近年來越來越多的晶片封裝技術提出，其中覆晶封裝尤其受到重視。在液晶面板元件中，驅動晶片的封裝是一個很關鍵角色。在液晶面板大型化的趨勢下，驅動晶片的接角數量不斷上升。而在輕薄化的要求下，封裝的厚度也必須漸漸降低。目前在玻璃基板上的覆晶封裝技術主要採用異向性導電膠做為貼覆黏合材料。但異向性導電膠對於接點間距過小的晶片不適用。因此本研究對應用非導電膠的覆晶封裝技術就進一步探討。非導電膠的應用研究大多以實驗的方式進行，鮮少以理論方法建立數學模型。數學模型的建立對封裝樣品產出前的性質及可靠度預測皆有幫助。
本文建立一個覆晶熱壓封裝過程的數學模型並與與實驗結果對比。此數學模型具有預測封裝間隙、錫球殘留應力以及錫球變形的能力。
此數學模型與實際實驗數據比較中，第一種樣品晶片的熱壓過程過於快速，所以僅能比較最終的封裝高度。實驗和模擬的誤差約在8%以內。第二種晶片在熱壓過程中封裝高度的動態變化和模擬的趨勢一致，但實驗的結果較快達到最終穩定狀態。對於此現象推論是由於膠材性質的經驗公式對硬化過程中的黏度預測失準造成。
藉由分析此模型的輸入參數可以發現大部分的覆晶熱壓封裝中膠體的流動可以視為平板流，錫球造成的阻力可以忽略不計。而非導電膠在某些狀況下有可能在熱壓頭下降過程中便硬化，導致膠體內應力產生。
最後以本文提出的數學模型搭配有限元素軟體展示完整的分析流程，根據數值模擬結果發現封裝過程中的熱壓溫度降低可以有效減少最終封裝構體的最大翹曲。至於熱壓頭下壓力則須視設計需求而定，因為增加下壓力時，雖然錫球與基板接合點的接觸面積增加，但同時也會讓最後錫球內部殘留的壓應力減少。減少接觸電阻的同時也會讓封裝的可靠度下降。

In this decade, many new techniques have been introduced into the integrated circuit (IC) packaging industry. Packaging technology used in liquid crystal displays (LCDs) has requirements related to critical issues such as high density interconnects, thinner packaging size, and environmental safety. Driver IC chips are directly attached to LCD panels using flip chip technology with adhesives in the so called chip on glass (COG) packaging processes.
To investigate the dependence of the bonding force and bonding temperature on the flip chip thermal-compression packaging, this study established a mathematical model to analyze the flip chip packaging processes with non-conductive adhesives (NCAs). The plastic deformation of bumps and NCA flow between chip and substrate were taken into account in this model. The gap height and bump deformation after bonding can be estimated with this model.
Experimental work was carried out to compare with the mathematical model for the thermal-compression bonding of flip chip packaging using NCA. The calculated and experimental final gap heights of Chip A did not match perfectly. The mismatch of the final gap heights between the calculated and experimental results shows that the solder bumps on Chip A are tougher than the prediction which may result from the difference in solder material proprieties.
In order to observe the dynamic of the thermal-compression bonding process, Chip B was particular-designed. The experimental and calculated gap heights with respect to the elapsed time showed that the gap height reduced faster in experiment than calculated. The poor estimate of viscosity in the high temperature may be the major cause for this phenomenon. For residual stress prediction, this model gave the distribution of the bonding force applied on NCA and bumps. The calculated result of this model implies in some cases the NCA may gel before the end of bonding process. With the information provided by this model, the residual stress can be further simulated by a procedure considering complete three stages of simulation.
According to the whole simulation in this work, the best tactic for the flip chip packaging process using NCA is bonded at the lower temperature. This reduces maximum warpage and only slightly decreases the average compressive residual stress in the bottom of bumps. As talking to magnitude of the bonding force, it depends on design demand. The bigger bonding force leads to the larger bump contact area with the substrate, but also leads to the smaller average compressive residual stress in the bottom of bumps. The bonding force during the flip chip thermal bonding process will affect the contact resistance and reliability of packaging at the same time.

[1] Li Y, Wong CP. Recent advances of conductive adhesives as a lead-free alternative in electronic packaging: Materials, processing, reliability and applications. Mater Sci Eng R 2006;51:1-35.
[2] Ho PS, Wang GT, Ding M, Zhao JH, Dai X. Reliability issues for flip-chip packages. Microelectron Reliab 2004;44:719-737.
[3] Kristiansen H, Liu J. Overview of conductive adhesive interconnection technologies for LCD's. IEEE Trans Compon Packag Manuf Technol A 1998;21:208-214.
[4] Tian MP, Panel designs and module assembly of TFT LCDs Wu-Nan books, Taipei, 2008.
[5] Chan YC, Luk DY. Effects of bonding parameters on the reliability performance of anisotropic conductive adhesive interconnects for flip-chip-on-flex packages assembly I. Different bonding temperature. Microelectron Reliab 2002;42:1185-1194.
[6] Chiu YW, Chan YC, Lui SM. Study of short-circuiting between adjacent joints under electric field effects in fine pitch anisotropic conductive adhesive interconnects. Microelectron Reliab 2002;42:1945-1951.
[7] Teh LK, Anto E, Wong CC, Mhaisalkar SG, Wong EH, Teo PS, Chen Z. Development and reliability of non-conductive adhesive flip-chip packages. Thin Solid Films 2004;462-463:446-453.
[8] Yim MJ, Paik KW. Design and understanding of anisotropic conductive films (ACF's) for LCD packaging. IEEE Trans Compon Packag Manuf Technol A 1998;21:226-234.
[9] Yim MJ, Paik KW. The contact resistance and reliability of anisotropically conductive film (ACF). IEEE Trans Adv Packag 1999;22:166-173.
[10] Wu CML, Liu JH, Yeung NH. The effects of bump height on the reliability of ACF in flip-chip. Solder Surf Mt Tech 2001;13:25-30.
[11] Zhang JH, Chan YC. Research on the contact resistance, reliability, and degradation mechanisms of anisotropically conductive film interconnection for flip-chip-on-flex applications. J Electron Mater 2003;32:228-234.
[12] Kwon WS, Paik KW. Fundamental understanding of ACF conduction establishment with emphasis on the thermal and mechanical analysis. Int J Adhes Adhes 2004;24:135-142.
[13] Chung CK, Paik KW. Effects of the Degree of Cure on the Electrical and Mechanical Behavior of Anisotropic Conductive Films. J Electron Mater 2010;39:410-418.
[14] Hwang JC. Advanced low-cost bare-die packaging technology for liquid-crystal displays. IEEE Trans Compon Packag Manuf Technol A 1995;18:458-461.
[15] Hatada K, Fujimoto H, Kawakita T, Ochi T. A new LSI bonding technology: micro bump bonding assembly technology. In: Electronic Manufacturing Technology Symposium, 1998. p.23-27.
[16] Chang SM, Jou JH, Hsieh A, Chen TH, Jao JN, Wu HS. Internal stress and connection resistance correlation study of microbump bonding. IEEE Trans Compon Packag Technol 2001;24:493-499.
[17] Yim MJ, Hwang JS, Kwon W, Jang KW, Paik KW. Highly reliable non-conductive adhesives for flip chip CSP applications. IEEE Trans Electron Packag Manuf 2003;26:150-155.
[18] Cheng HC, Ho CL, Chiang KN, Chang SM. Process-dependent contact characteristics of NCA assemblies. IEEE Trans Compon Packag Technol 2004;27:398-410.
[19] Zhang XW, Wong EH, Rajoo R, Iyer MK, Caers J, Zhao XJ. Development of process modeling methodology for flip chip on flex interconnections with non-conductive adhesives. Microelectron Reliab 2005;45:1215-1221.
[20] Chen ZG, Kim YH. A new COP bonding using non-conductive adhesives for LCDs driver IC packaging. Displays 2006;27:130-135.
[21] Kim BY, Chen ZG, Kim YH. Chip-on-glass bonding using sn bump and non-conductive adhesive for LCD application. Mol Crys Liq Crys 2006;458:199-206.
[22] Kim SY, Oh TS, Lee WJ, Kim YH. Low temperature and ultra fine pitch joints using non-conductive adhesive for flip chip Technology. In: Electronic Packaging Technology, 2006. p.1-4.
[23] Lee SM, Kim BG, Kim YH. Non-Conductive Adhesive (NCA) Trapping Study in Chip on Glass Joints Fabricated Using Sn Bumps and NCA. Mater Trans 2008;49:2100-2106.
[24] Chen MY, An CC, Chang SM, Kao KS, Tsang J, Yang SS, Chen C, Lin CK. Theoretical Stress Calculation and Experimental Results of "NCF-type Compliant-Bumped COG". In: Electronics Packaging Technology Conference, 2007. p.71-74.
[25] Cheng HC, Hwang WY, Kao KS, Tsang J, Yang SS, An CC, Chang SM. Thermal-mechanical process simulation of an advanced NCF technology. IEEE Trans Electron Packag Manuf 2009;32:301-310.
[26] Lin CK, Chen C, Chang S-M, An CC, Lee HT, Kao KS, Tsang J, Yang SS. Electrical characterization of fine-pitch compliant bumps. In: Microsystems, Packaging, Assembly and Circuits Technology Conference, 2009. p.395-400.
[27] Kim BG, Lee SM, Kim YH. The Reliability of 30 mm pitch COG joints fabricated using Sn/Cu bumps and non-conductive adhesive. In: Electronic Materials and Packaging, 2007. p.1-3.
[28] Kim BG, Lee SM, Jo YS, Kim SC, Harr KM, Kim YH. Highly reliable, fine pitch chip on glass (COG) joints fabricated using Sn/Cu bumps and non-conductive adhesives. Microelectron Reliab 2011;In Press, Corrected Proof.
[29] Gutowski TG. A resin flow/fiber deformation model for composites. SAMPLE J 1985;16:58-64.
[30] Wan JW, Zhang WJ, Bergstrom DJ. Influence of transient flow and solder bump resistance on underfill process. Microelectron J 2005;36:687-693.
[31] Wan JW, Zhang WJ, Bergstrom DJ. An analytical model for predicting the underfill flow characteristics in flip-chip encapsulation. IEEE Trans Adv Packag 2005;28:481-487.
[32] Young WB, Yang WL. The effect of solder bump pitch on the underfill flow. IEEE Trans Adv Packag 2002;25:537-542.
[33] Peng SW, Young WB. Application of the Underfill Model to Bump Arrangement and Dispensing Process Design. IEEE Trans Electron Packag Manuf 2010;33:122-128.
[34] Kamal MR, Ryan ME. The behavior of thermosetting compounds in injection molding cavities. Polym Eng Sci 1980;20:859-867.
[35] Young WB, Yang WL. Underfill viscous flow between parallel plates and solder bump. IEEE Trans Compon Packag Technol 2002;25:695-700.
[36] Patankar SV, Numerical heat transfer and fluid flow, Hemisphere, 1980.
[37] Sourour S, Kamal MR. Differential scanning calorimetry of epoxy cure: isothermal cure kinetics. Thermochimica Acta 1976;14:41-59.
[38] Herschel WH, Bulkley R. Konsistenzmessungen von Gummi-Benzollösungen. Colloid Polym Sci 1926;39:291-300.
[39] The properties of NCA, http://www.aft-website.com/products/04/AE-901/, 1 Jan 2010.
[40] Lau JH, Electronic packaging: design, materials, process, and reliability, McGraw-Hill, New York, 1998.
[41] Chang CH, Young WB. Development of a mathematical model for thermal-compression bonding of the COG packaging process using NCA. Microelectron Reliab 2011;51:860-865.
[42] Farley D, Dasgupta A, Caers JFJ. Mechanics of Adhesively Bonded Flip-Chip-on-Flex Assemblies. Part II: Effect of Bump Coplanarity on Manufacturability and Durability of Non-Conducting Adhesive Assemblies. J Adhes Sci Technol 2008;22:1757-1780.
[43] Castro JM, Macosko CW. Kinetics and rheology of typical polyurethane reaction injection molding systems. SPE ANTEC Paper 1980;26:434-438.
[44] Ramberg W, Osgood R. Description of stress-strain curves by three parameters. Tech Note 902, NACA 1943.
[45] Zhu FL, Zhang HH, Guan RF, Liu S. The effect of temperature and strain rate on the tensile properties of a Sn99.3Cu0.7(Ni) lead-free solder alloy. Microelectron Eng 2007;84:144-150.
[46] Plumbridge WJ. Solders in electronics. J Mater Sci 1996;31:2501-2514.