• 마이크로전자및패키징학회지
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• 제17권4호
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• pp.73-76
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• 2010

A two-facet approach was used to investigate the parametric performance of functional high-speed DDR3 (Double Data Rate) DRAM (Dynamic Random Access Memory) die placed in different types of BGA (Ball Grid Array) packages: wire-bonded BGA (FBGA, Fine Ball Grid Array), flip-chip (FCBGA) and lead-bonded $microBGA^{(R)}$. In the first section, packaged live DDR3 die were tested using automatic test equipment using high-resolution shmoo plots. It was found that the best timing and voltage margin was obtained using the lead-bonded microBGA, followed by the wire-bonded FBGA with the FCBGA exhibiting the worst performance of the three types tested. In particular the flip-chip packaged devices exhibited reduced operating voltage margin. In the second part of this work a test system was designed and constructed to mimic the electrical environment of the data bus in a PC's CPU-Memory subsystem that used a single DIMM (Dual In Line Memory Module) socket in point-to-point and point-to-two-point configurations. The emulation system was used to examine signal integrity for system-level operation at speeds in excess of 6 Gb/pin/sec in order to assess the frequency extensibility of the signal-carrying path of the microBGA considered for future high-speed DRAM packaging. The analyzed signal path was driven from either end of the data bus by a GaAs laser driver capable of operation beyond 10 GHz. Eye diagrams were measured using a high speed sampling oscilloscope with a pulse generator providing a pseudo-random bit sequence stimulus for the laser drivers. The memory controller was emulated using a circuit implemented on a BGA interposer employing the laser driver while the active DRAM was modeled using the same type of laser driver mounted to the DIMM module. A custom silicon loading die was designed and fabricated and placed into the microBGA packages that were attached to an instrumented DIMM module. It was found that 6.6 Gb/sec/pin operation appears feasible in both point to point and point to two point configurations when the input capacitance is limited to 2pF.

• Journal of Welding and Joining
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• 제19권4호
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• pp.406-412
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• 2001

This study is focussed on the numerical prediction of the thermal fatigue life of a ${\mu}BGA$(Micro Ball Grid Array) solder joint. Numerical method is used to perform three-dimensional finite element analysis for Sn-37mass%Pb. Sn-3.5mass%Ag solder alloys during the given thermal cycling. Strain values, along with the result of mechanical fatigue tests for solder alloys were then used to predict the solder joint fatigue life using the Coffin-Manson equation. In this study, a practical correlation for the prediction of the thermal fatigue life is suggested by using the dimensionless variable $\gamma$. As a result. it could be found that Sn-3.5mass%Ag has longer fatigue life than Sn-37mass%Pb in low cycle fatigue. In addition. the result with ${\gamm}ashow$a good agreement with the FEA results.

• Journal of Welding and Joining
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• 제21권3호
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• pp.92-98
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• 2003

This paper describes the numerical prediction of the thermal fatigue life of a $\mu$BGA(Micro Ball Grid Array) solder joint. Finite element analysis(FEA) was employed to simulate thermal cycling loading for solder joint reliability. Strain values, along with the result of mechanical fatigue tests for solder alloys were then used to predict the solder joint fatigue life using the Coffin-Manson equation. The results show that Sn-3.5mass%Ag solder had the longest thermal fatigue life in low cycle fatigue. Also a practical correlation for the prediction of the thermal fatigue life was suggested by using the dimensionless variable ${\gamma}$, which was possible to use several lead free solder alloys for prediction of thermal fatigue life. Furthermore, when the contact angle of the ball and chip has 50 degrees, solder joint has longest fatigue life.

• 마이크로전자및패키징학회지
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• 제8권3호
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• pp.1-9
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• 2001

본 논문에서는 마이크로 납볼 격자 배열 ($\mu$BGA)패키지의 검사 알고리듬을 제안하였다. 이 알고리듬의 개발은 납볼 배열의 미세 크기 때문에 사람의 사각으로는 결함을 식별하기 어려운 점에 기인하였다. 특히, 여기에서 보인 자동 시각 $\mu$BGA 검사 알고리듬은 소위 말하는 이차원 오차뿐만 아니라 볼의 높이 오차까지 검사할 수 있다. 검사 알고리듬은 특수하게 제작된 청색 조명 하에서 이차원 $\mu$BGA 영상을 사용하고 회전 불변 알고리듬으로 영상을 처리하였다. 그리고 2개의 카메라를 사용하여 높이 오차를 검출할 수 있었다 모의실험결과, 제안한 알고리듬이 기존 방법에 비하여 괄목할 만큼 납볼 결함을 검출할 수 있음을 보였다.

• International journal of advanced smart convergence
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• 제8권3호
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• pp.39-45
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• 2019

This paper presents an optical technique for the three-dimensional (3D) shape inspection of micro solder balls used in ball-grid array (BGA) packaging. The proposed technique uses an optical source composed of spatially arranged light-emitting diodes (LEDs) and the results are derived based on the specular reflection characteristics of the micro solder balls for BGA A vision system comprising a camera and LEDs is designed to capture the reflected images of multiple solder balls arranged arbitrarily on a tray and the locations of the LED point-light-source reflections in each ball are determined via image processing, for shape inspection. The proposed methodology aims to determine the presence of defects in 3D BGA shape using the statistical information of the relative positions of multiple BGA balls, which are included in the image. The presence of the BGA balls with large deviations in relative position imply the inconsistencies in their shape. Experiments were conducted to verify that the proposed method could be applied to inspection without sophisticated mechanism and productivity problem.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.873-878
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• 2000

Semiconductor packaging technology is changed rapidly according to the trends of the micro miniaturization of multimedia and information equipment. For I/O limitation and fine pitch limitation, DIP and SOP/QFP are replaced by BGA/CSP. This is one of the surface mount technology(SMT). Solder ball is bumped n the die pad and connected onto mounting board. In ball bump formation, vacuum suction type ball alignment process is widely used, However this type has some problems such as ionization, static electricity and difficulty of fifo(first-input first-out) of solder balls. Seesaw type is reducing these problems and has a structural simplicity and economic efficiency. Ball cartridge velocity and ball aligned plate angle are Important variables to improve the ball alignment Process. In this paper, seesaw-type CSP solder ball loader is developed and the optimal velocity and plate angle are proposed.

• 한국진공학회지
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• 제13권3호
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• pp.127-131
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• 2004

BGA(ball grid array) package에서 솔더볼의 피로강도에 대한 솔더 조성에 대한 영향을 조사하기 위하여 패키지 신뢰성 시험을 실시하였다. 공정조성 솔더 63Sn/37Pb, 62Sn/36Pb/2Ag, 63Sn/34.4Pb/2Ag/0.5Sb 솔더를 이용하여 제조된 시편을 MRT Lv3 (moisture resistance test level) 조건에서 전처리 후 T/C(temperature cycle test) 실험을 수행하였다. 각각의 신뢰성 시험에 대하여 전단강도를 측정하였으며, 미세 조직 사진을 얻었다. 또한, SEM (scanning electron microscope)과 EDX (energy dispersive X-ray)를 이용하여 파괴 기구에 대한 분석을 실시하였다. Sn63Pb34.5Ag2Sb0.5 솔더에서 Au-Sn 성장비는 63Sn/37Pb, 62Sn/36Pb/2Ag 솔더에 비해 느리다 솔더 조성에 따른 솔더볼의 전단응력 저하에 대하여 논의하였다.

• Journal of Mechanical Science and Technology
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• 제16권7호
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• pp.919-926
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• 2002

In this study, the numerical prediction of the thermal fatigue lie? of a $\mu$BGA (Micro Ball Grid Array) solder joint was focused. Numerical method was performed using the three-dimensional finite element analysis for various solder alloys such as Sn-37%Pb, Sn-3.5%Ag, Sn-3.5%Ag-0.7%Cu and Sn-3.5%Ag-3%In-0.5%Bi during a given thermal cycling. Strain values obtained by the result of mechanical fatigue tests for solder alloys, were used to predict the solder joint fatigue life using the Coffin-Manson equation. The numerical results showed that Sn-3.5%Ag with the 50-degree ball shape geometry had the longest thermal fatigue life in low cycle fatigue. A practical correlation for the prediction of the thermal fatigue life was also suggested by using the dimensionless variable γ. Additionally Sn-3.5Ag-0.75Cu and Sn-2.0Ag-0.5Cu-2.0Bi were applied to 6$\times$8$\mu$BGA obtained from the 63Sn-37Pb Solder. This 6$\times$8$\mu$BGA were tested at different aging conditions at 130$\^{C}$, 150$\^{C}$, 170$\^{C}$ for 300, 600 and 900 hours. Thickness of the intermetallic compound layer was measured thor each condition and the activation energy thor their growth was computed. The fracture surfaces were analyzed using SEM (Scanning Electron Microscope) with EDS ( Energy Dispersive Spectroscopy).

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 춘계학술대회논문집
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• pp.437-442
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• 2005

In this paper, we proposed the 2-dimensional inspection algorithm for micro-BGA(Ball Grid Array) device using a vision system. The proposed method uses the subpixel algorithm for high precision. The proposed algorithm preferentially extracts the package area of device in the input image. After the extraction of package area, each ball areas are extracted by ball search window method. The parameters for inspection are calculated for the extracted ball area. In the simulation results, we have the average error within $17{\mu}m$.

• 마이크로전자및패키징학회지
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• 제19권1호
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• pp.81-87
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• 2012

본 논문에서는 마이크로 BGA 패키지 내외부의 마이크로 볼의 3차원 형상을 측정하는 광학 측정 시스템을 제안하고 이를 구현한다. 대부분의 시각 검사 시스템은 마이크로 볼의 복잡한 반사 특성 때문에 검사에 어려움을 겪고 있다. 정확한 형상의 측정을 위해서, 특별히 설계된 시각 센서 시스템을 제안하고, 위상이송 모아레 간섭계의 측정원리에 기반한 형상측정 알고리즘을 제안한다. 센서 시스템은 4개의 서브시스템을 보유한 패턴 투사 시스템과 영상획득 시스템으로 구성된다. 패턴 투사용 서브시스템은 공간상으로 서로 상이한 투사 방향을 가지며, 이는 측정 물체에 각기 다른 입사 방향을 가지는 패턴 조명이 투사될 수 있도록 하는 것을 목적으로 한다. 위상이송 모아레 간섭계의 구현을 위한 정밀 위상이송을 위해서, 각 서브시스템의 패턴 격자는 PZT 구동기를 이용하여 일정 간격으로 이송한다. 최종적으로 측정되는 마이크로 볼의 경면반사와 그림자 영역을 효과적으로 제거하기 위해서, 다중 패턴 투사 시스템과 영상획득 시스템을 구현하고, 이를 테스트한다. 특히, 다중 프로젝션을 이용하여 획득되는 다중 높이 정보를 효과적으로 융합하기 위하여, 베이지안 센서 융합 이론을 기반으로한 센서 융합 알고리즘이 제안된다. 제안되는 시스템의 원리검증과 성능확인을 위해, 마이크로 BGA볼과 기판 범프의 측정대상물에 대해서, 측정 반복성을 중심으로 실험이 수행되었으며, 획득된 실험 결과를 분석하고 논의한다.