Main activities and results 2017

 WP3 – Reliability of the novel Sn binary and ternary alloys as lead-free solder joints (Mibatron SRL, UPB-CSSNT)

Task 3.1. – Specific solderability testing of the obtained Sn alloys according to the electronic industry standards

Samples of Sn nanostructured alloys coatings have been subjected to the so-called “dip and look test” as well as to the measurement of the wetting angle, in order to assess the solderability in accordance with: IPC-TM-650, Method 2.4.12 Solderability-immersion method; IPC J-STD-003C Solderability – Tests for printed circuit boards; IPC-A 600- Acceptance of printed circuit boards.

 SnAg from ILM SnAg from ILEG SnNi from ILEG
SnCu from ILEG SnIn from ILEG Sn-rGO
SnAgCu from ILEG SnNiCu from ILEG

Images of the performed micro-sections in order to determine the contact angle for each Sn alloy coating type obtained from different ionic liquid analogues (ILEG –eutectic mixtures of choline chloride and ethylene glycol; ILM – eutectic mixtures of choline chloride and malonic acid).

 

The quality of solder joint has been assessed using IPC-TM-650 procedure 2.1.1- Microsectioning and IPC-610E- Acceptability of Electronic Assembly.
Solder joint assembly samples (min.5 pcs.) have been prepared and subjected to the previously mentioned tests. The interfaces as well as the failed structures of the solder joint configurations have been examined using scanning electron microscopy (SEM) and optical microscopy for the integrity of the joints and have been assessed by electrical resistance measurements.

Planting flow of the components on PCBs

 

Solder joint assessment involving solder joint assembly samples (SnNiCu alloy deposit) – the solder joints showed a proper adhesion to the substrate with no fractures

 

Task 3.2. Accelerated aging testing of the obtained Sn alloys

Tin whiskers evaluation test after 2880 h of exposure at controlled temperature and humidity (60 ±5 °C and 87 +3/-2 % RH)

a) SnAg ILM b) SnAg ILM
a) SnAg ILEG b) SnAg ILEG
a) SnNi b) SnNi
a) SnAgCu b) SnAgCu
a) SnNiCu b) SnNiCu

SEM images of the electrodeposited Sn alloys: (a) initial, (b) after 2880 h of exposure at controlled temperature and humidity (60 ±5 °C and 87 +3/-2 % RH )

 

No whiskers appearance was evidenced during the performed tests

 

Long term ex-situ corrosion investigations in various simulated aggressive environments

 

Polarization curves in semilogarithmic coordinates for Sn alloys electrodeposited from ionic liquid analogues during continuous immersion test in 0.5M NaCl (initial and after 360 h of conditioning, 25oC, 3 mV.s-1)

 

Corrosion parameters determined from polarization curves in 0.5M NaCl for the investigated Sn alloys

 

WP 4 – Anode design and electrochemical evaluation (Porto University, UPB-CSSNT)

The development of various Sn nanostructured alloys coatings in order to act as an anode in Li-ion battery:

  • Ni-Sn alloy nanowires

SEM images for the Sn-Ni alloy nanowires with ratio of 0.5M:0.5M from ChCl:EG IL (i=-1.5mA, 15min) at 65ºC

  • Sn-Co alloy nanowires

SEM images for the Sn-Co alloys nanowires with ratio of 0.5M:0.5M from ChCl:EG IL (i=-1.5mA, 15min, 65ºC).

  • Sn-Ni and Sn-Co alloys electrodeposited on Ni nanofoam to increase the surface area

SEM images for Sn-Ni (48% Ni) alloy onto Ni foam with ratio of 0.5M:0.5M from ChCl:EG IL (i=-0.15A, 30min, 65ºC).

SEM images for Sn-Co (14% Co) alloy onto Ni foam with ratio of 0.5M:0.5M from ChCl:EG IL (i=-0.15A, 30min, 65ºC).