Electrical characterization of individual metal‐coated polymer spheres used in isotropic conductive adhesives

Isotropic conductive adhesives (ICAs) filled with metal‐coated polymer spheres (MPS) have been proposed to improve the mechanical reliability compared to conventional ICAs filled with silver flakes. The electrical properties of MPS play an important role in the electrical performance of macroscopic MPS‐based ICAs. This article deals with the electrical characterization of individual MPS using a nanoindentation‐based flat punch method, in which the resistance and the deformation of single MPS were monitored simultaneously. Four groups of silver‐coated polymer spheres (AgPS) with identical polymer cores but different silver coating thicknesses were tested. The resistance of AgPS decreases gradually with increasing deformation degree of particles, and increases when the deformation of particles is reduced. In addition, the resistance of individual AgPS is dependent on the physical properties of the silver coating, such as thickness, uniformity, and porosity. The thicker the silver coating is, the lower and more stable the resistance of AgPS is. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43764.     

Effect of Curing Procedures on the Electrical Properties of Epoxy-Based Isotropic Conductive Adhesives

The effects of different curing and post-heating treatment procedures on the electrical properties of isotropic conductive adhesives (ICAs) were investigated in this work. The results showed that the bulk resistivity of ICAs cured by multi-step method was lower than that cured by the one-step method, even though they were cured for the same periods. It was also found that the electrical resistance of ICAs continued to decrease during the subsequent post-heating treatment processes. The in situ monitoring the variations in electrical resistance was studied during the curing and post-heating treatment process, and it was found that the cooling process continued to decrease the electrical resistivity of ICAs. The trend of the evidence has been consistent and indicated that the internal stress of ICAs, which depended on the curing and post-heating treatment temperatures, had a significant effect on the electrical resistivity of ICAs. Meanwhile, it was proved that the bulk resistivity of ICAs increased as the internal stress of ICAs weakened by the addition of PEG.     

Nanocomposites of Polyaniline as Conductive Adhesives

Electrically conductive adhesives are emerging as the best possible alternative to traditional tin/lead soldering. In this work polyaniline (PANI) as powder and as nano-fibres was introduced as filler into epoxy/anhydride matrix to produce isotropic conductive adhesives (ICAs). PANI nano-fibres show uniform dispersion and thus percolation threshold is low. Uniformity and smaller size of nano-fibres help in formation of a strong epoxy network with least hindrance from filler phase. This results in better impact performance of these ICAs. SEM observations show an improved diffusion of nano-PANI into the epoxy matrix. Overall, the properties obtained with PANI nano-filler show a significant improvement when compared to PANI powder of macroscopic dimensions.     

Aging effects on the electrical properties of silver-filled epoxy adhesives

Electrically conductive adhesives, such as silver-filled epoxies, are used in many applications where standard soldering or direct metal-to-metal connections are not feasible. Anomalous behavior at these connections has been observed as the development of increasing resistance over time in the absence of mechanical failure between the adhesive and substrate. The results of aging of electrically conductive adhesive joints to aluminum- and gold-metallized substrates show that little change occurs at low humidity under an ambient flow of nitrogen. With increasing humidity and temperature, there is a measurable increase in resistance over time, particularly in the case of aluminum-metallized substrates. Secondary ion mass spectrometry (SIMS) was used to investigate interfacial phenomena that may be responsible for increasing resistance observed in the aluminum-metallized samples exposed to accelerated aging. Preliminary results from this technique indicate the presence of an oxide layer between the adhesive and the metallization layer that is consistent with increasing resistance measured for samples exposed to accelerated aging. The results also support the conclusion that deterioration at the adhesive-aluminum interface, and not degradation in the bulk adhesive, is the primary cause of increasing resistance.     

Development of Polypyrrole/Epoxy Composites as Isotropically Conductive Adhesives

As a possible replacement for lead bearing solders, metal filled isotropically conductive adhesives (ICAs) have shown a lot of potential recently. But still they have to come a long way and overcome their limitations like low impact strength and moisture instability. The current paper attempts to address the limitations of these ICAs by using intrinsically conducting polymer as a filler in place of metals. Conducting polymer (CP) polypyrrole (PPy) was incorporated as a filler in an epoxy/anhydride (EP) system and its application as an isotropic conductive adhesive was studied. PPy was synthesized by chemical polymerization using dodecyl-benzene sulphonic acid (DBSA) as dopant. The composites with varying PPy concentrations were studied for curing behavior and thermal degradation properties using DSC and TGA, respectively. The composites show good impact properties and conductivity at very low filler concentrations. SEM observations established that PPy particles were dispersed in the epoxy matrix uniformly. The overall characteristics of these conductive adhesives establish that they can be used as conductive adhesives in the electronics industry.     

Epoxy‐based adhesives filled with flakes ag‐coated copper as conductive fillers

The flake core–shell Cu‐Ag powders are prepared and characterized. Isotropic conductive adhesives (ICAs) filled with flake silver‐coated copper was prepared by using epoxide resin as matrix and tetraethylenepentamine as curing agent. The flake silver‐coated copper was characterized by scanning electron microscopy, X‐ray diffraction, energy dispersive X‐ray spectroscopy, and TG‐DTA. The results show Ag content in the surface of coated copper is up to 96.32%. Oxidation resistance of flake Cu‐Ag powders with high surface Ag content is improved greatly investigated by TG‐DTA. And bulk resistivity and shear strength of ICAs are measured. It was found that the percolation threshold of ICAs filled with flake Cu‐Ag powders is as low as 40 wt%. The ICAs have good overall performances. And the main influence factor on electric resistivity was analyzed. POLYM. COMPOS., 38:846–851, 2017. © 2015 Society of Plastics Engineers     

Increase in flame retardance of glass‐epoxy laminates without halogen or phosphorous compounds by simultaneous use of incombustible‐gas generator and charring promoter

Highly flame‐resistant glass‐epoxy laminates without flame‐retarding additives such as halogen and phosphorous compounds have been developed to overcome environmental problems caused by these additives. The laminates consist mainly of a self‐extinguishing epoxy‐resin compound (phenol aralkyl), an incombustible‐gas generator (amino‐triazine‐novolac hardener: ATN hardener), and inorganic materials such as a charring promoter (zinc molybdate on talc: ZMT) and a limited amount of harmless metal hydroxide (aluminum trihydroxide: ATH). They are highly flame‐resistant and have other beneficial characteristics, including soldering‐heat resistance, humidity resistance, electronic properties, and processing advantages. These qualities make them applicable enough to replace the FR‐4 type printed wiring boards (PWBs) that are widely used today. Simultaneously using the ATN hardener and ZMT in the laminates, including the epoxy‐resin compound and ATH, greatly improved their flame retardance. We then reduced the amount of ATH to obtain even better flame retardance in the laminates. This reduction of the ATH, consequently, improved other practical characteristics such as soldering‐heat resistance, humidity resistance, and electronic properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3367–3375, 2006     

Evaluation of poly(1,4-cyclohexylene dimethylene terephthalate) blends for improved processability

Poly(l,4-cyclohexylene dimethylene terephthalate) (PCT) exhibits superior heat deflection temperature when compared to conventional polyesters such as poly(butylene terephthalate) or poly(ethylene terephthalate). It is subject to degradation, however, at the processing temperatures normally employed to extrude or mold this material. Several approaches were taken to broaden the processing window of this material including: blending PCT with other crystalline and amorphous polymers to allow for lower processing temperatures, addition of conventional stabilizers, addition of crosslinking agents to maintain viscosity during processing and the addition of lubricants to improve processing. Key parameters included physical properties, rate of degradation, extruder torque measurements vs. time, and Differential Scanning Calorimetry (DSC) analysis (melting point and glass transition). All systems tested produced significant reduction of the intrinsic viscosity (molecular weight) for PCT during processing. The most successful approach was the blending of various polymers with PCT to lower extruder processing temperatures. Reductions in processing temperature may have resulted from improved heat transfer due to the presence of a lower melting polymer, reduction in melting point of the blend, or changes in the frictional characteristics of the PCT in the extruder. Transesterification may have played a role in compatibilizing some polyester mixtures. As expected, certain polymers had major'effects on the flow behavior of the blend. Tradeoffs were obtained in physical and thermal properties. A combined approach of polymer blending and the use of lubricants, stabilizers or crosslinking agent may hold the most promise for future development work. Thermal resistance under vapor phase soldering conditions was best for LCP/PCT blends and worst for PBT/PCT blends. Additional evaluations of the blend materials will include solvent resistance, processability, thermal resistance, dimensional stability, heat aging resistance, flammability, and specific end use tests.     

装饰胶黏剂现状及发展趋势

简要介绍了装饰胶黏剂的现状及国内外状况,重点介绍了SBS型和氯丁型装饰胶黏剂.对两种胶黏剂的基本组成、特性、分类、性能的提高及发展前景分别进行了阐述,指出SBS装饰胶黏剂对多种材料都具有良好的粘接性能,可与传统的氯丁型胶黏剂相媲美,同时提出了改进SBS装饰胶性能的措施.SBS胶黏剂综合性能优良,不仅是环境友好型胶黏剂,而且是今后装饰胶黏剂的主要发展趋势,用途不断扩大,具有良好的市场前景.     

The properties of soldering mask hardened by means of UV using acrylate and methacrylate oligomers

The properties of soldering masks based on epoxyacrylic, epoxymethacrylic esters, and monomers: 2-ethylhexyl acrylate, triethylene glycol dimethacrylate, and triethylene glycol phthalate dimethacrylate have been described. The thixotropic properties, printability, adhesion to the surface, and resistance to soldering have been determined. © 1995 John Wiley & Sons, Inc.     

耐高温胶黏剂

耐高温胶黏剂的研究开始于20世纪50年代后期,目的是满足航空和电子工业的需要。至今已报道过许多种耐高温胶黏剂,其中一部分已用于工业生产。这类胶黏剂应用广泛,其中有刹车系统的粘接、高速飞机的油箱密封、高速飞机和航天飞机的结构粘接。未来一段时间,市场需求将迅速增加。本文讨论了几类可以用来配制耐高温胶黏剂的聚合物,其中有聚苯并噻唑、聚酰亚胺、聚喹噁啉及聚硅氧烷。     

Survey of polyurethane adhesives

Polyurethane chemistry provides a means to ‘tailor’ adhesives to specific needs. This is being achieved by polyurethane technology at a cost of more sophisticated application/bonding equipment and a need for better control of raw materials and adhesive processing conditions.     

Polyimides in lithography

Polyimides and Polyamide-imides have a high thermal and dimensional stability, good properties, and resistance to attack by solvents. These features, along with their electrical properties, have led to their wide acceptance in the electronics industry. Specifically, Polyimide masks are superior to conventional resists during metal deposition, sputter etching, and chip soldering, for which high-temperature stability is essential. Such a mask is prepared by selectively etching the polyamide-imide with in organic solvent such as ethylenediamine. The reaction of ethylenediamine with polyamide-imides has been applied successfully in metallizing semiconductors by the lift-off method; also, polyamide-imides have been used as a reworkable protective coating for semiconductor modules.     

高邻位腰果酚-苯酚-甲醛树脂的合成及表征

在原苯酚甲醛高邻位树脂体系中引入具有长链烷基的取代酚——腰果酚进行改性,通过IR、DSC、TG等手段对高邻位腰果酚-苯酚-甲醛树脂的结构、固化性能及耐热性进行了分析,结果表明,合成树脂结构中含有腰果酚,且树脂结构属于高邻位结构,该树脂耐热性优于苯酚甲醛高邻位树脂;腰果酚的引入使固化速度和时间稍有减慢,但不影响固化工艺.制备了腰果酚-苯酚-甲醛-丁腈胶黏剂,胶黏剂具有优异的韧性及粘接性能.     

耐高温热固性树脂胶粘剂的研究动态

综述了耐高温热固性树脂胶粘剂的发展过程与研究现状,介绍了近年来国内外几种性能优异的热固性树脂胶粘剂,提高其高温性能的一些主要途径和改性方法,并介绍了新型功能填料在树脂中的应用情况,最后对耐高温热固性树脂胶粘剂的总体发展趋势进行了展望。     

Adhesive bonding of RIM urethane

Two techniques for bonding reaction injection moulded urethane to itself and to other substrates are described. For in-mould bonding, details of substrate preparation, choice of adhesive and processing conditions are given. Where the geometry of the parts is complex, the structural bonding of individually moulded components has to be carried out: the development and properties of a two-part urethane adhesive designed for this purpose are detailed.     

化学镀镍合金及在电子工业中的应用

综述了 化学镀镍磷、镍硼、镍 三元合 金 等镀 层及 其 复合 化学 镀 镍合 金镀 层 的耐 蚀、电阻 、焊 接、电磁及磁 特性,并概 述了化 学镀镍合 金镀层 在电子工 业中应用     

耐高温胶粘剂的研究进展

文章对当前国内外耐高温胶粘剂进行综述。介绍了各类耐高温胶粘剂的物化性能，以及提高耐高温胶粘剂耐高温性能的一些技术途径和改性方法，并对今后耐高温胶粘剂的发展趋势进行展望。     

无氰镀金工艺的研究

由于氰化物镀金含有剧毒的氰化物,为了保护工人的身体健康和减少对环境的污染,研究亚硫酸盐无氰镀金工艺,该工艺可以得到耐蚀性优良、抗变色性能好、导电性好、焊接性好、接触电阻低,且稳定、耐高温、质软、耐磨的镀金层,同时介绍了镀金时应注意的事项和影响因素.     

纸塑复合胶粘剂的研究现状和动向

纸塑复合制品是现代包装行业应用较广泛的一种复合材料,而纸塑复合胶粘剂是纸张和塑料薄膜复合工本文综述了溶剂型和水基型两类纸塑复合胶粘剂的研究现状,并提出今后的研究方向是开发环境友好胶粘剂、高固含量乳液和功能性胶粘剂.