World's largest multi-layer flexible PCBs
A patented process innovation (UK Patent 2498994, U.S. Patent 9226410) has extended Trackwise’ capability to the manufacture of flexible multilayer printed circuit boards of any length, more than 8m/300 inches in length, making these the world’s largest flexible multilayer PCBs.
In high value, mass- critical applications, boards of such length can be used as an alternative to traditional wiring harnesses, offering significant benefits in terms of reliability, repeatability and moreover in the reduction of space required and weight – up to 75% saving.
Flexible printed circuit boards were developed 50 years ago as a replacement for wire harnesses – in order to save weight and space – and are now a multi-billion dollar global industry.
The application of flexible PCBs has however been limited due to the length of product available. Due to manufacturers’ limits (typically 610mm), product application has in general been limited to inside a box or equipment – rather than between boxes. Until now:
As a result of a patented process innovation Trackwise is now able to offer length-unlimited multi-layer flexible printed circuit boards – a globally unique capability.
A few PCB manufacturing process steps are static in nature and equipment used in these static processes defines the capability: Drilling, Imaging, Pressing, Plating
Trackwise’ innovation changes these static processes and makes them dynamic; innovative modification of existing PCB and roll-to-roll electrolaminate equipment and manufacturing techniques.
The outcome of this is that, rather than the supply chain defining the limits the only limit is that of the application itself.
Flexible printed circuits were developed 60 years ago as a replacement for wire harnesses – and the fact that the technology has grown into a multi-billion dollar global industry is clear evidence of the widespread benefits of employing flex circuits. This global industry is supported by globally accepted standards, specifications and design guidelines, a mature material supply chain and a widespread talent pool of designers and fabricators.
The benefits of using flex PCBs in place of conventional wire harnesses are well documented – and Improved Harness Technology™ simply expands the field of application of those benefits – from unit level to subsystem or even system level.
In no particular order:
Reduction in interconnect size
Flexible circuits employ the thinnest dielectric substrates available today for making electronic interconnections. In some cases, it is possible to produce flexible circuits having a total thickness less than 50μm (0.002″), including a protective cover layer.
This reduction in size, coupled with their planarity, makes them suitable for bonding to – or even within – the structure to which they are mounted. This further reduces the physical volume occupied by the interconnect.
Reduction in interconnect weight
The weight reduction possibilities of using flex PCBs to replace conventional wire harnesses are the main attractor for aerospace applications.
A corresponding benefit of reduction in interconnect size is reduction in interconnect weight. Thinness equals reduced weight.
Conventional wire harnesses will use a minimum wire gauge that is selected for mechanical (strength) reasons, rather than sized by what is required electrically. As a flex PCB is an integral composite structure, the integral construction provides the mechanical strength and so it is not necessary to select large conductors for strength. The copper cross-section can thus be reduced to what is required in order to carry the current load or to satisfy voltage drop requirements.
Reduction in interconnect assembly time – and risk – and cost
The main reduction benefit is derived both from the ability to reduce the number of assembly operations required and from the user’s ability to build and test the circuit completely prior to committing the circuit to assembly. This especially applies to wire harness replacement applications.
While the design may be in error, a flexible circuit cannot induce errors of a human nature. Human error in hand-assembly is a constant risk. An area especially vulnerable is in the assembly of hand-built wire harnesses. With flexible circuits, all design features are controlled by the design itself. As a result, with the exception of process-induced errors in manufacturing, it is not possible to route circuits to points other than those designated by the circuit design.
For more information regarding replacing shielded twisted pairs with flex, please download the following white paper:
LVDS – twisted pairs representation in PCB tracking.
Trackwise ability to manufacture length-unlimited multilayer flex PCBs is unique.
Some manufacturers can make 40’ (12m) – even 100’ (30m) long circuits but these are single and double sided circuits only.
Some manufacturers can make 2.4m – even 5m long multilayer circuits but Trackwise length-unlimited offering is unique.
A printed circuit board is the implementation of customer requirements – so please define yours and we will try to help.
Max. width 600mm Max length Unlimited
Max. width 600mm Max length 2200mm
Not all materials are available in roll-form so please ask.
Copper up to 2oz
Aluminum for lightweight GND
Trackwise is investing in its in-house capability and capacity to manufacture long flex and 2018 will see further important developments.
As a result of work carried out under a European Clean Sky research project, LHTFPCB – Large High Temperature Flexible Printed Circuit Boards – Trackwise (UK) and Rogers (Belgium) are pleased to be able to offer large format (up to many metres in length) flex PCBs, demonstrated to be capable of operating at temperatures up to 260C for long durations, even in high vibration environments, 40gRMS.
As aero engines are designed to run hotter as part of a drive to increase efficiency, such high temperature circuitry offers the designer the ability to increase control of the engine.
The flex PCBs have been manufactured using Rogers’ PEEK based circuit materials – also highly chemically inert and with high radiation resistance.
Additional work is being carried out on extending the temperature range and/or longer life at 260C by means of additional oxidation barriers.
Test equipment (thermal cycling and RV ovens) has been developed capable of proving high temperature flex PCB performance at temperatures up to 400C. These are available at Trackwise for use in other applications.
The LHTFPCB project has completed, with TRL 6.
Clean Sky is the most ambitious aeronautical research programme ever launched in Europe. Its mission is to develop breakthrough technologies to significantly increase the environmental performances of airplanes and air transport, resulting in less noisy and more fuel efficient aircraft, hence bringing a key contribution in achieving the Single European Sky environmental objectives.
For more information please visit LHTFPCB.
Patented process innovation – allows for the manufacture of flexible multilayer printed circuits of any length
- UK Patent Number 2498994 – granted March 2014
- US Patent Number 9226410 – granted January 2016
- China Patent Number CN 104145539 B – granted April 2018
- International Patent Application No. PCT/GB2013/050147 – EU, Canada, Brazil