on expensive power substrates, have limited power dissipation capabilities, multiply interconnection devices thus impacting reliability, and present large dimensions which doesn’t make them ideal for embarked systems.

Then an original solution was required to address all those issues and provide an optimised half-bridge module design for high power applications.

SOLUTION

The heart of the solution is a leadframe (see figure 1). This leadframe is typically made of copper. Power MosFet’s and diodes are eventually soldered on this leadframe and then wirebonded. The leadframe can be either insert moulded before dies assembly or transfer moulded after dies assembly.

But the leadframe is designed in such a way that it provides directly the following functions:

1.      Circuitry and signals tracking.

2.      Heatsinking.

3.      Interconnecting.

The immediate advantages to most of the half-bridge modules on the market are:

1.      No added power substrate (alumina based or Insulated Metal Substrate) is required.

2.      No added heatsink is required. The dies are directly soldered on copper slugs whose thickness can be optimised to suit the dissipated power.

3.      No added connector is required. The leadframe provides directly high powe...