Electrical-optical Circuit Boards Research Articles

Large-Scale Silicone-Rubber-Based Optical Interconnect Packaged With FR4

Polydimethylsiloxane (PDMS)-based large-scale electrical-optical circuit boards (EOCBs) have been developed based on a combination of a large-scale PDMS waveguide fabrication technique and a process for efficient interfacial bonding between PDMS optical layers and standard FR4 (fiberglass-reinforced epoxy and grade 4 on flame retardance) printed circuit board materials using a specially developed surface adhesion promoter (SAP). The main mechanism of forming a good bonding between PDMS and FR4 has been identified. The optical properties of the PDMS waveguide layer remained unchanged by the addition of the SAP. According to the defined test procedures from the Institute of Printed Circuits, the International Electro Technical Commission, and Telcordia, the environmental stability of packaged EOCBs has been tested with the result that they exhibited excellent mechanical, optical, and thermal stabilities. The mechanical stability limit of the tested EOCBs is determined only by the intrinsic mechanical stability of the used PDMS materials. The optical waveguide propagation loss at 850 nm is less than 0.1 dB/cm after surviving from the defined environmental test procedures.

Design for reliability of polysiloxane-based electrical-optical circuit boards

Based on the standards for optical components in telecommunications (Telcordia) and general printed circuit boards (Institute of Printed Circuits and International Electro Technical Commission), three environmental stability verification tests are concluded for polysiloxane-based electrical-optical circuit boards (EOCBs). In terms of defined test models, the respective acceleration factors are determined. Combining the acceleration factors and proposed reliability objective of 400 failures in time (FITs) (one FIT is equal to one device failure in 10(9) device hours of operation) at the 90% confidence level, EOCB test sample size to each acceleration test are deduced, and a corresponding amount of samples are prepared for mechanical and optical stabilities verification. In addition to the good mechanical stability the results exhibit, the packaged EOCBs have low and stable optical loss values (<0.1 dB/cm) and numerical aperture even at extreme environmental conditions. Furthermore, a total failure rate of 400 FITs is predicted for 14.4 yr of operation at 25 degrees C and moderate humidity conditions (20% relative humidity).

Quality Standardization for Polydimethysiloxane-Based Optical Interconnect Production From Optical Aspects

The influences of waveguide materials, fabrication conditions, and packaging substrates on the optical waveguide properties of electrical-optical circuit boards have been investigated by systematic variation of these conditions. Pt catalyst in polydimethysiloxane, casting mould sidewall roughness, interlay thickness, and packaging substrates show sensitive impact on optical waveguide insertion loss and in terms of defined target of optical loss, the basic quality criteria can be defined before production.

Cost-effective waveguide integration method for large-scale electrical-optical-circuit-board production

Based on KMnO 4 wet etching technology, a low-cost waveguide integration technique of polydimethysiloxane (PDMS) based electrical-optical-circuit-board (EOCB) with FR4 substrates was developed, which is quite suitable for large-scale EOCB production. The optical and mechanical properties of the PDMS waveguide layer remained unchanged before and after waveguide integration. The mechanical stability limit of the tested EOCBs is determined only by the intrinsic mechanical stability of the used PDMS materials. The optical waveguide propagation loss at 850 nm is less than 0.1 dB/cm after surviving the defined environmental test procedures.

Electrical–Optical Circuit Boards Optical Waveguides and Coupling Elements Based on the Thin Glass Layer Concept

A new approach to realize optical layers in thin glass sheets for hybrid electrical–optical integration into printed circuit boards (PCB) is presented and first results are discussed. The multimode optical waveguides in the glass layers are made by ion exchange from salt melt. The glass layers can be laminated in between standard PCB base materials. The coupling elements are made of thin glass too.

PDMS-based optical waveguide layer for integration in electrical–optical circuit boards

This paper reports on the optical properties of polydimethylsiloxane (PDMS) as a high-performance optical material system for optical interconnects. It is shown that optical PDMS layers laminated into printed circuit boards meet the requirements for low cost, low loss (0.06 dB/cm at 850 nm), high temperature ( > 290 ∘ C ) stable and mechanically robust electrical–optical circuit boards. A first production line for optical waveguide layers will be discussed.

Environmental stability of PDMS-waveguides for electrical-optical circuit boards

The environmental stability of polydimethylsiloxane (PDMS)-based optical waveguides implemented in electrical-optical circuit boards has been tested against international standards. Temperature shock, moisture treatments, dry heat exposure as well as soldering float showed only a moderate impact on optical waveguide performance.

Polysiloxane optical waveguide layer integrated in printed circuit board

A hybrid electrical-optical circuit board is demonstrated using polysiloxane as low-loss and high-temperature stable waveguide material system. After board lamination at 180°C for two hours and a subsequent annealing at 230°C for 5 minutes the waveguide insertion loss is 0.05 dB/cm at 850 nm wavelength.

Optical Interconnects on and in Printed Circuit Boards

Two types of short distance optical interconnects for on-board applications are presented: Small diameter plastic optical fibre (POF) links and multimode polymer waveguide layers integrated in multilayer printed circuit boards (PCB). POF links with fibre numbers up to 128 and link lengths up to 50 cm are realized with total transmission loss values below 2 dB at 660 nm. First tests of 10 cm long temperature stable multimode polymer waveguides laminated into standard multilayer PCBs demonstrate the capabilities of combined electrical-optical circuit boards.

Integration of polymer optical waveguides into printed circuit boards

Temperature stable polymer optical waveguides have been realised and integrated into printed circuit boards (PCBs). A special waveguide fabrication process has been developed which is compatible with standard PCB processing technologies. Multimode waveguides with a 100 × 100 µm2 cross-section have been produced by hot embossing thin polymer foils. Embedding of the waveguide foils into multilayer PCBs has led to a hybrid electrical-optical circuit board solution.