According to a new supply chain report this morning, LG Display is pushing for a diversification of the polyimide (PI) varnish supply chain for the PI substrates of Apple iPhone OLEDs. LG Display has been conducting quality tests on polyimide (PI) varnish with Japan's UBE since the end of last year. 

PI varnish is a liquid product required when making a PI substrate for a flexible organic light-emitting diode (OLED). The PI substrate for a flexible OLED is made by forming a liquid PI varnish on a glass substrate for a carrier, solidifying it to make a PI substrate, and then removing the glass substrate for the carrier using the laser lift-off (LLO) process. All iPhone OLEDs use flexible OLEDs based on a PI substrate. 

It has been reported that the results of the PI varnish quality test that UBE has been conducting with LG Display since the end of last year were not good. It is presumed that this is due to the fact that LG Display's iPhone OLED line was optimized for products from Kaneka, the existing PI varnish supplier. 

Apple is known to have pointed out that LG Display's PI varnish products have different properties from the PI varnish from Ubeco used by Samsung Display. If the product properties differ by company, customers will have more to worry about. 

Samsung Display sources its PI varnish through SU Materials, a joint venture with Ubeco. BOE, another of Apple’s iPhone OLED partners, also uses PI varnish from Ubeco. 

Even if Ube Kosan passes LG Display's PI varnish quality test and delivers it in the end, it is expected to be differentiated from the PI varnish that Samsung Display is applying to iPhone OLED. This is because it is difficult to supply the same product to competing companies.

The remaining variable is the LLO process change. If LG Display changes some of the LLO processes in the iPhone OLED line as early as next year, it could affect the performance of the PI substrate (PI varnish) remaining after removing the carrier glass substrate in the process. The Elec