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The effects of the functionality of an epoxy monomer on the composite properties and reliability of anisotropic conductive
films (ACFs) in a flip-chip package were investigated. Three epoxy monomers with different functionalities (f=2–4) were considered.
The ACFs prepared using epoxy monomers with higher functionality resulted in lower molecular weight between crosslinks (Mc). As the Mc decreased, the elastic modulus (E′) and coefficient of thermal expansion (CTE) were improved. These results were highly consistent
with the rubber elasticity theory. The reliability performance of the flip chip on organic substrate assemblies using ACFs
were also investigated as a function of epoxy functionality. The ACFs prepared by using higher functional epoxy monomers showed
improved reliability performance. 相似文献
3.
Myung Jin Yim Jin-Sang Hwang Jin Gu Kim Jin Yong Ahn Hyung Joon Kim Woonseong Kwon Kyung-Wook Paik 《Journal of Electronic Materials》2004,33(1):76-82
Anisotropic conductive film (ACF) has been used as interconnect material for flat-panel display module packages, such as liquid
crystal displays (LCDs) in the technologies of tape automated bonding (TAB), chip-on-glass (COG), chip-on-film (COF), and
chip-on-board (COB). Among them, COF is a relatively new technology after TAB and COG bonding, and its requirement for ACF
becomes more stringent because of the need of high adhesion and fine-pitch interconnection. To meet these demands, strong
interfacial adhesion between the ACF, substrate, and chip is a major issue. We have developed a multilayered ACF that has
functional layers on both sides of a conventional ACF layer to improve the wetting properties of the resin on two-layer flex
for better interface adhesion and to control the flow of conductive particles during thermocompression bonding and the resulting
reliability of the interconnection using ACF. To investigate the enhancement of electrical properties and reliability of multilayered
ACF in COF assemblies, we evaluated the performance in contact resistance and adhesion strength of a multilayered ACF and
single-layered ACF under various environmental tests, such as a thermal cycling test (−55°C/+160°C, 1,000 cycles), a high-temperature
humidity test (85°C/85% RH, 1,000 h), and a high-temperature storage test (150°C, 1,000 h). The contact resistance of the
multilayered ACF joint was in an acceptable range of around a 10% increase of the initial value during the 85°C/85% RH test
compared with the single-layered ACF because of the stronger moisture resistance of the multilayered ACF and flex substrate.
The multilayered ACF has better adhesion properties compared with the conventional single-layered ACF during the 85°C/85%
RH test because of the enhancement of the wetting to the surface of the polymide (PI) flex substrate with an adhesion-promoting
nonconductive film (NCF) layer of multilayered ACF. The new ACF of the multilayered structure was successfully demonstrated
in a fine-pitch COF module with a two-layer flex substrate. 相似文献
4.
Advanced integrated circuit packaging processes require good bondability and reliability between various mating surfaces.
A key factor affecting this requirement is surface cleanliness. Plasma cleaning is the most suitable process for optimum surface
cleanliness. An investigation of O2, Ar, and O2/SF6 plasma cleaning was carried out on a flexible substrate to study the adhesion of anisotropic conductive adhesive film for
flip chip bonding. Surface roughness was found to increase substantially after the plasma treatment. Adhesion strength was
evaluated by 90° peeling tests both for untreated and plasma-treated flex. A higher adhesion strength of anisotropic conductive
film (ACF) bond was observed after plasma cleaning. The surface morphology of plasma treated and untreated flex substrate
before bonding, as well as the fracture surfaces after the peel test for both cases, was characterized by secondary electron
image techniques of scanning electron microscopy (SEM). Based on the detailed SEM findings, extensive comparisons were made
between the plasma treated and the untreated samples. Mechanical interlocking is found to be responsible for higher peel strength
of the plasma treated flex bonding. It was also proposed to select the right flexible substrate for highly reliable, ACF bonded
flip chip on flex substrate. 相似文献
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A novel method (the V-shaped curve) is presented to predict the failure probability of anisotropic conductive film (ACF) in IC/substrate assemblies. The Poisson function is used to calculate the probability of opening failure in the vertical gap between the pads, while the box and modified box models are used to estimate the probability of bridging failure between the pads in the pitch direction. The opening and bridging probabilities are combined using probability theory to establish four different failure prediction models. The results reveal that the model combining the Poisson function for fewer than six particles per pad with the modified box model provides the most accurate predictions of the failure probability of ACF in IC/substrate assemblies. 相似文献
7.
Anisotropic conductive film (ACF) suffers a major drawback in regard to reliability even though it has merits, such as reduction
in interconnection distance, high performance, and environmental friendliness. The factor of thermal warpage may lead to a
highly unreliable electrical connection in the assembly. The work presented in this paper focuses on the online contact-resistance
behavior of the ACF joint during thermal shock and compares the results of two different types of dies (Au/Ni bump and bumpless).
For this work, we used a flip chip of 11 × 3 mm2 in dimension. The flex substrate used was made of polyimide film with an Au/Ni/Cu electrode and daisy-chained circuit for
a matching die-bump pattern. The ACF that was used is an epoxy resin in which nickel and gold-coated polymer balls are dispersed.
Tests for three different thermal-cycling profiles (125°C to −55°C, 140°C to −40°C, and 150°C to −65°C) were carried out.
The samples bonded at a temperature of 180°C, and a pressure of 80 N was used. The initial contact resistances of Au/Ni bump
and bumpless samples were 0.25 ω and 0.4 ω respectively. A comparative study was carried out from the results obtained. The
results showed that for the flip-chip-on-flex (FCOF) packages having an Au/Ni bump, the increase in online contact resistance
is higher than that of the FCOF packages having bumpless chips. For example, in the thermal-cycling profile of 140°C to −40°C,
the online contact resistance for the Au/Ni bump raised to 4.6 ω after 180 cycles, whereas it was only 1.3 ω for the bumpless
sample. The bump height and bump materials were found to be the main factor for such variation. Results show that, above the
glass-transition temperature (Tg), the ACF matrix becomes less viscous, which reduces its adhesive strength and lets the higher bump height of the chip result
in a higher standoff of the package and thus sliding is easier to take place. The responses by the assemblies in hot and cold
conditions are examined, and in-chamber behavior of the assembly is studied and explained. 相似文献
8.
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
9.
Yeh-Fang Duann Jen-Hung Chiang Shung-Jim Yang Hsun-Wen Chang 《Journal of Electronic Materials》2005,34(7):1026-1029
The 63Sn-37Pb solder ball (φ=300 μm) was attached to gold-nickel-plated plastic ball grid array (PBGA) substrates, with gold
and nickel thicknesses of 0.6 μm and 7 μm, respectively. The thickness of the intermetallic compound (IMC) in solder balls
was measured following each instance of infrared (IR) reflow (90 sec at 230 °C), level II preconditioning, a pressure cooking
test (for 96 h or 168 h), and a temperature cycle test (with 500 or 1,000 cycles). Scanning electron microscopy (SEM) was
used to identify the cross-section sites of the solder balls following testing. Following all the reliability tests, the IMC
demonstrated that an IMC thickness exceeding 5 μm will reduce the solder ball shear strength owing to diffusion of Ni into
the solder balls. 相似文献
10.
Hyoung-Joon Kim Chang-Kyu Chung Yong-Min Kwon Myung-Jin Yim Soon-Min Hong Se-Young Jang Young-Joon Moon Kyung-Wook Paik 《Journal of Electronic Materials》2007,36(1):56-64
The formation of process-related bubbles that become entrapped inside the anisotropic conductive film (ACF) layer during bonding
processes remains an issue. The formation of these bubbles is strongly influenced by the process variables, such as bonding
pressure and bonding temperature. Therefore, bonding process variables of bonding temperature, bonding pressure, and type
of flexible substrate (FS) were changed in order to investigate the effects of the changes as they concern the formation of
bubbles. According to the results, the tendency toward bubble formation was closely related to these three factors. The bubble
area increased as the bonding temperature increased. Moreover, the shape and tendency of bubbles coincided with temperature
distribution in␣the ACF layer. Two different types of FS, each with different surface roughnesses and energies, were used.
The bubbles formed only on the FS with the larger roughness and lower surface energy. According to the results from a surface
energy measurement of FS types using goniometry, a FS with a higher surface energy is favorable for a bubble-free assembly,
as the higher surface energy provides better wettability. In addition, in order to investigate the effect of bubbles on the
reliability of ACF joints, the pressure cooker test (PCT) was performed, and all samples with bubbles electrically failed
after 72 h of a PCT, as the process-related bubbles provided a moisture penetration path and entrapment site for moisture.
However, all type 1 test vehicles (TVs) survived even after 120 h of a PCT. Therefore, Ar and O2 plasma treatments were performed on the FS with the lower surface energy in order to improve the surface energies and wettability.
Following this, the bubbles were successfully removed at rigid substrate (RS)–FS bonding joints using ACFs. 相似文献
11.
采用直流脉冲反应磁控溅射方法生长W掺杂ZnO(ZnO:W,即WZO)透明导电氧化物(TCO)薄膜并研究了氧气流量对薄膜微观结构、组分、表面形貌以及光电性能的影响。实验结果表明,WZO薄膜具有良好的(002)晶面择优取向生长,且适当的氧气流量是制备优质WZO薄膜的关键因素。WZO薄膜表面形貌受薄膜结晶质量的影响。当氧气流量为2.08×10-7 m3/s时,WZO薄膜在400~1 500nm透过率达到84.5%,电阻率为4.61×10-3Ω.cm,迁移率为20.5cm2v-1s-1。XPS测试表明WZO薄膜中Zn和W均处于氧化态,其中W元素呈现W6+价态。 相似文献
12.
采用射频磁控溅射法沉积制备了(002)ZnO/A l/Si复合结构。研究了Al薄膜对(002) ZnO/Al/Si复合结构的声表面波器件(SAWD)基片性能影响以及当ZnO 薄膜厚度一定时的Al膜最佳厚度。采用X射线衍射(XRD)对Al和ZnO薄膜进行了结构表征 ,采用 扫描电镜(SEM)对ZnO薄膜进行表面形貌表征,并从薄膜生长机理角度进行了分析。结果 表明,加Al薄膜有利于ZnO薄膜按(002)择优取向生长,并且ZnO 薄膜的结晶性能提高;与(002)ZnO/Si结构基片相比,当Al薄膜 厚为100nm时,(002)ZnO/Al/Si结构中ZnO薄 膜的机电耦合系数提高 了65%。 相似文献
13.
金属有机化学气相沉积(MOCVD)技术生长的绒面ZnO透明导电(ZnO-TCO)薄膜应用于Si基薄膜太阳电池上能够形成"陷光结构",以提高薄膜太阳电池效率和稳定性。本文将电子束反应蒸发技术生长的掺W的In2O3(In2O3:W,(IWO)薄膜作为缓冲层,应用于MOCVD-ZnO:B薄膜与玻璃之间,可促进ZnO:B薄膜的生长,并且有效提升薄膜的光散射特性。当IWO缓冲层厚度为20nm时,获得的IWO/ZnO:B薄膜的电阻率为2.07×10-3Ω.cm,迁移率为20.9cm2.V-1.s-1,载流子浓度为1.44×1020 cm-3;同时,薄膜具有的透过率大于85%,且在550nm处绒度较ZnO:B薄膜提高了约9.5%,在800nm处绒度较ZnO:B薄膜提高了约4.5%。 相似文献