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Journal of ELECTRONIC MATERIALS, Vol. 46, No. 1, 2017
DOI: 10.1007/s11664-016-4895-5
2016 The Minerals, Metals & Materials Society
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Web End = A Study on the Nanober-Sheet Anisotropic Conductive Films (NS-ACFs) for Ultra-Fine-Pitch Interconnection Applications
SANG-HOON LEE1 and KYUNG-WOOK PAIK1,2
1.Department of Materials Science and Engineering, KAIST, 373-1, Guseong-dong, Yuseong-gu, Daejeon 305-701, Republic of Korea. 2.e-mail: [email protected]
Nanober-sheet anisotropic conductive lms (NS-ACFs) were invented to overcome the limitations of high joint resistance and short-circuit issues of ultra-ne-pitch interconnections. The NS-ACFs have great advantages in terms of suppressing conductive particle movement during the ip-chip bonding process. In a 20-lm ultra-ne-pitch with 7-lm bump spacing ultra-ne-pitch chip-on-glass assembly, suppression effects of conductive particle movement were signicantly improved by using the NS-ACFs because an unmelted NS inside the ACFs suppressed the mobility of conductive particles so that they would not ow out during the bonding process. The NS-ACFs could signicantly increase the capture rate of conductive particles from 31% up to 81% compared to conventional ACFs. Moreover, excellent electrical contact properties were obtained without melting the nanober material which was essential for the conventional nanober ACFs. The NS-ACFs are promising interconnection materials for ultra-ne-pitch packaging applications.
Key words: Nanober-sheet (NS), nanober, electrospinning, anisotropic conductive lms (ACFs), ultra-ne-pitch interconnection, plasma etching
INTRODUCTION
Fine-pitch interconnection technology has become a very important eld in packaging industry since the demands of smart electronic devices such as tablet personal computers, televisions, smartphones have risen dramatically. The packaging industry requires more advanced technology to fulll customer needs in electronic devices such as high-performance, multi-functionality, and compactness.13 As a consequence, more input/output pins are required within the limited space resulting in the narrower pitch and bump space for ultra-ne-pitch interconnection technology of electronic devices.46
In the ip-chip packaging area, anisotropic conductive lms (ACFs), well-known interconnecting adhesive materials which consist of thermosetting resin and conductive particles in a lm format, have
been widely used to provide anisotropic electrical conduction and adhesion between bumps and electrodes.79 However, in ultra-ne-pitch interconnections, electrical problems have become serious issues with the conventional ACFs as the pitch and space between bumps and electrodes have become ner and ner.10 Bumps with longer length and narrower width have caused less number of conductive particles captured between the bump...