Based on the advantages of higher output efficiency, higher utilization, higher production, lower cost, no requirement for advanced process, higher device density, improved electrical performance and enhanced thermal management, there are many foreign manufacturers and domestic manufacturers all have developed the FOPLP technology in the past ten years. The related technologies including die first & face down for FOPLP technology, die first & face up for FOPLP technology and RDL first for FOPLP technology have been developed. The challenges including die shift, panel warpage, RDL process capability, relayed equipment, and market share also need to be considered for a long time along with the developing of FOPLP technology. During the whole process of FOPLP packaging, organic materials including epoxy molding compound (EMC), dry film, photosensitive polyimide (PSPI) and photoresist (PR) were applied to guarantee the performance of packaged chips.

The colorless polyimide (CPI) has been drawn much attention for its application in transparent electronics, such as the camera under panel (CUP) in organic light-emitting diode display (OLED) display which required a high transmittance (Tr%). The high temperature (even to 450℃) process of the preparation of OLED device may have huge challenges on the properties of CPI, so we designed a series of aging test experiments to study the influence of test temperature and atmosphere on the Tr% of CPI films with structure of Glass/SiO2/CPI/SiO2. With the increasing of aging temperate from 430℃ to 450℃ and 470℃, the Tr% of the film decrease obvious, especially responding the wavelength from 400nm to 600nm. The samples with aging test all had a low Tr% than the sample without aging. Comparing with the sample without aging, the loss transmission were 0.22%, 1.42% and 4.82% for the films aging with 430℃, 450℃ and 470℃ in N2 atmosphere, respectively. Meanwhile, the influence of aging atmosphere on the Tr% was also researched with nitrogen and air. The film aging with nitrogen had a higher Tr% than that aging with air, the loss transmission were 1.22% and 1.42% compared with the sample without aging test.