Performance of Sn–3.0Ag–0.5Cu composite solder with TiC reinforcement: Physical properties, solderability and microstructural evolution under isothermal ageing

TLDR: In this paper, the effect of nano-reinforcement that was successfully introduced into a SAC305 lead-free solder alloy with different weight fractions through a powder-metallurgy route was quantitatively analyzed.

About: This article is published in Journal of Alloys and Compounds.The article was published on 2016-11-15 and is currently open access. It has received 62 citations till now. The article focuses on the topics: Solderability & Soldering.

Figures

Fig. 2 Retained ratios of TiC reinforcement in solder billets and solder joints after reflow as function of nominal weight fraction of TiC added

Fig. 3 Effect of temperature of instantaneous CTE for plain and composite solders

Table 1 Melting parameters of different solder alloys (in ºC)

Fig. 4 DSC curves for different solders: (a) SAC;（b）SAC/0.05 TiC;（c）SAC/0.1 TiC;（d）SAC/0.2TiC

Fig. 1 TEM images of the original TiC nanoparticles: (a) and (b) bright-field images: (c) selected area diffraction pattern

Frequently asked questions

Q1. How is TiC a potential reinforcement for solder joints?

relatively high 71 electrical and thermal conductivity also make TiC a potential reinforcement for 72 composite solders without affecting significantly their performance. 

Q2. What contributions have the authors mentioned in the paper "Tic reinforcement: physical properties, solderability" ?

17 This paper is focused on the effect of TiC nano-reinforcement that was 18 successfully introduced into a SAC305 lead-free solder alloy with different weight 19 fractions ( 0, 0. 05, 0. 1 and 0. 2wt % ) through a powder-metallurgy route. The obtained SAC/TiC solders were also studied extensively 22 with regard to their coefficient of thermal expansion ( CTE ), wettability and thermal 23 properties. 

Q3. What are the main disadvantages of Sn-Ag-Cu solder joints?

with a continuing trend of miniaturization and 41 high integration in electronics, Sn-Ag-Cu solder joints are more frequently exposed to 423higher current density, larger joule heat and bigger thermal-mechanical stress. 

Q4. What is the effect of the additives on the shear strength of the composite solder joints?

The 354 enhancement in shear strength of composite solder joints are mainly attributable to the 355 significantly supressed growth of Cu3Sn in the composite solder joints. 

Q5. What is the effect of Al2O3 nanoparticles on solder joints?

Fouzder et al. [10] reported that incorporation of Al2O3 55 nanoparticles showed a positive effect on microstructural refinement of a solder 56 matrix and improvement of both microhardness and shear strength of solder joints. 

Q6. What is the effect of dispersion strengthening on the microhardness of the composite solder?

Since microstructure of an alloy has a crucial effect on its 390 microhardness, refined Ag3Sn IMCs and the accompanying dispersion-strengthening 391 effect can thus explain the improvement of microhardness in the studied SAC/TiC 392 composite solders. 

Q7. What is the effect of TiC reinforcement on the morphology of the interfacial?

the diffusional direction and the interfacial atomic concentration 249 of Cu and Sn atoms in the SAC/TiC/Cu system might be influenced by TiC 250 reinforcement. 

Q8. What is the way to improve the performance of a solder alloy?

At present, introducing an appropriate amount of foreign particles into the matrix 48 of a traditional solder alloy is regarded as a potentially feasible approach to improve 49 the performance of the solder alloy. 

Q9. What is the likely explanation for the voids in the Kirkendall layer?

According to 356 previous studies, Kirkendall voids are more likely formed in a Cu3Sn layer because of 357 different diffusional rates of metal atoms [24]. 

Q10. What are the properties of the solder alloys exposed to ageing?

Mechanical properties 332Mechanical properties (including shear strength and microhardness) of the 333 studied solder alloys exposed to ageing of different durations were also studied; the 334 results of mechanical testing are presented in Figs. 11 and 12 together with typical 335 microstructures of the solder matrix. 

Q11. What is the effect of TiC on the growth of interfacial IMCs?

On the other 309 hand, the enrichment of reinforcement could also decreases a concentration gradient 310 of Sn atoms at the interface and, thus, lower the growth of interfacial IMC (especially, 311 for Cu3Sn). 

Q12. How much of the RROR was lost during the reflow process?

In addition, evidently, the RROR was additionally diminished 155 considerably during the reflow process: only a small fraction (approximately 10-30 156 wt. %) of the total amount of TiC remained in the final solder joints. 

Q13. What is the reason for the increase in wettability of the solder alloys?

These results indicate that the 221 relatively small addition of TiC nanoparticles into solder matrix contributes to 222 improve wettability of the composite solder alloys. 

Q14. What is the morphology of the as-reflowed SAC 269 solder?

It can be seen that the interfacial IMCs of the as-reflowed (0 h) SAC 269 solder show a common scallop-like morphology, while a “porous” interface was 270 found in all as-reflowed (0 h) composite solders; the degree of porosity was directly 271 proportional to the fraction of TiC reinforcement. 

Q15. What is the reason for the decrease in the contact angle of the composite solder?

the contact angle firstly decreased - from 215 34.7° for the non-reinforced SAC to 30.3° for the composite solder with 0.1 wt.%