REEL TO REEL ASSEMBLY MADE POSSIBLE WITH FLEX CIRCUITRY
Author: Kevin Corrigan Company: Sheldahl Date Published: 9/10/1996
Surface Mount International
Abstract: Flex circuitry is one of the fastest growing technologies in electronic packaging. Acceptance in all types of products from consumer to automotive has fueled a large increase in the quantity and type of flex circuits on the market. Along with this growth has been an increase in the demand for assembling and handling technologies for flex. High volume users of flex have found increasing cost reductions by placing more and more components on the flex rather than using them merely as jumper circuits and simple interconnects. Flex circuits now often incorporate main system boards into their design. Although growing, flex circuitry is only a relatively small portion of the total electronic circuit board production and assembly in the world. Most equipment for electronic assembly is designed for hardboards. There is very little equipment available that is designed specifically to assemble flex circuits. As a result of this, assemblers of flex circuitry have had to become innovative in the way that the flex is run through the assembly equipment. Either the equipment must be modified, or the flex must be made to handle like a hardboard to be handled and transported through the equipment. Typically, flex circuits are “rigidized” in some fashion so that they appear and handle like rigid boards. The flex is usually pinned or taped onto a bare piece of rigid material such as FR4. After components are placed and reflowed, the circuit must be removed, usually by hand, and sent on it’s way through test and further assembly. There is a lot of manual handling of the flex and recycling and cleaning of the rigidizing boards. After component assembly, the circuits are in panel form, and require manual handling for singulating and further assembly. Singulated flex circuits are difficult for automation to handle, largely because of the difficulty in locating and picking the unit with a robot. Now, for the first time, a new generation of SMT equipment is available that is designed specifically for high volume component assembly to flex. The system, called ReelmountTM, was developed jointly by Philips EMT, Sheldahl and Molex; Philips as the equipment supplier, Sheldahl as the material supplier and Molex as the launch The system takes advantage of the economy of roll to roll fabrication of flex and roll to roll assembly of components.