What Is Cu Clip Encapsulation

Power chips achieve connection with external circuits through packaging, and their performance depends on the support of the packaging. In high-power applications, power chips are typically packaged as power modules for use. Chip interconnection refers to the electrical connections on the surface of the chip, which in traditional modules are generally aluminum bonding wires.

    Figure Traditional power module package cross-section

At present, commercial silicon carbide power modules still largely employ the traditional silicon IGBT module packaging technology with wire bonding, facing challenges such as high parasitic parameters at high frequencies, insufficient heat dissipation capability, low temperature resistance, and inadequate insulation strength, which restricts the excellent performance of silicon carbide semiconductors. In order to address these issues and fully exploit the enormous advantages of silicon carbide chips, many new packaging technologies and solutions tailored for silicon carbide power modules have emerged in recent years.

Figure silicon carbide power module bonding mode

The bonding material evolved from gold wire bonding in 2001, to aluminum wire bonding (with tape) in 2006, copper wire bonding in 2011, and Cu Clip bonding in 2016. For low-power devices, the transition from gold wire to copper wire was driven by cost reduction. For high-power devices, the transition from aluminum wire (with tape) to Cu Clip was driven by the need for product performance enhancement, as higher power requirements demand higher standards.

Figure (a) lead bonding and (b) Cu Clip power module structure

Figure (left) copper wire and (right) copper strip connection process

Cu Clip, also known as copper strip or foil, is a packaging technology where a solid copper bridge is welded to solder to connect the chip and pins. Compared to traditional bonding methods, Cu Clip technology offers several advantages:

The connection between the chip and pins is achieved using copper strips, partially replacing the standard wire bonding method between the chip and pins. This results in unique packaging resistance values, higher current capacity, and better thermal conductivity.

There is no need for silver plating at the soldering points of the pins, which can significantly save costs associated with silver plating and mitigate the expenses related to defective silver plating.

The product appearance remains completely consistent with normal products. It is mainly applied in servers, laptops, batteries/drives, graphics cards, motors, power supplies, and other fields.

Currently, there are two bonding methods for Cu Clip:

Full copper strip bonding method:

- Both the gate pad and source pad use the Clip method. This bonding method is costlier and more complex but yields better Rdson and thermal effects.

Copper strip with wire bonding method:

- The source pad uses the Clip method while the gate uses the wire bonding method. This bonding method is slightly cheaper than the full copper strip method, saves wafer area (suitable for small gate areas), and is somewhat simpler in process compared to full copper strip bonding. It also yields better Rdson and thermal effects.

Related Product Showcase

Copper Clip Process Power Packaging

Anshun Copper Clip process packaging, applied in power device packaging.

  Using copper blocks to connect the Source of MOSFETs to the leadframe to achieve better Rdson and thermal effects.

 Advantages of Copper Clip

  ●electrical property

  ●thermal properties

 Clip Bond Application Application domain n the field of power electronics, the current-carrying capacity of wire bonding will eventually reach its limit. Tape bonding has emerged as an alternative to wire bonding and tape automated bonding (TAB), and many traditional ultrasonic wedge wire bonding machines can easily adapt to handle tape bonding, making it quite attractive.

Laser tape bonding is a new application of laser micro-welding in the electronics industry, especially in the field of power electronics. It is particularly suitable for bonding wires to battery terminals and for connecting to direct copper bonded (DCB) substrates and copper terminals in power electronic modules. Laser bonding enables tape bonding applications for larger currents.