High power and fine pitch assembly using solder Anisotropic Conductive Films (ACFs) combined with ultrasonic bonding technique

2010 ◽  
Author(s):  
Kiwon Lee ◽  
Kyung Wook Paik
Keyword(s):  
High Power ◽  
Conductive Films ◽  
Ultrasonic Bonding ◽  
Fine Pitch ◽  
Bonding Technique

scholarly journals Low Temperature Flex-on-Flex Assembly Using Polyvinylidene Fluoride Nanofiber Incorporated Sn58Bi Solder Anisotropic Conductive Films and Vertical Ultrasonic Bonding

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Tae-Wan Kim ◽  
Kyung-Lim Suk ◽  
Sang-Hoon Lee ◽  
Kyung-Wook Paik
Keyword(s):  
Polyvinylidene Fluoride ◽  
Short Circuit ◽  
Flexible Substrate ◽  
Capture Rate ◽  
Bonding Process ◽  
Conductive Films ◽  
Ultrasonic Bonding ◽  
Fine Pitch ◽  
Solder Balls ◽  
Bonding Method

In this study, solder ball incorporated polyvinylidenefluoride (PVDF) nanofiber was added into the ACF system to overcome short circuit issues of fine pitch flex-on-flex (FOF) assembly. Also, in order to improve the thermal mismatch of the flexible substrate which can lead to electrode misalignment during the bonding process, low melting temperature Sn58Bi solder balls were used with vertical ultrasonic (U/S) bonding method. When performing FOF assembly using PVDF nanofiber/Sn58Bi solder ACF and vertical ultrasonic bonding, PVDF nanofiber/Sn58Bi solder ACFs showed 34% higher solder capture rate on an electrode compared to conventional Ni ACFs and conventional Sn58Bi solder ACFs. Additionally, PVDF nanofiber/Sn58Bisolder ACFs showed 100% insulation between neighboring electrodes where conventional Ni ACFs and conventional Sn58Bi solder ACFs showed 75% and 87.5% insulation. Other electrical properties such as contact resistance and current handling capability as well as reliability test of PVDF nanofiber/Sn58Bi solder ACFs showed improved results compared to those of conventional Ni ACFs, which proves the formation of stable solder joint of PVDF nanofiber/Sn58Bi solder ACFs.

Hybrid Bonding Methods Using Ultra Precision Cutting for 3D-SIC

2012 ◽  
Vol 2012 (DPC) ◽  
pp. 001701-001730
Author(s):  
Taiji Sakai ◽  
Nobuhiro Imaizumi ◽  
Masataka Mizukoshi ◽  
Masayuki Kawase ◽  
Ryoji Tanimoto ◽  
...  
Keyword(s):  
Narrow Gap ◽  
Oxidation Layer ◽  
Solid Diffusion ◽  
Fine Pitch ◽  
Single Crystal Diamond ◽  
Thermocompression Bonding ◽  
Ultra Precision ◽  
Lower Height ◽  
Cu Oxidation ◽  
Bonding Technique

We have developed Cu-Cu/adhesives hybrid bonding technique by using collective cutting of Cu bumps and adhesives in order to achieve high density 3D-SIC. It is considered that progression of fine pitch interconnection leads to lower height of bonding electrodes, resulting in narrow gap between 3D-SICs. Therefore, it is difficult to fill in adhesive to such a narrow gap 3D-SICs after bonding, so we consider that hybrid bonding of pre-applied adhesives and Cu-Cu thermocompression bonding must be advantageous, in terms of void less bonding and minimizing bonding stress by adhesives and also low electricity by Cu-Cu solid diffusion bonding. In the present study, we adapted the following process; at first adhesives were spin coated on the wafer with Cu post and then pre-baked. After that, pre-applied adhesives and Cu bumps were successfully cut by single crystal diamond bite. Typical adhesives may cause bite damage with continuous cutting, but in this research, we selected low damage adhesive against continuous cutting, which is important properties to commercial uses. Then, chips with adhesives were attached to substrates and Cu oxidation layer was removed by exposing formic acid atmosphere. Finally permanent bonding was done at 225 degree C for 30 minutes. We concluded that solid diffusion between bonded Cu bumps could be achieved and no adhesive residue could be seen between bonded interfaces by TEM/EDX analysis.

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