Copper Is Here to Stay in Power Electronics

时间： 2021-08-22 来源：Rogers

技术问答

选型帮助

研发客服

商务客服

While silicon is the most common element used for power semiconductors, copper is the most popular choice for conductor traces on printed circuit boards (PCBs) and Ceramic Substrates due to its electrical conductivity. Copper is a well-established material for base plates and heat sinks because of its thermal conductivity. Furthermore, it has become important for the metallization and interconnection of power devices. The ever-growing power density, current carrying capability, and reliability requirements are factors to why copper is already widespread in the industry. Copper is readily available, relatively inexpensive, and not likely to disappear anytime soon.

Copper versus Aluminum

Aluminum is the most popular alternative to copper, depending on the application. For example, aluminum is the preferred material in heat sinks because it is less expensive and lighter than copper. However, copper is a more desirable alternative for certain applications when higher heat conductivity outweighs the available weight savings. At room temperature, copper has a thermal conductivity of 400 W/m-K, whereas aluminum´s conductivity is 235 W/m-K. Consequently, all other factors like a heat sink made of copper dissipate more heat than an aluminum heat sink. Thus, numerous power modules with integrated copper pin fin heat sinks have been accepted by the market and are successfully operating in the field of hybrid and electric vehicles today.

Aluminum and its alloys are widely used for chip metallization. They exhibit a low electrical resistance and excellent adhesion on silicon and silicon oxide layers. Despite that, copper metallization has been introduced to replace aluminum by taking advantage of its lower resistivity and higher thermal conductivity. Lower resistivity allows higher current flow per unit area with less joule heat generation; while higher thermal conductivity dissipates heat more efficiently. These two distinct advantages for copper enable greater current flows and miniaturization. Unfortunately, copper cannot be structured as easily as aluminum in dry etching processes. Therefore, not all chips come with copper metallization. Moreover, cost and stress issues are limiting the copper metallization thickness between 5 μm to 10 μm, though thicker layers would certainly support higher current drivability, higher heat capacity, and heat dissipation. Although, some workarounds are possible as demonstrated by Danfoss with its bond buffer technology: by sintering a thin copper foil on top of the chips.

Reliability is another driving factor to establish copper as a standard chip metallization. The main cause for failure in state-of-the-art power modules is the bond-wire lift-off. As a consequence, new solutions to interconnect multiple chips in a power module have been developed to replace conventional aluminum wires. Many solutions rely on copper material in different shapes and geometries: wires, ribbons, pillars, clips, or lead frames which can be soldered, sintered, or welded on the chips. Other solutions include planar interconnecting and chip embedding technologies where top side electrical contacts are connected due to filled copper vias.

Heavy copper is no longer heavy enough

Conductor traces in PCBs' inner and outer layers and ceramic substrates are predominantly made of copper, even though some substrates exist with aluminum metallization.

Copper thickness can be specified as the weight of copper in ounce per square foot (oz/ft²). Most commercially available PCBs are manufactured for low power applications with copper traces made of copper weights ranging from 0.5 oz/ft² (18 µm) up to 3 oz/ft² (105 µm). For higher power applications, heavy copper circuits can be manufactured with copper weights between 4 oz/ft² (140 µm) and 20 oz/ft² (686 µm). Copper weights above 20 oz/ft² are also possible and are referred to as extreme copper.

Particularly, Direct Bonded Copper (DBC) and Active Metal Brazed (AMB) substrates are used to attach and connect multiple power devices in parallel to a module to achieve the required power rating for a given application. These substrates are available with typical copper thickness ranging from 127 µm up to 800 µm. However, the trend for miniaturization holds for power modules, too. Hence, module makers are pushing the limits of semiconductor and packaging technologies, to further increase the output power in existing or even smaller footprints. Moreover, as the increase in performance should not impact cost and reliability, substrates and base plate or heat sink have to be attached with new joining technologies or even better integrated into one single component. This eventually leads to the development of substrates with copper layers thicker than 1 mm.

Generally, thick copper layers are manufactured with the same wet chemical etching process as standard copper layers. Because of its isotropic characteristic, wet chemical etching becomes inadequate for patterning thick copper layers, since it results in wide trenches between conductor tracks, and customers require narrow trenches to reduce the footprint of their modules. Thus, specialized structuring techniques have to be developed instead to achieve narrow gaps, straight sidewalls, and negligible undercuts.

Development projects have been initiated and are ongoing at ROGERS PES to deliver market-driven solutions that fit your specific needs. As an example, multilayer ceramic substrates and enhanced DBC substrates have been presented at the last PCIM exhibition and there are many more new products to come.

发送到邮箱 |
+1 赞 0
收藏
评论 0
| 转发至：

本文由董慧转载自Rogers，原文标题为:Copper Is Here to Stay in Power Electronics，本站所有转载文章系出于传递更多信息之目的，且明确注明来源，不希望被转载的媒体或个人可与我们联系，我们将立即进行删除处理。

全部评论（0）

暂无评论

Applications for Metallized Ceramic Substrates

Direct Bonded Copper (DBC) and Active Metal Brazed (AMB) ceramic substrates are used in multi-chip modules for electric power conversion in order to convert. Each application comes with its own specific requirements for the multi-chip power modules, hence the variety of substrates inside the modules. In this blog, we look at common applications for multi-chip power modules to understand the rationale behind each technology. The common applications are industrial equipment, consumer, new energy, rail traction and automotive.

厂牌及品类发布时间 : 2021-08-15

Rogers curamik® Ceramic Substrates offer superior thermal properties and have applications in many of the world‘s most advanced electronic systems

There are many advantages in choosing a ceramic substrate over other substrates based on metal or plastic. Rogers curamik® Ceramic Substrates offer superior thermal properties such as high-heat conductivity, extended heat capacity and enhanced thermal spreading.

厂牌及品类发布时间 : 2022-04-21

Rogers Corporation’s Curamik® Ceramic Substrates, Low Inductive ROLINX® Laminated Busbars Power Renewable Energy Sources

The 2024 Paris Summer Olympic Games have captivated audiences worldwide, and part of that excitement has centered around the new and innovative technology applications utilized in this year’s games. Many of these technologies are enabled by materials that Rogers Corporation manufactures, including applications in footwear, 5G wireless infrastructure, renewable energy, and more.

厂牌及品类发布时间 : 2024-08-08

Rogers developed Thermal Simulation Tools to Accelerate Time to Market

The team at Rogers developed a series of simulation tools using our extensive experience. In this blog, Rogers will showcase a small portion of these simulation tools using a simplified thermal model.

设计经验发布时间 : 2022-06-11

curamik® CERAMIC SUBSTRATES Technical data sheet

型号- CURAMIK®

数据手册 - ROGERS - Version 1.19en - 1.19 PDF 英文下载查看更多版本

Rogers Expands Capabilities and Services with New Application Laboratory

Rogers Corporation today announced that the new application laboratory was completed, expanding the company‘s assembly, testing and inspection capabilities and services at the curamik® production site in Eschenbach.

产品发布时间 : 2024-06-19

Lower Your Total Cost of Ownership with High Performance Si3N4 AMB Substrates

As the market and technology leader for metallized ceramic substrates, Rogers has quickly identified the opportunity to unleash the commercial and technological potential of such innovative products. Rogers is now capable of delivering Si3N4 AMB substrates with improved thermal performance to its broad customer base. While the final qualification is ongoing, first samples are already available for customer evaluation. Furthermore, thermal simulations can be performed to understand the substrates´ potential benefits for your application.

厂牌及品类发布时间 : 2021-09-23

curamik® CERAMIC SUBSTRATES Product Information

型号- CURAMIK®

快速参考指南 - ROGERS - Version 2.16 - 2017/08/01 PDF 英文下载查看更多版本

Rogers Corporation’s Power Electronics Solutions Group to Showcase curamik® Ceramic Substrates ＆ ROLINX® Eco Busbars at the PCIM 2023

Rogers Power Electronics Solutions (PES) group will be exhibiting at PCIM Europe and showcasing the whole curamik® ceramic substrate portfolio and ROLINX® Eco — a new generation aluminum busbar with unique features.

厂牌及品类发布时间 : 2023-04-29

Rogers Germany GmbH Receives TOP 100 Seal for Successes in Innovation，Which Has Made a Name for Itself in the Field of Ceramic Substrates and Cooling Solutions

This year is the first time Rogers Germany has received the TOP 100 award. Rogers Germany is active in the field of power electronics and has made a name for itself in the field of ceramic substrates and cooling solutions.

厂牌及品类发布时间 : 2023-03-10