Optimal Hot Plate Temperature and Pressing Time in Attachment Process for Flexible Damper

Transcription

1 Optimal Hot Plate Temperature and Pressing Time in Attachment Process for Fxib Damper JIRAPHON SRISERTPOL 1, SORADA KHAENGKARN 1 AND WARONG PUNGPIPAT 1 1 School of Mechanical Engineering, Institute of Engineering Suranaree University of Technology 111 University Avenue, Muang District, Nakhon Ratchasima, THAILAND jiraphon@sut.ac.th Abstract: - An attachment process of fxib damper and fxib printed circuit board in HDD manufacturing process is very important. The poor quality of adhesion causes the peel of the fxib damper during a caning and annealing processes. Additionally, the peel strength depends on a temperature of hot plate and a pressing time in the attachment process. This paper presents a testing controlr developed on LabVIEW program. This controlr is impmented based on IPC/JPCA-6202 standard to determine a minimum temperature and a pressing time that obtain the high peel strength of an ultra-pure viscoelastic damping polymer, used in HDD process. In an experiment, the investigated parameters are the hot pate temperature at C and the pressing time 3, 5, 7 and 9 seconds. The result of experiment shows that the peel strength that exceeds 0.7 N/mm is established, where an optimum point at 70 C and 7 seconds were applied. This result can be applied to reduce flaws in HDD process. Key-Words: - peel strength, fxib damper, attachment process, IPC-TM650, HDD Manufacturing Process, Ultra-Pure Viscoelastic Damping Polymer 1 Introduction Nowadays, data storage technologies are developed rapidly. These technologies include the development of data transfer speed and capacity to support demand of customers. A precision of voice coil motor movement is an important parameter to the position of HGA which is attached on an arm. During an operation, the arm is on HDD media disc. The energy storage on fxib printed circuit during the movement of arm will affect incorrect position of HGA. Therefore, a fxib damper is attached on the fxib printed circuit for reducing the energy storage. The attachment process of the fxib damper will control compression force and time when it adheres on the fxib printed circuit board. The fxib damper is held on fxib printed circuit board by Ultra-Pure Viscoelastic Damping Polymer. The attachment process of fxib damper have defect about 2 to 5 percents after the caning and annealing processes. The result of pass and fail product is shown in Fig. 1. This paper studies the relation between temperature and time which are used to install the fxib damper. Moreover, the time in the process is optimized. The result can be used to improve an efficiency of the fxib damper attachment process. The peel test is used to determine the strength of adhesive joints. The peel ang and rate influenced to the energy losses within adhesive layer. [1] Moreover, The factors such as the nature of adhesive, [2] The mechanical properties and geometries of backing and the substrate have the seriously effect on the test too. [3,4,5,6] Therefore, the experiment should be controld by following the standard of testing. The reliability of experimental results can develop the relation between the strength of adhesion to temperature and time in the attachment process. [7] (a) (b) Fig. 1 (a) good product (b) rejected product by peeling off 2 Materials and Methods 2.1 The IPC/JPCA-6202 standard testing Requirement in adhesion strength test based on IPC/JPCA-6202 standard [8] discussed below - The surface of the specimen must be can without dust, smut and oil etc.. ISSN: X 484 ISBN:

2 - Material of the specimen must be the same the actual materials which used in the manufacturing process. - Test at Temperature 0-40 C, Humility 60-70% RH and Pressure kpa. - Peel ang is 90±5 degree - Peel rate is about 50 millimeter per second - Record the peel force continuously at 3 data per second - Find the average peel force at steady state (Regardss the overshoot and transient state which may cause the irregular adhesive layer and the evenness edge of fxib damper because of cutting process.) as shown in the Fig. 2. the temperature of the fxib damper is constant at press is required to check the temperature of the heat control by adjusting the temperature to C. When the temperature is constant as reference, the press set will be working by press for 7 seconds and then read the result from the trial. Experiment is repeated 50 times per temperature and the test results were found to change the temperature in the range of ±1 C as shown in the Fig. 4. average of tension force Peel strength = N/mm (1) speciment thickness Fig. 2 Measurement of Peel force Peel force at operating period 2.2 Equipment The heating set used in the fxib damper attachment process. This heating set can adjust the PID controlr from temperature measurement with thermocoup. The temperature control act schedud to run of the solid state relay to ab/disab of the heat bar which embedded in the metal base as shown in the Fig. 3. Fig. 4 Hot plate temperature in the process Peel test set Peel test set was designed to test the peel strength from the attachment process on the actual piece as shown in the Fig. 5. Peel test set consist of two main parts which are holding and pulling part as shown in the Fig. 6 and reading data part. In hand of the specimen must ensure that the base of the specimen, a fxib printed circuit board, must be hold in place during the test to prevent the error of the data. The part of damper that is puld to peel off required to fix and be perpendicular to the fxib printed circuit board. The specimen must be pull to move constantly and maintain the direction of pull in accordance with requirements of the experiment. Fig. 3 Temperature control system diagram The specimen is placed on the metal base whi the fxib damper attachment. Therefore, to keep Fig. 5 Peel test set The ngth of the specimen and the distance of the peel off damper which defined the distance of pull, must be consider they will affect the ang of ISSN: X 485 ISBN:

3 pull. Standards required by the above specified ang to pull the specimen at 90 ±5 degrees. Therefore, in the order to comply the requirements to consider the ratio between the distance to pull and the ngth of the specimen does not exceed as show in the Fig. 7. Fig. 8 Connection diagram from force gauge to DAQ card Differential signal connection are set as shown in Fig. 8 to reduce the noise stored in the cab. Then read the peel force by LabVIEW [9] and record the data to the computer as shown in the Fig. 9. Fig. 6 Clamping and pulling set Fig. 9 Force measurement apparatus Fig. 7 Proportion of peeling distance and specimen ngth The reading data from the tensi test use the force gauge ALGOL HF-5 will send the analog output in form of voltage which must be convert to the digital output using analog to digital circuit in NI USB-6008 DAQ card. Unipolar signal type is determined that the voltage in the range of 0-1 volts since the peel test is the one direction test and peel force was approximately in the unit kgf to fit with the range usage and get the resolution of data is maximum. Peel force from the test will be displayed in graph. Then, consider that during pulling which has to be constant only to find the average peel force and calculate the peel strength by (1). Before using measurement system will need to check the reliability of the measurement system by statistical methods to determine the variability of the measurement system (GR&R) by the relationship between reading data of the weight from force gauge and the data value which calculated through LabVIEW Program (Regression) and compare the average reading data from Pair-T test. The results of the monitoring system to measure the value in the criterion which can accept the values read by LabVIEW. That is reliab as detaid monitoring various conditions in Tab 1. ISSN: X 486 ISBN:

4 Tab 1 Measurement probability Checking Criteria Condition Result Decision Reliability of %Contribut < 7.7% 0.03% Measuring e system (GR&R) > 5 82 Relationship between Force gauge and LabVIEW (Regression) Average data comparing (Pair-T Test) # of distinct of categories R-Square > 90% 100% P-Value > Results and Discussion 3.1 Temperature effect on the peel strength The study of experimental result shown the effect temperature to the peel strength. In this experiment held constant and equal pressing force in every temperature testing. The temperature testing are 25, 40, 50, 60,70 and 80 o C. During the test the edges of attachment was audited every testing temperature. The data was analyzed by One-way ANOVA[10] in Minitab programs for determination of average peel strength. Fig. 10 showed that the peel strength was not difference at the temperature from 25 o C to 60 o C but the peel strength was increased at the temperature higher than 70 o C. During the testing process, it didn t have unusual behavior until at the temperature higher than 80 o C the adhesive material was melted as shown in Fig.11. The melted material was unwanted thing in the production process. Fig. 11 Overhang adhesive layer on the fxib damper. 3.2 Time effect on the peel strength This experiment sected a constant temperature at 70 o C because the peel strength material was accommodation and didn t have exceeded edge. The pressing force was held constant within 3, 5, 7 and 9 seconds. The average value of peel strength was analyzed by One-way ANOVA in Minitab programs for determination of average peel strength. Fig.12 had shown the effect of time to the peel strength. The highest value of strength occurred at 9 seconds. At the pressing time is 3 seconds, the bubbs were occurred in the adhesive layer as shown is Fig. 13. The bubbs were the cause of defect in the attachment process when the product passed to caning and annealing process. Fig. 10 Peel strength vs Temperature Fig. 12 Peel strength vs Pressing time ISSN: X 487 ISBN:

5 Fig. 13 Bubb in adhesive layer From the experimental results found that the proper temperature and the pressing time were 70 o C and 7 seconds, respectively. The data was analyzed for comparison with average peel strength from ordinary systems by using 2 samps T-Test in Minitab program. When the system used temperature at 70 o C and the time period at 7 seconds, the result shown that the system have the peel strength higher than the ordinary system. The average values of increased strength was 9 % when compare with the result at room temperature. Peeling strength (N/mm) Peel strength compared between 25 C vs 70 C 25 C Fig. 14 Peel strength compared between ordinary and new system. 4 Conclusion This work found that the increased hot plate temperature and pressing time cause the peel strength increase. The optimal hot plate temperature and pressing time are 70 C and 7 seconds, respectively, with the peeling strength exceed 0.7 N/mm. This result can be applied to reduce the peed off parts during a caning and annealing process of the fxib damper. 70 C References: [1]Masuda, R., Inoue, H., Kishimoto, K. Hayakawa, M., and Inao, Y. Estimation of peeling strength and behavior for adhesive sheet using multi-axes driven peel test. Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A, Vol. 76, Issue 763, 2010, pp [2]Zhang, L. and Wang, J., A generalized cohesive zone model of the peel test for pressure-sensitive adhesives, International Journal of Adhesion & Adhesives, Vol. 29, 2009, pp [3]Muelr, S., Investigation of the Correlation of Peel Strength and Pad Adhesion Measurement using Different Printed Circuit Board Base Materials, paper presented in the Ectronics Manufacturing Technology Symposium, 1998, pp [4]Satoru, I., Takehiro, M., Shin, F., Nobuhiro, F. and Kazufuyu, S. Effect of a metallic interfacial layer on peel strength deterioration between a Cu thin film and a polyimide substrate. Journal of Vacuum Science & Technology B: Microectronics and Nanometer Structures, Vol. 5, Issue 1, 1997, pp [5] Wiechmann, R., Experiences with peel strength., Circuit World, Vol. 32, Issue 3, 2006, pp [6]Masuda, R., Omiya, M., Inoue, H., and Kishimoto, K., Effect of peel rate on interfacial strength, Key Engineering Materials, Vol I, 2007, pp [7]Wei, Y. and Hutchinson, J.W., Interface strength, work of adhesion and plasticity in the peel test, International Journal of Fracture, Vol.93, Issue 1-4, 1998, pp [8]Association Connecting Ectronics Industries IPC/JPCA-6202 Performance Guide Manual for Sing-and Doub-Sided Fxib Printed Wiring Boards. Online: [9]Chamniprasart, K., Mechanical Measurement by LabVIEW, Mechanical Engineering, Suranaree University of Technology, [10]Montgomery, D. C., Runger, G. C., and Hube, N. F., Engineering Statistics, 3 rd Ed. John Wiy & Sons Inc ISSN: X 488 ISBN: