High-Frequency and Low-Temperature Thermosonic Bonding of Lead-Free Microsolder Ball on Silver Pad Without Flux

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Fuliang Wang ◽  
Junhui Li ◽  
Lei Han
Keyword(s):  
Low Temperature ◽  
High Frequency ◽  
Bonding Strength ◽  
Bonding Temperature ◽  
Lead Free ◽  
High Bonding Strength ◽  
Solder Balls ◽  
Laser Soldering ◽  
Free Solder ◽  
Bonding Method

Lead-free solder balls are environment friendly; however, they require a high bonding temperature, which causes problems in the microelectronics package industry. To reduce the bonding temperature, a 60 kHz high-frequency thermosonic bonding method is proposed and realized using a lab bonder. Experimental results showed that this method could be used to bond a 300 μm-diameter Sn–Ag–0.5Cu microsolder ball onto a silver pad without flux at a low temperature of 160 °C in 3 s. A ball shear test showed that the high frequency led to a high bonding strength of 58.8 MPa, and a dimpled structure was observed at the bonding interface by SEM. Compare with the reflow method or laser soldering method, the proposed method requires a low bonding temperature and leads to a high bonding strength.

Effect of Thickness of Pd Plating Layer on Shear Strength of Lead-Free Solder Ball Joint With Electroless Ni/Pd/Au Plated Electrode

2011 ◽  
Author(s):  
Takahiro Kano ◽  
Ikuo Shohji ◽  
Tetsuyuki Tsuchida ◽  
Toshikazu Ookubo
Keyword(s):  
Reaction Layer ◽  
Shear Force ◽  
Solder Ball ◽  
Lead Free ◽  
Joint Interface ◽  
Lead Free Solder ◽  
Solder Balls ◽  
Free Solder ◽  
Ball Joints ◽  
Electroless Ni

An electroless Ni/Pd/Au plated electrode is expected to be used as an electrode material for lead-free solder to improve joint reliability. The aim of this study is to investigate the effect of the thickness of the Pd layer on joint properties of the lead-free solder joint with the electroless Ni/Pd/Au plated electrode. Solder ball joints were fabricated with Sn-3Ag-0.5Cu (mass%) lead-free solder balls and electroless Ni/Pd/Au and Ni/Au plated electrodes. Ball shear force and microstructure of the joint were investigated. The (Cu,Ni)6Sn5 reaction layer formed in the joint interface in all specimens. The thickness of the reaction layer decreased with increasing the thickness of the Pd layer. In the joint with a Pd layer 0.36 μm thick, the remained Pd layer was observed in the joint interface. In the joint, impact shear force decreased compared with that of the joint without the remained Pd layer. On the contrary, when the thickness of the Pd layer was less than 0.36 μm, the Pd layer was not remained in the joint interface and impact shear force improved. Impact shear force of the joint with the electroless Ni/Pd/Au plated electrode was higher than that with the electroless Ni/Au one.

scholarly journals Growth Kinetics of Reaction Layers in Flip Chip Joints with Cu-cored Lead-free Solder Balls

2004 ◽  
Vol 45 (3) ◽  
pp. 754-758 ◽  
Author(s):  
Ikuo Shohji ◽  
Yuji Shiratori ◽  
Hiroshi Yoshida ◽  
Masahiko Mizukami ◽  
Akira Ichida
Keyword(s):  
Growth Kinetics ◽  
Flip Chip ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Balls ◽  
Free Solder ◽  
Kinetics Of Reaction ◽  
Kinetics Of

Low Temperature Anodic Bonding for MEMS Applications

2002 ◽  
Author(s):  
J. Wei ◽  
Z. P. Wang ◽  
L. Wang ◽  
G. Y. Li ◽  
Z. Q. Mo
Keyword(s):  
Low Temperature ◽  
Bonding Strength ◽  
Transition Period ◽  
Bonding Temperature ◽  
Testing Machine ◽  
Acoustic Microscopy ◽  
Anodic Bonding ◽  
Dominant Factor ◽  
Glass Wafer ◽  
Bonding Parameters

In this paper, anodic bonding between silicon wafer and glass wafer (Pyrex 7740) has been successfully achieved at low temperature. The bonding strength is measured using a tensile testing machine. The interfaces are examined and analyzed by scanning acoustic microscopy (SAM), scanning electron microscopy (SEM) and secondary ion mass spectrometry (SIMS). Prior to bonding, the wafers are cleaned in RCA solutions, and the surfaces become hydrophilic. The effects of the bonding parameters, such as bonding temperature, voltage, bonding time and vacuum condition, on bonding quality are investigated using Taguchi method, and the feasibility of bonding silicon and glass wafers at low temperature is explored. The bonding temperature used ranges from 200 °C to 300 °C. The sensitivity of the bonding parameters is analyzed and it is found that the bonding temperature is the dominant factor for the bonding process. Therefore, the effects of bonding temperature are investigated in detail. High temperatures cause high ion mobility and bonding current density, resulting in the short transition period to the equilibrium state. Almost bubble-free interfaces have been obtained. The bonded area increases with increasing the bonding temperature. The unbonded area is less than 1.5% within the whole wafer for bonding temperature between 200 °C to 300 °C. The bonding strength is higher than 10 MPa, and increases with the bonding temperature. Fracture mainly occurs inside the glass wafer other than in the interface when the bonding temperature is higher than 225 °C. SIMS results show that the chemical bonds of Si-O form in the interface. Higher bonding temperature results in more oxygen migration to the interface and more Si-O bonds. The bonding mechanisms consist of hydrogen bonding and Si-O chemical reaction.

Effect of Sb additions on the creep behaviour of low temperature lead-free Sn–8Zn–3Bi solder alloy

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Guang Ren ◽  
Maurice Collins
Keyword(s):  
Low Temperature ◽  
Solder Alloy ◽  
Creep Behaviour ◽  
Lead Free ◽  
Coefficient Of Determination ◽  
Secondary Creep ◽  
Lead Free Solder ◽  
Solder Alloys ◽  
Content Type ◽  
Free Solder

Purpose This paper aims to investigate the creep behaviour of the recently developed Sn–8Zn–3Bi–xSb (x = 0, 0.5, 1.0 and 1.5) low temperature lead-free solder alloys. Design/methodology/approach An in-house compressive test rig was developed to perform creep tests under stresses of 20–40 MPa and temperature range 25°C–75 °C. Dorn power law and Garofalo hyperbolic sine law were used to model the secondary creep rate. Findings High coefficient of determination R2 of 0.99 is achieved for both the models. It was found that the activation energy of Sn–8Zn–3Bi solder alloy can be significantly increased with addition of Sb, by 60% to 90 kJ/mol approximately, whereas the secondary creep exponent falls in the range 3–7. Improved creep resistance is attributed to solid solution strengthening introduced by micro-alloying. Creep mechanisms that govern the deformation of these newly developed lead-free solder alloys have also been proposed. Originality/value The findings are expected to fill the gap of knowledge on creep behaviour of these newly developed solder alloys, which are possible alternatives as lead-free interconnecting material in low temperature electronic assembly.

Effect of Cooling Rate on Intermetallic Compounds Formation in Sn-Ag-Cu-In Solder

2018 ◽  
Vol 941 ◽  
pp. 2075-2080
Author(s):  
Kenji Miki ◽  
Tatsuya Kobayashi ◽  
Ikuo Shohji ◽  
Yusuke Nakata
Keyword(s):  
Solder Joint ◽  
Cooling Rate ◽  
Shear Force ◽  
Bonding Temperature ◽  
Lead Free ◽  
Joint Interface ◽  
Lead Free Solder ◽  
Vacuum Atmosphere ◽  
Free Solder ◽  
Large Formation

The effect of the cooling rate in bonding on IMCs formation and their morphology in the solder joint with Sn-3.0Ag-0.7Cu-5.0In (mass%) lead-free solder was investigated. As the substrate, the Cu plate and the Cu plate with electroplated Ni were prepared. Bonding was conducted in the vacuum atmosphere, and bonding temperature and time were 300°C and 10 minutes, respectively. The cooling rates in the bonding were changed from 0.02°C/s to 0.2°C/s. In both Cu/Cu and Cu/Ni joints, scallop-shaped IMCs form at the joint interfaces regardless of the cooling rate. In the Cu/Cu joint, Cu6(Sn,In)5 and Cu3(Sn,In) layers form at the joint interface. In the Cu/Ni joint, (Cu,Ni)6(Sn,In)5 and (Cu,Ni)3(Sn,In) layers form at the joint interface with Cu and the (Cu,Ni)6(Sn,In)5 layer forms at the joint interface with Ni. Die shear force of the Cu/Ni joints are a little larger than those of the Cu/Cu joints. Fracture occurs in the boundary between the scallop-shaped layer or the granular IMC layer and the layered IMC in both joints. The cooling rate from the peak temperature to solidification is an important factor to decide the shape of formed IMC. When the cooling rate is high and supercooling becomes large, formation of pillar-shaped IMCs occurs easily.

Cu-Cu low temperature bonding based on lead-free solder with graphene interlayer

2019 ◽  
Vol 115 (12) ◽  
pp. 122102 ◽  
Author(s):  
Wenhua Yang ◽  
Jie Zhou ◽  
Xinyuan Jiang ◽  
Ximing Ye ◽  
Xiaofeng Xuan ◽  
...  
Keyword(s):  
Low Temperature ◽  
Lead Free ◽  
Lead Free Solder ◽  
Free Solder ◽  
Low Temperature Bonding
Sign in / Sign up

Export Citation Format

Share Document