Final Report Summary - LHTFPCB (Demonstration of a large, high temperature, flexible printed circuit board)
Executive Summary:
The objective of the SAGE3 is to develop and demonstrate a large 3-shaft bypass engine. The technological challenge is to increase the level of control on the engine core without the burden of heavy interconnection systems.
Flexible printed circuit boards have been considered as a replacement for conventional wire harnesses, in order to save weight, in order to save space – but both the high temperatures and the large engine size (requiring large, single piece, printed circuits) are potential barriers to implementation. Printed circuits are typically qualified for use up to 150C and are typically manufactured in lengths up to 610mm, exceptionally 914mm.
In this context, the LHTFPCB (Large High Temperature Flexible Printed Circuit) project aimed to support the end user in the design of a high temperature flexible PCB and, through trials of flexible laminates manufactured from advanced polymers, progress the temperature at which a flexible printed circuit can operate from the current state of the art maximum of 200°C into the desired range of 260°C (minimum) up to 400°C (target).
The Project developed the materials and manufacturing processes that enable this high temperature performance in a large format, such that the required overall length of 5m can be implemented in a single piece multilayer printed circuit, without joints.
Project Context and Objectives:
The objective of the SAGE3 is to develop and demonstrate a large 3-shaft bypass engine. The technological challenge is to increase the level of control on the engine core without the burden of heavy interconnection systems.
In this context, this Project aimed to support the end-user in the design of a high temperature flexible PCB and, through trials of flexible laminates manufactured from advanced polymers, progress the temperature at which a flexible printed circuit can operate from the current state of the art maximum of 200°C into the desired range of 260°C (minimum) up to 400°C (target).
The Project plan was to develop the materials and manufacturing processes that enable this high temperature performance in a large format, such that the required overall length of 5m can be implemented in a single piece multilayer printed circuit, without joints.
Validation to TRL6 was to be achieved through coupon tests on representative hardware in a bespoke environmental chamber, subjecting the coupons to combined heat and random vibration loading.
Full size PCBs were supplied for integration and test at engine level. These engine tests are end-user responsibility; the Project providing support to integration and test.
Project Results:
The Project has manufactured and tested sample multilayer flex PCBs manufactured from combinations of advanced polymers.
The sample PCBs have been long duration (up to 164 days) thermal cycling tested in ovens at temperatures between 260C and 330C (two returns to ambient per day) and then random vibration tested (8hours at 40g RMS) at temperature (260C).
Post-test microsection analysis has indicated rate of propagation of polymer degradation from the circuit edge, allow circuit design rules to be established.
As the principal mode of polymer degradation is oxidisation, opportunities exist for further improving circuit performance and life by increasing robustness and performance of oxygen barrier. 330C remains an achievable objective.
The Project has manufactured and supplied to the end-user large format, single piece, multilayer flex PCBs - demonstrating a clear advantage over current manufacturing process allowing point to point PCB harnesses without intermediate joints.
Potential Impact:
The single piece, multilayer flex PCBs were not subjected to an engine test as planned, as the end-user was unable to provide a suitable test vehicle and so a formal TRL6 Capability Readiness Review (CRR) was not held.
The project has demonstrated that the long, multilayer flex technology is viable, and there is a clear weight advantage in making PCB technology available to a wider proportion of the engine due to the temperature increase achieved. There is also a clear advantage over current manufacturing process allowing point to point PCB harnesses without intermediate joints.
The products for the test rig and the large format items delivered were manufactured on development equipment, and although not part of this project a termination system needs to be developed and a formal Manufacturing Readiness Process (MCRL) would need to be completed before industrialisation. There now needs to be a concise business case generated, but this may only be possible after the termination costs and full production environment is better understood.
Trackwise has started a UK funded R&D project continuing the development of long, multilayer flex technology to develop a production process and a termination system with Airbus as an end user. This would be airframe mounted, rather than engine mounted and therefore in a more benign environment. However, this would still increase the maturity of the technology and the end-user has expressed an interest to see how this develops in the longer term.
Project members, Trackwise and Rogers, are continuing to work together on related technology where the experience gained by the project has been useful – wing ice protection systems. Although this is cold environment, as opposed to hot, the same polymers are to be used and the manufacturing experience gained in the project is being applied.
List of Websites:
www.lhtfpcb.co.uk
Project website contact: Philip Johnston, +44 1684 299930 philip.johnston@trackwise.co.uk
Webmaster contact: Tony Hodder, +44 7810 553350, tony@hodderonline.co.uk
The objective of the SAGE3 is to develop and demonstrate a large 3-shaft bypass engine. The technological challenge is to increase the level of control on the engine core without the burden of heavy interconnection systems.
Flexible printed circuit boards have been considered as a replacement for conventional wire harnesses, in order to save weight, in order to save space – but both the high temperatures and the large engine size (requiring large, single piece, printed circuits) are potential barriers to implementation. Printed circuits are typically qualified for use up to 150C and are typically manufactured in lengths up to 610mm, exceptionally 914mm.
In this context, the LHTFPCB (Large High Temperature Flexible Printed Circuit) project aimed to support the end user in the design of a high temperature flexible PCB and, through trials of flexible laminates manufactured from advanced polymers, progress the temperature at which a flexible printed circuit can operate from the current state of the art maximum of 200°C into the desired range of 260°C (minimum) up to 400°C (target).
The Project developed the materials and manufacturing processes that enable this high temperature performance in a large format, such that the required overall length of 5m can be implemented in a single piece multilayer printed circuit, without joints.
Project Context and Objectives:
The objective of the SAGE3 is to develop and demonstrate a large 3-shaft bypass engine. The technological challenge is to increase the level of control on the engine core without the burden of heavy interconnection systems.
In this context, this Project aimed to support the end-user in the design of a high temperature flexible PCB and, through trials of flexible laminates manufactured from advanced polymers, progress the temperature at which a flexible printed circuit can operate from the current state of the art maximum of 200°C into the desired range of 260°C (minimum) up to 400°C (target).
The Project plan was to develop the materials and manufacturing processes that enable this high temperature performance in a large format, such that the required overall length of 5m can be implemented in a single piece multilayer printed circuit, without joints.
Validation to TRL6 was to be achieved through coupon tests on representative hardware in a bespoke environmental chamber, subjecting the coupons to combined heat and random vibration loading.
Full size PCBs were supplied for integration and test at engine level. These engine tests are end-user responsibility; the Project providing support to integration and test.
Project Results:
The Project has manufactured and tested sample multilayer flex PCBs manufactured from combinations of advanced polymers.
The sample PCBs have been long duration (up to 164 days) thermal cycling tested in ovens at temperatures between 260C and 330C (two returns to ambient per day) and then random vibration tested (8hours at 40g RMS) at temperature (260C).
Post-test microsection analysis has indicated rate of propagation of polymer degradation from the circuit edge, allow circuit design rules to be established.
As the principal mode of polymer degradation is oxidisation, opportunities exist for further improving circuit performance and life by increasing robustness and performance of oxygen barrier. 330C remains an achievable objective.
The Project has manufactured and supplied to the end-user large format, single piece, multilayer flex PCBs - demonstrating a clear advantage over current manufacturing process allowing point to point PCB harnesses without intermediate joints.
Potential Impact:
The single piece, multilayer flex PCBs were not subjected to an engine test as planned, as the end-user was unable to provide a suitable test vehicle and so a formal TRL6 Capability Readiness Review (CRR) was not held.
The project has demonstrated that the long, multilayer flex technology is viable, and there is a clear weight advantage in making PCB technology available to a wider proportion of the engine due to the temperature increase achieved. There is also a clear advantage over current manufacturing process allowing point to point PCB harnesses without intermediate joints.
The products for the test rig and the large format items delivered were manufactured on development equipment, and although not part of this project a termination system needs to be developed and a formal Manufacturing Readiness Process (MCRL) would need to be completed before industrialisation. There now needs to be a concise business case generated, but this may only be possible after the termination costs and full production environment is better understood.
Trackwise has started a UK funded R&D project continuing the development of long, multilayer flex technology to develop a production process and a termination system with Airbus as an end user. This would be airframe mounted, rather than engine mounted and therefore in a more benign environment. However, this would still increase the maturity of the technology and the end-user has expressed an interest to see how this develops in the longer term.
Project members, Trackwise and Rogers, are continuing to work together on related technology where the experience gained by the project has been useful – wing ice protection systems. Although this is cold environment, as opposed to hot, the same polymers are to be used and the manufacturing experience gained in the project is being applied.
List of Websites:
www.lhtfpcb.co.uk
Project website contact: Philip Johnston, +44 1684 299930 philip.johnston@trackwise.co.uk
Webmaster contact: Tony Hodder, +44 7810 553350, tony@hodderonline.co.uk