The Reliability Study Of COB-LED Based On Solderable Anisotropic Conductive Adhesive

The resolution of LED display can be improved by miniaturization of pixel unit.However,the miniaturization of the size and spacing of LED chips will greatly improve the difficulty of die bonding.The connection materials must have the ability of ultra-fine spacing connection to ensure the smooth process of die bonding.As a new type of bonding material,compared with conventional solder,Solderable Anisotropic Conductive Adhesive has the ability of ultra-fine spacing connection,low curing temperature and simple process,which is suitable for the COB package of Mini-LED display.Therefore,this paper studies the reliability of COB-LED based on Solderable Anisotropic Conductive Adhesive.Firstly,The COB-LED based on Solderable Anisotropic Conductive Adhesive samples were prepared.The luminous flux of the sample chip is about 6% lower than the chip based on conventional solder;The reason of the low luminous flux of the sample chip is analyzed,and the reliability of the sample chip is preliminarily proved by the switch aging test.Secondly,Constant current accelerated life test was designed for a normal temperature group and a high temperature group.The change rule of the photoelectric performance of the chip during the test is analyzed.It was shown by the test that the luminous flux of the chip decreases exponentially with the aging time,the main wavelength has no obvious change,and the forward voltage is rising.The mathematical model of luminous decay is established.It is estimated that the life of the chip is more than 20,000 hours,which can reach the mainstream level in the market.Finally,Hygrothermal aging test was designed.The change rule of the photoelectric performance of the chip during the test is analyzed.Two chips failed during the High temperature and high humidity aging test,and the average luminous flux of the remainingeight chips dropped to 72.8% of the initial value;The failure mode and mechanism of the chip are analyzed;The measures to improve the performance and reliability of COB-LED based on Solderable Anisotropic Conductive Adhesive are proposed.In this paper,the life characteristics and reliability of COB-LED based on Solderable Anisotropic Conductive Adhesive are studied,and enough test data are provided,enabing Solderable Anisotropic Conductive Adhesive can be applied in the field of Mini-LED display.