摘要:
分别以松香、氢化松香、歧化松香和聚合松香为主要活性成分配制不同的液体助焊剂,采用扩展率试验法研究各助焊剂对Sn0.7Cu无铅钎料在铜基板上润湿性能的影响,测试了助焊剂的物理性能,分析了扩展率≥75%时的焊点形貌,并与市售无铅焊接用非松香基助焊剂进行对比. 结果表明:松香及改性松香含量的增加能提高助焊剂对Sn0.7Cu钎料在铜基板上的扩展率,而酸值对于松香及改性松香的助焊性能影响很大,酸值较高的松香产品具有较好的助焊性能. 在相同含量时松香对Sn0.7Cu钎料的助焊效果最好,其后依次为氢化松香、歧化松香和聚合松香;随着质量分数的提高,松香和改性松香扩展率均可提高至70%以上,达到SJ/T 11389—2009中L级无卤素松香基助焊剂要求. 除聚合松香外,其余的扩展率可高于75%,达到SJ/T 11389—2009中M级无卤素松香基助焊剂要求,并且各质量分数条件下助焊剂物理稳定性及干燥度均合格,铜板腐蚀性较低,焊后表面绝缘电阻均≥1. 0 × 108Ω;市售810A型无铅非松香基助焊剂的扩展率与松香质量分数40%时的助焊剂具有相似的扩展率,但松香助焊剂所形成的焊点饱满,表面光亮,且成形性更优.%A series of liquid soldering fluxes were prepared with rosin,hydrogenated rosin,disproportionated rosin and polymerized rosin as active ingredient,respectively. The effects of these soldering fluxes on the wettabilities of Sn0.7Cu lead-free solder to the copper plate were investigated by using spreading ratio method. The comparative experiment of 810A type commercially available flux was tested as well. The physical performances of these soldering fluxes were tested and the appearance of soldered joints at the spreading ratio above 75% was analyzed. The results showed the spreading ratios increased gradually with the increase of the content of active ingredient. The acid value influenced the help welding ability of rosin markedly,and the sample with higher acid value showed better spreading ratio. When the contents of active ingredients were the same,the soldering flux obtained from rosin showed the best solder ability,then the hydrogenated rosin,disproportionated rosin and polymerized rosin in sequence. With the increasing of contents, the spreading ratios of rosin and modified rosin were higher than 70%. This matched with the request of L level halogen-free rosin based flux of SJ/T 11389—2009. Except for polymerized rosin, the spreading ratios of rosin and modified rosin could get to 75% above in some contents. This matched with the request of M level flux of SJ/T 11389—2009. The physical stability,dryness and corrosivity to copper plate of these fluxes all met the standard, and the surface resistance ( SIR ) after welding concerned with the soldering flux was over 1. 0 × 108Ω. Rosin showed better appearance of welding spot than the 810A flux.