Optoelectronic standards: optoelectronics moves forward with new standards and strategies.

At the end of 2001, much of the buried optical fiber that comprised the global telecommunication and World Wide Web network carried no traffic; the fiber was "dark" or "unlit." Now, reports indicate that less than 20% of that buried fiber, which makes up the backbone of the long-haul network, is actually being used.

However, a new data demand-pull by individual users is expected. While current datacom or premise networks are connected with relatively low bandwidth optical pipes to the backbone, users in business complexes, educational campuses and neighborhoods could supply the demand-pull if given the local capability. Extensions of fiber-optic networks would grant users convenient and low cost broadband. If individual computer users were provided with real broadband connections, such as 1 Gbit Ethernet, the expected data demand-pull would be tremendous. Thus, new standards are greatly needed in this area of optoelectronics.

The telecommunications industry has already embraced photonics as the preferred mode for terrestrial and undersea communication, and the packaging and assembly industries are beginning to learn the new rules of light. As the industry and its customers become accustomed to the freedom of portable electronics, fiber optics and its components, design characteristics and system issues will become extremely important. The trend to wireless will only continue to accelerate at a hectic pace.

In 2001, an effort was initiated to identify the needs of the optoelectronic industry. IPC and members of its Photonics Manufacturers Association Council developed IPC-STD-0040, Optoelectronic Assembly and Packaging Technology, an umbrella document that provides a roadmap and tutorial on why new standards are needed and how they must be focused.

To mirror previous packaging levels assigned to electronic equipment and to demarcate manufacturing products intended for the optoelectronic market, IPC-STD-0040 has established the following four levels of optoelectronic packaging:

* Level 0: Uncased device, such as lenses, isolators, laser diodes or waveguide beam splitters 

* Level 1: Single device or multiple devices in a package, such as a multichip module (MCM) package integrating optical, optoelectronic components and integrated circuit (IC) components

* Level 2: Modules and product boards, such as a transponder on a daughter card

* Level 3: Mother board with product boards or cabling, such as a transponder mounted on a mother board.

Level 0 deals with unpackaged devices that primarily relate to the device manufacturing process, while Levels 1-3 relate to the assembly process(es) necessary to produce a quality optoelectronic product.

Many standards relating to process details or overviews of the technology are needed to accomplish optoelectronic implementation strategies. More information about available services is also needed. Requirements for fiber optic cable and interconnection devices need to be available and easily understood. The differences between the optoelectronic packages and their input/output (I/O) relationships are important. Some technologies have addressed reliability issues by providing a ruggedized mounting structure that integrates optoelectronic parts with electronic packages.

The ability to do failure analysis and methodologies for process control definition are also a major requirement in some of the standards. Some people have suggested that the industry needs a reliability database to help clarify what standards exist and what standards are needed.

Many previous standards have been for the long haul optical fiber cable. Some of these standards are overly robust and, due to the amount of testing required, will not gain the acceptance needed to incorporate optoelectronics in the home, office or school. For this reason, a series of standard numbers have been reserved by IPC to provide a logical information strategy that relates to the products being produced and the level of product types.

Table 1 shows an example of numbers that have been reserved for this task, with different levels and possible topics identified for each column.

IPC has reserved numbers 8400 to 8439. The 84 represents the family of optoelectronics standards proposed, the third digit represents the level for which the standard is intended (level 0, 1, 2 or 3) and the final digit is the major focus of the standard. When more than one number is needed, a dash number will be applied, expanding the original 40 numbers into 400 possible number segments.

IPC-STD-0040 also describes 23 standards that need to be created. Table 2 outlines several standards currently in development or high on the priority list (the numbers are project identifications, not standard numbers).

TABLE 1: Optoelectronic level to standard functionality matrix.

Opto Level    Admin    Design    Components

              1        2         3

0 (840)
1 (841)                          Std. 303 *
                                 Std. 311 ([degrees])
2 (842)                          Std. 311 ([degrees])
3 (843)

Opto Level    Materials Fab           Board    Board Physical

              4                       5        6

0 (840)
1 (841)       Std. 313 ([degrees])
              Std. 315 ([degrees])
2 (842)       Std. 313 ([degrees])
              Std. 315 ([degrees])
3 (843)       Std. 313 ([degrees])

Opto Level    Assembly                Assy. Physical

              7                       8

0 (840)
1 (841)       Std. 318 ([degrees])    Std. 309 ([degrees])
2 (842)       Std. 318 ([degrees])    Std. 309 ([degrees])
3 (843)       Std. 318 ([degrees])

Opto Level    Test/Reliability

              9

0 (840)
1 (841)       Std. 309 ([degrees])
              Std. 311 ([degrees])
2 (842)       Std. 309 ([degrees])
3 (843)

* Development of this standard has already begun. ([degrees]) Denotes a
high priority standard.

TABLE 2: Proposed standardization effort.

Project                     Description

Standard 303 *              Handling of photonic components and fiber
                            optic cable--specifies the proper methods
                            for handling photonic components and fiber
                            optic cable--during receiving inspection,
                            warehousing, staging, processing, testing,
                            packaging for shipping and shipping.

Standard 309 ([degrees])    Quality assurance of optoelectronic compo-
                            nents and assemblies--describes the tests
                            and test methods required to ensure the
                            quality and reliability of optoelectronic
                            components and assemblies.

Standard 311 ([degrees])    Moisture absorption precautions for opto-
                            electronic packages--provides guidelines
                            for acceptable water vapor content in
                            devices, its impact and methods for meeting
                            predetermined vapor content.

Standard 313 ([degrees])    Material requirements for optical inter-
                            connecting substrates--creates definition
                            for optoelectronic substrate materials.

Standard 315 ([degrees])    Attachment materials for optoelectronic
                            assembly--defines attachment materials that
                            are specifically required for support of
                            optoelectronics.

Standard 318 ([degrees])    Methods for optoelectronic component
                            attachment and alignment--specifies methods
                            (soldering, bonding, and mechanical faste-
                            ners) for attaching and aligning of opto-
                            electronic components using during assembly
                            processes.

* Development of this standard has already begun.

([degrees]) Denotes a high priority standard.

Assembly Standards Update

The following industry consensus standards have been published this quarter:

IPC Roadmap 2003

* J-STD-O02B, Solderability Tests for Component Leads, Terminations, Lugs, Terminals and Wires

* J-STD-003A, Solderability Tests for Printed Boards

* J-STD-027, Mechanical Outline Standard for Flip Chip or Chip Scale Configurations

* IPC-2221A, Generic Standard on Printed Board Design

* IPO2226, Sectional Design Standard for High Density Interconnect (HDI) Printed Boards

* IPC-2546, Sectional Requirements for Specific Printed Circuit Board Assembly Equipment

The following standards are being balloted for industry acceptance:

* J-STD-004A, Requirements for Soldering Fluxes 

* IPC-HDBK-005, Soldering Paste Handbook to Support J-STD-005 Requirements for Soldering Pastes

* IPC-0040, Optoelectronic Assembly and Packaging Technology

* IPC-CM-770E, Guidelines for Printed Board Component Mounting

* IPC-2251, Design Guidelines for Electronic Packaging Utilizing High Speed Techniques

* IPC-7351, Generic Requirements for Surface Mount Design and Land Patterns

* IPC/SMEMA-9851, Equipment Interface Specification

Dieter Bergman is the director of technology transfer with IPC, Northbrook, IL; [phone]; [e-mail].