Understanding of the raw material components of flexible circuits (i.e., base film, sticky layer and metal foil) as well as exactly how they are incorporated makes it possible to analyze them in more deepness and, a lot more especially, to learn about the available companion- rial selections and also their properties. This process makes it possible for designers making knowledgeable choices based on the impact of each choice on the end product

FLEXIBLE BASE FILMS

Various materials have actually been made use of as base films or substratums for flexible circuits manufacture, including:

– Fluoropolymer movies, such as Teflon ®
. – Aramid fiber-based papers as well as towels, such as Nomex ®
. – Formable composites, such as those represented by Bend/Flex ®.
– Various flexible epoxy-based compounds.
– Thermoplastic movies, such as polyethylene, polyvinyl chloride, polyvinyl fluoride, as well as polyetherimide.

All of these film and thin compounds have been utilized in flexible circuits manufacture at once or an additional and also a number of them continue to be utilized in particular applications. The price of products could differ widely.

The most preferred and most commonly specified flexible base materials are polyester (PET) and polyimide (PI). The choice substratum polymer to utilize is established by a combination of economics, final result application and assembly processing temperature levels, which are significantly essential to satisfy EU-legislated lead-free demands, Polyimide and polyester may dominate present applications, however there are alternative film innovations that can see raised use for a number of strong reasons. Polyethylenenaphthalate (PEN), for instance, resembles an eye-catching inter mediate choice in regards to cost and also efficiency.

One more material of increasing interest as the sector moves to greater frequency digital electronic devices is fluid crystal polymer (LCP). This product has a number of eye-catching physical and also electric buildings. As an example, LCP materials have naturally low wetness absorption properties (0.02% to 0.1%) that should preclude the requirement for the baking that is commonly part of the polyimide manufacturing process due to its even more hygroscopic nature. The low moisture uptake is additionally a crucial factor in creating a low signal loss environment. With a loss tangent of 0.003 as well as a dielectric constant of around 2.9 LCP is very attractive for high-speed applications. One more appealing attribute of LCP is that it is chemically etchable, a feature it shows polyimide. This ability is something that can be made use of to advantage in producing both exotic as well as relatively mundane buildings.

Slim fluoropolymer laminates are likewise prospect products to offer future flex circuit interconnection requirements. While not always fit to vibrant applications, PTFE companion- rials might locate usage in applications where reduced loss as well as reduced dielectric constant are required. Regular loss tangent values for PTFE materials are less than 0.001 and the dielectric consistent typically can be found in the 2.0 to 2.4 range. Business such as Taconic are targeting simply such applications for materials they are establishing for the flex circuit market. The laminate mate- rial is based upon PTFE. FEP is a by-product of PTFE with a much reduced thaw factor of 550 ° F vs. 640 ° F for
PTFE. As noted earlier, the selection of product is additionally mostly influenced by the assembly innovation to be used for components on the completed product. This is where designers should seriously think about the trade-offs related to product as well as product choice. It is possible to make an informed choice that would not, under regular scenarios, be considered right. Such decisions are normally based upon special expertise of the best ways to prevent troubles associated with the friend-rial residential property limits of the picked substratum.