Composition Optimization Of Cu-P Based Amorphous Solder And Its Brazing Performance Research

This article describes the performance characteristics of Cu-P base brazing alloy and its application prospect in the related fields,also expounds some problems encountered in brazing process.To reduce cost and improve the brazing performance,composition of solder alloy and brazing technique would be optimized.Five different compositions Cu-P base solders were designed to be made into amorphous ribbon through single roller quenching equipment,and the ribbon would be brazed with unparalleled instead of clearance in vacuum,with effect analysis of alloy elements on amorphous formation ability and brazing properties.Comparative experiment of amorphous ribbon and normal crystalline solder were carried out in order to systematic study the performance of Cu-P base filler metal.Differential scanning calorimetry?DSC?analysis was used to test the two solders' melting characteristics in the heating process.Spreading area of melting solders on pure copper plate was used to test the wettability of filler metal for red copper in vacuum condition.As to the brazed joint of Cu-P base amorphous solder on red copper under vacuum,using X-ray diffraction?XRD?,scanning electron microscopy?SEM?,metallography microscope and nanometer indentation apparatus and other modern testing methods to study the effect of alloy elements and brazing technique on microstructure and mechanical properties of brazed joint.Experimental result shows that: Amorphous forming ability of Cu₇₆P₁₄Ni₈Sn₂,Cu₇₆P₍140Ni₇Sn₃,Cu₇₅P₁₄Ni₈Sn₃,Cu₇₄P₁₄Ni₈Sn₄,and Cu₇₄P₁₄Ni₉Sn₃ is good,with the amorphous ribbon having smooth surface,uniform thickness,and good flexibility which would not fracture being folded in half.And Cu₇₅P₁₄Ni₈Sn₃ keeps the best integrated performance in the five compositions.Compared with normal crystalline solder,similar kind of Cu-P base amorphous solder possesses lower liquidus and narrower melting temperature range.The addition of Ni and Sn is benefit for the narrowing of solder's melting temperature range.Heating temperature and holding time have great influence on wettability of solder,which make the spreading area of Cu-P base amorphous filler metal on pure copper decreases after the first increases as they rising.And the maximum was acquired at 660? with 12 min holding time.Comparatively,the normal crystalline solder leads to different result which the spreading area enlarges all the way with the increase of heating temperature and holding time.The wettability of Cu-P base amorphous solder is better than similar kind of normal crystalline filler metal under same soldering process.The brazed joint of Cu-P base amorphous solder achieves metallurgical combination with red copper substrate,and the whole brazing seam is composed of elements diffusion zone,interfacial region caused by interaction of solder and base metal and the central area consist of solder residue.The diffusion and interfacial region are basically copper base solid solution,while the central area is mainly composed of copper base solid solution and Cu-P,Ni-P fragility phase.The hardness distribution of whole brazing seam area is rising gradually from copper substrate to central area,and the fragility phase in central district owns the highest.With the rising of heating temperature and holding time,brazed joint's shear strength increase at first and decrease subsequently,and the mechanical properties of brazed joint have an obviously promotion brazing with unparalleled clearance.The highest shear strength of brazing joint with Cu-P base amorphous solder is 55 MPa,which is Cu₇₅P₁₄Ni₈Sn₃ get under 670? with 12 min holding time in the experiment.