Brave C&H of Taiwan recently has succeeded in applying polymide (PI) material on screen producing, which will enable it to regain competiveness on the PV cell-manufacturing market. The breakthrough is a timely boon for the company, which has been plagued by problems of using photo emulsion for screen printing. The printing quality of a screen is affected by the screen’s knot design, the compatibility of the screen with emulsion, and its compatibility with conductive pastes.
Chen Kan-Fu, general manager of Brave C&H, pointed out that due to the limited amount in need it was unable to secure competitive photosensitive emulsion from foreign suppliers. The company started to conduct R&D on PI material four years ago, in order to offset the advantage of rivals who possess strong photosensitive-emulsion technology.
To enhance efficiency and offset the impact of China's new 531 policy, players in the field have rushed to introduce selective emitter (SE) technology, which is known to have lower power resistance and higher efficiency. However, traditional knotless screen printing cannot be coupled with SE process, which has eventually forced players to switch to fine-line printing.
Unlike traditional emulsion, Brave’s PI screen does not absorb solvents. This helps to prevent the shrinkage of the finger openings and allows the laser light to carve out lines as fine as possible. In addition, their process can be applied to produce knotless screens with ultra fine-line patterns, and more importantly there is no pattern shift problem. Therefore Brave easily solved the difficulties that commonly happens when the SE process is combined with traditional knotless screen. Furthermore, Brave PI screen can boost the overall PV-cell conversion rate by 22%. "Our technology is the only solution enabling the coupling of SE and knotless printing," remarked Chen Kan-Fu.
After hitting the market in Oct. 2017, ultra-fine line screens coupled with PI has had a good reception on the market and shipment has begun following two to three months of testing at major factories in Taiwan, South Korea, and China. Given the growing popularity of SE processes and SE-based screen printing, Brave C&H looks forward to strong sales growth in 2019.