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Literature Review 2.1 Electrically Conductive Adhesives 2.1.2 Conduction Mechanisms in Isotropic Conductive Adhesives 2.1.4 Review of Reliability Studies on Isotropic Conductive Adhesive (ica) Joints 2.2 Theories of Adhesion 2.2.1 Adsorption 2.2.2 Chemical Bonding 2.3 Water Adsorption and Diffusion
| Content Provider | Semantic Scholar |
|---|---|
| Abstract | Electrically conductive adhesives (ECAs) are gaining great interest as potential solder replacements in microelectronics assemblies. Basically, there are two types of ECAs, isotropic conductive adhesive (ICA) and anisotropic conductive adhesive (ACA) [1]. Although the concepts of these materials are different, both materials are composite materials consisting of a polymer matrix containing conductive fillers. Typically, ICAs contain conductive filler concentrations between 20 and 35 vol.%, and the adhesives are conductive in all directions. ICAs are primarily utilized in hybrid applications and surface mount technology [2]. In ACAs, the volume fractions of conductive fillers are normally between 5 and 10 vol.% and the electrical conduction is generally built only in the pressurization direction during curing. ACA technology is very suitable for fine pitch technology [2] and is principally used for flat panel display applications, flip chips and fine pitch surface mount devices [3]. Compared to conventional solder interconnection technology, conductive adhesives are believed to have the following advantages [4,5]: 1). More environmental friendly than lead-based solder; 2). Lower processing temperature requirements; 3). Finer pitch capability (ACAs); 4). Higher flexibility and greater fatigue resistance than solder; 5). Simpler processing (no need to get rid of flux); 6). Non-solderable (inexpensive) substrates can be used (e.g., glass). Despite the advantages of ECA technology, the replacement of solder by this technology has not been widely adopted by the electronics industry. Lower electrical conductivity than solder [6-7], poor impact resistance [3] and long-term electrical and mechanical stability [4,8-11] are several critical concerns that have limited wider applications 9 of electrically conductive adhesive technology. Numerous studies are being conducted to develop a better understanding of the mechanisms underlying these problems and to improve the performance of conductive adhesives for electronic applications. Electrically conductive adhesives consist of a polymer binder that provides mechanical strength and conductive fillers, which offer electrical conduction. Polymers are commonly classified as either thermosets (such as epoxies, polyimides, silicones and acrylic adhesives) or thermoplastics. With different applications of ECAs, polymer binders can be of either type. For conductive fillers, metallic materials such as gold, silver, copper, and nickel or nonmetallic materials such as carbon have found application in ECA technology. Thermoplastics are also referred to as remeltables and hot melts. This class of polymers typically has a long linear molecular structure, which allows these materials to melt and flow when heated to a specific melting point without significantly altering their intrinsic properties. Generally, thermoplastic adhesives … |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://scholar.lib.vt.edu/theses/available/etd-04222002-174259/unrestricted/Chapter2.PDF |
| Alternate Webpage(s) | https://theses.lib.vt.edu/theses/available/etd-04222002-174259/unrestricted/Chapter2.PDF |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
