FAQ for Extended Length Flexible Circuits

Extended length flexible circuits are larger than “typically” offered sizes in the interconnect industry.   The length of these oversized circuits can be anywhere from 2 feet to 10 feet or longer.   A long continuous flexible circuit can offer design advantages over using normal sized circuits where multiple connections and connection assembly steps are required.  By eliminating connectors and the assembly labor required for the connections, the long length circuit can be lighter, more flexible, lower overall cost and more reliable.  All Flex designates extended length circuits as Maxi-Flex®.

The following are some common questions we receive regarding our Maxi-Flex® Product.

Q. Why are there so few flexible circuit fabricators that offer extended length circuits?
A. Most of the standard equipment used in the industry is geared toward 12 x 18 inch or 18 x 24 inch panel sizes, based on standard rigid board process technology. Oversized circuits are a relatively small niche within the industry and require custom fabrication equipment and techniques that many fabricators have avoided due to capital expense.  All Flex has been building this type of part for over 20 years and has developed some unique processing capabilities relative to extended length circuit fabrication.

Q. What are the biggest challenges in producing a Maxi-Flex®?
A. There are a number of process steps where the “standard” equipment and tooling need significant modification.   Many of the challenges are related to material handling. Since opens and shorts render a part useless, any defect in the length of a circuit reduces panel yield.

Q. What applications are Maxi-Flex® circuits commonly used in?
A. We see a variety of applications.  Any application where having a long thin continuous interconnect system would be ideal.   Unmanned Aerial Vehicles (UAV) and medical probing systems are a couple of applications driving existing demand, but like other flexcircuit applications, demand is often generated by the imagination of a creative engineer.

Q. Can a Maxi-Flex® have a multilayer construction?
A. It is quite common for Maxi-Flex® circuits to have several layers, but limitations occur because of unique processing requirements. As a design layout consequence, the higher density region of the circuit may need to be confined to some subset area of the overall circuit size.

Q. Will feature to feature tolerances be different for Maxi-Flex®?
A. Feature to feature specifications are often restricted to within small zones of a Maxi-Flex®.  Tolerances within smaller zones are similar to tolerances held on standard sized circuits.   Dimensional tolerances spanning the length of the circuit need to be reviewed on a case by case basis.

Q. Is impedance control offered on Maxi-Flex®?
A. Yes, it is very common for Maxi-Flex® circuits to be built to meet impedance specifications. Impedance control often requires thinner copper and thicker dielectric. As circuits become lengthy, material construction options are important considerations. Since oversized circuits are usually built on laminates that have been fabricated in a continuous roll process, limitations in thicknesses and constructions are possible.

Q. What are the line width and spacing limitations for Maxi-Flex®?
A. Like all good questions about capability, the answer is usually “it depends”. The probability of a circuit trace having a flaw is a function of its length and width. As trace runs get lengthy, and especially if combined with multiple traces, the chance of a circuit flaw increases and yield can be an issue. All Flex has produced extended length circuits with <3 mil lines and spaces.

Q. Can you build circuits for catheter applications?
A. We have successfully built parts for catheter applications but these parts are often on the leading edge of our capability. Design features need to be known before an unequivocal answer can be given to this question.

Q. What is the lead time for Maxi-Flex® Circuits?
A. We quote 3-4 week lead times depending on construction, complexity, and the load in the factory at a given point in time.  Shorter lead times may be possible on an expedited basis.

An extended length circuit can be fully customized to meet most requirements.  Maxi-Flex® circuits provide customers with a single interconnect solution for physically large electronic systems and are offered in a variety of customized constructions including heater circuits.