One of the limitations of flexible circuitry has been performance at extremely high temperatures. For purposes of this discussion, the definition of “extremely high” is temperatures that exceed 150°C – 200°C on a continuous basis or 288°C on an intermittent basis (solder float test). All Flex has recently developed a new class of flexible circuits and flexible heaters with dramatically improved high temperature performance by combining a new material construction with unique fabrication processing.
All Flex has commercialized this product for applications requiring performance at continuous operating temperatures of 250°C. This product development has been in response to growing marketplace demands for higher temperature applications.
As stated in previous posts, the adhesive system in a laminate is normally the weakest link. There are adhesives that can withstand higher temperatures than 200°C, but they lack the properties that are needed for a circuit to remain flexible or avoid layer delamination. Adhesiveless laminates are available, but creating the flexible structure with a laminated insulating film reintroduces an adhesive into the composite structure. The All Flex composite achieves premium performance by combining new materials and a unique fabrication process.
The following are a few questions that one might have concerning this new product:
Q. Does the new material construction have similar flex properties to the existing material constructions used?
A. Each of the many material constructions that are used for flexible circuit fabrication may have slightly different flexibility properties. The flex properties of the new material are similar to traditional laminates used in fabricating flexible circuits.
Q. Can this new material be used for double sided and multilayer construction?
A. Yes, the base materials are available as di-clad and bond-ply.
Q. Does the new construction have the same chemical and mechanical properties of the lower temp materials?
A. The chemical and mechanical properties of the new construction are very similar to existing polyimide laminates used in military and commercial applications.
Q. What copper thickness is the new construction available in?
A. The new construction is currently available in .5 oz and 1 oz thick copper.
Q. Is the new construction UL rated?
A. Yes the new constructions are UL rated to 94V-0 and 746F.
What is the current availability of circuitry and heaters produced with the high temperature capability?
A. All Flex maintains an inventory of the materials used and can meet delivery turn times comparable to other polyimide laminates.
Q. Is the high performance construction available for the oversize circuits and heaters i.e. Maxi-flex®?
A.Yes The new high temperature product allows All Flex to expand its niche offering of extended length Maxi-flex® products, with flexible circuits and heaters that exceed 24” lengths.
Q. What testing has been performed on this new construction?
A. This material has undergone a variety of tests consistent with those specified in IPC 6013 and IPC-4202, 4203, 4204. See our blog post on flexible circuit material testing.
Q. What markets and applications are ideal for the high performance constructions?
A. Markets requiring thermal management at extreme temperatures include down-hole oil drilling, semiconductor processing, medical diagnostics and instrumentation, and a multitude of military/aerospace requirements.
For more information on the high performance construction properties and applications, schedule a design consultation with one of our application engineers.