Investigation Of Ratcheting Strain Properties And Bonding Reliability Of Anisotropic Conductive Adhesive Film

With the development of electronics, the miniaturization and integration aredemanded. As a new kind of green packaging bonding material, anisotropicconductive adhesive file (ACF) meets those requirements, and it has attracted moreand more attention in electronic industry. In recent years, the researches on the bodingtechnology and the mechanical property of ACF materials have been conducted,which promoted the development of electronic industry. But the study on the effect ofenvironment on the reliability is limited. In view of these shortcomings, a series ofexperiments on the reliability of COG assembly with the effect of environment wereconducted in this paper. COG assembly is bonded by ACF materials, so that themechanical properties of ACF have close relation with the reliability of COG. Firstly,the effect of hygrothermal aging on the ratcheting behavior was researched. On thebasic study of ACF, the effects of hygrothermal aging and thermal cycling aging onthe bonding reliability and conductive reliability were studied. Specific contents are asfollows:The ratcheting behavior of ACF materials with the effect of hygrothermal agingwas researched. The results show that: with the effect of hygrothermal aging, theratcheting strain of ACF increases first and then decrease, and the influences of meanstress, stress amplitude and loading rate on the ratcheting property are weakened byhygrothermal aging. The cycling stability of ACF is enhanced by hygrothermal aging.By hygrothermal aging, the coupling effects of temperature, electric current andstress on the adhesion and electrical properties of COG assembly were studied. It isfound that: The shear strength of COG assembly has close relation with loading rate.The maximum shear force of COG assembly firstly increases and then decreases withincreasing loading rate in range of10~70μm/s, peaks at50μm/s. The maximum shearforce decreases with the increase of hygrothermal aging time. The functions of themaximum shear force with aging time were obtained by fitting experiment data. Thereal-time resistance in shear process and hygrothermal aging were detected. Due tohygrothermal, the resistance increases remarkably with the aging time.By thermal cycling aging, the coupling effects of temperature, electric currentand stress on the adhesion and electrical properties of COG assembly were studied. The maximum shear force of COG assembly increases initially and then decreaseswith increase aging time. The functions of the maximum shear force with aging timewere obtained by fitting experiment data. The real-time resistance of COG assemblyincreases remarkably with temperature, but it increases slightly with the increase ofthermal cycling aging time. However, the real-time resistance exhibits circulationchanges corresponding to thermal cycling.