Journal of the Korea Academia-Industrial cooperation Society (한국산학기술학회논문지)

The Korea Academia-Industrial cooperation Society (한국산학기술학회)
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Optimization of Elastic Modulus and Cure Characteristics of Composition for Die Attach Film

다이접착필름용 조성물의 탄성 계수 및 경화 특성 최적화

  • Sung, Choonghyun (Division of Advanced Materials Engineering, Dong-Eui University)
  • 성충현 (동의대학교 신소재공학부)
  • Received : 2019.02.08
  • Accepted : 2019.04.05
  • Published : 2019.04.30
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Abstract

The demand for smaller, faster, and multi-functional mobile devices in increasing at a rapidly increasing rate. In response to these trends, Stacked Chip Scale Package (SCSP) is used widely in the assembly industry. A film type adhesive called die attach film (DAF) is used widely for bonding chips in SCSP. The DAF requires high flowability at high die attachment temperatures for bonding chips on organic substrates, where the DAF needs to feel the gap depth, or for bonding the same sized dies, where the DAF needs to penetrate bonding wires. In this study, the mixture design of experiment (DOE) was performed for three raw materials to obtain the optimized DAF recipe for low elastic modulus at high temperature. Three components are acrylic polymer (SG-P3) and two solid epoxy resins (YD011 and YDCN500-1P) with different softening points. According to the DOE results, the elastic modulus at high temperature was influenced greatly by SG-P3. The elastic modulus at $100^{\circ}C$ decreased from 1.0 MPa to 0.2 MPa as the amount of SG-P3 was decreased by 20%. In contrast, the elastic modulus at room temperature was dominated by YD011, an epoxy with a higher softening point. The optimized DAF recipe showed approximately 98.4% pickup performance when a UV dicing tape was used. A DAF crack that occurred in curing was effectively suppressed through optimization of the cure accelerator amount and two-step cure schedule. The imizadole type accelerator showed better performance than the amine type accelerator.

더욱 작고 얇고 빠르며, 많은 기능을 가진 모바일 기기에 대한 요구가 그 어느 때보다 높다. 이에 대한 기술적 대응의 하나로 여러 개의 칩을 적층하는 Stacked Chip Scale Package(SCSP)가 어셈블리 업계에서 사용되고 있다. 다수의 칩을 접착하는 유기접착제로는 필름형 접착제인 die attach film(DAF)가 사용된다. 칩과 유기기판의 접착의 경우, DAF가 기판의 단차를 채우기 위해서는 고온에서 높은 유동성이 요구된다. 또한 와이어 사이를 채우면서 고용량 메모리와 같이 동일한 크기의 칩을 접착하는 DAF의 경우에도, 본딩 온도에서 높은 유동성이 요구된다. 본 연구에서는 DAF의 주요 원재료 3성분에 대한 혼합물 설계 실험계획법을 통하여 고온에서 낮은 탄성계수를 갖도록 최적화하고, 이에 따른 점착 특성 및 경화 특성을 평가하였다. 3성분은 아크릴 고분자(SG-P3)와 연화점이 다른 두 개의 고상에폭시 수지(YD011과 YDCN500-1P)이다. 실험계획법 평가 결과에 따르면, 고온에서는 아크릴 고분자 SG-P3의 함량이 작을수록 탄성계수가 작은 값을 나타내었다. $100^{\circ}C$에서의 탄성계수는 SG-P3의 함량이 20% 감소한 경우, 1.0 MPa에서 0.2 MPa 수준으로 감소하였다. 반면, 상온에서의 탄성계수는 연화점이 높은 에폭시 YD011에 의해 크게 좌우되었다. 최적 처방은 UV 다이싱 테이프를 적용시 98.4% 수준의 비교적 양호한 다이픽업 성능을 나타냈다. 유리칩을 실리콘 기판에 부착하고 에폭시를 1단계 경화시킨 경우, 크랙이 발생하였으나, 아민 경화 촉진제의 함량 증가와 2단계 경화를 통하여 크랙의 발생을 최소화할 수 있었다. 이미다졸계 촉진제가 아민계 촉진제에 비해 효과가 우수하였다.

Keywords

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Fig. 1. Structure of SCSP using (a) FOW and (b) dummy chip

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Fig. 2. Concept of thermomechanical properties of DAF

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Fig. 3. Design of experiment for 3 component mixture and experimental results.

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Fig. 4. Contour plot of elastic modulus (MPa) at (a) 30℃, (b) 80℃, and (c)100℃.

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Fig. 5. Cox response trace plot for elastic modulus at (a)30℃, (b) 80℃, and (c)100℃.

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Fig. 6. Crack after (a)1 step and (b)2 step curing.

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Fig. 7. Standard samples for evaluating cure crack.

Table 1. Optimized DAF recipe for low elastic modulus at 80℃ and 100℃.

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Table 2. 180° peel strength and pickup performance of optimized recipes.

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Table 3. Cure crack performances according to catalyst type and amount.

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Table 4. Effect of the amount of catalyst on the cure crack performance.

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References

  1. X. Zhang, John H. Lau, C. S. Premachandran, Ser-Chong Chong, Leong Ching Wai, Vincent Lee, T. C. Chai, V. Kripesh, Vasarla Nagendra Sekhar, D. Pinjala and F. X. Che, "Development of a Cu/Low-k Stack Die Fine PitchBall Grid Array (FBGA) Package for System in Package Applications", IEEE Transactions on Components, Packaging and Manufacturing Technology, vol. 1, no. 3, pp. 299-309, 2011. DOI: https://doi.org/10.1109/TCPMT.2010.2100292
  2. Yasuki Fukui, Yuji Yano, Hiroyuki Juso, Yuji Matsune, Koji Miyata, Atsuya Narai,Yoshiki Sota, Yoshikazu Takeda, Kazuya Fujita, Morihiro Kada, "Triple-Chip Stacked CSP", Proc. of 50th Electronic Components and Technology Conference, pp. 385-389, May, 2000. DOI: https://doi.org/10.1109/ECTC.2000.853182
  3. B. H. Oh, H. Y. Loo, P. T. Oh and E. K. Lee, "Challenges in Stacked CSP Packaging Technology," Proc. of International Conference on Electronic Materials and Packaging, Kowloon, pp. 1-4, 2006 DOI: https://doi.org/10.1109/EMAP.2006.4430609
  4. S. Takeda, T. Masuko, N. Takano, T. Inada, "Die Attach Adhesives and Films", Materials for Advanced Packaging. Springer, pp. 407-436, 2009.
  5. S. C. Kheng, M. Teo and C. Lee, "Assessment of Die Attach Film for Thin Die and SiP Applications," Proc. of 2006 Thirty-First IEEE/CPMT International Electronics Manufacturing Technology Symposium, Petaling Jaya, pp. 288-293, 2006 DOI: https://doi.org/10.1109/IEMT.2006.4456468
  6. A. Teng Cheung, "Dicing die attach films for high volume stacked die application," 56th Electronic Components and Technology Conference, San Diego, CA, pp. 1312-1316, 2006. DOI: https://doi.org/10.1109/ECTC.2006.1645824
  7. S. Abdullah, S. M. Yusof, I. Ahmad, A. Jalar and R. Daud, "Dicing Die Attach Film for 3D Stacked Die QFN Packages," Proc. of 32nd IEEE/CPMT International Electronic Manufacturing Technology Symposium, San Jose, CA, pp. 73-75, 2007. DOI: https://doi.org/10.1109/IEMT.2007.4417054
  8. L. Chen, J. Adams, HW Chu and X. Fan, "Modeling of moisture over-saturation and vapor pressure in die-attach film for stacked-die chip scale packages", Journal of Materials Science: Materials in Electronics, vol 27, pp. 481-488, 2016 https://doi.org/10.1007/s10854-015-3778-5
  9. H. H. Jiun, I. Ahmad, A. Jalar, and G. Omar, "Effect of laminated wafer toward dicing process and alternative double pass sawing methods to reduce chipping," IEEE Transactions on Electronics Packaging Manufacturing., vol. 29, no. 1, pp. 17-24, 2006. DOI: https://doi.org/10.1109/TEPM.2005.862625
  10. Song S.N, Tan H.H., Ong P.L., "Die Attach Film Application in Multi Die Stack Package", Proc. of 7th Electronics Packaging Technology Conference, Singapore, pp. 848-852, 2005. DOI: https://doi.org/10.1109/EPTC.2005.1614517
  11. J. O. Bang, K. H. Jung, Y.M. Lee, S. B. Jung, "Thermo-Mechanical Behavior of Die Attach Film on Flexible PCB Substrate for Multi-Chip Package", Journal of Nanoscience and Nanotechnology, vol. 17, pp3130-3134, 2017. https://doi.org/10.1166/jnn.2017.14016
  12. B. U, Kang, "Interfacial Fracture Behavior of Epoxy Adhesives for Electronic Components", Journal of the Korea Academia-Industrial Cooperation Society, vol. 12, no. 3, pp1479-1487, 2011. https://doi.org/10.5762/KAIS.2011.12.3.1479
  13. Tee Swee Xian and P. P. Nanthakumar, "Dicing die attach challenges at multi die stack packages," Proc. of 35th IEEE/CPMT International Electronics Manufacturing Technology Conference (IEMT), Ipoh, pp. 1-5, 2012. DOI: https://doi.org/10.1109/IEMT.2012.6521797
  14. M. Teo, S. C. Kheng and C. Lee, "Process and Material Characterization of Die Attach Film (DAF) for Thin Die Applications," Proc. of 2006 International Conference on Electronic Materials and Packaging, Kowloon, pp. 1-7, 2006 DOI: https://doi.org/10.1109/EMAP.2006.4430572
  15. C. H. Toh, Mehta Gaurav, Tan Hua Hong and P. L. Ong Wilson, "Die attach adhesives for 3D same-sized dies stacked packages," Proc. of 58th Electronic Components and Technology Conference, Lake Buena Vista, FL, pp. 1538-1543. 2008. DOI: https://doi.org/10.1109/ECTC.2008.4550180
  16. M. Lee, Y. Lin, P. Pan, Y. Lin and C. Lin, "Film over wire (FOW) selection for copper wire application," Proc. of 8th International Microsystems, Packaging, Assembly and Circuits Technology Conference (IMPACT), Taipei, pp. 306-309, 2013. DOI: https://doi.org/10.1109/IMPACT.2013.6706662
  17. J. Liang, C. Ku and C. Chung, "Applications of film over wire and die attached film in a stacked chip scale package," Proc. of 11th International Microsystems, Packaging, Assembly and Circuits Technology Conference (IMPACT), Taipei, pp. 289-292, 2016. DOI: https://doi.org/10.1109/IMPACT.2016.7800052
  18. C. L. Chung, C. W. Ku, H. C. Hsu and S. L. Fu, "Comparison between die attach film (DAF) and film over wire (FOW) on stack-die CSP application," Proc. of 2009 European Microelectronics and Packaging Conference, Rimini, pp. 1-3, 2009.