本研究利用冷噴塗製程製備銅之塗層，分析研究其噴塗完成之銅鍍層之性質，以驗證冷噴塗在PCB應用之可能性，本研究中使用之冷噴塗氣體為99.5% 之氮氣，設備之噴塗工作溫度約為600至800℃之間，而噴塗壓力設定為5MPa，並使用業界最常使用之四種銅粉來做為噴塗粉末(分別為電解型與氣霧型)，將不同銅粉經過冷噴塗後完成之樣品依序均勻研磨以及以0.05µm的氧化鋁粉(Al¬2O¬3)拋光液進行拋光處理後，再進行SEM分析觀察，電解之銅粉與基材之結合介面較為平緩，機械連鎖效應較不明顯，其附著力不佳，故導致其塗層與基材分離；氣霧型之球型銅粉與基材結合處則是較不規則，其粉末對基材所產生之機械連鎖效應較強，其塗層與基材結合程度也較優異。一般紅銅之硬度為50~100HV，業界實務使用上會以大於85.2HV為標準，將四個試片樣品分別作硬度測試，四種試片之硬度皆大於85.2HV，而電解型與氣霧型銅粉塗層樣品之硬度皆是在110HV以上，其原因為冷噴塗時粉末顆粒之溫度並沒有達到再結晶之溫度，粉末顆粒在衝擊時產生塑性變形，而金屬在塑性變形時，晶粒會發生滑移、拉長、破碎和纖維化，此時金屬內部產生了殘餘應力等，導致其硬度會大於一般紅銅之硬度;並結合粒徑分析之結果，發現當最大粒徑與最小粒徑差距越大時，其硬度會有較差之硬度表現，粒徑差異較小時，試片也有較佳之硬度。接著取氣霧型與電解型兩種塗層硬度較優異之試片並將Sn-3.0 wt.%Ag-0.5wt.%Cu比例之焊料(SAC305)藉由助焊劑協助焊接，經升溫至攝氏250度後，並將試片進行SEM分析其在冷噴塗塗層上之機械性質、潤濕性與接觸角，觀察到焊錫與塗層間之接觸角皆小於31度符合文獻之角度，且兩種粉末之冷噴塗塗層的IMC尺寸皆低於10µm，證明兩者在實際應用上符合現今使用之標準且同時具有高度發展之潛力

In this study, the cold spraying process was used to prepare copper coatings, and the properties of the copper coatings after spraying were analyzed and studied to improve the deficiencies of the electroplated copper production method used in PCBs. The cold spraying gas used in this study was 99.5% nitrogen. The working temperature is about 600 to 800℃, and the spraying pressure is set to 5MPa, most commonly used copper powders are used as spraying powders (atomized and electrolytic type). The samples are ground and polished before analyzed by SEM. The bonding surface of the electrolytic powder to the substrate was observed to be very smooth. The mechanical chain effect is weak, which leads to the separation of the coating from the substrate; the atomized copper powder and the substrate are more irregular at the bonding interface. The powder has a strong mechanical chain effect to the substrate, and the bonding between the coating and the substrate is also excellent. Generally, the hardness of copper is about 50~100HV, the industry will use a standard of greater than 85.2HV. The hardness of four specimens all greater than 85.2HV, and all of them are above 110HV, because that the temperature of the powder particles during cold spraying does not reach the recrystallization temperature, and the powder particles started plastic deformation during impact. When the metal is plastically deformed, the crystal grains will slip, break, and become fibrillated. At this time, residual stresses are generated in the metal, resulting in its hardness being greater than that of ordinary copper, combined with the particle size analysis. As a result, it was found that when the range between the maximum and the minimum particle size is larger, the hardness will have poorer performance. When the particle size difference is closer, the samples will also have better hardness. Take two samples, which has the best hardness and use the solder (SAC305) with the proportion of Sn-3.0 wt.%Ag-0.5wt.%Cu to help the soldering with flux. After the temperature was raised to 250 °C, the wettability and contact angle of the solder joint after the solder test will be analyzed by SEM. The IMC size of two types of coatings after cold spray process are less than 10μm, which proves that the two types of coatings not only reach the industrial standards but also have high development potential in practical applications.

[1] Irissou, E., Legoux, J. G., Ryabinin, A. N., Jodoin, B., & Moreau, C. (2008). Review on cold spray process and technology: part I—intellectual property. Journal of Thermal Spray Technology, 17(4), 495-516.

[2] Champagne, V.K. (2007). The cold spray materials deposition process (Vol. 187). Elsevier Science.

[3] Stoltenhoff, T., Kreye, H., & Richter, H. J. (2002). An analysis of the cold spray process and its coatings. Journal of Thermal spray technology, 11(4), 542-550.

[4] Borchers, C., Gärtner, F., Stoltenhoff, T., Assadi, H., & Kreye, H. (2003). Microstructural and macroscopic properties of cold sprayed copper coatings. Journal of applied physics, 93(12), 10064-10070.

[5] Dykhuizen, R. C., & Smith, M. F. (1998). Gas dynamic principles of cold spray. Journal of Thermal spray technology, 7(2), 205-212.

[6] Schmidt, T., Assadi, H., Gärtner, F., Richter, H., Stoltenhoff, T., Kreye, H., & Klassen, T. (2009). From particle acceleration to impact and bonding in cold spraying. Journal of thermal spray technology, 18(5), 794-808.

[7] Assadi, H., & Gärtner, F. (2003). Thorsten Stoltenhoff, Heinrich Kreye. Acta Mater., 51, 4379-4394.

[8] Grujicic, M., Zhao, C. L., DeRosset, W. S., & Helfritch, D. (2004). Adiabatic shear instability based mechanism for particles/substrate bonding in the cold-gas dynamic-spray process. Materials & design, 25(8), 681-688.

[9] Ning, X. J., Kim, J. H., Kim, H. J., & Lee, C. (2009). Characteristics and heat treatment of cold-sprayed Al–Sn binary alloy coatings. Applied Surface Science, 255(7), 3933-3939.

[10] Papyrin, A., Kosarev, V., Klinkov, S., Alkhimov, A., & Fomin, V. M. (2006). Cold spray technology. Elsevier.

[11] Maev, R. G., & Leshchynsky, V. (2009). Introduction to low pressure gas dynamic spray: physics and technology. John Wiley & Sons.

[12] Irissou, E., Legoux, J. G., Arsenault, B., & Moreau, C. (2007). Investigation of Al-Al2O3 cold spray coating formation and properties. Journal of Thermal Spray Technology, 16(5-6), 661-668.

[13] Lee, H. Y., Yu, Y. H., Lee, Y. C., Hong, Y. P., & Ko, K. H. (2004). Cold spray of SiC and Al2O3 with soft metal incorporation: A technical contribution. Journal of thermal spray technology, 13(2), 184-189.

[14] Maev, R. G., & Leshchynsky, V. (2006). Air gas dynamic spraying of powder mixtures: theory and application. Journal of Thermal Spray Technology, 15(2), 198-205.

[15] Li, Z., Pradeep, K. G., Deng, Y., Raabe, D., & Tasan, C. C. (2016). Metastable high-entropy dual-phase alloys overcome the strength–ductility trade-off. Nature, 534(7606), 227-230.

[16] Papyrin, A. N. (2005). Effect of the substrate surface activation on the process of cold spray coating formation. In ITSC 2005 Conference Proceedings.

[17] Van Steenkiste, T. H., Smith, J. R., & Teets, R. E. (2002). Aluminum coatings via kinetic spray with relatively large powder particles. Surface and Coatings Technology, 154(2-3), 237-252.

[18] McCune, R. C., Donlon, W. T., Popoola, O. O., & Cartwright, E. L. (2000). Characterization of copper layers produced by cold gas-dynamic spraying. Journal of Thermal Spray Technology, 9(1), 73-82.

[19] RCSMFGDLNRAJXSS, D. (1999). Impact of High Velocity Cold Spray Particles. Thermal Spray Technology, 8(4), 559-564.

[20] Li, W. Y., Liao, H., Li, C. J., Bang, H. S., & Coddet, C. (2007). Numerical simulation of deformation behavior of Al particles impacting on Al substrate and effect of surface oxide films on interfacial bonding in cold spraying. Applied Surface Science, 253(11), 5084-5091.

[21] Grujicic, M., Saylor, J. R., Beasley, D. E., DeRosset, W. S., & Helfritch, D. (2003). Computational analysis of the interfacial bonding between feed-powder particles and the substrate in the cold-gas dynamic-spray process. Applied Surface Science, 219(3-4), 211-227.

[22] Fauchais, P. L., Heberlein, J. V., & Boulos, M. I. (2014). Thermal spray fundamentals: from powder to part. Springer Science & Business Media.

[23] Assadi, H., Gärtner, F., Stoltenhoff, T., & Kreye, H. (2003). Bonding mechanism in cold gas spraying. Acta Materialia, 51(15), 4379-4394.

[24] Hussain, T., McCartney, D. G., Shipway, P. H., & Zhang, D. (2009). Bonding mechanisms in cold spraying: the contributions of metallurgical and mechanical components. Journal of Thermal Spray Technology, 18(3), 364-379.
[25] Schmidt, T., Gärtner, F., Assadi, H., & Kreye, H. (2006). Development of a generalized parameter window for cold spray deposition. Acta materialia, 54(3), 729-742.

[26] Li, C. J., Li, W. Y., & Liao, H. (2006). Examination of the critical velocity for deposition of particles in cold spraying. Journal of Thermal Spray Technology, 15(2), 212-222.

[27] Kang, K., Yoon, S., Ji, Y., & Lee, C. (2008). Oxidation dependency of critical velocity for aluminum feedstock deposition in kinetic spraying process. Materials Science and Engineering: A, 486(1-2), 300-307.

[28] Li, C. J., Wang, H. T., Zhang, Q., Yang, G. J., Li, W. Y., & Liao, H. L. (2010). Influence of spray materials and their surface oxidation on the critical velocity in cold spraying. Journal of Thermal Spray Technology, 19(1-2), 95-101.

[29] Price, T. S., Shipway, P. H., McCartney, D. G., Calla, E., & Zhang, D. (2007). A method for characterizing the degree of inter-particle bond formation in cold sprayed coatings. Journal of thermal spray technology, 16(4), 566-570.

[30] Hussain, T., McCartney, D. G., & Shipway, P. H. (2012). Bonding between aluminium and copper in cold spraying: story of asymmetry. Materials Science and Technology, 28(12), 1371-1378.

[31] Gärtner, F., Stoltenhoff, T., Schmidt, T., & Kreye, H. (2006). The cold spray process and its potential for industrial applications. Journal of Thermal Spray Technology, 15(2), 223-232.

[32] Stoltenhoff, T., Kreye, H., & Richter, H. J. (2002). An analysis of the cold spray process and its coatings. Journal of Thermal spray technology, 11(4), 542-550.

[33] Koivuluoto, H., Coleman, A., Murray, K., Kearns, M., & Vuoristo, P. (2012). High pressure cold sprayed (HPCS) and low pressure cold sprayed (LPCS) coatings prepared from OFHC Cu feedstock: overview from powder characteristics to coating properties. Journal of thermal spray technology, 21(5), 1065-1075.

[34] Stoltenhoff, T., Borchers, C., Gärtner, F., & Kreye, H. (2006). Microstructures and key properties of cold-sprayed and thermally sprayed copper coatings. Surface and Coatings Technology, 200(16-17), 4947-4960.

[35] Phani, P. S., Rao, D. S., Joshi, S. V., & Sundararajan, G. (2007). Effect of process parameters and heat treatments on properties of cold sprayed copper coatings. Journal of Thermal Spray Technology, 16(3), 425-434.

[36] Venkatesh, L., Chavan, N. M., & Sundararajan, G. (2011). The influence of powder particle velocity and microstructure on the properties of cold sprayed copper coatings. Journal of thermal spray technology, 20(5), 1009-1021.

[37] Assadi, H., Schmidt, T., Richter, H., Kliemann, J. O., Binder, K., Gärtner, F., ... & Kreye, H. (2011). On parameter selection in cold spraying. Journal of thermal spray technology, 20(6), 1161-1176.

[38] Gärtner, F., Stoltenhoff, T., Schmidt, T., & Kreye, H. (2006). The cold spray process and its potential for industrial applications. Journal of Thermal Spray Technology, 15(2), 223-232.

[39] Vidaller M. V. List A., Gärtner F., Klassen T., Dosta S., Guilemany J. M. Ti6Al4V cold gas sprayed coatings: impact morphologies, splat adhesion and correlations to coating microstructures. Proceedings of the ITSC 2013, Busan Republic of Korea May 13-15, 2013.

[40] Wu, J., Fang, H., Yoon, S., Lee, C., & Kim, H. (2006). Critical velocities for high speed particle deposition in kinetic spraying. Materials transactions, 47(7), 1723-1727.

[41] Yin, S., Wang, X., Suo, X., Liao, H., Guo, Z., Li, W., & Coddet, C. (2013). Deposition behavior of thermally softened copper particles in cold spraying. Acta Materialia, 61(14), 5105-5118.

[42] Kim, H. J., Lee, C. H., & Hwang, S. Y. (2005). Superhard nano WC–12% Co coating by cold spray deposition. Materials Science and Engineering: A, 391(1-2), 243-248.

[43] Li, C. J., Li, W. Y., Wang, Y. Y., & Fukanuma, H. (2003). Effect of spray angle on deposition characteristics in cold spraying. Thermal Spray, 91-96.

[44] Li, W. Y., Yin, S., & Wang, X. F. (2010). Numerical investigations of the effect of oblique impact on particle deformation in cold spraying by the SPH method. Applied Surface Science, 256(12), 3725-3734.

[45] Li, W. Y., Yin, S., & Wang, X. F. (2010). Numerical investigations of the effect of oblique impact on particle deformation in cold spraying by the SPH method. Applied Surface Science, 256(12), 3725-3734.

[46] Chen, S. W., & Yen, Y. W. (1999). Interfacial reactions in Ag-Sn/Cu couples. Journal of electronic Materials, 28(11), 1203-1208.

[47] Yoon, J. W., & Jung, S. B. (2005). Interfacial reactions between Sn–0.4 Cu solder and Cu substrate with or without ENIG plating layer during reflow reaction. Journal of alloys and compounds, 396(1-2), 122-127.
[48] Smith, D. R., & Flegal, A. R. (1995). Lead in the biosphere: recent trends. Ambio, 21-23.

[49] McCormack, M., & Jin, S. (1994). Improved mechanical properties in new, Pb-free solder alloys. Journal of Electronic Materials, 23(8), 715-720.

[50] Kattner, U. R. (2002). Phase diagrams for lead-free solder alloys. Jom, 54(12), 45-51.

[51] Kim, K. S., Huh, S. H., & Suganuma, K. (2002). Effects of cooling speed on microstructure and tensile properties of Sn–Ag–Cu alloys. Materials Science and Engineering: A, 333(1-2), 106-114.

[52] Shen, Y. A., Lin, C. M., Li, J., Gao, R., & Nishikawa, H. (2019). Suppressed Growth of (Fe, Cr, Co, Ni, Cu) Sn 2 Intermetallic Compound at Interface between Sn-3.0 Ag-0.5 Cu Solder and FeCoNiCrCu0.5 Substrate during Solid-state Aging. Scientific reports, 9(1), 1-5.