| 1. |
- Du, Wenhui, et al.
(författare)
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New fast curing isotropic conductive adhesive for electronic packaging application
- 2010
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Ingår i: Proceedings - 2010 11th International Conference on Electronic Packaging Technology and High Density Packaging, ICEPT-HDP 2010; Xi'an; 16 August 2010 through 19 August 2010. - 9781424481422 ; :Article number 5582446, s. 199-201
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Konferensbidrag (refereegranskat)abstract
- With the rapid development of technologies on high density assembly and packaging in electronic industry, isotropic conductive adhesive (ICA) has been paid more and more attention as a potential substitute of solder, due to its advantages of low processing temperature, simple processing conditions and good manufacturability. However, the curing time of most traditional ICA is more than half an hour. The process duration of ICA is 2 or 3 times longer than that of solder. Thus, low efficiencies of energy using and product manufacturing has been one of factors which limits widely application of ICA. Generally, the curing speed of ICA depends on types and amount of curing agent as well as curing temperature. In our previous experiments, the effects of curing temperature and amount of curing agent have been investigated. So, the present work attempts to choose a new kind of curing agent to shorten process duration of ICA. By using new curing agent, the curing duration of ICA could be shortened in 5 minutes with a high curing rate compared with the previous version. In addition, the basic performance including bulk resistivity and viscosity are also investigated in this work. Finally, we present some discussions about the further optimization of performance, for example regarding the ways of achieving better electrical conductivity with lower filler content and improvement of viscosity etc. © 2010 IEEE.
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| 2. |
- Lai, Huaxiang, et al.
(författare)
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Effects of BN and SiC nanoparticles on properties of conductive adhesive
- 2010
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Ingår i: Proceedings - 2010 11th International Conference on Electronic Packaging Technology and High Density Packaging, ICEPT-HDP 2010; Xi'an; 16 August 2010 through 19 August 2010. - 9781424481422 ; :Article number 5582434, s. 235-239
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Konferensbidrag (refereegranskat)abstract
- Isotropic conductive adhesives (ICAs) are a type of interconnect material used more and more widely in computer, robot, mobile phone, LED and so on. Compared with traditional solders, isotropic conductive adhesives have better working plasticity, creep resistance and heat resistance. In particular, isotropic conductive adhesives are more responsive in high density packaging than solder, which determines the dominance of ICAs in high density packaging in the future. In order to improve the thermal conductivity of ICA with acceptable electrical conductivity, Ag flakers, BN and SiC nanoparticles were added into the matrix. The content of silver flakes was 75wt%, and the content of nanoparticles (BN or SiC) in the isotropic conductive adhesives were 0wt%, 0.5wt%, 1.5wt%, 2.5wt%, 3wt%, 5wt% in weight. The conductive adhesives were coated on the PCBs with stencil printing and fifty SR1206 chip components were mounted on a PCB using conductive adhesive. All samples were cured at 150°for 1h. Further research into the reliability of the above isotropic conductive adhesives after temperature & humidity and thermal-cycling was carried out to analyze the effects of BN and SiC nanoparticals on the properties of ICA. The condition of the temperature & humidity test was 85 ° /85%RH, 500h. The thermal-cycling test was -40 °∼125°, 500 cycles and the soaking time and ramping rate were 19min and ±15°/min. Changes to electrical resistance were used to estimate the reliability of the isotropic conductive adhesives in this study. The microstructure of the failure samples was observed using a Scanning Electron Microscope (SEM). The water absorption of all ICAs is the same after 94h temperature and humidity aging and the rate of water absorption is also the same during the aging. The ICA with 3% boron nitride nanoparticles and 75% micron silver flakes shows the best temperature and humidity reliability, with the fewest cracks on the interface between ICA and component. After 500h thermal cycling aging, the resistance reduces in the first 100h and maintains in a certain value after 332h cycled thermal. The samples have no wide cracks but a few small ones on the interface. © 2010 IEEE.
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| 3. |
- Liu, Yangming, et al.
(författare)
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Numerical investigation on the thermal properties of the micro-cooler
- 2010
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Ingår i: Proceedings - 2010 11th International Conference on Electronic Packaging Technology and High Density Packaging, ICEPT-HDP 2010; Xi'an; 16 August 2010 through 19 August 2010. - 9781424481422 ; :Article number 5583917, s. 634-638
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Konferensbidrag (refereegranskat)abstract
- The micro-pin-fins prepared on the back side of the power chip enable heat removal on the level of modern microsystem demands. Carbon nanotube (CNT) has been proven to be a potential material for micro-cooler because of its superior advantages including high thermal conductivity, good mechanical property and so forth. And there emerges various applications of CNT in the micro-cooler system. In the present paper, micro-pin-fin heat sink with gas impinging jet as the cooling medium is analyzed. The heat dissipation of forced air convection cooling with micro-pin-fin structures made of aligned carbon nanotube arrays has been taken into consideration. The three-dimensional computational fluid dynamics (CFD) simulation was carried out. The temperature distribution and the pressure drop are studied in the cases of various geometrical parameters of the micro-pin-fin heat sinks at the same heating power prescribed. The fluid flow and the heat transfer phenomena in the micro-pin-fins heat sinks are investigated. The heat removal efficiency of the air microcooler is evaluated. An array of 8×8 fins with the optimized fin-to-base length ratio achieves the best cooling effect © 2010 IEEE.
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| 4. |
- Tao, W., et al.
(författare)
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Reliability characterisation of bi-modal high temperature stable Isotropic Conductive Adhesives
- 2010
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Ingår i: Proceedings - 2010 11th International Conference on Electronic Packaging Technology and High Density Packaging, ICEPT-HDP 2010, Xian, 16-19 August 2010. - 9781424481422 ; :Article number 5582437, s. 225-228
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Konferensbidrag (refereegranskat)abstract
- Conductive adhesives are generally considered to be one of the strongest candidates for replacement of solder in electronics industry. However, some problems related to the performance have so far limited wider applications of conductive adhesives. One of the major problems is tendency to degrade during temperature and humidity aging. In this paper, two kinds of Isotropic Conductive Adhesives (ICA) with high temperature stable matrix and different fillers were fabricated. The first one was fabricated by simply adding silver flakes into matrix as filler using this high temperature stable matrix based on highly cross-linked aromatic functional groups. For the second one, in addition to silver flakes, nanosilver particles with different weight percentages were also added as filler into matrix to form a bi-modal ICA. The weight percentages of nano-silver particles in filler are 1wt%, 2wt% and 3wt% respectively. The filler content of these two ICAs are both 75wt% in total. All test samples were cured at 150°for 1 hour. The random distribution of the silver flakes in the adhesive was observed by SEM. The bulk resistivity of the ICAs with different fillers was investigated to characterize the electrical conductivity of the ICA. The results show that addition of small amount of nano-silver particles improve the electric conductivity of the ICA but the excessive amount of nano-silver particles led to the increase of the ICA's bulk resistivity. The humidity (85°/85RH) test was carried out and the resistances of the samples were measured. It was shown that some electrical resistance increase was observed during the humidity testing with time. The addition of the nano-particles has also some negative effect of the electrical resistance change. But the effect is limited in a few percentage range of the nano-particle addition.
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| 5. |
- Zhang, X., et al.
(författare)
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Printed monopole antenna with extremely wide bandwidth on liquid crystal polymer substrates
- 2011
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Ingår i: Proceedings - 12th International Conference on Electronic Packaging Technology and High Density Packaging, ICEPT-HDP 2011, Shanghai, 8-11 August 2011. - 9781457717680 ; , s. 1157-1159
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Konferensbidrag (refereegranskat)abstract
- This letter presents a printed monopole antenna with extremely wide bandwidth on a liquid crystal polymer (LCP) substrate. It consists of a hollowed elliptical monopole, two trapeziform ground planes and a tapered co-planar waveguide (CPW) feeder. By using standard processing technology, this monopole antenna is fabricated on the direct metalized LCP film substrate. The fabricated antenna can achieve an extremely wide impedance bandwidth, a nearly omnidirectional radiation pattern and a compact size, which verifies that LCP materials are very suitable as substrates for commercial wireless applications.
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| 6. |
- Zhang, Zhfei, et al.
(författare)
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Characterization of CNT Enhanced Conductive Adhesives in Terms of Thermal Conductivity
- 2012
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Ingår i: ECS Transactions. - : The Electrochemical Society. - 1938-5862 .- 1938-6737. - 9781607683186 ; 44:1, s. 1011-1017
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Konferensbidrag (refereegranskat)abstract
- CNTs have excellent thermal, electrical and mechanical properties. They can be used in various ways. One researched field of application is CNT-polymer composites which combine common technologies with advanced materials. This paper will focus on the thermal property of CNT-Ag-filled adhesives and compares the new materials with conventional, electrical Ag-filled conductive adhesives. Several analytical methods, FTIR, Raman analysis, SEM and TEM have been carried out to examine the different surface conditions after physicval and chemical modification of CNTs. The thermal conductivities of composites containing different types of CNTs were investigated. The incorporation of CNTs into polymers resulted in enhancement of the thermal conductivity compared to Ag-filler. The increase of thermal conductivity with addition of CNT filler is obvious, especially for the purified CNT. The value of thermal conductivity is about two times higher than the Ag-filled conductive adhesive. However, improvement on thermal conductivity of the surface modified CNT-filled conductive adhesives is not so obvious. Since the thermal conduction in CNT is by phonon transfer, the nanometric size and the huge interface lead to strong phonon-scattering at the interface. Thus, a relatively low interfacial area, weak interfacial adhesion promotes the conduction of phonons and minimizes coupling losses. According to this, the non-treated MWCNTs seem to have the highest potential to improve the thermal conductivity of epoxies.
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| 7. |
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| 8. |
- Carlberg, Björn, 1983, et al.
(författare)
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Polymer nanofiber based continuous metal phase composite for thermal management applications
- 2010
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Ingår i: 3rd Electronics System Integration Technology Conference, ESTC 2010; Berlin; Germany; 13 September 2010 through 16 September 2010. - 9781424485536 ; , s. Art. no. 5642950-
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Konferensbidrag (refereegranskat)abstract
- A new composite design approach for thermal interface materials is presented. A porous electro spun nanofiber network composed of temperature stable poly imide was infiltrated with liquid phase indium at a pressure of 30 MPa. The polymer phase defmes composition and geometry, while the continuous metal phase gives binding to surfaces and high thermal conductivity. The composite was characterized by assembly of tri-layer copper/TIM/copper sandwich structures and subsequent xenon flash measurements extracting the thermal properties of the intermediate TIM layer. The interfacial contact resistance was found to be 8 Kmm2/W and the thermal conductivity was 28 W/mK, indicating the potential for use in thermal management applications.
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| 9. |
- Casa, Marcello, et al.
(författare)
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Development and characterization of graphene-enhanced thermal conductive adhesives
- 2014
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Ingår i: 15th International Conference on Electronic Packaging Technology, ICEPT 2014; Wangjiang HotelChengdu; China; 12 August 2014 through 15 August 2014. - 9781479947072 ; :Art. no. 6922700, s. 480-483
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Konferensbidrag (refereegranskat)abstract
- According to Moore's Laws, complexity and power densities of electronic devices are increased during the last decades, moreover their dimensions are shrinking to nanometers causing hot-spot temperature escalation. Thermal management, therefore, becomes a critical issue for next generation of electronics. This scenario motivates development of novel thermal conductive adhesive (TCA) with enhanced thermal conductivity. Conventional TCAs use polymers as the matrix (base material) and utilize large loading weight fraction of the filler, usually silver particles, to achieve the thermal conductivity of 1-4 W/ m K at room temperature [1]. Lately it was discovered that graphene exhibit superior thermal conductivity [2] even when they are incorporated with matrix materials [3], which offers a potential to develop high thermal conductive graphene-filled compound. In this paper, a new functionalized graphene and its filled TCA have been developed and characterized. Starting from pristine graphite flakes, graphene was prepared through chemical exfoliation and functionalized with a nano silver layer to form a special metal/graphene hybrid material. Moreover, an efficient method to uniformly disperse the nano-scaled graphene hybrid material in silver-epoxy matrix was developed. Cross-section view of SEM has shown a homogeneous component structure, and TGA analysis of hybrid material is given. The developed compound is based on a commercial TCA which is composed with epoxy matrix and micro-sized Ag flakes. Thermal characterization through Laser-flash equipment has indicated that a significant thermal conductivity improvement was achieved through adding functionalized graphene into the material. Different TCA samples with different weight percentages of functionalized graphene ranging from 0 % (reference) to 11.5 % were prepared and tested to study thermal conductivity change. Data show that a thermal conductivity value of 7.6 W/ m K is reached when the graphene/silver percentage is 11.5 % that is almost 4 times higher than our reference.
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| 10. |
- Chen, S., et al.
(författare)
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A solder joint structure with vertically aligned carbon nanofibres as reinforcements
- 2014
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Ingår i: Proceedings of the 5th Electronics System-Integration Technology Conference, ESTC 2014. - 9781479940264 ; , s. Art. no. 6962851-
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Konferensbidrag (refereegranskat)abstract
- In this paper, a solder joint structure was developed for the electronic packaging industry. Vertically aligned carbon nanofibres (VACNFs) were grown, transferred and used at the interface between Si/Au pads and Sn-3.0Ag-0.5Cu (SAC305) alloy as reinforcements in order to increase the solder joint thermal fatigue resistance. The transfer and assembly processes related to VACNFs were optimised and developed. The thermal cycling test results show that the thermal fatigue life of VACNF/SAC305 solder joints is 40% longer than that of pure SAC305. The dye and pry analysis and scanning electron microscopy observation prove that the VACNFs can effectively delay the crack propagation near the interface and consequently prolong the solder joint thermal fatigue life.
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