雜談GaN技術

增強型 GaN 功率器件（eGaN® FETs 和 ICs）為用戶提供了區分其最終產品的途徑。這項新技術在支持我們的設備和電子設備的隨處可見的電源供應和輸送電路中顯著提高了效率。

Written by Michael de Rooij and Alana Nakata - Efficient Power Conversion

Published in: PCIM Europe 2017; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management; Proceedings of

eGaN FETs, which are available in non-traditional chip scale packages (CSP) as land grid array (LGA) and/or ball grid array (BGA) formats, have repeatedly demonstrated higher power density and higher efficiency performance than equivalent MOSFETs across various applications ^{[1, 2]}. Those improvements are contingent upon proper layout practices documented extensively in ^{[1, 3]} that minimize unwanted parasitic elements. Over the seven years since eGaN FETs were first launched into the market there have been a total of 127 device failures out of a total of more than 17 billion hours in actual use in the field, 75 of which were a result of poor assembly technique or poor printed circuit board (PCB) design practices ^[4]. Designers are becoming more familiar with the PCB design rules that affect manufacturability and are less forgiving compared to MOSFETs due to their relatively smaller sizes. This paper will cover the various guidelines for PCB design that maximize the performance of eGaN FETs and reliability yet still rely on existing PCB manufacturing capabilities.

The previous installment in this series focused on the physics of failure surrounding thermo-mechanical reliability of EPC eGaN® wafer level chip-scale packages. A fundamental understanding of the potential failure modes under voltage bias is also important. This installment will provide an overview of the physics of failure associated with voltage bias at the gate electrode of gallium nitride (GaN) field effect transistors (FETs). Here we look at the case of taking the gate control voltage to the specified limit and beyond to investigate how eGaN FETs behave over a projected lifetime.

The first three installments in this series covered field reliability experience and stress test qualification of Efficient Power Conversion (EPC) Corporation’s enhancement-mode gallium nitride (eGaN®) field effect transistors (FETs) and integrated circuits (ICs).  Excellent field reliability that was documented is the result of applying stress tests covering the intended operating conditions the devices will experience within applications.  Of equal importance is understanding the underlying physics of how eGaN® devices will fail when stressed beyond intended operating conditions (e.g. datasheet parameters and safe operating area).  This installment will take a deeper dive into the physics of failure centered around thermo-mechanical reliability of eGaN® wafer level chip-scale packages (WLCSP).

The first two installments in this series reported in detail on field reliability experience of Efficient Power Conversion (EPC) Corporation’s enhancement-mode gallium nitride (eGaN®) FETs and integrated circuits (ICs). The excellent field reliability of eGaN® devices demonstrates stress-based qualification testing is capable of ensuring reliability in customer applications. In this installment we will examine the stress tests that EPC devices are subjected to prior to being considered qualified products.

Efficient Power Conversion (EPC) Corporation’s enhancement-mode gallium nitride (eGaN®) FETs and integrated circuits (ICs) are finding their way into many end user applications such as LIDAR, wireless charging, DC-DC conversion, RF base station transmission, satellite systems, and audio amplifiers.

Efficient Power Conversion (EPC) Corporation’s enhancement-mode gallium nitride (eGaN®) FETs continue to expand into new market applications due to the competitive performance advantages over traditional power MOSFETs. Wireless power, DC-DC conversion, RF base station transmission, satellite systems, audio amplifiers, and LiDAR are just a few example applications that can take advantage of the superior performance of eGaN FETs.

The contribution that gallium nitride semiconductor technology is making in medical applications can be measured not only in dollars saved, but also more importantly in its contribution to the speed of intervention, diagnostic accuracy and patient comfort. Because of its superior performance and small size, GaN components (FETs and ICs) are enabling end applications such as wireless power charging, higher resolution diagnostics, and precision surgical robotics. These applications are improving ways health care is being provided.

In my 40 years’ experience in power semiconductors I have visited thousands of customers, big and small, on every continent except Antarctica. When the issue invariably turns to the packaging of the power semiconductor – transistor, diode, or integrated circuit – the requests for improvement fall into six categories:

1. Can you make the package smaller?
2. Can you reduce the package inductance?
3. Can you make the product with lower conduction losses?
4. Can you make the package more thermally efficient?
5. Can you sell the product at a lower price?
6. Can you make the package more reliable?

eGaN^® FETs and integrated circuits from EPC have taken a very different approach to packaging power semiconductors – we have ditched the package altogether!

In March 2010 Efficient Power Conversion (EPC) proudly launched our GaN technology at the CIPS conference in Nuremberg, Germany.  Parts and development kits were readily available off-the shelf and therefore designers could immediately get started with a new state-of-the-art semiconductor technology.

At that time, we listed four key attributes we believed a new semiconductor technology needed in order to be really disruptive to the end markets.  A lot has happened in the six years since.  GaN has continued to ascend as the presumptive replacement for the aging power MOSFET, yet there are still a few design engineers and technical managers that remain skeptical.  So let’s look again at these four key attributes and see where GaN stands in addressing them.