IR transparent solderable resin for co-packaged optics
Sabic has developed a high-heat, near-infrared (IR)-transparent resin for injection-molded lenses used in co-packaged optical transceivers and other optical connectors.
The EXTEM RH1016UCL resin is one of the first IR-transparent thermoplastics that can robustly withstand the 260°C peak temperature of printed circuit board (PCB) reflow soldering for the molded part. This helps enable optical connectors to be mounted with other components in one step in co-packaged optics for data centre links.
Co-packaging optical connectors with application specific integrated circuits (ASICs) used for Ethernet switching, and relocating them to the PCB, can reduce the power required to drive the interface between these components.
In contrast to pluggable optics, co-packaged optics place higher demands on materials. They must be able to retain their shape during the stresses of the PCB assembly process, which includes very high reflow soldering temperatures of up to 260°C. While glass can withstand this heat, it is difficult to produce complex lenses and arrays using glass, and the parts typically require time-consuming secondary grinding and polishing. Molding glass components is possible, but it is expensive and difficult to scale.
The resin also provides high-throughput, precision micro-molding to provide more design freedom when moving from pluggable optics to co-packaged optics. Good flow properties support thin-wall designs and efficient, multi-cavity molding, and this has been validated by a major technology OEM in the United States.
At the ECOC Exhibition in Switzerland this week, SABIC is displaying parts molded from EXTEM RH1016UCL resin, including aspherical test lens and a mountable lens array with multi-fiber push-on (MPO) connector pins, as well as a 12-lens tool used for material testing.
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“Co-packaged optics are a next-generation technology that can help increase data center reliability and reduce power usage and costs by bringing the optics much closer to the main switching ASIC,” said Florian Jung, global business manager, ULTEM and EXTEM, SABIC’s Specialties Business. “Producing complex, miniaturized lenses and arrays for co-packaged optics calls for new materials that can overcome the design, manufacturing scalability and system cost drawbacks of glass. SABIC’s new EXTEM RH1016UCL resin addresses these needs while helping to advance this emerging technology and opening new opportunities to help improve PCB integration density and energy efficiency.”
During PCB assembly, EXTEM RH1016UCL resin demonstrates excellent dimensional and optical stability to avoid part deformation and retain signal integrity. On top of this, the material’s high refractive index and near IR transparency help elevate lens performance. The availability of optical constants for EXTEM RH1016UCL resin in the materials database of Zemax OpticStudio® helps optical designers create new and innovative interconnects.
“Using a special chemistry, we developed a new EXTEM resin with very high heat resistance that now supports the placement of optical interconnects with thermoplastic lenses close to the ASIC chip prior to PCB assembly,” said Gabrie Hoogland. “Co-packaging helps make the electronic signal path as short and seamless as possible to facilitate very high data transmission rates. To assist customers in adopting EXTEM RH1016UCL resin, SABIC’s global technology centers provide micro-molding capabilities, including state-of-the-art equipment to test optical properties and constants, metrology, reflow soldering stability and application (hydro)aging.”
The company is also showing a spherical test lens and lens array molded from its ULTEM 3310TD resin, which targets optical transceiver collimator lenses used in single-mode fibre optic systems.
The new EXTEM resin is available globally.
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