INTERCONNECTION
Why photonic packaging and CPO offer an alternative to copper interconnects
Dr. Larry Zu, CEO at Sarcina Technology F
or over 30 years the semiconductor packaging sector has predominately used copper interconnects, replacing previously favored aluminum-based interconnects. Copper is an effective electrical conducting material and has higher resistance to electromigration than aluminum. However, although copper interconnects have worked well for short distances, this is not the case if the signal journey is longer than one or two meters due to the excessive insertion loss of a copper cable. Today there are also concerns about signal weakening at high frequencies making high-speed data transmission a challenge, as well as power consumption which can be considerable. As the semiconductor industry moves at a rapid pace, the issues with copper- based interconnects are becoming more obvious. Unfortunately, it is now clear that copper interconnects cannot satisfy the (high performance computing) inside the are required and this is where photonic step forward as an alternative.
CPO advantages
transmission are incorporated straight into the long copper trace between the switch and the optical module with short, high- used in advanced architectures, including chiplet-based systems and it is widely crucial role in the development of the new
loss can be reduced and high-speed signal integrity enhanced, because the optical components are integrated directly into a package. Data throughput is increased by using high-bandwidth optical engines that lead to higher data transfer rates.
as much of an issue than previously with signaling uses far less power at high data rates than electrical signaling, which is a fundamental factor for high-performance systems.
Latency reduction is another advantage like those seen in racks or between chips/ modules, can generate latency problems. shrinks the gap between optical components and the semiconductor dice. This means that long electrical interconnects are not needed, which reduces latency and speeds up data transfer.
32 MARCH 2026 | ELECTRONICS FOR ENGINEERS
bottlenecks such as interconnection issues, it is considered to be an essential part of photonic packaging and photonic package its full potential.
CPO challenges
losses and poor device performance. Sub- waveguides and photonic components techniques with etched features or alignment markers can be less accurate but
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