62laminate (CCL) manufacturers besides film manufacturers. Yet, the three leading corporates were not completely defeated as they continued to grow, at least, in terms of their production quantity. Meanwhile, quite a large number of the newcomers have gradually disappeared for their low market competitivity.The polyimide film market has expanded tremendously since the 21st century while unfortunately with no significant technology development nor breakthrough concept products that would change the market structure. There were, still, a barrage of new materials came to the market when we take a macro viewpoint of the flexible circuit industry as a whole. This time, we are going to take a deeper look at the materials of coverlay (CL) of flexible circuits.Traditionally, polyimide film or CCL has been developed as the base material for practical use as the main material for flexible circuits so CL was not considered as an option at all indeed. However, the polyimide film for CL use was more than the base material in terms of the usage amount. It was, hence, somewhat strange that no manufacturers have ever tried reaching out to work on the development of CL materials for such a long time.List of abbreviationsCCL : Copper Clad LaminateCL : CoverlayPI : PolyimideAbout the AuthorFounder and Managing Director of DKN Research LLC, based in Massachusetts, USA. Engages in engineering, technology development, and product design of various electronic packaging technolo-gies. Has more than 30 years of experience in fields related to electronic packaging and is the industry’s foremost expert on flexible circuit board. Leads the industry with the technology of super high-density flexible composite circuit boards. Has published more than 100 papers related to technology and business and has also written books and lectured on several related fields.DKN Research LLCDominique K. Numakuradnumakura@dknresearch.com38. The development of new CL materials The Summary of the Previous ArticlesIn the 21st century, cellular phones were taken up by users en masse and flexible circuits became the main wiring material for the production. The demand on polyimide (PI) thus grew in a rapid rate. The use of tape circuits based on polyimide film has also become the new standard in driver modules for various types of displays including flat screen TVs. Since the usages of these devices have spread to almost every cor-ner of the world, the consumption of polyimide film simply soared. As the increase in market demand was followed by the enormous pressure on manufacturers to cut operational costs, new manufacturers in Taiwan and South Korea started to commercialize their new polyimide one after another that the oligopoly of the three leading corporates eventually col-lapsed. These new manufacturers included many copper-clad tale 9New coverlays appearing one after another while there’s still room for improvement
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