Understanding of the raw material aspects of flexible circuits (i.e., base movie, glue layer and also steel aluminum foil) and how they are incorporated makes it possible to examine them in more depth as well as, much more specifically, to learn about the available mate- rial options as well as their properties. This process allows designers making knowledgeable choices based upon the effect of each choice on the final product
FLEXIBLE BASE FILMS
Several products have been utilized as base films or substrates for flexible circuits produce, including:
– Fluoropolymer movies, such as Teflon ®
. – Aramid fiber-based documents and towels, such as Nomex ®
. – Formable composites, such as those stood for by Bend/Flex ®.
– Various flexible epoxy-based compounds.
– Thermoplastic films, such as polyethylene, polyvinyl chloride, polyvinyl fluoride, and polyetherimide.
All of these movie as well as thin composites have been used in flexible circuits manufacture at once or an additional as well as a number of them continue to be utilized in particular applications. The cost of materials can differ commonly.
The most popular as well as most generally defined flexible base products are polyester (PET) and also polyimide (PI). The choice substratum polymer to make use of is figured out by a combo of economics, output application as well as assembly processing temperature levels, which are significantly essential to satisfy EU-legislated lead-free needs, Polyimide as well as polyester could control existing applications, but there are alternate movie technologies that can see boosted usage for a variety of strong factors. Polyethylenenaphthalate (PEN), as an example, appears like an appealing inter mediate selection in terms of cost as well as performance.
An additional product of boosting passion as the sector moves to higher regularity electronic devices is liquid crystal polymer (LCP). This material has a number of eye-catching physical as well as electrical buildings. As an example, LCP materials have inherently reduced dampness absorption properties (0.02% to 0.1%) that should preclude the requirement for the baking that is frequently part of the polyimide manufacturing procedure because of its even more hygroscopic nature. The reduced moisture uptake is likewise a crucial factor in developing a reduced signal loss atmosphere. With a loss tangent of 0.003 as well as a dielectric constant of around 2.9 LCP is really eye-catching for high-speed applications. An additional eye-catching attribute of LCP is that it is chemically etchable, a feature it shows to polyimide. This ability is something that can be used to advantage in creating both unique as well as reasonably mundane building and constructions.
Thin fluoropolymer laminates are additionally prospect products to offer future flex circuit interconnection requirements. While not necessarily fit to dynamic applications, PTFE friend- rials might locate usage in applications where low loss as well as low dielectric constant are required. Common loss tangent values for PTFE materials are less than 0.001 as well as the dielectric constant frequently is available in the 2.0 to 2.4 range. Business such as Taconic are targeting just such applications for materials they are establishing for the flexible circuits market. The laminate mate- rial is based on PTFE. FEP is a derivative of PTFE with a much reduced thaw factor of 550 ° F vs. 640 ° F for
PTFE. As noted earlier, the selection of product is likewise greatly influenced by the assembly innovation to be utilized for elements on the completed product. This is where developers need to seriously consider the trade-offs connected with product as well as material choice. It is possible to make a notified decision that would not, under typical scenarios, be considered appropriate. Such decisions are typically based upon special expertise of how to circumvent problems connected with the companion- rial building limitations of the selected substrate.