Nonwoven Aramid Reinforcement We’re Baaaack!

1 Material Witnessby: Chet GuilesOctober 22, 2015 Nonwoven Aramid Reinforcement We re Baaaack! Jewish theologians of the 1st Century AD there was a significant debate about whether or not resurrection was possible. PCB designers in the early 21st century have had a similar concern about future availability of 85NT Nonwoven Aramid laminate and prepreg. The stakes may be somewhat less (depending on your theological bent), but the future of a wide variety of programs designed around the properties of (Dare I mention the name?) Thermount have been hanging in the balance. What was Thermount exactly and why was there such a furor when DuPont announced its premature demise? And how did we achieve the Second Coming ?The original 85NT product was based on high strength para- Aramid fiber with a meta- Aramid fibrid binder. The para- Aramid fibers have a high tensile modulus (fiber modulus of about 19 mpsi) and a negative linear coefficient of thermal expansion (CTE of about -4 ppm/ C), and the fibrid held the fibers together in a uniform matrix.

2 Produced in a high-end papermaking process, the resulting substrate was a yellow Aramid paper material that produced laminates with a unique and useful set of properties. For a polyimide Aramid composite the benefits look like this: Tg of Pure Polyimide (250 C) Low in-plane (X,Y) expansion of 7-9 ppm/ C Excellent dimensional stability and enhanced registration Decomposition temperature of 426 C, compared with 300-360 C for typical high-performance epoxies, offering outstanding high-temperature life Polymeric Reinforcement results in PCBs typically 25% lighter in weight than conventional glass-reinforced laminates Laser ablatable for high speed formation of microvias as small as 25 m in clad laminates as thin as Electrical and mechanical properties meeting the requirements of IPC-4101/53 Compatible with lead-free processing RoHS/WEEE compliantThe earliest military adoption of Aramid reinforced laminates was in the guidance system for the Tomahawk Cruise Missile, a significant success in terms of test results (thermal cycled better than the prior woven Aramid technology)

3 And field performance. The combat proven Tomahawk gave the then relatively new substrate a kick-start. I still have the jacket patch that the Tomahawk PWB development guys gave me. And there was some real pride in achievement in the ongoing field success of that program. Later uses of 85NT materials included a wide variety of military and commercial avionics. The first generation avionics for the Boeing 777 were designed on this platform, and it replaced heavy Copper-Invar-Copper (CIC) in a number of older designs. In addition to these, the Iridium telecommunications satellite constellation used 85NT for a number of its PWB July of 2006 the imminent demise of the DuPont Thermount product was announced to its customer base, and in November, 2006, in a letter from Ralph Hutton (President, DuPont Teijin Advanced Papers), they said that: Due to a dramatic reduction in demand for Thermount Reinforcement for consumer applications in Japan, and due to insufficient global demand for the foreseeable future (Translation: The over-hyped ALIVH process was too expensive to license and too difficult or too something -- to be viable?)

4 , we are unable to continue accepting orders for Thermount Reinforcement of any kind beyond December 31st, 2006. 2015, 2014, 2013, 2012, 2011, 2010, 2009, 2008 Arlon Incorporated Thermount is a tradename of the E. I. DuPont de Nemours Company, Wilmington, DENorth America:Arlon EMD, 9433 Hyssop Drive, Rancho Cucamonga, California 91730 Tel: (909) 987-9533 Fax: (909) 987-8541 Southern Europe:Arlon EMD, 9, rue Marcelin Bertholet, 92160 Antony, France Tel: (33) 146744747 Fax: (33) 146666313 Northern Europe:Arlon EMD, Ulness Walton Lane, Leyland, PR26 8NB, UKTel: (44) 1772452236 Talk about Shock and Awe ! Despite calls from senior officials at major Military-Aerospace OEM s and others, DuPont expressed no interest in rescinding their decision, or in licensing their manufacturing technology or otherwise providing ongoing support. Shipment of the Thermount (hereinafter referred to as the T-word ) ceased mid-2007 after Arlon and a number of its customers purchased a substantial stock as buffer for existing programs and transition material anticipating finding a drop-in , Nonwoven Aramid is back, and though I have tried to keep this column from being purely commercial, as best I know, Arlon is the only company that committed the resources and time to work with potential suppliers to develop a replacement for Thermount that meets all the performance criteria of the original 85NT product.

5 In fact what we have now is a drop-in replacement that will match both in process and properties the original. That was not easy to accomplish and several very well qualified vendors tried and failed to meet the exacting requirements for the substrate. The project took longer than had originally been expected, though stocks of the old material have held up well enough to protect ongoing programs for the entire duration of the development you can see from the following microphotographs, the registration and hole quality of the new Aramid Reinforcement is essentially identical to that of the original DuPont product. The12-layer test coupons were made in the same press and lamination cycle using parameters developed for the original 85NT those who have been frustrated trying to find alternative technologies for their critical SMT boards, I think I can say with a great degree of confidence that Arlon s 85NT is back and that you won t be disappointed with its processability or performance!

6 , 3, 4 49 240 min 7-9, 90-100 - 60 4 to 5 > 900 3 to 4 415 900 to 1000 , 3, 49 240 min 7-9, 90-100 - 60 4 to 5 > 900 3 to 5 416 900 to 1000 85NT New Reinforcement Source Typical Values 85NT Original Laminate Typical Values Thickness per ply % RC Tg X, Y, z CTE % expansion T-288 Peel Strength AR, AS Solder Float Pressure Vessel Water Uptake Decomposition, onset, 5% Electric Strength Until next time, this is the Material Witness wishing you happy fabrication and a great Winter 2015.