Unleashing IMPCB Benefits in Motor Controls

Aug 1, 2006 12:00 PM
By Michael Dreyer, Vice President and General Manager, Laird Technologies, St. Louis

Just around the corner is a new breed of inverter technology for motor-control applications. The limitations of the traditional tried and true, direct-bonded copper (DBC) IGBT-based industrial motor-control inverters are about to be eclipsed by a new and exciting breed of motor-control inverter based on insulated metal printed circuit boards (IMPCBs).

Using IMPCB, also referred to as insulated metal substrates, these products promise to take industrial motor-control applications to the next level. Implementing techniques such as component integration and standard pc-board fabrication, these next-generation devices offer dramatic increases in reliability and significant reductions in manufacturing costs. IMPCB technology will be able to replace performance-limiting DBC IGBT technology in many existing devices and applications, and be directly relevant to a plethora of other emerging devices, creating a myriad of new opportunities.

In today's standard product, chip and wire-fabricated DBC IGBT modules, the single most limiting factor is terminal inductance — the issue that these next-generation inverter devices have the ideal technology to overcome. Terminal inductance is the largest inductance in the module and has a significant impact on current parameters, externally with interconnect and internally with terminal size and construction, as well as limiting the maximum switching speed.

To muddy the waters even further, high-current device parameters such as short-circuit currents are difficult to pretest at the die level. This means that existing products do not lend themselves to mass production and have compound yield issues. This, of course, translates directly into high costs for the end user. If there is a need for multiple, larger IGBT die assemblies, their complexity forces users to construct inverters around available building blocks, meaning users are left to their own devices when addressing terminal, busbar, mechanical and thermal mounting issues.

IMPCB inverters were developed to address the limitations of DBC IGBT devices, especially current limitations and the cost of manufacturing. The significant advantage of these devices is they can be built with an integral metal base plate (aluminum or copper) using standard pc-board fabrication, and assembled with standard surface-mount devices (SMDs) and reflow techniques. SMD IMPCB inverters use prepackaged, pretested available IGBTs and MOSFETs, making them integral mechanical, electrical and thermal entities with thermal conductivity 10 to 20 times better than an FR4 pc board. This has the key advantage of reducing costs by using existing fabricators with established reliability. Moreover, because the substrate is defined by artwork, programmable drilling and singulation, each product may be optimized for its specific function and application.

Because interconnects are now on the substrate surface, inductance is reduced and interconnects become reliable, quiet and efficient because extra terminals, busbars and mounting hardware is eliminated. For applications that demand larger IMPCB inverters, this new platform provides better power dissipation, thereby allowing switching devices to run cooler and provide higher operating currents.

For emerging applications, IMPCB technology will unlock new opportunities in untapped areas of industrial motor controls. For example, large-area IMPCB products, without the limitations of traditional DBC-based designs, will integrate the technology into higher current and horsepower motor controllers. IMPCB-based technology also will be the ideal candidate for addressing the higher temperature and mechanical requirements of automotive inverters and emerging electric vehicle and hybrid inverter applications.

Worldwide markets for IMPCB-based technology are just beginning to unfold. IMPCB technology has been used in Japan for more than 25 years, for commercial 3-phase motor controls in appliances. However, the United States and Europe have yet to capitalize on the full potential of IMPCB technology, which means these regions are potentially an untapped market, ripe for profitable and far-reaching expansion. Look for IMPCB-based technology to be one of the most significant technological advancements in motor control as it finds applicability in countless present-day and emerging markets and applications.

Michael Dreyer has more than 16 years in the electronics industry, including 12 years with Motorola where he held several technical and management roles with the semiconductor products sector. Dreyer, who joined Laird Technologies in 2005, earned his BSEE and MSEE degrees from the University of South Florida.