Origami is the art of folding paper, it was believed to have originated in Japan, but historical evidence exists that suggests it existed in several parts of the world during the same time period. One starts with a flat sheet of paper and by making a series of folds and creases ends up with a 3 dimensional figure. Creating even just a simple figure takes imagination and a unique ability to visualize in three dimensions. Why does this sound familiar?
Most think of PCB design in terms of a series of flat layers. Thin flexible circuits offer another level of design. Since a flex can be folded and creased, it can be designed to occupy three dimensions. On several occasions I have had potential customers describe their flexible circuit application as an “origami interconnect” challenge. It wasn’t much of a stretch to imagine this concept as a metaphor for the challenges faced by our sales engineers. In the flexcircuit world, we are frequently dared to design origami circuits.
All Flex has designed and fabricated several 3 dimensional origami models made from flexible circuit material constructions and displayed them at trade shows, or provided them as illustrations to clients. The purpose of creating these “origami flex” sales samples is to emphasize the potential flexible circuits have to solve complex three dimensional packaging problems. A couple of the “origami flex” models are shown below.
The flat state of the origami dog shown in figure 2 is shown below in figure 3.
I am often asked to compare the price of a flexcircuit to a rigid board on a square inch area comparison. My answer usually makes a reference suggesting “if you don’t take advantage of the flexibility, the rigid circuit will be less expensive”. But consider the task of trying to create a 3 dimensional dog using rigid PCB’s. The design would involve multiple circuit boards, routed out in different shapes, and connected with wires and connectors to arrive at something similar. It could be accomplished, but would certainly not be considered as very elegant. And in this extreme example, the cost to achieve a complex shape like the origami dog with rigid PCB’s would be several times more costly than using flex.
Of course, even the most intricate electronic package will seldom require something as complicated as an origami shape (disassembly of a Single Lens Reflex camera might be an exception). However, origami flexible circuits do highlight some advantages of flexcircuitry for electronic packaging. The value of flex increases dramatically when one thinks of it as a multi-planar interconnect system that can be flexed and folded to significantly increase the effective density of the interconnections. Reducing interconnections, whether in the form of soldered wires, connectors, or multiple rigid PCB’s, demonstrates how the value might be harnessed in a variety of diverse applications.
Three dimensional modelling software has provided a boost for flexcircuit adoption. These design tools help expose the multi-dimensional potential of flexible circuits. Avoiding bends near solder joints, or close to regions with nickel/gold surface treatments, are examples of hard knock lessons learned through experience. Flexible circuit engineers have exposure to a wide variety of applications and can assist with guidelines for “origami circuits” when helping customers imagine designs squeezed into a housing requiring multi-planar interconnection shapes.
Fully exploiting the 3 dimensional potential of flexible circuits will often translate into cost, weight and space reduction as well as reliability improvement. Contacting a circuit supplier with ideas early in the design phase is the best way to take advantage of the utility offered by this origami interconnect medium.