ENEPIG 표면처리에서의 Sn-Ag-Cu 솔더조인트 신뢰성: 2. Pd 촉매 시간의 영향

허석환,이지혜,함석진,Huh, Seok-Hwan,Lee, Ji-Hye,Ham, Suk-Jin 한국마이크로전자및패키징학회 2014 마이크로전자 및 패키징학회지 Vol.21 No.3

솔더조인트의 신뢰성에는 인쇄회로기판의 표면처리 특성이 많은 영향을 미치고 있다. 본 연구에서는 ENEPIG 표면처리에서 Sn-4.0wt%Ag-0.5wt%Cu (SAC405) 솔더와 Pd 촉매 처리 시간에 따른 high speed shear 에너지 및 파괴 모드를 연구하였다. 또한 Pd 촉매 처리 시간과 무전해 Ni-P 도금의 표면 거칠기 (Ra)와의 관계를 규명하였다. Pd 촉매 처리 시간이 길어질수록 Ni-P nodule의 면적은 넓어지고, Ni-P 도금의 표면 거칠기 (Ra)는 감소한다. 이러한 영향으로 질산 기상 처리한 시편의 high speed shear 평가후 quasi-brittle과 brittle 모드의 점유율은 감소한다. 이는 Pd 촉매 처리 시간의 증가가 SAC405 솔더조인트의 신뢰도를 향상시키는 역할을 한다는 것을 나타낸다. The reliability of solder joint is significantly affected by the property of surface finish. This paper reports on a study of high speed shear energy and failure mode for Sn-4.0wt%Ag-0.5wt%Cu (SAC405) solder joints with the time of Pd activation. The nodule size of electroless Ni-P deposit increased with increasing the time of Pd activation. The roughness (Ra) of electroless Ni-P deposit decreased with increasing the time of Pd activation. Then, with $HNO_3$ vapor, the quasi-brittle and brittle mode of SAC405 solder joint decreased with increasing the time of Pd activation. This results indicate that the increase in the Pd activation time for Electroless Ni/ Electroless Pd/ Immersion Au (ENEPIG) surface finish play a critical role for improving the robustness of SAC405 solder joint.

고온고습 전압인가(Biased HAST) 시험에서 인쇄회로기판의 이온 마이그레이션 불량 메커니즘

허석환,신안섭,함석진,Huh, Seok-Hwan,Shin, An-Seob,Ham, Suk-Jin 한국마이크로전자및패키징학회 2015 마이크로전자 및 패키징학회지 Vol.22 No.1

전자 제품의 경박 단소화 및 고집적화가 이루어 지면서 반도체 칩뿐만 아니라 유기 기판도 고집적화가 요구되고 있다. 본 연구는 인쇄회로기판의 미세 피치 회로에 대한 고온고습 전압인가 시험을 실시하여 불량 메커니즘을 연구하였다. $130^{\circ}C/85%RH/3.3V$와 $135^{\circ}C/90%RH/3.3V$ 시험조건에서 고온고습 전압시험(Biased HAST)의 가속 계수는 2.079로 계산되었다. 불량 메커니즘 분석을 위하여 집속이온빔(FIB) 분석이 이용되었다. (+)전극에서는 콜로이드 형태의 $Cu_xO$와 $Cu(OH)_2$가 형성되었으며, (-)전극에서는 수지형태의 Cu가 관찰되었다. 이를 통해 $Cu^{2+}$ 이온과 전자($e^-$)가 결합한 수지상 Cu에 의해 절연파괴가 일어난다는 것을 확인하였다. By the trends of electronic package to be smaller, thinner and more integrative, organic printed circuit board is required to be finer Cu trace pitch. This paper reports on a study of failure mechanism for PCB with fine Cu trace pitch using biased HAST. In weibull analysis of the biased HAST lifetime, it is found that the acceleration factor (AF) of between $135^{\circ}C/90%RH/3.3V$ and $130^{\circ}C/85%RH/3.3V$ is 2.079. A focused ion beam (FIB) was used to polish the cross sections to reveal details of the microstructure of the failure mode. It is found that $Cu_xO/Cu(OH)_2$ colloids and Cu dendrites were formed at anode (+) and at cathode (-), respectively. Thus, this gives the evidence that Cu dendrites formed at cathode by $Cu^{2+}$ ion migration lead to a short failure between a pair of Cu nets.

ENEPIG 표면처리에서의 Sn-Ag-Cu 솔더조인트 신뢰성: 1. 무전해 Ni-P도금의 두께와 표면거칠기의 영향

허석환,이지혜,함석진,Huh, Seok-Hwan,Lee, Ji-Hye,Ham, Suk-Jin 한국마이크로전자및패키징학회 2014 마이크로전자 및 패키징학회지 Vol.21 No.3

전자 제품의 경박 단소화 및 고집적화가 이루어 지면서 실리콘 집과 인쇄회로기판의 인터커넥션의 고신뢰도가 요구되고 있다. 본 연구는 Sn-4.0wt%Ag-0.5wt%Cu (SAC405) 솔더와 다양한 무전해 Ni-P 도금 두께에서의 high speed shear 에너지 및 파괴 모드를 연구하였다. 파괴 모드 분석을 위하여 집속이온빔(FIB) 분석이 이용되었다. 질산 기상 처리하지 않은 $1{\mu}m$ Ni-P 시편에서 낮은 shear 에너지가 나왔으며, 이는 솔더레지스트 선단에서 파단의 원인을 제공하는 것이 확인되었다. 질산 기상 처리한 시편에서 무전해 Ni-P 도금 두께가 커질수록 취성 파괴 모드는 감소한다. 또 Ni-P 도금 두께와 표면 거칠기(Ra)는 반비례 관계를 가진다. 이는 Ni-P 도금의 표면 거칠기를 낮추면 SAC405 솔더 조인트의 신뢰도를 향상시킨다는 사실을 나타낸다. By the trends of electronic package to be smaller, thinner and more integrative, the reliability of interconnection between Si chip and printed circuit board is required. This paper reports on a study of high speed shear energy of Sn-4.0wt%Ag-0.5wt%Cu (SAC405) solder joints with different the thicknesses of electroless Ni-P deposit. A high speed shear testing of solder joints was conducted to find a relationship between the thickness of Ni-P deposit and the brittle fracture in electroless Ni-P deposit/SAC405 solder. A focused ion beam (FIB) was used to polish the cross sections to reveal details of the microstructure of the fractured pad surface with and without $HNO_3$ vapor treatment. The high speed shear energy of SAC405 solder joint with $1{\mu}m$ Ni-P deposit was found to be lower without $HNO_3$ vapor, compared to those of over $3{\mu}m$ Ni-P deposit. This could be due to the edge of solder resist in $1{\mu}m$ Ni-P deposit, which provides a fracture location for the weakened shear energy of solder joints and brittle fracture in high speed shear test. With $HNO_3$ vapor, the brittle fracture mode in high speed shear test decreased with increasing the thickness of Ni-P deposit. Then the roughness (Ra) of Ni-P deposits decreased with increasing its thickness. Thus, this gives the evidence that the decrease in roughness of Ni-P deposit for Eelectroless Ni/ Electroless Pd/ Immersion Au (ENEPIG) surface play a critical role for improving the robustness of SAC405 solder joint.

흡습 및 탈습의 특성화를 통한 전자 패키징 소재의 습기 수착 수준

박희진(Heejin Park),함석진(Suk-Jin Ham) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11

The moisture within polymeric material used in flexible electronic packaging devices causes failures during manufacturing process due to vapor pressure at interfacing layer and functional defects due to deterioration of mechanical or electrical properties. Knowledge of moisture sorption properties of material is essential in optimal material development and analysis of reliability of integrated packaging devices. In this paper, both temperature dependent absorption and desorption properties according to Arrhenius equation are parameterized and the effects of water activities and temperature are discussed as well. Activation energy obtained from parameterized diffusivity determines acceleration factor in equivalency of moisture sorption level, which enables to estimate the effect of moisture diffusivity on the equivalent total elapsed testing time required for evaluating MSL(moisture sorption level). The acceleration factor of flexible electronic module is exampled by estimating diffusivity at both accelerated and water spraying condition, which is compared with estimation from polyethylene terephthalate (PET).

전자 패키징 소재의 수착 특성화를 통한 신뢰성 평가

박희진(Heejin Park),함석진(Suk-Jin Ham) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.3

무전해 Ni-P 두께와 Assembly Process가 Solder Ball Joint의 신뢰성에 미치는 영향

이지혜,허석환,정기호,함석진,Lee, Ji-Hye,Huh, Seok-Hwan,Jung, Gi-Ho,Ham, Suk-Jin 대한용접접합학회 2014 대한용접·접합학회지 Vol.32 No.3

The ability of electronic packages and assemblies to resist solder joint failure is becoming a growing concern. This paper reports on a study of high speed shear energy of Sn-4.0wt%Ag-0.5wt%Cu (SAC405) solder with different electroless Ni-P thickness, with $HNO_3$ vapor's status, and with various pre-conditions. A high speed shear testing of solder joints was conducted to find a relationship between the thickness of Ni-P deposit and the brittle fracture in electroless Ni-P deposit/SAC405 solder interconnection. A focused ion beam (FIB) was used to polish the cross sections to reveal details of the microstructure of the fractured pad surface with and without $HNO_3$ vapor treatment. A scanning electron microscopy (SEM) and an energy dispersive x-ray analysis (EDS) confirmed that there were three intermetallic compound (IMC) layers at the SAC405 solder joint interface: $(Ni,Cu)_3Sn_4$ layer, $(Ni,Cu)_2SnP$ layer, and $(Ni,Sn)_3P$ layer. The high speed shear energy of SAC405 solder joint with $3{\mu}m$ Ni-P deposit was found to be lower in pre-condition level#2, compared to that of $6{\mu}m$ Ni-P deposit. Results of focused ion beam and energy dispersive x-ray analysis of the fractured pad surfaces support the suggestion that the brittle fracture of $3{\mu}m$ Ni-P deposit is the result of Ni corrosion in the pre-condition level#2 and the $HNO_3$ vapor treatment.

미세 압축 시험을 통한 마그네슘의 결정방위에 따른 변형 특성 연구

김규석(Gyu Seok Kim),김미양(Miyang Kim),함석진(Suk-Jin Ham) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.5