Browse Prior Art Database

HIGH-DENSITY POWER PACKAGE FOR USE IN MOTOR CONTROL INVERTERS

IP.com Disclosure Number: IPCOM000008265D
Original Publication Date: 1997-Sep-01
Included in the Prior Art Database: 2002-May-31
Document File: 4 page(s) / 189K

Publishing Venue

Motorola

Related People

Joe L. Martinez, Jr.: AUTHOR [+2]

Abstract

The need exists in electronic packaging for high-power densities. The increased demand for more efftcient heat removal is driving the need for liquid cooled concepts. A packaging concept incorporating liquid cooling is presented here for use in power modules which have operating currents greater than 100 amps at voltage ratings above 6OOV.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 43% of the total text.

Page 1 of 4

MO-LA Technical Developments

HIGH-DENSITY POWER PACKAGE FOR USE IN MOTOR CONTROL INVERTERS

by Joe L. Martinez, Jr. and James Fusaro

ABSTRACT

  The need exists in electronic packaging for high-power densities. The increased demand for more efftcient heat removal is driving the need for liquid cooled concepts. A packaging concept incorporating liquid cooling is presented here for use in power modules which have operating currents greater than 100 amps at voltage ratings above 6OOV.

BACKGROUND

  Motor control inverters require the use of high- current, high-voltage power switches. The power switches incorporate electronic switching devices known as power modules. These switches are typically arranged electrically as shown in Figure 1. A power module package can be made in any combination of single-switches, dual-switches and six-packs. It is up to the end user to use any combi- nation of the illustrated electrical circuits to achieve the most economical approach for the customer's system.

  The power module is typically composed of Insulated Gate Bipolar Transistors (IGBT) and Free-wheeling diodes in parallel. Today, typical power densities are in the range of 200-300 W/cm'. The limitation in power density is directly propor- tional to the cooling method employed and the

packaging technology used.

  Packaging for conventional power modules incorporates various materials soldered together to form a thermal stack which is the path for conduc- tive heat transfer. The package is then mounted to a heatsink which is either air or liquid cooled (see Figure 2). Aside from the large thermal resistance encountered by the various materials used in the thermal stack, a larger contributor to thermal resis- tance, if not the largest contributor, is the contact thermal resistance between the module's baseplate and the heatsink.

SOLUTION

  The proposed solution is to eliminate the contact thermal resistance and the use of an external heatsink. The idea is to integrate the cooling medium into the package in a cost effective and manufacturable manner.

  The package incorporates a dielectric structure such as a Direct-Bonded Copper (DBC) substrate onto which the silicon die (IGBT and diodes) are mounted (see Figure 3). An Insulated-Metal Substrate (IMS) can also be incorporated as the dielectric structure. The difference in DBC and IMS is the composition of the dielectric material. DBC is composed of a ceramic layer sandwiched between two layers of copper. IMS is composed of an epoxy layer sandwiched between two layers of metal. One layer of copper or metal is used to form the conduc- tive pads for the electrical circuit. In the case of DBC, the other layer is used for soldering the DBC onto a baseplate or mounting the structure onto a heatsink. The DBC/IMS is attached to the housing with an adhesive, then silicone-gel is poured on top of the transistors and a cover is attached on top (see Figure 5). The plastic housing may incorporate insert-molded leads or leadf...