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1.
Kyoung-Sik Moon Silvia Liong Haiying Li C. P. Wong 《Journal of Electronic Materials》2004,33(11):1381-1388
The contact resistance stability of isotropically conductive adhesives (ICAs) on non-noble metal surfaces under the 85°C/85%
relative humidity (RH) aging test was investigated. Previously, we demonstrated that galvanic corrosion has been shown as
the main mechanism of the unstable contact resistance of ICAs on non-noble metal surfaces. A sacrificial anode was introduced
into the ICA joint for cathodic protection. Zinc, chromium, and magnesium were employed in the ICA formulations as sacrificial
anode materials that have much lower electrode-potential values than the metal pad surface, such as tin or tin-based alloys.
The effect of particle sizes and loading levels of sacrificial anode materials were studied. Chromium was not as effective
in suppressing corrosion as magnesium or zinc because of its strong tendency to self-passivate. The corrosion potential of
ICAs was reduced by half with the addition of zinc and magnesium into the ICA formulation. The addition of zinc and magnesium
was very effective in controlling galvanic corrosion that takes place in the ICA joints, resulting in stabilized contact resistance
of ICAs on Sn, SnPb, and SnAgCu surfaces during the 85°C/85% RH aging test. 相似文献
2.
以环氧树脂为基体,银粉为填料,制备出IC封装用导电银胶。研究了环氧树脂与银粉的比例、银粉的形貌和粒径以及触变剂SiO2的用量对导电银胶触变性的影响。结果表明,银胶触变性随树脂/银粉质量比的减小而增大,当其为0.2时,触变指数达到5.68。在一定粒径范围内,银胶的触变性与银粉粒径呈反比关系;银胶触变性随SiO2的用量增大而增大。 相似文献
3.
In this study, a systematic experimental work was performed to evaluate the reliability of the anisotropic conductive adhesive
film (ACF) joint at high temperature for flip-chip-on-flex (FCOF) assemblies. A four-point probe method was developed to measure
the contact resistance at high temperature. Measurement was also conducted along the length of the chip. The correlation between
the increased resistance and the failure mechanism was investigated using scanning electron microscopy (SEM). Initially, the
contact resistance increased linearly with rising temperature, but later, it increased abruptly. This changeover was related
to the glass-transition temperature (Tg) of the ACF matrix. The coefficient of thermal expansion (CTE) is very high at temperatures above Tg; thus, the ACF swells too much, reducing the mechanical contact of the particles with the bump and/or pad. Again, as the
adhesive strength becomes weaker at temperatures above the glass transition, it is unable to resist the thermal stress of
the flex. The cumulative thermal stress at the edges dislodges the particles from the interconnection. Even below Tg, the thermal stress at the edges is higher than the middle point. Thus, the contact resistance varied from the middle joint
of the chip to that of the corner at the same high temperature. To reduce the contact resistance at the corner joint of the
FCOF packages bonded by ACF, a square-shaped chip instead of a chip with a higher aspect ratio should be used. It was also
suggested to use an adhesive with a higher glass-transition temperature and lower CTE. 相似文献
4.
Although there have been many years of development, the degradation of the electrical performance of anisotropically conductive
adhesive or film (ACA or ACF) interconnection for flip-chip assembly is still a critical drawback despite wide application.
In-depth study about the reliability and degradation mechanism of ACF interconnection is necessary. In this paper, the initial
contact resistance, electrical performance after reliability tests, and degradation mechanisms of ACF interconnection for
flip-chip-on-flex (FCOF) assembly were studied using very-low-height Ni and Au-coated Ni-bumped chips. The combination of
ACF and very-low-height bumped chips was considered because it has potential for very low cost and ultrafine pitch interconnection.
Contact resistance changes were monitored during reliability tests, such as high humidity and temperature and thermal cycling.
The high, initial contact resistance resulted from a thin oxide layer on the surface of the bumps. The reliability results
showed that the degradation of electrical performance was mainly related to the oxide formation on the surface of deformed
particles with non-noble metal coating, the severe metal oxidation on the conductive surface of bumps, and coefficient of
thermal expansion (CTE) mismatch between the ACF adhesive and the contact conductive-surface metallization. Some methods for
reducing initial contact resistance and improving ACF interconnection reliability were suggested. The suggestions include
the removal of the oxide layer and an increase of the Au-coating film to improve conductive-surface quality, appropriate choice
of conductive particle, and further development of better polymeric adhesives with low CTE and high electrical performance. 相似文献