The root of iPhone 6 plus touch screen is failure lies with touch IC chips on the mother board. So why we have touch IC problem see more in iPhone 6 plus. Most probably the answer is iPhone 6 plus board design. Or the other fault which we can guess is both touch ic chip on iPhone 6 plus are not under fill. iPhone 6 plus touch screen failure caused by two ic chip named as meson u2402 and cumulus u2401. if there are no lines on the lcd and just the touch is not working this is caused by meson chip, and if there are lines on the lcd it is controlled by cumulus ic. A good repair on iPhone 6 plus touch screen failure is to replace both mason and cumulus ic