The COB transceiver uses chip-on-board technology to connect the laser and receiver to the PCB directly. The below figure shows a typical COB optical components appearance.

Figure 1: COB Transceiver Appearance

COB technology is become mature and widely used in many industries, especially in high-speed telecommunications. COB provides superior electrical and thermal performance. In the optical transceiver industry, COB is mainly used in 25G SFP28 SR, 40G QSFP+ SR4, 40G QSFP+ PSM4, 100G QSFP28 SR4, 100G QSFP28 PSM4, 25G AOC, 40G AOC and 100G AOC, etc.

What is a BOX Packaging Transceiver?

A BOX packaging is also called an airtight package. The optical chip is encapsulated in a metal box filled with inert gas to protect the optical components from the external environment and to improve heat dissipation. The optical path is isolated from the outside world by an optical window.

The figure below shows a BOX packaging 100G TOSA.

Figure 2: Box Packaging TOSA Appearance

Compared with COB packaging, box packaging is traditional packaging technology with more stable optical and electrical performance. In the optical transceiver industry, BOX is mainly used in long-reach transceivers such as 25G SFP28 LR, 40G QSFP+ LR4, 40G QSFP+ ER4, 100G QSFP28 LR4, 100G QSFP28 ER4, 100G QSFP28 ZR4.

COB vs. BOX Packaging Transceiver Optics: What is The Difference?

Conclusion

The above COB vs. BOX packaging transceiver optics comparison shows that COB packaging provides better electrical and thermal performance. In contrast, BOX packaging offers stable optical and electrical performance. From the user’s point of view, the main difference between COB and BOX Packaging transceiver optics is the difference in performance, different use scenarios, and different prices. When choosing COB or BOX packaging, you should consider your specific application and make the best choice.