Optimization of solder paste quantity considering the properties of solder joints

Abstract

Purpose The purpose of this paper is to find an optimum between the quantity of solder paste and the desired properties of the soldered joint. A reduction of solder paste quantity is recognized as an opportunity to save money. On the other hand, the quantity of solder paste significantly influences the final properties of the soldered joint. The purpose is also to design recommendations for manufacturers of electronic assemblies. Design/methodology/approach The processing of the paper was initiated by a literature review. The expert analysis was the next step. The result of analysis was a fishbone diagram. Subsequently, the experiment was designed. Seven types and three volume of solder pastes and two aperture shapes of the stencil were used. The measured parameters were mechanical strength, electrical resistance, voids area and intermetallic compound (IMC) thicknesses. The results of the experiment were evaluated and recommendations for practice were defined. Findings The carried out research has confirmed the influence of solder paste quantity on the shear strength, electrical resistance, voids area and IMC thickness of solder joint. The article presents the results achieved for solders Sn42Bi58, Sn42Bi57.6Ag0.4, SnAg3.0Cu0.5, SnCu0.7Ag1.0NiGe, SnAg3.5Bi0.5In8.0 and Sn62.5Pb36.5Ag1.0. Reduction of solder paste quantity down to 74 per cent (i.e. one quarter of quantity) decreases mechanical shear strength less than 10 per cent. Recommendations relating to the optimal reduction of solder paste quantity have been designed for each solder paste. Originality/value Contribution of the paper is impact assessment of solder paste quantity on the properties of the soldered joint. It was carried out a large number of experiments and measurements which verify this effect. Such a comprehensive overview of the results is not yet available in the literature. Recommendations for manufacturers of electronic assemblies are also the benefit of article.

Overview of Selected Issues Related to Soldering

“…), components (geometry, shape, terminal oxidation, etc.) and the process (thickness, the shape and the parameters of the solder paste's printed layer, temperature profile) [22][23][24][25][26]. An example of macrovoids in the solder joints of a soldered BGA package on the PCB is given in Figure 18.…”

Transient Numerical Modelling of the Pin-in-Paste Technology

“…The rheological properties of the solder paste were described by the Al-Ma'aiteh model (3) [19], with parameters valid for a Type-4 solder paste (particle size range is 20-38 µm).…”

“…(2) placing the electronic components (also the TH components in this case) into the deposited solder paste; (3) soldering the components by transporting the printed circuit assembly through a reflow oven, in which the thermal profile is carefully adjusted by setting the proper temperature of individual heating zones (Figure 1). The rapid spread of pin-in-paste technology requires exhaustive analyses of the holefilling by solder paste and optimization of the stencil printing process.…”

“…Optimizing the stencil printing process can improve both the quality and the reliability of solder joints [3]. During the optimization, parameters affecting the process shall be considered, such as the rheological properties of solder paste, the printing speed, and the geometry/orientation of apertures and plated holes for SM and TH components, respectively [4,5].…”

Investigation of the Mechanical Properties of Mn-Alloyed Tin-Silver-Copper Solder Solidified with Different Cooling Rates

“…The reliability problems are caused by the relatively high silver content, which is regularly hyper-eutectic (>1.35 wt.%) in these alloys [ 6 ]. Even if the reflow profile is precisely monitored [ 7 , 8 ] during the soldering process, and the volume of the solder paste is thoroughly adjusted [ 9 ], electronic assemblies and devices can exist in which reliability criteria cannot be met. For instance, in a harsh operating environment, such as overpressure [ 10 , 11 ], the joints prepared from SAC305 alloy can underperform.…”