During the 1980s, electronics companies began a two-fold move toward outsourced manufacturing and away from a vertical manufacturing infrastructure to focus on their core competencies. This is evident in the rise of fabless design companies, the rise in electronic packaging companies, and the success of companies focused on system-level assembly. The rise of this new type of manufacturing environment has led to a very nimble, highly complex infrastructure with international capabilities.

Figure 1. The 3D nature of optoelectronic packages makes these systems different from electronics, which are predominantly 2D.
A primary driver for this movement was the enormous growth of the personal computer business that began in the mid 1980s and continued unabated through the 1990s. The product focus for outsourced electronics manufacturing falls into three categories: silicon die, packaged components, and assembled boards that were combined in the final product enclosure or box.

By the time the telecommunications bubble began in earnest in the mid to late 1990s, this easily scalable infrastructure was in place for the manufacturing explosion that was to occur. The telecommunications bubble, in particular, fed rapid growth in the electronics contract manufacturing market. Unfortunately, optoelectronics could not handle the ramp-up nearly as well.

Optoelectronics: Unique Physical Considerations

By the 1980s, the three primary product categories mentioned above were largely two-dimensional. While some components were three-dimensional and mounted to boards, all electrical signals were still carried in two-dimensional traces.

The nature of most of these products was such that the “guts” of the systems were contained within the two-dimensional space that made up the logic space of the semiconductor. Other than that, the remaining parts of the system existed to support and transfer the information that was created within the semi-conductor devices. However, in the relatively nascent world of optics — which, from a manufacturing perspective, was primarily driven by the telecom industry — the support nature of the various components was wildly different.

When a new electronic component is added to a device the rules are straight- forward. However, when a system or product introduces the use of photonics — whether in the visible or infrared — the optics part of the system must take priority throughout the device; all other design considerations — including electrical, mechanical, and thermal — must wrap themselves around the optics of the system if it is to function properly.

The key reason for this is the high frequency of light and what this means to signal propagation. Low-frequency electrical signals can follow virtually any kind of metal trace; these can be straight or winding. Higher frequency electrical signals will interact with their surrounding medium, and this additional complexity must be taken into account during the design phase of the project. In other words, components can be placed almost anywhere on an electronic because the signal will follow a convenient metal path that may have numerous twists and turns.

Optical systems propagate light via free space or through fibers. Free space requires a series of bulk optical elements; the optics cannot move or change (by thermal expansion/contraction) without adversely affecting the signal. Systems that use optical media, such as optical fibers or waveguides to propagate light, depend on the media’s ability to create total internal reflection to capture the light and transmit it with minimal loss. Unlike metal traces, however, fibers are severely limited in their ability to bend or twist, and there still remains the issue of coupling the light in and out of the waveguide.

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