糊状钎剂浓度对其黏附行为的影响

针对糊状钎剂在钎料表面难以均匀润湿铺展的问题,采用金相显微镜、润湿角测定仪、表面张力仪等分析设备,对不同浓度糊状钎剂在钎料表面的黏附行为进行研究。结果表明:糊状钎剂的黏附层随浓度的增大而逐渐增厚,薄黏附层发生少量收缩现象,厚黏附层发生大量下滑脱落及收缩现象。对于理想表面,不同浓度糊状钎剂的黏附张力相同。对于实际表面,表面条纹槽对糊状钎剂具有附加压力作用,附加压力是黏附层收缩发生滞后现象的主要原因。随着糊状钎剂浓度的增大,附加压力和滞后阻力减小,收缩加剧。薄黏附层收缩需满足:ΔWC≥A+ΔP,即收缩现象发生与否主要取决于黏附张力和附加压力。

Effect of Paste Flux Concentration on Adhesion Behavior

In view of the problem that paste flux is difficult to spread uniformly on the surface of filler metal,the adhesion behavior of the different concentrations of paste flux on the surface of filler metal was studied by the equipment of OM,wetting angle tester and surface tensiometer.The results show that adhesive layer is gradually thickened with the increase of the concentration of paste flux.A small amount of shrinkage appears in the thin adhesive layer,however,mass paste flux slides off filler metal when adhesive layer is thicker,accompanying by severe aggregation and shrinkage.For the ideal surface,the adhesive tension of paste flux with different concentrations of paste flux is the same.For the actual surface,the stripe groove additional pressure is formed when paste flux wets stripe groove,and the additional pressure is the main reason for the lagging phenomenon of the shrinkage of the adhesive layer.With the increase of paste flux concentration,the additional pressure decreases,the hysteresis resistance decreases,and the shrinkage increases.A relationship is satisfied when the shrinkage takes place in thin adhesive layer,this is △Wc ≥ A + △p.Whether the shrinkage occurs mainly depends on the adhesion tension and the additional pressure.