METHODS OF CONNECTING flex PCB

Connecting a flexible circuits to other elements of an electronic system is a vitally important element in system design, manufacture and assembly. There are numerous methods of making flexible circuits connections. Virtually all connector manufacturers have connectors that were either specially built for flex or are readily adaptable to flex PCB designs. One innovative connector manufacturer, Beta Phase (Menlo Park, CA), actually made its connectors out of flexible circuits, producing high-performance connectors with very high pin-count equivalents. The concept (fig. 7-29) was ahead of its time and did not get much use outside of extreme performance applications. However, the technology was purchased by Molex and some elements of the earlier concepts are now available and other connector manufacturers now have comparable products on the market.

FLEX PCB CONNECTOR TYPES

Some basic connectors are simple devices, including insulation displacement connectors and crimpor clincher-type connectors, which have proven popular in applications where
cost is important. They are not generally considered suitable for high-reliability applications.

To make both male and female pin-in-socket connectors, swaged or brazed pins can be attached directly to the flex PCB. These have also enjoyed some success in certain low-end product areas where performance is not a key concern.
Sculptured ® flex PCB technology has the ability to integrate the connector directly into the flex PCB itself. This method is suitable for a number of different electronic applications because discrete joining of pins to the flexible circuits is not required. By using this technology, it is possible to have edge contacts that extend, unsupported, beyond the edge of the flex PCB. It is then possible to simply post-form the leads as required to create a viable male pin connector for mating with a compatible socket.

Another option allows the flex PCB to interface with a common PCB edge connector. For this application, the end of the flexible circuits is configured with compatible contact spacing specified for the edge connector, a thin, reinforced laminate stiffener is placed behind the flex and the flex is folded and bonded to the stiffener (fig. 7-30).
Edge card contact constructions can also be created by folding the contact area of a flexible circuits around a stiffener. This is a simple and relatively inexpensive way to interconnect a flex PCB. It is analogous to edge card contacts on rigid boards for which there are numerous different types of mating connecter solutions available. Because the flex PCB is thin, it is possible to accommodate a wide range of connector designs by simply altering the thickness of the stiffener used with the flex PCB.

There are many ways to prepare a flexible circuits for interconnection. They include structures that are both integral (made a part of the circuits) and integrated (having interconnection features added to the circuits after fabrication).

With the exception of edge card connections, integral interconnections are often designed for one-time interconnection application, while integrated interconnections are normally separable.