Aluminium and aluminium alloy hard soldering technology

Aluminium joints find wide application in the welded structures of air conditioning systems, aeronautics, electrical engineering, radio engineering, and many other areas of industry. In spite of their unquestionable qualities, aluminium and aluminium alloy soldering brings about considerable setbacks, especially in the case of highly alloyed aluminium compounds. The problems result from the physical and chemical properties of such materials. For instance, highly alloyed aluminium requires specific solders of sufficiently low melting point, as well as special sources of heat in order to ensure even soldering. An additional problem results from the considerable aluminium-to-oxygen chemical affinity that produces the resultant Al₂O₃ layer on the surface as an integral and barely fusible coat. This article presents the problems related to aluminium and aluminium alloy joining as well as basic methods of aluminium soldering.     

Selection of soldering temperature for ultrasonic-assisted soldering of 5056 aluminum alloy using Zn-Al system solders

The conditions for sound butt-joints of 5056 aluminum alloy containing 4.6 mass% Mg using Zn-xAl (x = 5, 13, and 38 mass%) solder at the relevant temperatures were investigated. Each solder foil was inserted between faying surfaces of 5056 aluminum rods. Ultrasonic vibration at a frequency of 19 kHz was applied to the faying surfaces through an aluminum substrate at soldering temperatures for 4 s in air. The strength of obtained solder joints was measured by tensile tests. The microstructure in the solder layer after the soldering process was evaluated with an SEM-EDX. The results of tensile tests revealed that joints soldered under the liquidus temperature of Zn-Al solders showed higher strength than joints soldered over the liquidus temperature. In the joints soldered over the solder liquidus temperature, the joint strength decreased with an increase in soldering temperature. It was caused by the formation of MgZn₂ in the solder layer due to dissolution of 5056-Al into the solder liquid during the soldering process. On the other hand, ultrasonic-assisted soldering under the solder liquidus temperature suppressed dissolution of 5056-Al and improved the joint strength by reducing the formation of MgZn₂.     

Electroplating onto aluminium and its alloys

ABSTRACT

This paper will look at surface treatment of aluminium and its alloys and explore what steps are required in order to successfully electroplate onto it to achieve a sound adherent finish.     

Dissolution of Cu into Sn-based solders during reflow soldering

Cu contents in pure Sn and Sn-37Pb solders were measured as a function of reflowing time. The results indicated that the contents are significantly higher than that of the Cu solubility limit in each solder. Several plausible causes for the excess dissolution of Cu into the solders were explored with experimental observations.     

Ag元素含量对Sn-Ag-Cu钎料焊接性的影响

以Sn-xAg-0.5Cu为基体制备了低银无铅钎料,其中Ag元素的质量分数分别为0.3%,0.5%,0.7%,0.9%.借助钎料合金的DSC熔化曲线,分析了Ag元素含量对合金熔点的影响规律.通过比较各组钎料合金在Cu基板上的铺展面积和铺展率,分析了Ag元素含量的变化对各组钎料润湿性的影响规律.结果表明,随着Ag元素含量...     

Corrosion inhibitors for aluminium and its alloys in neutral media

On the basis of results so far available on inhibitors for water, sodium chloride and other salt solutions new results are reported which were obtained with respect to the inhibition in sodium persulfate solutions. The inhibitors studied in this context show increasing efficiency in the order nicotinic acid - quinonline - pyridine - alpha-picoline - 2,4-lutidine. The efficiency is primarily due to the nitrogen atom facilitating chemisorption of the particular compound to the metal surface. The efficiency may be interpreted in terms of the increased electron density of the heterocyclic system at the nitrogen atom.     

Sn-3.0Ag-0.5Cu-xNi无铅焊料及焊点的性能

研究了Ni元素对Sn-3.0Ag.0.5Cu无铅钎料熔点、润湿性、拉伸性能及焊点性能的影响.结果表明,镍的添加对Sn-3.OAg-0.5Cu钎料的润湿性有所改善,添加量为0.03%～0.1%时,随着镍含量的增加,润湿时间逐渐递减,润湿力逐渐增大,镍含量在0.05%时润湿时间最短,镍含量在O.1%时润湿力最大.但当镍含量到0.15%时,润湿时间反而增长,润湿力下降;镍提高了合金的抗拉强度、断后伸长率及焊点的抗剪强度.当镍含量为0.05%时,抗拉强度最高,当镍含量为0.1%时,断后伸长率和抗剪强度最高,扫描断口表现为明显的韧性断裂特征;镍的添加量为0.05%~0.1%效果较好.     

Resistance welding of aluminium and aluminium alloys

Special features of the process of resistance welding of aluminium and its alloys and also equipment manufactured by the CEA and supplied by Weber Comechanics are described.     

亚共晶Sn-Zn系合金无铅焊料的性能

通过差热分析(DTA),研究Sn-xZn合金(x=2.5~9)的非平衡熔化性能,发现在加热速度为5℃/min时,Sn-6.5Zn与Sn-9Zn的熔化特性相同;通过浸润法和铺展法表征Sn-xZn合金在Cu基材表面上的润湿性。结果表明:Sn-6.5Zn在Cu基材表面上的润湿性优于Sn-9Zn。研究速率为10-3s-1和10-1s-1时Sn-xZn的拉伸性能,结果发现:Sn-6.5Zn的抗拉强度与Sn-9Zn的相当,而延伸率高于Sn-9Zn。以搭接焊及界面剪切实验研究Sn-xZn/Cu焊点界面强度,发现焊点界面剪切强度随x的增加而提高,在x≥6.5时趋于稳定;x=6.5时剪切力最大,表明Sn-6.5Zn在Sn-Zn系中具有最好的钎焊工艺性能。     

High temperature soldering of SiC particulate aluminium matrix composites (series 2000) using Zn–Al filler alloys

Abstract

The present paper evaluates the solderability of three discontinuously reinforced aluminium matrix composites. The tested composites were an aluminium alloy of the 2000 series (AA2014) reinforced with different percentages of silicon carbide particles (6, 13, and 20 vol.-% respectively). A similar study was carried out on the unreinforced aluminium alloy for comparative purposes. Three low temperature filler alloys of the Zn–Al system were used for soldering. Drop formation tests were performed to evaluate the wettability of the molten filler alloys and sample joints (single overlap specimens) were produced to determine solder penetration in the joint clearance. Microstructural studies of the joints were carried out to determine the effects of the solid reinforcement particles on molten pool behaviour and solidification mechanisms.     

Relative porosity in aluminium and in aluminium alloys

Abstract

Pores are readily formed in aluminium alloy castings. Density and porosity area fraction are often used quantitatively to evaluate the quality of aluminium alloy castings. This study used the relative porosity, the ratio (d _c ? d _r)/d _c, where d _c is the density of the chilled sample and d _r is the density of the reduced-pressure test sample, to evaluate the quality of aluminium and Al–6Si and Al–13Si alloys. The bursting of degassing bubbles on the free surface of the melt brought debris of oxide particles into the melt, which were eventually trapped in the castings after pouring. These particles were accompanied with air pockets and/or engulfed by bubbles, resulting in pores shown on the sections of poured castings.     

不同钎料对激光钎焊焊点力学性能的影响

采用半导体激光再流焊系统研究SnAgCu／SnAgCuCe在铜基板的润湿性以及焊点的力学性能,同时对比红外再流焊,研究两种焊点在热循环过程中的可靠性．结果表明,随着激光输出功率的增加,无铅钎料的铺展面积逐渐增加;当激光输出功率增加到某一特定范围时,无铅钎料的润湿铺展性能达到最佳．同时,随着激光加热时间的增加,无铅钎料的...     

Mechanical properties of QFP micro-joints soldered with lead-free solders using diode laser soldering technology

Soldering experiments of quad flat package(QFP) devices were carried out by means of diode laser soldering system with Sn-Ag-Cu and Sn-Cu-Ni lead-free solders, and competitive experiments were also carried out not only with Sn-Pb eutectic solders but also with infrared reflow soldering method. The results indicate that under the conditions of laser continuous scanning mode as well as the fixed laser soldering time, an optimal power exists, while the optimal mechanical properties of QFP micro-joints are gained. Mechanical properties of QFP micro-joints soldered with laser soldering system are better than those of QFP micro-joints soldered with IR reflow soldering method. Fracture morphologies of QFP micro-joints soldered with laser soldering system exhibit the characteristic of tough fracture, and homogeneous and fine dimples appear under the optimal laser output power.