The behaviour of TiB2 coated steel in Sn-Ag–Cu based solder melt was investigated. The samples were subjected to immersion tests in static solder melt for 40 days at 593 K. The reactions at the solder/native oxide layer covered TiB2/substrate and solder/oxide layer-free TiB2/substrate interfaces were investigated with X-ray diffraction, secondary neutral mass spectrometry, X-ray photoelectron spectroscopy, scanning electron microscopy and energy dispersive spectroscopy. The thermodynamic background of possible reactions is also presented. It was found that neither oxide covered, nor oxide layer-free TiB2 showed any observable reaction with the Sn-Ag–Cu solder melt.

The goal of this research is to study the applicability of the diffusion boriding process as a high-temperature thermochemical heat treatment to enhance the lifetime of steel selective soldering tools. The main purpose of the work is to discuss the behavior of double-phase (FeB/Fe2B) iron-boride coating on the surface of different steels (DC04, C45, CK60, and C105U) against the stationary SAC309 lead-free solder liquid alloy. The boride coating was formed on the surface of the steel samples through the powder pack boriding technique. The microstructure of the formed layer was examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The borided samples were first cut in half and then immersed into a stationary SAC309 lead-free solder liquid alloy (Sn–3Ag–0.9Cu) for 40 days. Microstructure examinations were performed by SEM with energy-dispersive spectroscopy and an elemental distribution map after the dissolution test. Excessive dissolution/corrosion of the original steel surface was observed at the steel/SAC interfaces, leading also to the formation of Fe–Sn intermetallic phases. This was found to be the major reason for the failure of selective soldering tools made of steel. On the contrary, no dissolution and no intermetallic compounds were observed at the FeB/SAC and at the Fe2B/SAC interfaces; as a result, the thicknesses of the FeB and Fe2B phases remained the same during the 40-day dissolution tests. Thus, it was concluded that both FeB and Fe2B phases show excellent resistance against the aggressive liquid solder alloy. The results of the dissolution tests show a good agreement with the thermodynamic calculations.

Selective soldering tools, such as nozzles and soldering irons are made of iron, or high purity ARMCO iron. The lifetime of these components is limited to around one month of continuous operation due to a degradation process during which the reactive solder melt dissolves iron atoms from the tool. A physical simulator was designed and produced to study the reaction between C45 steel samples and calm SAC305 solder melt. Experiments were performed up to 20 days of reaction which was followed by scanning electron microscope based microstructure analysis. It was shown that after a few days of reaction, the SAC305 alloy dissolved a notable amount of Fe. Increasing the reaction time a clearly distinguishable Fe-Sn intermetallic layer formed at the C45 steel/solder melt interface. The thickness of the intermetallic layer increased with further increasing the reaction time.

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The aim of our research is to develop an economic material combination exhibiting good wetting with solder alloy melts and enhanced lifetime against erosion in lead-free soldering applications. Iron-nitrides have strong bonds compared to metals, therefore they are expected to have increased resistance against erosion in solder melts compared to iron soldering tools. The first step of our research is to find the proper substrate material for nitride coating to obtain the desired wetting behaviour. The present paper focuses on the substrate material selection through wetting examinations of nitrided W302, 42CrMo4 and C45 steels with SAC 305 solder alloy melt. It was found that the substrate composition strongly affects the wetting contact angle. The best wetting was achieved with the C45 type steel substrate. The correlation between substrate composition, compounds formed during nitriding and wetting behaviour is discussed.