K. Bukat

Silver nanoparticles effect on the wettability of Sn‐Ag‐Cu solder pastes and solder joints microstructure on copper

Purpose – The purpose of this paper is to investigate the influence of silver nanoparticle additions on the wetting properties of Sn‐Ag‐Cu (SAC) solder paste. In this investigation, the basic solder paste contained 85 wt.% of commercial Sn 96.5 Ag 3 Cu 0.5 powder (with the particle sizes in the range of 20‐38 μm) and 15 wt.% of self‐prepared middle activated rosin flux. To this paste was added 0.5, 1, 2 and 4 wt.% of self‐prepared silver nano‐powders of different grain sizes (from 9 to 138 nm). After the pastes had stabilized, their wetting properties were tested. The main goal of these investigations was to improve the wetting properties of SAC solder paste and to find correlations between the results of the wetting of solder paste with nanoparticles on the copper substrate with the microstructure of the solder joints.Design/methodology/approach – The following methods were applied for the wetting solder paste investigation: spreading on the copper substrate, contact angle measurement on the copper and w...

Evaluation of the influence of Bi and Sb additions to Sn-Ag-Cu and Sn-Zn alloys on their surface tension and wetting properties using analysis of variance -ANOVA

Purpose – The purpose of this paper is a comparable evaluation of the influence of a particular element (Bi and Sb) added to Sn‐Ag‐Cu and Sn‐Zn alloys on their surface and interfacial tensions, as well as the wetting properties on the Cu substrate expressed by the wetting angle.Design/methodology/approach – The authors applied the L8 orthogonal Taguchi array to carry out the experiments and discussed the results using analysis of variance (ANOVA).Findings – It was expected, on the base of previous studies, the decrease of the surface and interfacial tensions and thus improving wettability after the Bi and Sb addition to Sn‐Ag‐Cu and Sn‐Zn alloys. Unfortunately, the obtained results on the quinary Sn‐Ag‐Cu‐Bi‐Sb alloys and the quaternary Sn‐Zn‐Bi‐Sb alloys do not confirm these trends. The performed analyses suggest that the compositions of the quinary Sn‐Ag‐Cu‐Bi‐Sb alloys, as well as the quaternary Sn‐Zn‐Bi‐Sb alloys, do not have optimal compositions for practical application. The Cu, Bi and Sb elements i...

Thermophysical properties and wetting behavior on Cu of selected SAC alloys

Purpose – The purpose of this paper is to study the effect of copper concentration in near‐eutectic liquid SAC solders on their thermophysical properties: viscosity, surface tension, density; as well as wetting behavior on copper substrates at 523 K.Design/methodology/approach – Viscosity, surface tension, and density were studied over a broad range of temperatures with the recently developed Roach‐Henein method. The obtained results were compared with the data from modified capillary, maximum bubble pressure, wetting balance and dilatometric measurements. Wetting angles measured with wetting balance method were compared with the results of sessile drop measurements.Findings – The results obtained indicate that increasing concentration of copper in the alloy results in higher density, surface tension and viscosity, but differences resulting from copper concentration on wettability are relatively small. At 523 K, the density is: 7.097, 7.186, 7.232 g cm−3, the surface tension is: 538.1, 553.5, 556.7 m Nm−1...

Investigation of the effect of indium addition on wettability of Sn‐Ag‐Cu solders

Purpose – The purpose of this paper is to investigate the influence of In additions on the wetting properties of the Sn2.86Ag0.40Cu (in wt%) eutectic‐based alloys, on a copper substrate, in the presence of a flux. The main goal was to find correlations between the results of the wetting balance (WB) and the sessile drop (SD) method, in relation to the contact angles.Design/methodology/approach – The WB method was applied for the wetting measurements, at 250°C, in an air atmosphere and in the presence of a flux. The SD measurements were conducted at the same temperature, in the presence of the same flux, but in an Ar atmosphere, while the maximum bubble pressure (MBP) and dilatometric measurements were conducted in an Ar+H2 atmosphere. The density data from the dilatometric method were used for the determination of the surface tension by means of MBP, and the WB method was used to determine the surface and interfacial tension. Next, the surface tension data from these two methods were compared. The WB data...

A reliability study of the lead-free solder connections of miniature chip components on hybrid circuits

The results of the influence of lead-free solder paste, design and process parameters on the attachment reliability of chip surface-mounted components (SMCs) on thick-film conductor pads are presented. The purpose of the investigation was to compare the quality of the soldered joints made with new solder pastes that do not contain lead with joints soldered with standard SnPb solders. The miniature zero-ohm chip resistors were soldered with selected lead-free solder pastes. The visual appearance of the solder joint according to the standards of lead-free soldered components was compared with components soldered with SnPb solders. On the test sample with soldered chip resistors connected in series, the solder-joint resistance was measured before and after temperature cycling. On the same test sample the solder-joint resistance changes were measured with impedance spectroscopy. After temperature cycling the damaged samples were analysed with SEM and EDS. The reliability test results after temperature cycling indicate two lead-free solder pastes that are the most convenient for chip-component soldering on thick-film conductor pads with the reliability of the joints being equal or better than solder joints with Pb-containing solder paste.

Investigation of Sn‐Zn‐Bi solders – Part II: wetting measurements on Sn‐Zn7Bi solders on copper and on PCBs with lead‐free finishes by means of the wetting balance method

Purpose – The purpose of this paper is to investigate the influence of Bi additions on the wetting properties of SnZn7Bi alloys (Bi=1 and 3 per cent by mass) on a copper substrate and printed circuit boards (PCBs) with lead‐free finishes (SnCu, immersion Sn, Ni/Au, organic solderability preservative) in the presence of fluxes. The practical implications of the results is the main purpose of these investigations.Design/methodology/approach – A wetting balance method was used for wetting measurements at 230 and 250°C in nitrogen and air atmospheres in the presence of ORM0‐ or ROL0‐type fluxes. The PCBs were investigated ‘as received’ and after accelerated aging. The analysis of variance (ANOVA) analysis was performed in order to explain how the main factors of the experiments (the Bi content in the alloy (1 or 3 per cent), the test temperature and the test atmosphere) influenced the wetting ability of SnZn7Bi on Cu substrates.Findings – As expected, a higher temperature and a higher Bi content in the alloy ...

SAC solder paste with carbon nanotubes. Part II: carbon nanotubes’ effect on solder joints’ mechanical properties and microstructure

Purpose – The purpose of this work is to investigate the influence of carbon nanotube additions to solder paste on the solder joints mechanical strength and their microstructure. In our investigation, the basic solder paste contains 85 wt.% of the commercial Sn96.5Ag3Cu0.5 powder (with the particle sizes in the range of 20‐38 μm) and 15 wt.% of the self‐prepared middle activated rosin flux. To this paste we added the 0.01, 0.05 and 0.1 wt.% of the self‐modified CNT by functionalized them by mineral acid and than esterificated by methanol (FCNTMet) or polyethylene glycol 400 (FCNTPG). After the pastes had stabilized, the reflow soldering process of “zero ohm” chip resistors on PCBs with Ni/Au and SAC (HASL) finishes was carried out and then shear strength of the solder joints was measured. The correlations between the mechanical strength of solder joins without and with the carbon nanotubes and their microstructure were analysed.Design/methodology/approach – For shear strength measurement of solder joints,...

Sac 305 solder paste with silver nanopowder and carbon nanotubes addition - basic properties of pastes and solder joints

In the previous work we have been engaged in experiments of the solder paste consisting of nanoparticles of silver with different grain sizes, and also carbon nanotubes (CNT) before and after modification. The basic properties of the tested pastes were very promising. Here we would like to present our findings on mixed solder pastes that consist of silver nanopowder and modified CNT. Such mixtures have not been presented in the literature yet. In this article the results of basic tests such as slump, solder ball etc. as well as results of shear tests of solder joints will be presented.

Investigation of the wetting of PCBs with SnCu (HASL) and Snimm finishes by SnZnBiIn solders

Purpose – The purpose of this article is to establish why the wetting on PCBs with SnCu (HASL) and Snimm finishes in the presence of a flux is better than the wetting of those on a copper substrate. The practical aspect of the obtained results is the main goal of these investigations.Design/methodology/approach – The authors applied the wetting balance method for the wetting measurements at 230 and 250°C, in nitrogen atmosphere, in the presence of the ORM0 type flux. The PCBs with the SnCu (HASL) and Snimm finishes were investigated in the state “as received”. To establish the wetting properties of the SnCu (HASL) and Snimm finishes on the PCBs, wetted by the investigated SnZnBiIn alloys, the SEM and EDX analyses were performed.Findings – The authors obtained very good wetting results of the PCBs with the SnCu and Snimm finishes, wetted by the SnZn7Bi3In4 alloys. By applying the SEM and EDX methods, it was possible to establish that the barrier layer which was created during the HASL process between the c...

Investigation of properties of the SAC solder paste with the silver nanoparticle and carbon nanotube additives and the nano solder joints

Several nanomaterials like silver nanoparticles and carbon nanotubes were obtained and their size and microstructure were investigated. The silver nanoparticles were characterized by different grain size (from below 10 nm up to 200 nm) and microstructure. The diameter of the carbon nanotubes was 5 ÷ 50 nm and the length 0.5 ÷10 µm (max 100 µm). These nanomaterials were mixed with our own prepared SAC solder paste. Several technological properties of the “nano” solder pastes were investigated like spreading, wetting, solder ball and slump. The “nano” solder pastes were used for soldering on Cu substrates. Some mechanical properties of the “nano” solder joints were also investigated. Microstructure of the “nano” solder joints were carried out using SEM equipped with energy dispersive X-ray spectroscopy (EDS) system. Relation between properties of the solder joints with nano particles and their microstructure was analyzed.