There is also 1 mil material available from Sanmina SCI if you are determined to use such thicknesses. My experience is that it is not necessary to do so. Lee Ritchey > [Original Message] > From: Andresakis, John <John.Andresakis@xxxxxxxxxxxxx> > To: Lee Ritchey <leeritchey@xxxxxxxxxxxxx>; Steve Weir <weirsi@xxxxxxxxxx>; Bowden, Ivor <ibowden@xxxxxxxxxxxxxxxxx> > Cc: si-list@xxxxxxxxxxxxx <si-list@xxxxxxxxxxxxx> > Date: 12/18/2009 10:59:49 AM > Subject: RE: [SI-LIST] Re: PCB thin dielectrics > > Gentlemen, > > As Lee points out, it is an engineer's job to avoid single sourcing when possible. But as Steve indicated, there are 2 sources of 1 mil material. The HK04 (DuPont) and BC24 (Oak-Mitsui) products are used by a number of companies as interchangeable. Ivor, for what it sounds like what you are trying to do, either material would be acceptable. > > Let me know if you further information on our BC24 or other materials. > > Best Regards, > > John Andresakis > VP of Strategic Technology > Oak-Mitsui Technologies, LLC > 80 1st Street Hoosick Falls, NY 12090 > > Office: (518) 686-8088 > Cell: (518) 368-1556 > > > -----Original Message----- > From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Lee Ritchey > Sent: Friday, December 18, 2009 1:17 PM > To: Steve Weir; Bowden, Ivor > Cc: si-list@xxxxxxxxxxxxx > Subject: [SI-LIST] Re: PCB thin dielectrics > > Problem with most of these materials is they are single source with all that entails. I do just fine with standard laminates by using thin prepregs between the power planes. This does not result in single sourcing. I know that puts a crimp in those companies that offer special materials, but an engineer's job is to do what he can to avoid single sources when doing designs. > > Sorry Steve! Didn't mean to step on you here. > > Lee Ritchey > > > > [Original Message] > > From: steve weir <weirsi@xxxxxxxxxx> > > To: Bowden, Ivor <ibowden@xxxxxxxxxxxxxxxxx> > > Cc: <si-list@xxxxxxxxxxxxx> > > Date: 12/18/2009 9:24:18 AM > > Subject: [SI-LIST] Re: PCB thin dielectrics > > > > Ivor, there are about four materials to know about: > > > > Except for exotic applications the big thrill in thin dielectrics is > > reduction in inductance. This lets you get rid of a bunch of bypass > > caps, and/or yield lower impedance to the power attachment of your IC > > package, and in a number of cases do things like reduce layer counts > > depending on the specifics of your power distribution scheme. With > > proper design a thin dielectric lets you use far fewer bypass > > capacitors to cover the frequency ranges from about 5MHz up to around > > 100MHz - 300MHz where the bypass network impedance crosses over into > > the interconnect impedance. Above the crossover, the thinner > > dielectric gives you lower impedance period. For unloaded materials > > the impedance improvement is almost linear to the ratio of the > > thickness: IE 1mil material is about 1/3 the impedance of a 0.0035" glass epoxy cavity. > > The impedance peaks caused by modal resonances come down faster than > > the thickness ratio. > > > > In the thinner than 0.0035 camp there is: > > > > $ BC2000 50um > > $$ DuPont HK04 24um polyimide / Oak Mitsui BC24 24um epoxy $$$DuPont > > HK04 18um polyimide $$$$Dupont HK04 12um polyimide / Oak Mitsui BC12 > > epoxy $$$$$$OakMitsui BC12T BT loaded epoxy / Oak Mitsui BC8 8um epoxy > > / 3M Cply BT loaded epoxy > > > > I provide application support to DuPont for HK04 materials. The 24um > > material is cheap enough now that in many applications it reduces > > total cost versus an equivalent performance bypass system using > > thicker dielectric. > > > > Best Regards, > > > > > > Steve. > > > > Bowden, Ivor wrote: > > > Hi SI people, > > > > > > > > > Could I get some comments on the use of "thin" (<0.0035") > > > dielectrics > in PCBs, in terms of available materials, cost, reliability, dielectric strength, trace width vs dielectric constant, power plane capacitance, stories, studies, useful web links, any other pertinent issues? Base question is, could this be a practical way to increase PCB layer count while maintaining overall PCB thickness? > > > > > > > > > > > > Any / all information / comments welcome. > > > > > > > > > > > > Thanks, > > > > > > > > > > > > Ivor Bowden > > > > > > > > > > > > > > > ____________________________________________________________________ > > > ___ This e-mail and any files transmitted with it are proprietary > > > and > intended solely for the use of the individual or entity to whom they are addressed. If you have reason to believe that you have received this e-mail in error, please notify the sender and destroy this email and any attached files. Please note that any views or opinions presented in this e-mail are solely those of the author and do not necessarily represent those of the Curtiss-Wright Corporation or any of its subsidiaries. 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