• Journal of the Microelectronics and Packaging Society
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• v.22 no.2
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• pp.55-59
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• 2015

Novel low-volume solder-on-pad (SoP) process is proposed for a fine pitch Cu pillar bump interconnection. A novel solder bumping material (SBM) has been developed for the $60{\mu}m$ pitch SoP using screen printing process. SBM, which is composed of ternary Sn-3.0Ag-0.5Cu (SAC305) solder powder and a polymer resin, is a paste material to perform a fine-pitch SoP in place of the electroplating process. By optimizing the volumetric ratio of the resin, deoxidizing agent, and SAC305 solder powder; the oxide layers on the solder powder and Cu pads are successfully removed during the bumping process without additional treatment or equipment. The Si chip and substrate with daisy-chain pattern are fabricated to develop the fine pitch SoP process and evaluate the fine-pitch interconnection. The fabricated Si substrate has 6724 under bump metallization (UBM) with a $45{\mu}m$ diameter and $60{\mu}m$ pitch. The Si chip with Cu pillar bump is flip chip bonded with the SoP formed substrate using an underfill material with fluxing features. Using the fluxing underfill material is advantageous since it eliminates the flux cleaning process and capillary flow process of underfill. The optimized interconnection process has been validated by the electrical characterization of the daisy-chain pattern. This work is the first report on a successful operation of a fine-pitch SoP and micro bump interconnection using a screen printing process.

• Journal of Welding and Joining
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• v.20 no.5
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• pp.72-77
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• 2002

Flip-chip interconnection that uses solder bump is an essential technology to improve the performance of microelectronics which require higher working speed, higher density, and smaller size. In this paper, the shear strength of Cr/Cr-Cu/Cu UBM structure of the high-melting solder b01p and that of low-melting solder bump after aging is evaluated. Observe intermetallic compound and bump joint condition at the interface between solder and UBM by SEM and TEM. And analyze the shear load concentrated to bump applying finite element analysis. As a result of experiment, the maximum shear strength of Sn-97wt%Pb which was treated 900 hrs aging has been decreased as 25% and Sn-37wt%Pb sample has been decreased as 20%. By the aging process, the growth of $Cu_6Sn_5$ and $Cu_3Sn$ is ascertained. And the tendency of crack path movement that is interior of a solder to intermetallic compound interface is found.

• Journal of the Microelectronics and Packaging Society
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• v.9 no.1
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• pp.35-41
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• 2002

Flip-chip interconnection that uses solder bump is an essential technology to improve the performance of micro-electronics which require higher working speed, higher density, and smaller size. In this paper, the shear strength of Cr/Cr-Cu/Cu UBM structure of the high-melting solder bump and that of low-melting solder bump after aging is evaluated. Observe intermetallic compound and bump joint condition at the interface between solder and UBM by SEM and TEM. And analyze the shear load concentrated to bump applying finite element analysis. As a result of experiment, the maximum shear strength of Sn-97wt%Pb which was treated 900 hrs aging has been decreased as 25% and Sn-37wt%Pb sample has been decreased as 20%. By the aging process, the growth of $Cu_6/Sn_5$ and $Cu_3Sn$ is ascertained. And the tendency of crack path movement that is interior of a solder to intermetallic compound interface is found.

• Proceedings of the Korean Reliability Society Conference
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• 2000.04a
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• pp.97-103
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• 2000

전자 산업의 발달에 따라 전자 패키지에서 소자의 소형화 및 고집적화가 가속화되고 그로 인해 interconnection 부분의 신뢰성 평가의 중요성이 나날이 증가되고 있다. 특히 이러한 interconnection 부분 중 솔더 접합부는 사용중 솔더와 UBM(Under Bump Metallurgy) 층 사이에 금속간화합물이 생성되어 접합 강도가 저하되는 것이 큰 문제로 지적되고 있다. 본 연구에서는 공정 Sn-Ag 솔더 접합부에 대해 열시효 시간에 따라 접합 강도를 측정하고 파괴 기구 및 파괴 경로의 분석을 통해 접합 강도 변화와의 연관성을 도출하고자 하였다. 그 결과 열시효 초기에는 미세 조직의 조대화 및 불균일 조대 성장이 가속화되면서 응력 및 변형 집중으로 인해 솔더 내부에서 연성 파괴가 일어나 급격한 접합 강도의 저하가 발생하였으나 금속간 화합물이 생성, 성장함에 따라 금속간 화합물 내부에서의 취성 파괴가 나타나면서 접합 강도 저하가 포화되는 경향을 보였다.