《柔性电路技术》（第三版）对于期望了解这一极其重要的使能互连技术者而言是一种必备品。
INTRODUCTION
Flexible circuits are not new to electronics manufacturing. Th e technology actually has a surprisingly long and rich history. Patents issued at the turn of the 20th century show clear evidence that early researchers were thinking of how flat conductors sandwiched between layers of insulating material could ease the layout of certain, primitive types of electrical circuits in early telephony switching applications. Some very famous turn-of-the-century researchers and scientists apparently turned their thoughts to novel methods for producing electrical interconnections as well. For example, based on notes in one of Thomas Edison’s lab books, it appears that he envisioned the flexible circuit’s precursor. In the notebook, Edison responded to an inquiry from his technical assistant, Frank Sprague, (later founder of Sprague Electric) as to how one might put conductors on insulating materials. One of Edison’s suggestions was to use conductor patterns of graphite powder in cellulose gum applied to linen paper. Th ere is no evidence that it was introduced into practice, but the idea is close in concept to polymer thick film circuits of today, which are common in a wide range of applications.
Significant production and use of flexible circuits in electrical or electronic applications seems to have been delayed until they were pressed into service during World War II, during which period German scientists were using flat conductor wiring harnesses, both in the gun turrets of tanks and in the V2 rocket. One story offered by US flex circuit pioneer Pat Bryan has it that a captured V2 rocket, used by US space-program researchers in the early 1950s, transported at least a portion of flex technology to the United States. Bryan, then working for Lockheed, took a piece of the circuit with him back to California to study and, ultimately, to employ in aerospace products.
Another important point of development was on the East Coast of the United States. Sanders Associates in New Hampshire, through the eff orts of Victor Dahlgren and company founder Royden Sanders, made signifi cantstrides in the same time frame, developing processes for printing and etching flat conductors on flexible base materials to replace wire harnesses. It appears, from advertisements of that time, that Photocircuits in New York was offering at least the idea of metal circuits on flexible base material (see Figure 1-1). Parlex was another early East Coast flex circuit manufacturer that became a leading supplier of flex to the military.
Growth and proliferation of flex circuit technology from that point was slow initially, but it has been accelerating ever since. Today, fl exible circuits—which are also known around the world also as fl exible printed wiring, flex print and flexi circuits and the acronym FPC—are used in nearly every imaginable type of electrical and electronic product. Much of the credit for the expansive use of fl ex circuits is due largely to the eff orts of Japanese electronics packaging engineers who have found countless new ways to employ flex technology. Over the last several years, fl exible circuits have remained one of the fastest growing of all interconnection-product
market segments. Given the versatility of the technology, it is easy to forecast that fl exible circuits will continue to attract increasing numbers of both users and manufacturers.
Flexible circuits represent a multibillion-dollar global market, with Japan—because of its application leadership— enjoying a signifi cant market share. Th e USA, once a close second, has fallen behind in share as production continues to shift to China and other places in Asia and South Asia. The USA remains a high-technology leader in areas such as high-frequency applications.