• Proceedings of the KAIS Fall Conference
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• 2010.05b
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• pp.981-984
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• 2010

생산성 증가 및 비용 절감을 위해 반도체 공정 기술을 단순화 시키는 것이 필요하다. WBL(Wafer Backside Lamination) 기술을 이용해 필름(film) 형태로 얇은 다이접착제를 웨이퍼(wafer)에 접착하여 반도체 칩과 PCB를 붙이는 방법과 직접 PCB에 다이접착제를 붙이는 방법을 사용하면 획기적으로 공정을 단순화 시킬 수 있다. 하지만 Lamination 기법은 고온을 이용하여 모듈화된 PCB에 접착하므로 전도와 복사에 의해 주변 접착제 필름이 녹아 버리는 문제점이 발생한다. 본 연구에서는 고온으로 인한 필름 융해 현상을 방지하기 위하여 배크라이트를 설치하였으며 CFD 해석을 통해 PCB와 반도체 칩을 접착시킬 때 열이 PCB에 미치는 영향을 살펴보았다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.261-267
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• 2020

The demand for faster, lighter, and thinner portable electronic devices has brought about a change in semiconductor packaging technology. In response, a stacked chip-scale package(SCSP) is used widely in the assembly industry. One of the key materials for SCSP is a die-attach film (DAF). Excellent flowability is needed for DAF for successful die attachment without voids. For DAF with high flowability, two-step curing is often required to reduce a cure crack, but one-step curing is needed to reduce the processing time. In this study, DAF composition was categorized into three groups: cure (epoxy resins), soft (rubbers), hard (phenoxy resin, silica) component. The effect of the composition on a cure crack was examined when one-step curing was applied. The die-attach void and flowability were also assessed. The cure crack decreased as the amount of hard components decreased. Die-attach voids also decreased as the amount of hard components decreased. Moreover, the decrease in cure component became important when the amount of hard component was small. The flowability was evaluated using high-temperature storage modulus and bleed-out. A decrease in the amount of hard components was critical for the low storage modulus at 100℃. An increase in cure component and a decrease in hard component were important for the high bleed-out at 120℃(BL-120).

• Journal of Adhesion and Interface
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• v.17 no.4
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• pp.136-140
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• 2016

In this study, a series of dimer acid-based polyamides with different diamines were synthesized by condensation polymerization and the polyamides were characterized by Fourier transform infrared spectroscopy (FT-IR). Effects of diamine structures on mechanical and thermal properties of polyamides were investigated. The tensile strength and lap shear adhesion strength of aromatic-based polyamide (DAP) were higher than those of aliphatic-based polyamide (DAH). In DSC thermogram, DAP has a high $T_g$ and $T_m$ compared with DAH. DAP's and DAH's softening point were $112-115^{\circ}C$ and $98-121^{\circ}C$, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.503-509
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• 2019

The demand for smaller, faster, and multi-functional mobile devices in increasing at a rapidly increasing rate. In response to these trends, Stacked Chip Scale Package (SCSP) is used widely in the assembly industry. A film type adhesive called die attach film (DAF) is used widely for bonding chips in SCSP. The DAF requires high flowability at high die attachment temperatures for bonding chips on organic substrates, where the DAF needs to feel the gap depth, or for bonding the same sized dies, where the DAF needs to penetrate bonding wires. In this study, the mixture design of experiment (DOE) was performed for three raw materials to obtain the optimized DAF recipe for low elastic modulus at high temperature. Three components are acrylic polymer (SG-P3) and two solid epoxy resins (YD011 and YDCN500-1P) with different softening points. According to the DOE results, the elastic modulus at high temperature was influenced greatly by SG-P3. The elastic modulus at $100^{\circ}C$ decreased from 1.0 MPa to 0.2 MPa as the amount of SG-P3 was decreased by 20%. In contrast, the elastic modulus at room temperature was dominated by YD011, an epoxy with a higher softening point. The optimized DAF recipe showed approximately 98.4% pickup performance when a UV dicing tape was used. A DAF crack that occurred in curing was effectively suppressed through optimization of the cure accelerator amount and two-step cure schedule. The imizadole type accelerator showed better performance than the amine type accelerator.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.9
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• pp.799-805
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• 2015

The further development of information, communication and digital media technologies requires the use of advanced, miniaturized semiconductor chips that operate at a high frequency. Die bonding and wire bonding methods for semiconductor packaging have been replaced by direct attachment to the substrate after forming a bump on the chip. However, the height of the bump or ball is an important factor for defects during assembly. This paper proposes an algorithm to measure the height of the bumps or balls in semiconductor packaging with greater accuracy. The performance of the proposed algorithm is experimentally validated. Non-contact 3D measurements of a shiny round ball is quite difficult, and it is not easy to obtain accurate data. This paper thus proposes an optical method and technique to improve the measurement accuracy.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.127-127
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• 2000

다이아몬드상 카본(Diamond-like Carbon, DLC) 필름은 비정질 재료로서 다이아몬드와 유사한 높은 경도, 내마모성, 화학적 안정성, 그리고 광학적 특성을 가지고 있으며, 낮은 마찰계수와 높은 탄성률 등으로 인해 많은 분야에서 응용이 연구되고 있는 재료이다. 그러나 DLC 필름이 이러한 우수한 특성이 가지고 있음에도 불구하고 수 GPa에 이르는 높은 압축 잔류 응력으로 인해 응용에 제약을 받고 있다. 이러한 압축 잔류 응력이 상당한 값에 이르게 되면 기판의 구속에서 벗어나게 되어, 기판으로부터 떨어지게 되고 굽힘을 받게 되는 delamination buckling 현상이 일어나기도 한다. 본 연구에서는 높은 잔류 응력으로 인해 자연적으로 발생하는 buckling 현상과 식각 과정을 통해 인위적으로 기판의 제한으로부터 필름을 완화시키는 freehang 방법을 이용하여 필름이 기판에 접착되는데 필요한 에너지를 평가하려고 한다. 본 실험에서는 rf-PACVD 장비를 이용하여 필름을 증착하였다. 이때 전극과 플라즈마 사이의 바이어스 음전압은 -100~700 Vb로 변화를 주었으며, 합성압력은 9mTorr로 고정하였다. 사용한 반응 가스는 메탄(CH4)이고, 아르곤(Ar)을 이용하여 모든 실험에서 동일하게 기판을 전처리 하였다. buckling 현상을 관찰하기 위해 사용된 기판은 slide glass이고, freehang을 제작하기 위해 사용된 기판은 (100) p-type Si wafer 이다. freehang 제작시 사용한 식각 용액은 KOH(5.6mol)이며 외부 요인을 제거하기 위해 7$0^{\circ}C$ 항온조를 사용하였다. Buckling 된 필름과 freehang은 광학 현미경과 전자 주사 현미경에 의해 관찰되었으며, 사인 함수 형태의 곡면을 가지고 있었다. 또한 freehang 제작시 각각의 주기와 진폭을 통해, 필름과 기판사이의 계면에너지와 buckling 되면서 새로 생성된 두 표면에너지 차이를 구할 수 있게 되고, 이를 통해 접착에너지를 평가할 수 있었다.

• Journal of Adhesion and Interface
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• v.22 no.3
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• pp.85-90
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• 2021

Generally, the tensile strength of carbon fiber reinforced composite (CFRP) should be determined to produce this material. The tensile strength was performed based on ASTM D3039, and this test could cause the error by specimens and human. In this research, the CFRP tensile test was performed with different thickness of specimens and tap, adhesive for attaching tap, and pressure of jig to hold the specimens, while the test was performed based on ASTM D3039. The tensile stress and modulus exhibited differently with different specimen thicknesses, and the 1~1.5 mm thickness of the specimen was optimized. In the case of 0.28 MPa jig pressure, the slip or fracture at the clamping area of the specimen has not occurred, and specimens were fractured to the center section of the specimen. The adhesive to attach jig on specimen should be used to exhibit high adhesive stress. Experimental parameters could cause errors. It is expected to achieve an accurate tensile property evaluation of composite materials via improvements in adhesives, tabs, and jigs.

• Journal of Adhesion and Interface
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• v.20 no.4
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• pp.140-145
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• 2019

In view of environmental considerations, the control of carbon dioxide (CO₂) and volatile organic compounds (VOCs) is one of important issues in the film and coating industries. Therefore, UV-curable system has been developed due to minimize emissions of VOCs and reduce CO₂ emission due to low energy consumption from fast curing. Also, biodegradable polymers economically are attractive because of environmental and economic concerns associated with huge waste plastics. In this study, UV-curable polyurethane acrylates with different compositions of biodegradable polylactide (PLA) diol and poly(ethylene glycol) as diols were synthesized and curing reaction of their end-capped acrylates was performed by UV exposure. Tensile strength, elongation, and Tg of the UV-cured polyurethane acrylates increased with PLA diol content in the diol while their hydrophilicity and thermal stability increased with the PEG content. These results indicated a property of UV-cured polyurethane acrylates could be controlled by environment-friendly diols.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.6
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• pp.373-380
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• 2018

We present the peridynamic dynamic fracture analysis to solve impact fracturing of multilayered glass impacted by a high-velocity object. In the most practical multilayered glass structures, main layers are glued by thin elastic masking films. Thus, it is difficult and expensive to construct the numerical model for such a multilayered structure. In this paper, we employ efficient numerical modeling of multilayered structures with a nonlocal ghost interlayer model in which ghost particles are distributed between main layers and they are interacting with each other in peridynamic way. We also consider a simple nonlocal contact condition in peridynamic frameworks to solve impact and penetration of the high-velocity impactor to the multilayered structure. Finally we can confirm the fracture capabilities of the method using a multilayered glass model in which 7 glass layers and a single elastic backing layer are affixed by polyvinyl butyral films.

• Journal of Adhesion and Interface
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• v.4 no.3
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• pp.14-20
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• 2003

In order to study the radiation curing behavior of poly(ethylene glycol 400) dimethacrylate and ethylene glycol dimethacrylate, we investigated the influence of temperature and photoinitiator concentration by photo-DSC. As the number of ethylene glycol unit, the concentration of photoinitiator, and the reaction temperature increased, the reaction speed of PEG400DMA and EGDMA increased. Although the reaction speed of PEG400DMA was lower than EGDMA, the overall conversion of PEG400DMA was high.