凝胶浇注法制备的纳米铜粉在导电胶中的应用

Application of nano-sized copper powders prepared by gel-casting method in conductive adhesives

以硝酸铜、石墨为原料,采用新颖的凝胶浇注法制备纳米铜粉,并利用硅烷偶联剂KH550对制备的纳米铜粉进行表面抗氧化处理;然后以纳米铜粉为导电填料、以双酚A型环氧树脂(E51)为载体,加入适量的固化剂和稀释剂、除泡剂、促进剂等制备纳米铜粉导电胶。采用X射线衍射(XRD)和透射电镜(TEM)等对制备铜粉的物相、粒度和形貌等进行表征;对预处理前后的纳米铜粉进行热重与差热(TG-DSC)分析;并研究纳米铜粉添加量对所制备导电胶电阻率和连接强度等性能的影响。结果表明:采用凝胶浇注法可制备高纯度、分散性良好、平均粒度约为60 nm的类球形铜粉;经硅烷偶联剂处理后,纳米铜粉的抗氧化性能明显提高;纳米铜粉添加量对所得导电胶的体积电阻率和连接强度有较大影响,纳米铜粉添加量为60%(质量分数)的导电胶的体积电阻率为1.7×10-3Ω·cm,连接强度为11.4 MPa。

Nano-sized copper powders were prepared by gel-casting method using copper nitrate and graphite as the main raw materials. Silane coupling agent KH550 was used in the surface antioxidant treatment of copper powders. Using the as-prepared nano-sized copper powders as conductive fillers and the bisphenol A epoxy resins （E51） as matrix, nano-copper filled conductive adhesives were prepared by adding appropriate amount of curing agent, thinner, defrother, promoter and other additive agents. X-ray diffraction （XRD） and transmission electron microscopy （TEM） were used to characterize the phase composition, particle size and morphology of the copper powders. The copper powders before and after anti-oxidation treatment was conducted by TG？DSC analysis. The influence of the nano-sized copper powder content on the resistivity and bonding strength of the adhesives was investigated. The results show that the copper powders prepared by gel-casting method are of high purity, well dispersibility and a mean particle size of about 60 nm. After being treated by silane coupling agent, the oxidation property of the nano-sized copper powders can be obviously improved. The content of nano-sized copper powders has a great effect on the volume resistivity and bonding strength of the conductive adhesives, the optimum sample with volume resistivity of 1.7×10-3 Ω·cm and bonding strength of 11.4 MPa can be prepared when the filling amount of nano-sized copper powders is 60% （mass fraction）.