PHOTONIC PACKAGING

State-of-the-art packaging technologies are often the key to production of cost-effective photonic components. This is true for both high-volume, low-cost devices and high-performance, limited-volume devices. For example, the cost of today's CD laser is dominated by the material and labor costs of the component optoelectronic packages. Japanese companies have invested heavily to develop low-cost packages and highly automated assembly methods for consumer products, and to develop robust, sophisticated packages for high-performance telecommunications devices. Relative to the United States, Japan has parity in high-performance packaging and leadership in low-cost packaging, with the exception of LED packaging, where Hewlett-Packard has a very strong market position.

Overview of Technology

The panel observed that many Japanese companies are doing significant work on low-cost assembly and packaging and use of automation, as well as on high-speed packaging technology and precision ceramics for photonics. In assessing the state of development and manufacturing of various devices, the panel often found it difficult to separate the costs of chip processing and packaging, due to the interrelatedness of the technologies and the nature of site visit discussions. Table 4.1 summarizes the status of automation and cost for various types of laser diodes produced in Japan. Only CD laser manufacturers use full automation, and that technology was not used until volume exceeded 1 million units/month.

Table 4.1
Laser Diode Types

Each large Japanese laser diode producer seems to have its own automation development group. The JTEC panel heard about automated packaging at Sanyo and Rohm, and attempts to minimize package costs were evident at Sanyo, where lead frame packages with open windows have been developed to undercut the traditional costs of CD-type laser packages that are hermetic. Closely associated with cost reduction through automated packaging is automated handling and packing of the laser diodes so that failures associated with electrostatic discharge (ESD) can keep yields to customers above 99.9 %.

For local-loop lasers, where prices are targeted at $30 in volume of one million/year (Endnote 1) , development of semiautomated packaging is underway at manufacturers such as NEC-Kansai. Here the goal is to develop a fiber-pigtailed laser diode that will operate without bias current or a thermoelectric cooler over -40 degrees to 85 degrees C for data rates to 1 Gbit/s. To reach the price goal, effort is focused on the cost-limiting step of fiber-pigtailing. NEC and others are developing passive fiber alignment using micromachined silicon to form both fiber alignment grooves and diode locator pedestals, each etched to submicron precision. At present, laser diodes and fibers can be reproducibly passively aligned and attached to achieve < 5 Db coupling loss. As discussed in the guided wave section above, this technology is not yet ready for production, but progress is very encouraging.

For packaging of high-speed telecommunications devices, Oki, Toshiba, and Fujitsu described their approaches to the JTEC panel. These included assemblies of micro-optic ball lenses, hermetic sealing, and semiautomation. For photonic hybrid assemblies (e.g., laser diode, photo diode, and IOC in one package), the panel's hosts at Hitachi described several generations of its PLC modules. Here, as in the low-cost passively aligned laser module, considerable R&D is required to reach the cost targets for local loop and FTTH applications.

Many companies in both the United States and Japan offer a full line of Bellcore-certified telecommunications laser diodes and photodetectors. Of note in the United States are AT&T, Lasertron, and Epitaxx; in Japan, all the major telecommunications component suppliers offer such products.

Kyocera specializes in producing the precision ceramic parts that are universally needed to package photonics. At present, nearly all such parts used by photonics industries worldwide are manufactured in Japan by Kyocera or its competitors. Their products, such as ceramic hybrids, laser submounts, fiber connector ferrules, and window assemblies, are often custom-designed in special design centers provided for customers. Kyocera has significant microwave and RF packaging expertise and has the ability to machine and manufacture ceramics to submicron precision. While throughout its operations Kyocera has been building on its basic ceramics business to move into higher-value products, it has decided not to offer fully packaged laser diodes, so as to not compete with its customers.

Substantial work on connectors is ongoing in the United States and Japan but is not reviewed in this report; however, it is worth noting one result developed at NTT for computer backplane connections. Known as the MU connector, NTT's novel miniature fiber-optic connector has four times the packing density of conventional connectors, and it can be mounted in a 100 mm width. NTT has also developed a set of installation tools for the connector and is involved in fully commercializing the device.


Published: February 1996; WTEC Hyper-Librarian