Studies of Temperature and Pressure Dependence in Thermocompression Gold Joints

Author(s):  
X. F. Ang ◽  
G. G. Zhang ◽  
J. Wei ◽  
Z. Chen ◽  
C. C. Wong

Low temperature interconnection is a critical component of 3D integration and packaging technology. In this study, we investigate the characteristics of thermocompression metal bonding using gold stud bumps formed on Si die in the temperature range of 100-300 °C and the pressure range of 200–600 g/bump. We observed a critical bonding temperature below which bonding did not occur and above which shear strength improves linearly with bonding temperature. This critical temperature can be interpreted to be the onset of the break-up of organic barrier films while the linear rise in shear strength can be attributed to the increase in the true bonded area. Above this critical temperature, the tensile strength of the Au-Au bond exhibits a maximum with increasing bonding pressure. This can be related to the pressure dependence of the interfacial stress distribution and its effect on unbonded radius, r. SEM fractographs of the failed surfaces suggest a combination of cohesive and adhesive failures along the bonded interface.

2009 ◽  
Vol 1156 ◽  
Author(s):  
Rahul Agarwal ◽  
Wouter Ruythooren

AbstractHigh yielding and high strength Cu-Cu thermo-compression bonds have been obtained at temperatures as low as 175°C. Plated Cu bumps are used for bonding, without any surface planarization step or plasma treatment, and bonding is performed at atmospheric condition. In this work the 25μm diameter bumps are used at a bump pitch of 100μm and 40μm. Low temperature bonding is achieved by using immersion bonding in citric acid. Citric acid provides in-situ cleaning of the Cu surface during the bonding process. The daisy chain electrical bonding yield ranges from 84%-100% depending on the bonding temperature and pressure.


Author(s):  
Nader Nadermanesh ◽  
Abdolhamid Azizi ◽  
Sahebali Manafi

The diffusion bonding of 7075, 6061 and 5083 aluminium alloys to AZ31B magnesium was investigated using copper interlayer. An optical microscope along with scanning electron microscopes, equipped with an energy dispersive spectrometry/electron probe microanalysis, was utilized to characterize the microstructure of the joint. The mechanical properties of the joint were also assessed by micro-hardness and shear strength tests. The results indicate the high effect of temperature on the bonding results; so that, with a small change in temperature, severe changes were observed in the bonding results. A temperature range of 475°C–485°C and a minimum duration of 30 min with a low bonding pressure of 0.4 MPa were identified as advisable process conditions. The joint evaluation revealed the formation of CuAl2, Cu9Al4 and Al-Mg-Cu ternary phases on the aluminium-copper side, as well as Cu2Mg, CuMg2 and Al-Mg-Cu ternary phases on the magnesium-copper side in the reaction layer. When increasing the bonding temperature and duration, the amount of intermetallic compounds and, as a result, the mechanical properties of the joints changed. The highest shear strength and micro-hardness, related to the bonding performed at 480°C and holding time of 45 min, were 31.03 MPa and 167 HV, respectively.


2010 ◽  
Vol 40 (3) ◽  
pp. 324-329 ◽  
Author(s):  
Byunghoon Lee ◽  
Jongseo Park ◽  
Junghyun Song ◽  
Kee-won Kwon ◽  
Hoo-jeong Lee

2005 ◽  
Vol 297-300 ◽  
pp. 2435-2440 ◽  
Author(s):  
Min Yang ◽  
Zeng Da Zou ◽  
Si Li Song ◽  
Xin Hong Wang

In this study, Si3N4 was bonded to Inconel600 with Nb/Cu/Ni interlayer by partial liquid phase diffusion bonding method under vacuum condition. The bonding temperature, bonding time, bonding pressure and cooling velocity was 1403K, 50min, 7.5MPa and 5K/min, respectively. The effects of interlayer thickness on the strength and fracture behaviors of joint were investigated through evaluating the strength of joints based on shear test and observing the fracture morphology by means of SEM. The results showed that the shear strength of joint changed with variation of the interlayer thickness. When the shear strength of joint increased, the location of fracture was changed from the ceramic/interlay interface to the reaction layer.


2006 ◽  
Vol 970 ◽  
Author(s):  
Pei-I Wang ◽  
Tansel Karabacak ◽  
Jian Yu ◽  
Hui-Feng Li ◽  
Gopal G. Pethuraja ◽  
...  

ABSTRACTWafer bonding is an emerging technology for fabrication of complex three-dimensional (3D) structures; particularly it enables monolithic wafer-level 3D integration of high performance, multi-function microelectronic systems. For such a 3D integrated circuits, low-temperature wafer bonding is required to be compatible with the back-end-of-the-line processing conditions. Recently our investigation on surface melting characteristics of copper nanorod arrays showed that the threshold of the morphological changes of the nano-rod arrays occurs at a temperature significantly below the copper bulk melting point. With this unique property of the copper nanorod arrays, wafer bonding using copper nanorod arrays as a bonding intermediate layer was investigated at low temperatures (400 °C and lower). 200 mm Wafers, each with a copper nanorod array layer, were bonded at 200 – 400 °C and with a bonding down-force of 10 kN in a vacuum chamber. Bonding results were evaluated by razor blade test, mechanical grinding and polishing, and cross-section imaging using a focus ion beam/scanning electron microscope (FIB/SEM). The FIB/SEM images show that the copper nanorod arrays fused together accompanying by a grain growth at a bonding temperature of as low as 200 °C. A dense copper bonding layer was achieved at 400 °C where copper grains grew throughout the copper structure and the original bonding interface was eliminated. The sintering of such nanostructures depends not only on their feature size, but also significantly influenced by the bonding pressure. These two factors both contribute to the mass transport in the nanostructure, leading to the formation of a dense bonding layer.


2021 ◽  
Vol 8 ◽  
Author(s):  
Bang Jiang ◽  
Qiaoxin Zhang ◽  
Lin Shi ◽  
Chundong Zhu ◽  
Zhiwen Chen ◽  
...  

Transient liquid phase sintering (TLPS) is a promising joining technology that can achieve high temperature resistant solder joints at low temperature, showing excellent potential in power electronics. In this work, Cu/Cu-In/Cu solder joints were successfully prepared by TLPS process. The effects of bonding pressure and holding time on the microstructure and shear strength of Cu-In TLPS joints at 260 and 320°C were studied. The results showed that as bonding pressure increased from 0.1–0.6 MPa, the porosity decreased and shear strength increased significantly. No obvious change was found as bonding pressure continued to increase to 1 MPa. As holding time increased at 260°C, Cu11In9 was formed and gradually transformed to Cu2In that can withstand elevated temperature. Meanwhile, the porosity decreased while shear strength increased. It was calculated that volume expansion (12.74%) occurred during the phase transition from Cu11In9 to Cu2In. When bonding temperature increased to 320°C, only Cu2In was detected and then gradually transformed to Cu7In3 with the growing holding time. As holding time reached 120 min, their porosity increased and lead to weak shear strength due to volume shrinkage (15.43%) during the phase transition from Cu2In to Cu7In3.


Author(s):  
S Bair

A thorough characterization of all viscous flow properties relevant to steady simple shear was carried out for five liquid lubricants of current interest to tribology. Shear stresses were generated to values significant to concentrated contact lubrication. Two types of non-Newtonian response were observed: shear-thinning as a power-law fluid and near rate-independence. Functions and parameters were obtained for the temperature and pressure dependence of the viscosity and of the time constant for the Carreau-Yasuda equation. Results are consistent with free volume and kinetic theory, but directly contradict many assumptions currently utilized for numerical simulation and for extracting rheological properties from contact measurements.


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