纳米银焊膏的烧结性能及其用于铜连接的研究

Study on the Sintering Characteristics and Application in Cu Bulk Bonding of Ag-nanoparticle Paste

采用化学还原法制备出粒径分布在20-80nm的纳米银焊膏,每个纳米银颗粒上包裹的有机壳防止纳米颗粒的聚合。通过扫描电镜（SEM）对不同温度下银烧结层的微观组织变化进行观察,在200℃条件下烧结30min后,银烧结层连接为联通多孔结构;高于250℃时银颗粒出现明显的长大现象。在250℃温度下,外加10MPa压力采用纳米银焊膏对镀银纯铜材料进行烧结连接,得到接头剪切强度达到39MPa。对接头断口的显微组织分析表明,纳米银颗粒形成致密的烧结结构,断口组织在低倍SEM下未观察到明显塑性变形痕迹,但在高倍SEM下断口处的微观组织呈现了韧窝状组织,具有韧性材料断口材料的微观特征。

Ag nanoparticle paste with size distribution of 20-80nm was prepared by chemical reduction reaction.Each nanoparticle was covered with a thin organic shell which can prevent its aggregation.Micro-structural evolution was observed using scanning electron microscope（SEM）.The results suggested that the sintered Ag layer was a connected porous-structure after sintered for 30min at 200℃.At sintering temperature above 250℃,some Ag grains grew up obviously.The sintering-bonding with Ag nanoparticle paste of silver plated pure coppers was performed at 250℃ under 10MPa.The joint had a shear strength of 39MPa.The microscopic analysis of sintered Ag layers from the sheared fracture appearance of joints showed that sintered Ag layer had a dense structure.There was no obvious trace of plastic distortion at the low magnification SEM images of fracture-appearance of joints.However,at high magnification SEM images displayed the dimple structure feature which is typical microstructure at fracture surface of ductile material.