• Title/Summary/Keyword: Surface Finish Technology

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Solder Joints Fatigue Life of BGA Package with OSP and ENIG Surface Finish (OSP와 ENIG 표면처리에 따른 BGA 패키지의 무연솔더 접합부 피로수명)

  • Oh, Chulmin;Park, Nochang;Hong, Wonsik
    • Korean Journal of Metals and Materials
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    • v.46 no.2
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    • pp.80-87
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    • 2008
  • Many researches related to the reliability of Pb-free solder joints with PCB (printed circuit board) surface finish under thermal or vibration stresses are in progress, because the electronics is operating in hash environment. Therefore, it is necessary to assess Pb-free solder joints life with PCB surface finish under thermal and mechanical stresses. We have investigated 4-points bending fatigue lifetime of Pb-free solder joints with OSP (organic solderability preservative) and ENIG (electroless nickel and immersion gold) surface finish. To predict the bending fatigue life of Sn-3.0Ag-0.5Cu solder joints, we use the test coupons mounted 192 BGA (ball grid array) package to be added the thermal stress by conducting thermal shock test, 500, 1,000, 1,500 and 2,000 cycles, respectively. An 4-point bending test is performed in force controlling mode. It is considered that as a failure when the resistance of daisy-chain circuit of test coupons reaches more than $1,000{\Omega}$. Finally, we obtained the solder joints fatigue life with OSP and ENIG surface finish using by Weibull probability distribution.

Sn-Ag-Cu Solder Joint Properties on Plasma Coated Organic Surface Finishes and OSP (플라즈마 유기막과 OSP PCB 표면처리의 Sn-Ag-Cu 솔더 접합 특성 비교)

  • Lee, Tae-Young;Kim, Kyoung-Ho;Bang, Jung-Hwan;Park, Nam-Sun;Kim, Mok-Soon;Yoo, Sehoon
    • Journal of the Microelectronics and Packaging Society
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    • v.21 no.3
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    • pp.25-29
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    • 2014
  • Plasma organic thin film for PCB surface finish is a potential replacement of the conventional PCB finishes because of environment-friendly process, high corrosion-resistance and long shelf life over 1 year. In this study, solder joint properties of the plasma organic surface finish were estimated and compared with OSP surface finish. The plasma surface finish was deposited by chemical vapor deposition from fluorine-based precursors. The thickness of the plasma organic coating was 20 nm. Sn-3.0Ag-0.5Cu (SAC305) solder was used as solder joint materials. From a salt spray test, the plasma organic coating had higher corrosion resistance than the OSP surface finish. The spreadability of SAC305 on plasma organic coating was higher than that on OSP surface finish. SEM and TEM micrographs showed that the interfacial microstructure of the plasma surface finish sample were similar to that of the OSP sample. Solder joint strength of the plasma finish sample was also similar to that of the OSP finished sample.

STUDY FOR DEVELOPMENT OF AN ADDITIVE FOR SEMI-BRIGHTNESS FINISH FOR NICKEL ELECTOPLATING

  • Han, M.K.;Lee, J.K.
    • Journal of the Korean institute of surface engineering
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    • v.32 no.3
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    • pp.208-210
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    • 1999
  • A new additive for semi-brightness finish in nickel electroplating, having a quarternary ammonium salt structure, has been developed in this study. The effectiveness of the new additive was tested in laboratory-scale eletroplating tests as well as in a full-scale factory plating line. An examination of the plated surface showed that the new additive is as good as the one produced by the most commonly used additive in the nickel plating industry. The plated surface was examined by SEM, EPMA, and Reflectance Spectroscopy, and was found to be compatible to the one obtained with commercial additives. The new additive has a shelf life comparable with those of other commercially available additives. The additive developed in this study has an excellent potential to be used commercially.

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Fabrication Process and CTQ Analysis of Organic Solderability Preservatives(OSP) Finish on Cu Pad for SMT (SMT(Surface Mounting Technology)용 Cu 패드의 유기솔더보전제 처리공정 및 CTQ(Critical-to-Quality)분석)

  • Lee, Hyo-Soo;Yi, Min-Su
    • Journal of the Microelectronics and Packaging Society
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    • v.14 no.1
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    • pp.1-9
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    • 2007
  • OSP(organic solderability preservatives) finish has been considered as a very effective process for substituting the metal surface treatment of Ni/Au finish because of lower cost, interface property and environmental issue of OSP finish. However, the discoloration of OSP layer is formed during assembly process consisting of various steps of temperature. The causes of discoloration and the characterization of solder joint were investigated with a degree of discoloration and the assembly process of OSP finished products, which was also compared statistically with that of conventional Ni/Au finished products. As the results, the solution of process trouble for OSP finished products is able to be offered.

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Ultrasonically Assisted Grinding for Mirror Surface Finishing of Dies with Electroplated Diamond Tools

  • Isobe, Hiromi;Hara, Keisuke;Kyusojin, Akira;Okada, Manabu;Yoshihara, Hideo
    • International Journal of Precision Engineering and Manufacturing
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    • v.8 no.2
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    • pp.38-43
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    • 2007
  • This paper describes ultrasonically assisted grinding used to obtain a glossy surface quickly and precisely. High-quality surfaces are required for plastic injection molding dies used in the production of plastic parts such as dials for cellular phones. Traditionally, in order to finish the dies, manual polishing by a skilled worker has been required after the machining processes, such as electro discharge machining (EDM), which leaves an affected layer, and milling, which leaves tooling marks. However, manual polishing causes detrimental geometrical deviations of the die and consumes several days to finish a die surface. Therefore, a machining process for finishing dies without manual polishing to improve the surface roughness and form accuracy would be extremely valuable. In this study, a 3D positioning machine equipped with an ultrasonic spindle was used to conduct grinding experiments. An electroplated diamond tool was used for these experiments. Generally, diamond tools cannot grind steel because of excessive wear as a result of carbon atoms diffusing into bulk steel and chips. However, ultrasonically assisted grinding can achieve a fine surface (roughness Rz of $0.4{\mu}m$) on die steel without severe tool wear. The final aim of this study is to realize mirror surface grinding for injection molding dies without manual polishing. To do this, it is necessary to fabricate an electroplated diamond tool with high form accuracy and low run-out. This paper describes a tool-making method for high precision grinding and the grinding performance of a self-electroplated tool. The ground surface textures, tool performance and tool life were investigated A ground surface roughness Rz of 0.14 um was achieved Our results show that the spindle speed, feed rate and cross feed affected the surface texture. One tool could finish $5000mm^2$ of die steel surface without any deterioration of the ground surface roughness.

A Study on the Optimum Finish Allowance for Machining Accuracy Improvement in the End Milling Processes (엔드밀 가공의 정밀도 향상을 위한 최적정삭여유에 관한 연구)

  • 최종근;김형선;김성초
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.13 no.3
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    • pp.8-15
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    • 2004
  • A significant error in the end milling processes is generated due to using slender tools of which the strengths are not sufficient. In order to obtain the desired machining accuracy, therefore, it is general that at first the rough cut is implemented, then the finish cut is followed. The rough cut eliminates large volume and the finish cut does the remained part. This remaining portion after the rough cut is called as the finish allowance. Larger finish allowances make it hard to get precise dimensions at a following finish cut. Smaller finish allowances are helpful for good dimension, but it sometimes is responsible for inferior surface qualities and over cuts. This study suggests a guidance for the optimum finish allowance for machining accuracy improvement, in which the rough cuts are regulated to remain the desired margins without any over cuts. Some experiments were carried out with various cutting conditions including the change of tool strengths and depth of cuts, and also extended to up millings as well as down millings.

Effects of PCB Surface Finishes on in-situ Intermetallics Growth and Electromigration Characteristics of Sn-3.0Ag-0.5Cu Pb-free Solder Joints (PCB 표면처리에 따른 Sn-3.0Ag-0.5Cu 무연솔더 접합부의 in-situ 금속간 화합물 성장 및 Electromigration 특성 분석)

  • Kim, Sung-Hyuk;Park, Gyu-Tae;Lee, Byeong-Rok;Kim, Jae-Myeong;Yoo, Sehoon;Park, Young-Bae
    • Journal of the Microelectronics and Packaging Society
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    • v.22 no.2
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    • pp.47-53
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    • 2015
  • The effects of electroless nickel immersion gold (ENIG) and organic solderability preservative (OSP) surface finishes on the in-situ intermetallics reaction and the electromigration (EM) reliability of Sn-3.0Ag-0.5Cu (SAC305) solder bump were systematically investigated. After as-bonded, $(Cu,Ni)_6Sn_5$ intermetallic compound (IMC) was formed at the interface of the ENIG surface finish at solder top side, while at the OSP surface finish at solder bottom side,$ Cu_6Sn_5$ and $Cu_3Sn$ IMCs were formed. Mean time to failure on SAC305 solder bump at $130^{\circ}C$ with a current density of $5.0{\times}10^3A/cm^2$ was 78.7 hrs. EM open failure was observed at bottom OSP surface finish by fast consumption of Cu atoms when electrons flow from bottom Cu substrate to solder. In-situ scanning electron microscope analysis showed that IMC growth rate of ENIG surface finish was much lower than that of the OSP surface finish. Therefore, EM reliability of ENIG surface finish was higher than that of OSP surface finish due to its superior barrier stability to IMC reaction.

The Effects of Ultrasonic Vibration on Surface Finish in Nano-second Laser Machining (나노초 레이저 가공에서 초음파 진동이 가공표면에 미치는 영향)

  • Kang, Bong-Chul;Kim, Gun-Woo;Cho, Sung-Hak;Park, Jong-Kweon;Yang, Min-Yang
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.19 no.3
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    • pp.402-406
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    • 2010
  • Conventionally, the machined surface roughness in nano-second(ns) laser machining is damaged and rough due to thermal effects. To obtain the improved surface finish, the ultrasonic vibration is applied to ns-laser machining. The ultrasonic vibration jig is developed to apply the ultrasonic high precision motion to workpieces. And then the ns-laser machining is conducted to compare the effects of the ultrasonic vibration. The results show that the surface roughness with ultrasonic vibration is smoother than that without the vibration. The phenomenon could be explained as enhancement of heat transfer by ultrasonic vibration.

A Study on the Centrifugal Barrel Machining of Round Face (원형단면의 정밀 원심 배럴가공에 관한 연구)

  • 고준빈;김우강;원종호
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.4
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    • pp.179-185
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    • 2004
  • Surface finish technology is highly demanded in the wide field of industry applications from ultra-precision parts to rough casting parts. Therefore, many kinds of surface finish technologies have been developed for each purpose. Because surface of a car's wheel cast is very rough it becomes the reason of the corrosion. This surface is coated to complement such problem but because surface is rough, the result of coating is not good and the coated metal peels off well. Therefore before the wheel is coated, it is necessary to grind the surface. In this study, we devised the plant to apply a barrel machining to improve the surface roughness and enhance the productivity. Also we could obtain the optimum barrel machining conditions for the proper surface roughness.

Effect of Disperse Dyeing on UV-curable Flame-retardant Finish of PET Fabrics (분산염료 염색공정이 PET직물의 UV경화형 방염가공에 미치는 영향)

  • Jeong, Yong-Kyun;Jang, Jin-Ho
    • Textile Coloration and Finishing
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    • v.20 no.2
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    • pp.66-74
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    • 2008
  • Effect of disperse dyeing on flame retardant finishing of PET fabrics via UV curing using three UV curable phosphorous-containing methacrylates and ammonium polyphosphate(APP) was investigated. The dye fixation and flame retardancy of PET fabrics did not change significantly with excellent durability to five laundering cycles irrespective of the dyeing and finishing sequence. However, the flame retardancy of Pekoflam-treated fabrics was lower than that of the UV treated and decreased substantially when heat treatment was carried out before the dyeing. The dyeability of the flame-retardant PET fabrics was not affected in the case of UV curing of the methacrylates alone. However, UV finishing after the dyeing caused significant decrease in K/S and ${\Delta}E$ due to changed refraction and inherent color of surface coating of the UV curable monomers and APP. Whereas the heat treatment with Pekoflam decreased both color fastness to laundering and sublimation, surprisingly the UV finish of PET fabrics before and after the dyeing increased the color fastness probably resulting from the presence of photopolymerized surface layer on the fabrics.