Minor Project

Minor Project

            My research question is whether type of amine curing agent is affecting curing temperature of epoxy system for read-write head in hard disk drive (HDD). The amine curing agent is an important component in epoxy adhesive because it induces the curing reaction and continues to complete reaction. However, there are several types of amine curing agents and they affect the curing temperature. Therefore, the amines are studied in order to formulate the epoxy adhesive whose curing temperature is match with temperature of process in HDD production.

            Researchers who have looked at this subject are Tanmoy Maity and Hongyang Cai. The former formulated epoxy adhesive with aromatic amine and the latter used aliphatic amine as curing agent.

            Maity et al (2007) reports that the curing behavior of epoxy adhesive with aromatic amine curing agents is investigated by differential scanning calorimetry (DSC) analysis. The curing temperature is widely about 150 – 210^oC.

            Cai et al (2008) reports that the DSC thermograms of aliphatic amine-epoxy systems show the curing temperature about 115 – 125^oC. This temperature is lower and narrower than results of Maity because the structure of aliphatic amines is more mobility than structure of aromatic amines at the same temperature.

            Debate centers on the basic issue of process temperature. The epoxy adhesive can be react if the temperature of production is not less than curing temperature of epoxy system.

            My work will be closer to the research of Cai et al (2008) because the temperature of production is 120 – 130^oC and the curing temperature of aliphatic amine-epoxy systems is about 115 – 125^oC. Moreover, the temperature of production should not be more than 150^oC because the read-write head will be damaged at high temperature.

            Finally, I expect my contribution will be the way to choose and formulate the amine-epoxy systems whose the curing reaction is appropriate for HDD production in order to increase the productivity and especially reduce any problem during operation. (318 words)

Reference List

Cai, H., Li, P., Sui, G., Yu, Y., Li, G., Yang, X., Ryu, S. (2008). Curing kinetics study 
               of epoxy resin/flexible amine toughness systems by dynamic and isothermal 
               DSC. Thermochimica Acta, 473, 101-105.

Maity, T., Samanta, B.C., Dalai, S., Banthia, A.K. (2007). Curing study of epoxy
              resin by new aromatic amine functional curing agents along with
              mechanical and thermal evaluation. Materials Science and
              Engineering: A, 464, 38-46.

Assignment#2: Writing an introduction

The Development of Epoxy Adhesive whose Properties are Suitable
for Head Gimbal Assembly Process

by

Tossapol Boonlert-uthai

Stage 1: The head gimbals assembly process (HGA) operates in a hard disk drive manufacturing plant. HGA is made by assembling slider (read-write head) on a suspension with adhesive in which it is an important part in a hard disk drive. According to the Head Gimbal Assembly Process in Western Digital (Bang Pa-in) Co., Ltd. (2012), there are two assembly lines. In the first assembly line, semi automation, is divided into two steps, which are dispensing glue from a syringe on a suspension in the area that will be adhered to the slider via an auto adhesive dispensing (ATD) machine. After that, the slider is then put down on the glue-dispensed area of a suspension and radiated ultraviolet (UV) light to cure an adhesive for setting via an optical system corporation (OSC)-automation slider bond. In this stage, an adhesive is partially cured to be able to hold a slider. On the second assembly line, automation one, auto core adhesion machine (ACAM) proceeds all steps in one machine. After that, the part is put in an IR oven to enable an adhesive to be completely solidified and dried. Finally, HGA is sent to the further stages such as quality control, cleaning and packing process.

Stage 2: The adhesive used for HGA process is an epoxy type. The component of epoxy adhesive depends on HGA process, UV curing and thermal curing. Therefore there are epoxy monomer, photoinitiator (for UV curing) and curing agent (for thermal curing) which are the main composition. Decker (1996) proposed the mechanism of UV curing in which a photoinitiator absorbs UV-radiation to cleave the radical or reactive species, such as free radicals and protonic acid that initiate cross-linking polymerization with a monomer according to a radical and cationic mechanism, respectively, and then obtains the polymer network. For the thermal curing reaction, epoxy or oxirane group reacts with amine group of curing agent is called polyaddition reaction (Petri, 2006, p.64). Furthermore, Golaz et al. (2013) reported that ambient temperature can influence rate of polymerization. When operating temperature increases, the adhesive’s viscosity decreases in which it can accelerate the rate of polymerization due to higher mobility of adhesive molecules.

Stage 3: There are several problems relating to process, for example, instability of adhesive’s viscosity, air bubbles in adhesive and degree of cure, have been encountered. Causes of the problems of epoxy adhesive have not been thoroughly studied. Data were collected from production line and inquiring the problems from authorities and engineers. After that, the problems are analyzed and some hypotheses are considered.

Stage 4&5: Therefore, this research aims to characterize the epoxy adhesive used in HGA process in terms of thermal, rheological and chemical properties of uncured and cured adhesive. After that the characteristics of epoxy adhesive are applied with the HGA process to use epoxy adhesive properly and efficiently. Afterwards, formulating epoxy adhesive whose properties are suitable for head gimbals assembly process than current adhesive will be performed.