• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.303-304
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• 2005

In this paper, we report a fluxless eutectic die bonding process which uses 80Au-20Sn eutectic alloy. The chip LEDs are picked and placed on silicon substrate wafers. The bonding process temperatures and force are $305\sim345^{\circ}C$ and 10$\sim$100gf, respectively. The bonding process was performed on graphite heater with nitrogen atmosphere. The quality of bonding are evaluated by shear test and thermal resistance. Results of fluxless eutectic die bonding show that shear strength is Max. 3.85kgf at 345$^{\circ}C$ /100gf and thermal resistance of junction to die bonding is Min. 3.09K/W at 325$^{\circ}C$/100gf.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.338-338
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• 2013

Monolithic three-dimensional integrated circuits (3D-ICs) 구현 시 bonding 과정에서 발생되는 aluminum (Al) 이나 copper (Cu) 등의 interconnect metal의 확산, 열적 스트레스, 결함의 발생, 도펀트 재분포와 같은 문제들을 피하기 위해서는 저온 공정이 필수적이다. 지금까지는 polymer 기반의 bonding이나 Cu/Cu와 같은 metal 기반의 bonding 등과 같은 저온 bonding 방법이 연구되어 왔다. 그러나 이와 같은 bonding 공정들은 공정 시 void와 같은 문제가 발생하거나 공정을 위한 특수한 장비가 필수적이다. 반면, 두 물질의 합금을 이용해 녹는점을 낮추는 eutectic bonding 공정은 저온에서 공정이 가능할 뿐만 아니라 void의 발생 없이 강한 bonding 강도를 얻을 수 있다. Aluminum-germanium (Al-Ge) 및 aluminum-indium (Al-In) 등의 조합이 eutectic bonding에 이용되어 각각 $424^{\circ}C$ 및 $454^{\circ}C$의 저온 공정을 성취하였으나 여전히 $400^{\circ}C$이상의 eutectic 온도로 인해 3D-ICs의 구현 시에는 적용이 불가능하다. 이러한 metal 조합들에 비해 indium (In)과 tin (Sn)은 각각 $156^{\circ}C$ 및 $232^{\circ}C$로 굉장히 낮은 녹는점을 가지고 있기 때문에 In-Sn 조합은 약 $120^{\circ}C$ 정도의 상당히 낮은eutectic 온도를 갖는다. 따라서 본 연구팀은 In-Sn 조합을 이용하여 $200^{\circ}C$ 이하에서monolithic 3D-IC 구현 시 사용될 eutectic bonding 공정을 개발하였다. 100 nm SiO2가 증착된 Si wafer 위에 50 nm Ti 및 410 nm In을 증착하고, 다른Si wafer 위에 50 nm Ti 및 500 nm Sn을 증착하였다. Ti는 adhesion 향상 및 diffusion barrier 역할을 위해 증착되었다. In과 Sn의 두께는 binary phase diagram을 통해 In-Sn의 eutectic 온도인 $120^{\circ}C$ 지점의 조성 비율인 48 at% Sn과 52 at% In에 해당되는 410 nm (In) 그리고 500 nm (Sn)로 결정되었다. Bonding은 Tbon-100 장비를 이용하여 $140^{\circ}C$, $170^{\circ}C$ 그리고 $200^{\circ}C$에서 2,000 N의 압력으로 진행되었으며 각각의 샘플들은 scanning electron microscope (SEM)을 통해 확인된 후, 접합 강도 테스트를 진행하였다. 추가로 bonding 층의 In 및 Sn 분포를 확인하기 위하여 Si wafer 위에 Ti/In/Sn/Ti를 차례로 증착시킨 뒤 bonding 조건과 같은 온도에서 열처리하고secondary ion mass spectrometry (SIMS) profile 분석을 시행하였다. 결론적으로 본 연구를 통하여 충분히 높은 접합 강도를 갖는 In-Sn eutectic bonding 공정을 $140^{\circ}C$의 낮은 공정온도에서 성공적으로 개발하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제24권1호
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• pp.59-66
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• 2000

To investigate the optimum brazing condition, variation of bonded structure and mechanical properties of novel brazed pure Al with bonding condition (brazing temperature, time and Si/flux ratio) was studied. A basic study of the bonding mechanism was also examined. The optimum brazing condition was obtained at $590^{\circ}$ for 2 minutes and the bonded structure showed that it is composed of almost entirely eutectic Al-Si with near eutectic composition. At higher brazing temperature $630^{\circ}$, hypoeutectic Al-Si structure was observed in the bonded area and resulted in erosion of base metal. The thickness of eutectic layer formed in optimum brazing temperature increased linearly with the square root of time, showing a general diffusion controlled process. The ultimate tensile strength of bonded joint brazed at an optimum brazing condition was about 60% of base metal and its fracture surface showed a brittle mode.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2001년도 춘계학술발표대회 개요집
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• pp.292-294
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• 2001

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2003년도 International Symposium
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• pp.253-257
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• 2003

The low temperature flip chip technique is applied to the package of the temperature-sensitive devices for LCD systems and image sensors since the high temperature process degrades the polymer materials in their devices. We will introduce the various low temperature flip chip bonding techniques; a conventional flip chip technique using eutectic Bi-Sn (mp: $138^{\circ}C$) or eutectic In-Ag (mp: $141^{\circ}C$) solders, a direct bump-to-bump bonding technique using solder bumps, and a low temperature bonding technique using low temperature solder pads.

• 한국안전학회지
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• 제32권1호
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• pp.9-14
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• 2017

Diffusion bonding is a technique that has the ability to join materials with minimum change in joint micro-structure and deformation of the component. The quality of the joints produced was examined by metallurgical characterization and the joint micro-structure developed across the diffusion bonding was related to changes in mechanical properties as a function of the bonding time. An increase in bonding time also resulted in an increase in the micro-hardness of the joint interface from 55 VHN to 180 VHN, The increase in hardness was attributed to the formation of intermetallic compounds which increased in concentration as bonding time increased.

• 한국생산제조학회지
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• 제23권4호
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• pp.355-360
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• 2014

Recently, the use of LED is increasing. This paper presents the new package process of thermal compression bonding using metal layered LED chip for the high power LED device. Effective thermal dissipation, which is required in the high power LED device, is achieved by eutectic/flip chip bonding method using metal bond layer on a LED chip. In this study, the process condition for the LED eutectic die bonder system is proposed by using the analysis program, and some experimental results are compared with those obtained using a DST (Die Shear Tester) to illustrate the reliability of the proposed process condition. The cause of bonding failures in the proposed process is also investigated experimentally.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기물성,응용부문
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• pp.30-32
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• 2005

This paper reports on an LTCC-based packaging method using Au/Sn eutectic bonding process for RF MEMS applications. The proposed packaging structure was realized by a micromachining technology. An LTCC substrate consists of metal filled vertical via feedthroughs for electrical interconnection and Au/Sn sealing rim for eutectic bonding. The LTCC capping substrate and the glass bottom substrate were aligned and bonded together by a flip-chip bonding technology. From now on, shear strength and He leak rate will be measured then the fabricated package will be compared with the LTCC package using BCB adhesive bonding method which has been researched in our previous work.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.393-395
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• 2005

The bonding for Aluminum and Copper in the air is investigated in this study. This bonding method does not include the special process of removing aluminum oxide films. In case of this bending, each metal Is heated at bonding temperature where is above eutectic temperature of Al-Cu system and below melting point of Aluminum. The liquefaction around the bonding surface occurs after the diffusion at solid state of each metal. This phenomenon is predicted by the temperature range above eutectic temperature of Al-Cu equilibrium phase diagram.

• 한국재료학회지
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• 제2권4호
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• pp.241-247
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• 1992

본 연구에서는 $Cu-Cu_2$O의 공정반응에 의한 구리와 알루미나의 직접접합에 대하여 연구 하였다. $1.5{\times}10^{-1}$torr, $1015^{\circ}C$에서 산화시킨 후 $10_{-3}$torr, 107$5^{\circ}C$에서 접합시킨 시편의 접합력과 계면특성을 인장시험, SEM, EDS 및 XRD를 통하여 분석하였다. 3분 산화시켜 접합하면 우수한 접합강도를 보이며 산화시간이 이보다 짧거나 길면 결합력은 저하하였다. 과단은 알루미나 공정조직 계면에서 발생하였으며 파단후 $Al_2O_3$표면에는 Cu쪽에서 빠져나간 $Cu_2$O nodule의 존재하였는 바 접합력은 $Cu_2$O-A$l_2O_3$계면보다는 $Cu-Cu_2$O계면에 좌우됨을 보여주고 있다. 접합력은 접합시간에 따라 완만한 증가를 보였으며 CuA$l_2O_4$및 $CuAlO_2$의 반응생성물이 접합중 형성되었다.