New liquid crystal polymer (LCP) flex circuits to meet demanding reliability and end-use applications requirements
Flex circuits made from LCP, a thermoplastic polyester, use a newly developed, adhesiveless, roll-to-roll process flow similar to that used for polyimide substrate, including vacuum metallization, additive plating and chemical etching of dielectric. Critical dimensions for both LCP raw test circuits and LCP-coverlayer-laminated LCP test circuits from multiple lots met the specification established for polyimide circuits. LCP circuits have also proven to be dimensionally stable at elevated temperature in common post-circuit operations including die attachment, wire bonding, encapsulation and solder reflow. Trace adhesion was not degraded after solder immersion at 280°C. Wire bonding has proven to be as straightforward as on polyimide, yielding strong wire bonds in a large process window. Integration studies with other materials such as LCP coverlayers and soldermasks that could enable a wide variety of product constructions with multiple materials are going forward. Initial parts passed the entire battery of reliability tests that included moisture resistance, thermal shock and temp-humidity-bias stressing to enable the definition of preliminary process conditions for a wide variety of soldermasks with different polymer chemistries. LCP-based flex circuits should have extended applications beyond those for existing polyimide offerings, due to their reduced moisture uptake and coefficient of humidity expansion and better electrical properties, particularly dissipation factor. These applications include liquid crystal display module (LCDM), medical, high frequency applications, high-density disk drive and integrated circuit packaging.
Recent Advancements in Flex Circuit Technology Using Liquid Crystal Polymer Substrates
The multichip, foldable package technology requires high-density and compact metallized substrates, thus offering an ideal new set of applications for flex circuits. Fine-featured flex circuits have traditionally been made with polyimide filins (25-76 micron typical thickness), but a new process has recently been developed with an alternative substrate -- liquid crystal polymer (LCP). Fine lines and spaces and dielectric features for advanced circuit designs equivalent to cutting-edge polyimide circuit features and not previously attainable with LCP substrates can now be produced on LCP. Flex circuits made from LCP use an adhesiveless, roll-to-roll process flow similar to that used for polyimide substrates, including vacuum metallization, additive plating and chemical etching of the dielectric.
Legal Process and the Discovery of Better Policies for Fostering Innovation and Growth
Our chapter concerns how legal process can lead to efficient policies for fostering innovation and growth. Future innovation will depend at least as much on how laws are made as on a priori analyses of the optimal content of those laws. Of particular importance is whether U.S. choice of law and choice of forum rules promote an efficient market for law. Our analysis supports three suggestions for improving the law to support growth. First, the rules governing the selection of the jurisdiction whose law governs productive activity can significantly affect growth and innovation. Second, any proposal aimed at increasing growth through a change in law or legal institutions should take account of the existence of multiple jurisdictions and parties’ ability to choose the jurisdiction whose law controls their transactions. Third, we suggest harnessing the power of jurisdictional competition among the states through a federal law enforcing contracting parties’ choice of law except to the extent states legislatively override the choice of law and regulate local transactions. We apply this analysis to several areas of the law that are critical to growth and innovation: non-competition clauses, business associations, the legal profession, internet law, insurance, property law, products liability, and franchise regulation.