In-Bi LOW-TEMPERATURE SOLDER STUDIED BY ULTRAFAST DSC

• Main Author: Hardian T., Muhammad
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/41440
• Institution: Institut Teknologi Bandung

Sn-Pb alloy is a commercial solder whose use must be abandoned. This is because commercial solder contains lead metal (Pb) which is a rare earth metal with a relatively high level of toxicity. Thus, the presence ofPb metal can cause pollution in water, soil and the environment with a threshold of 200 ppm. Therefore, this commercial solder becomes dangerous and not environmentally friendly. Furthermore, developing the lead-free solder which has the same quality as commercial solders need to be developed and adapted to its the application. There are several parameters and requirements that must be possessed by good lead-free solder such as low melting point, high mechanical properties (hardness, tensile strength, and shear strength), good wettabihty, good electrical conductivity, and low electrical resistance. One of the physical properties that must be possessed by lead-free solder is a low melting point. This is important to consider that many electronic devices use a substrate made of polymers (polypropylene) with a melting point of around 160 oc. There are two types of low temperature solder, namely ordered and disordered. The ordered phase is preferred in efforts to develop low temperature solder because it can overcome the problem of fragility at high homologous temperatures. One type of low temperature solder with promising ordered phases is the rn-Bi alloy. This In-Bi alloy has a melting point <160 oc, good wettability and is resistant to thennal-fatigue. ln the phase diagram, the ln-Bi alloy has 3 eutectic points and all of the eutectic points have a low melting point. In this study, the eutectic point region studied was the eutectic point with a high amount of Bi and had the highest melting point around 110 °C. Two Tn-Bi alloys with compositions lnt 9 Bi8t and ]n y,Bi 64 have been synthesized. The XRD pattern shows the presence ofBi and lnBi phases in the two ln-Bi alloys. The phase fraction ofinBi-phase at ln36 Bi64 was 80.2%, while In1 9Bi8t was 44.2%. The phase fraction oflnBi-phase increases simultaneously with the addition of the synthesized indium. Thermal analysis using ultrafast DSC shows that In 36Bi64 has a melting point between 110-120 °C and a crystallization point between 38-51 °C. Based on the melting temperature and crystallization temperature, it can be obtained that the value of L\T (undercooling) ofTn-Bi alloys and Bimetal was values of 81.7 oc and 102.6 °C, respectively. The value of L\ Tis linearly related to the fusion energy, so that the fusion energy of the Bi metal is greater than the In-Bi alloy during the solidification process. SEM images and optical microscopes show the ln-Bi alloy microstructure which consists of a mixture of 2 phases, namely the Bi phase and the eutectic phase, which are mostly lnBi-phase with very small amounts of Bi. EDX analysis shows that the composition of lni <JBisi contains more In, which is up to 30% of the In atom. The microstructure obtained is directly related to the mechanical properties, namely the hardness of the In-Bi alloy. The hardness value for the alloy with the composition ofJn1 9Bis1 is 79 ± 4.8 MPa, while the alloy with the composition ofln36Bi6-1 has a higher hardness value of 88.4 ± 6.9 MPa based on the vickers standard. While the hardness value is based on its phase, the Bi-phase is harder than the InBi-phase. All analyzes that was carried out was aim to gain a better understanding of the ln-Bi alloy as a promising lead-free solder material.