Preparation & characterization of electrophoretically deposited BN film for semiconductor package

• Main Author: Narayanasami, Jayaganasan
• Format: Thesis
• Language: English; English
• Published: 2017
• Subjects: T Technology (General); TA Engineering (General). Civil engineering (General)
• Online Access: http://eprints.utem.edu.my/id/eprint/20612/; https://plh.utem.edu.my/cgi-bin/koha/opac-detail.pl?biblionumber=105978

Boron Nitride (BN) is used in various applications such as in lubrication, as a releasing agent and also as a thermosetting insulator material and thermal enhancer because of its advanced material properties. Electrophoretic deposition (EPD) method is a new method for semiconductor industries and it has grown in the interest on making use of BN as a thermal interface material and electrical isolation in Transistor Outline (TO) packages. Hexagonal Boron Nitride (h-BN) stability in EPD suspension is essential to produce repeatability and reproducibility in the result of the deposition. However, h-BN particle has less functional group on its side wall to create bonding with the polymer matrix. In order to increase functional groups on its side wall, NaOH surface treatment which has been established by other researchers was performed. The purpose of this study is to prepare and characterise of the h-BN particles in EPD suspension using different types of suspension mediums and binders. The particle size characterization and Field-Emission Scanning Electron Microscopy (FESEM) on the as-received h-BN particle indicates that particle sizes were less than 1 μm but are in agglomerated forms in the De-ionized (DI) water suspension. Sedimentation test method of h-BN particles in four dispersion media (deionized water, Acetic acid solution, Sulphamic Acid & Ammonia) and using different binder (Polyethylene Glycol (PEG), Silane Coupling Agent, Polycationic 1 (PC 1), Polycationic 2 (PC 2). The result showed a combination of deionized water and PC 2 produced the highest stability for h-BN dispersion. Sedimentation test and zeta potential method were used to determine the optimum concentration of PC 2 addition in a h-BN suspension. EPD of h-BN was performed on TO package using different levels of PC 2 concentration (i.e. 0.2 – 1.0 wt%). Characterization of the EPD coating were performed in terms of thickness, microstructure analysis on surface and micrograph from FESEM, and surface roughness. The optimum concentration of PC 2 in order to achieve the highest h-BN stability was in the range of 0.3 – 0.4 wt%, with a corresponding deposition thickness of 8 μm. The obtained thickness was the highest among other samples, and had surface roughness of 570 nm. Critical factors that affected the deposition for h-BN EPD process were suspension ionic conductivity and excess PC 2 concentration. High conductivity and excess PC 2 concentration caused electric double layer of h-BN particles to be compressed thus resulting in a low deposition yield. Therefore, it is recommended that future works use ultra-pure DI water and excess binder of h-BN suspension need to be removed by centrifugal washing before undergoes EPD to reduce conductivity of h-BN suspension. Besides it also helps to achieve a high deposition thickness of h-BN for thermal conductive and electrical isolation application.