DIP-IPM vs. DIPIPM+™: A Deep Dive into Mitsubishi’s Compact IPM Evolution

Introduction: The Drive for Higher Power Density in Motor Control

In the world of low-power motor control, particularly for applications like home appliances, HVAC systems, and industrial pumps, the design mantra is consistently “smaller, more efficient, and more reliable.” For engineers, this translates into a relentless pursuit of higher power density. The challenge is to pack more power processing capability into a smaller physical volume without compromising on thermal performance or system longevity. This is where the Intelligent Power Module (IPM) has become an indispensable component.

Mitsubishi Electric, a pioneer in this field, has long set the standard with its IPM families. For years, the DIP-IPM (Dual-In-Line Package Intelligent Power Module) has been the go-to solution for countless compact inverter designs. It simplified development by integrating power switches (IGBTs), freewheeling diodes (FWDs), gate drivers, and protection circuits into a single, easy-to-use package. However, as power demands grew and thermal envelopes shrank, the limitations of the traditional DIP package became apparent. In response, Mitsubishi introduced the DIPIPM+™ series, representing a significant architectural evolution rather than a simple incremental update. This article provides a detailed, engineering-focused comparison between the classic DIP-IPM and the advanced DIPIPM+™, helping you understand their core differences and make informed selection decisions for your next project.

Understanding the Foundation: What is a Classic DIP-IPM?

Before diving into the advanced features of DIPIPM+™, it’s crucial to appreciate the design philosophy and structure of the original DIP-IPM. This foundational understanding highlights why it was so successful and where its inherent limitations created a need for innovation.

Core Architecture and Key Features

The classic DIP-IPM is built on a traditional leadframe structure encapsulated in a transfer-molded epoxy resin body, similar to many standard integrated circuits. This Dual-In-Line Package provides through-hole pins for easy mounting onto a printed circuit board (PCB).

Its primary value proposition lies in its high level of integration:

• Power Stage: It typically contains a three-phase bridge of IGBTs and FWDs, forming the core of an inverter.
• Gate Drive Circuitry: Integrated high-voltage ICs (HVICs) and low-voltage ICs (LVICs) provide optimized gate driving signals, level-shifting, and dead-time generation, removing a complex and sensitive part of the design process from the engineer’s plate.
• Protection Functions: Essential protection features are built-in, such as short-circuit protection (SC), under-voltage lockout (UV) for the control supply, and often over-temperature (OT) shutdown.
• Bootstrap Circuit: The module includes the necessary diodes and, in some cases, current-limiting resistors for the bootstrap power supply of the high-side gate drivers, further simplifying the external circuitry. You can learn more about this in Mitsubishi’s documentation on the DIPIPM™ bootstrap circuit.

This all-in-one approach dramatically reduced design time, component count, and PCB space, making it a favorite for high-volume, cost-sensitive applications.

The Inherent Limitations

Despite its success, the traditional DIP-IPM architecture has inherent physical limitations, primarily related to heat management. The power chips (IGBTs and FWDs) are mounted on a metal leadframe, and the heat must travel through this leadframe and the plastic molding compound to reach an external heatsink. This creates a relatively high thermal resistance (Rth). As application power levels increase, the heat generated by conduction and switching losses becomes more difficult to dissipate effectively, forcing designers to either limit the output current or employ larger, more expensive heatsinks.

The Next Generation: Introducing the DIPIPM+™ Package

The DIPIPM+™ was engineered specifically to overcome the thermal bottleneck of its predecessor. It retains the “plug-and-play” simplicity of the original but completely reimagines the internal structure to create a thermally superior package.

Key Innovations in DIPIPM+™

The most significant change in the DIPIPM+™ series is the move from a traditional leadframe to an insulated metal substrate, typically a Direct Bonded Copper (DBC) ceramic substrate. This is a technology borrowed from larger, high-power modules.

The key innovations include:

• Direct Bonded Copper (DBC) Substrate: Instead of a leadframe, the power chips are directly soldered onto a ceramic substrate (like Alumina or Aluminum Nitride) which is bonded to a copper baseplate. This structure provides excellent electrical isolation while creating a highly efficient, direct thermal path from the chip junction to the heatsink.
• Advanced Chip Technology: The DIPIPM+™ series incorporates Mitsubishi’s latest generation power chips, such as the 7th Generation CSTBT™ (Carrier Stored Trench-gate Bipolar Transistor). These chips offer a lower collector-emitter saturation voltage (VCE(sat)) and reduced switching losses, meaning less heat is generated in the first place.
• Optimized Internal Layout: The internal layout is optimized to reduce stray inductance, leading to cleaner switching waveforms and lower voltage overshoots, which enhances both reliability and EMI performance.

How These Changes Translate to Performance Gains

These architectural improvements deliver tangible benefits for the design engineer:

• Dramatically Lower Thermal Resistance: The Rth(j-c) (junction-to-case thermal resistance) of a DIPIPM+™ can be up to 50% lower than a comparable DIP-IPM. This is the single most important advantage, allowing for higher output current from the same size package or the use of a smaller heatsink for the same power level.
• Higher Power Density: With superior heat extraction and more efficient chips, DIPIPM+™ modules can handle significantly more power within a similar footprint, enabling more compact and powerful inverter designs. For a detailed look at our IGBT module offerings, you can explore the full catalog on our website.
• Enhanced Reliability and Lifetime: Lower operating junction temperatures directly translate to longer device lifetime and improved power cycling capability. The robust DBC structure is less susceptible to delamination and fatigue failures compared to traditional plastic packages under thermal stress.

Head-to-Head Comparison: DIP-IPM vs. DIPIPM+™

To make the choice clearer, let’s break down the differences across key engineering parameters. The table below summarizes the core comparison, followed by a more detailed analysis.

Parameter	Classic DIP-IPM	DIPIPM+™	Engineering Implication
Internal Substrate	Molded Leadframe	Insulated Metal Substrate (DBC)	DIPIPM+™ offers a much lower thermal resistance path.
Thermal Resistance (Rth j-c)	Higher	Significantly Lower (~30-50%)	Higher power output for a given junction temperature, or use of smaller heatsinks.
Power Chip Technology	Older IGBT Generations	Latest Generations (e.g., 7th Gen IGBT)	Lower VCE(sat) and switching losses, leading to higher overall efficiency.
Maximum Current Rating	Lower (e.g., up to ~30A)	Higher (e.g., up to ~50A or more)	Enables more powerful motor drives in the same compact form factor.
Package Footprint	Various standard DIP sizes	Often footprint-compatible with DIP-IPM	Allows for potential performance upgrades on existing PCB layouts (pinout must be verified).
Cost	Lower	Higher	DIPIPM+™ carries a premium for its advanced construction and performance.

Thermal Performance: The Critical Differentiator

Imagine heat as traffic. In a classic DIP-IPM, the heat generated at the chip junction has to navigate a narrow, winding country road (the leadframe and plastic) to get to the heatsink. In a DIPIPM+™, it has a direct, multi-lane superhighway (the DBC substrate). This fundamental difference in thermal architecture is why DIPIPM+™ can sustain higher power dissipation, allowing the chips to run cooler at the same load or handle higher currents before hitting their maximum junction temperature limit (Tj,max).

Electrical Performance and Integration

While thermal performance is the headline feature, the electrical benefits are also significant. The use of newer-generation IGBTs in DIPIPM+™ results in lower conduction losses (due to lower VCE(sat)) and lower switching losses. This improved efficiency not only saves energy but also reduces the amount of waste heat that needs to be managed, creating a virtuous cycle of better performance. Both families offer a similar suite of robust protection features, ensuring safe operation.

Practical Application & Selection Guide

Choosing between these two families is not about which is “better” in a vacuum, but which is the most appropriate for your specific design constraints and performance targets.

When is a Classic DIP-IPM Still the Right Choice?

Despite the advantages of DIPIPM+™, the classic DIP-IPM remains a highly viable option for many scenarios:

• Extreme Cost-Sensitivity: For high-volume consumer goods where every cent counts and the power requirements are modest (e.g., small fan motors, drain pumps), the lower unit cost of the DIP-IPM can be the deciding factor.
• Low-Power Applications: In applications well within the thermal limits of the DIP-IPM, the extra performance of a DIPIPM+™ would be over-engineering and not cost-effective.
• Legacy Designs: If you are maintaining or making minor updates to an existing product line based on a DIP-IPM, sticking with it avoids the cost and time associated with a full redesign and requalification process.

Why and When to Upgrade to DIPIPM+™? A Checklist

You should strongly consider specifying a DIPIPM+™ for your design if you answer “yes” to any of the following questions:

1. Are you designing a new, high-performance product? For all new designs, especially those targeting premium performance, starting with the superior DIPIPM+™ platform is a future-proof strategy.
2. Is your device operating in a high-ambient temperature environment? The superior thermal performance of DIPIPM+™ provides a larger safety margin.
3. Are you trying to shrink the product’s physical size? DIPIPM+™ allows for the use of a smaller, lighter, and less costly heatsink, or in some cases, can enable a fanless design.
4. Do you need to increase the output power of an existing design without increasing its footprint? If a DIPIPM+™ is available with a compatible footprint and pinout, it can be a powerful drop-in upgrade to boost performance.
5. Is long-term reliability a critical design parameter? The lower operating temperatures and more robust package construction of the DIPIPM+™ contribute to a longer operational life.

You can explore our range of intelligent power modules here to find the perfect fit for your application’s power and thermal requirements.

Conclusion: Choosing the Right IPM for Future-Proof Designs

The evolution from DIP-IPM to DIPIPM+™ is a clear illustration of the power electronics industry’s response to the market’s demand for greater power density. The classic DIP-IPM remains a cost-effective workhorse for less demanding applications. However, the DIPIPM+™, with its thermally advanced DBC structure and state-of-the-art silicon, represents the clear path forward for compact, high-performance motor control.

For engineers, the choice hinges on a careful analysis of the trade-offs between cost, performance, and design constraints. While the DIPIPM+™ has a higher initial component cost, it can often lead to a lower total system cost by reducing heatsink size, simplifying thermal management, and enhancing product reliability. By understanding the fundamental architectural differences detailed here, you can select the right Mitsubishi IPM to create a competitive, efficient, and robust solution for years to come.