• 마이크로전자및패키징학회지
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• 제6권1호
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• pp.59-64
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• 1999

본 연구에서는 솔더링(soldering)공정 전, 기판의 최적의 건조 시간과 PCB기판에 묻은 수분이 솔더링에 미치는 영향에 대하여 조사하고자 하였다. 실험결과, 솔더링 중 건조시간이 증가할수록 솔더링성(solderabillity)이 향상됨을 알 수 있었다. 즉, 건조된 시편이 함습한 시편에 비해 젖음 시간(wetting time)이 약 0.2초 짧고 젖음력(wetting force)이 2~4mN증가되었다. 338k에서 30분 이상 건조시켰을 때 최소 미납 결함과 리드와 기판의 최고 인장강도가 얻어 졌다. 또, 건조시간을 45분가지 증가시킬 때, 건조시간 증가에 따라 솔더볼 발생 양이 감소하였다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2011년도 춘계학술대회 및 Fine pattern PCB 표면 처리 기술 워크샵
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• pp.184-185
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• 2011

In this study, in order to obtain a high reflectivity for the LED lead frame, tin dip coating and tin plating were conducted respectively, and wettability of LED lead frame with tin solder also was tested by wetting balance tester. A Cu sheet was plated in Cu brighten electroplating bath and followed by immersion in a Sn electro-less plating bath [1]. On the other hand, in the dip coating process, a Cu sheet was dipped into molten tin. In the progress of wetting test, besides wetting balance curve, the maximum measured force($F_m$), the maximum withdrawal force($F_w$) and zero-cross time($t_0$) were obtained in various temperatures. With the maximum withdrawal force, the surface tension was calculated at different temperatures. The Cu sheet plated with bright Cu and Sn show a silver bright property while that of Cu dipped with Sn possessed a high reflectance density of 1.34GAM at $270^{\circ}C$.

• Journal of Welding and Joining
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• 제21권2호
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• pp.35-41
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• 2003

Sintered alumina ceramics were joined by 2 kinds of SiO$_2$-CaO-A1$_2$O$_3$ glass solders having a similar expansivity as alumina. Wetting of glass/alumina was examined by sessile drop method. The observation of interface and bending strength related to alumina/glass/alumina systems were investigated by means of SEM/EDX and 4-point bending test. the result are summarized as follow: (1) Wetting of glass solders on alumina was good at temperatures higher than 145$0^{\circ}C$. (2) When the joining temperature wan high, diffusion and/or reactions between solder md alumina took place at the interface. These diffusions and reactions occurring at the interface greatly affected the bending strength of joining body. (3) Highest strength corresponding to 80% that of alumina was obtained by the solder of 35SiO$_2$-35CaO-30A1$_2$O$_3$(wt%) glass.

• ETRI Journal
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• 제32권2호
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• pp.342-344
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• 2010

A novel, maskless, low-volume bumping material, called solder bump maker, which is composed of a resin and low-melting-point solder powder, has been developed. The resin features no distinct chemical reactions preventing the rheological coalescence of the solder, a deoxidation of the oxide layer on the solder powder for wetting on the pad at the solder melting point, and no major weight loss caused by out-gassing. With these characteristics, the solder was successfully wetted onto a metal pad and formed a uniform solder bump array with pitches of 120 ${\mu}m$ and 150 ${\mu}m$.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.661-662
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• 2006

This research is on a laser soldering using the micro solder-balls used in flip chip packaging process. A laser source used in laser soldering is Nd:YAG laser(250W and 60W). Solder-balls of 100, 300, $500{\mu}m$ size are used in experiments. The laser head to deliver a laser beam and the nozzle to transfer solder-balls are manufactured to bump solder-balls. After soldering solder-balls the shear test is carried out to determine the wetting at the interface between the surface and a solder-balls With the results of solder bumping tests a laminated molding is accomplished for manufacturing the three dimensional molding.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.168-170
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• 2007

Sn-Bi eutectic solder alloy have is good wetting and physical properties. The results of solder paste properties test, melting point is about $139^{\circ}C$ and spread test is represent spread properties of $7{\sim}16%$. The results of shear strength after as reflowed, thermal shock test, high temperature storage test of 500hr and 1000hr at $100^{\circ}C$. The shear strength value range is from 6000 to 11000gf, pull strength value range is from 2200 to 3300gf.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2002년도 춘계 기술심포지움 논문집
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• pp.104-108
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• 2002

This paper was investigated the lead free solder characteristics by P mass percentage chang e. Tension test, wetting balance test, spread test, and analysis of intermetallic compound after isothermal aging of Sn-2.5Ag-0.7Cu-0.005P, Sn-2.5Ag-0.7Cu-0.01P, Sn-2.5Ag-0.7Cu-0.02P, Sn-0.7Cu-0.005P were performed for estimation. By adding P on the solder alloys, it was showe d improvement of tensile strength, reduction of intermetallic compound growth and reduction of oxidization of fusible solder under wave soldering processes. After comparing solder alloy containing P with tin lead eutectic solder alloy, p containing solder alloys showed much better solderability than eutectic solder alloys.

• Journal of Welding and Joining
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• 제20권1호
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• pp.91-96
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• 2002

Three different kinds of substrate used in this study : bare Cu, electroless Ni/Cu substrate with a Nilayer thickness of $5\mu\textrm{m}$, immersion Au/electroless Ni/Cu substrate with the Au and Ni layer of $0.15\mu\textrm{m}$ and $5\mu\textrm{m}$ thickness, respectively. The wettability and interfacial tension between various substrate and Sn-3.5Ag solder were examined as a function of soldering temperature, types of flux. The wettability of Sn-3.5Ag solder increased with soldering temperature and solid content of flux. The wettability of Sn-3.5Ag solder was affected by the substrate metal finish used, i.e., nickel, gold and copper. Intermetallic compound formation between liquid solder and substrate reduced the interfacial energy and decreased wettability.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2000년도 Proceedings of 5th International Joint Symposium on Microeletronics and Packaging
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• pp.74-79
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• 2000

In an attempt to estimate the wetting properties of wettable metal layers by wetting balance method, an analysis of wetting curves of the coating layer was performed. Based on the analysis, wetting properties of UBM-coated Si-plate were estimated by the new wettability indices. The wetting curves of the one and both sides-coated UBM layers have the similar shape and show the similar tendency to the temperature. So the wetting property estimation of one side coating is possible with wetting balance method. For UBM of Si-chip, Cr/Cu/Au UBM is better than Ti/Ni/Au in the point of wetting time. At general reflow temperature, the wettability of high melting point solders(Sn-Sb, Sn-Ag) is better than that of few melting point ones(Sn-Bi, Sn-In).The contact angle of the one side coated plate to the solder can be calculated from the farce balance equation by measuring the static state force and the tilt angle.

• 한국공작기계학회논문집
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• 제16권5호
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• pp.151-156
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• 2007

In this paper, the creep characteristics of lead and lead-free solder joint were investigated using the QFP(Quad Flat Package) creep test. Two kind of solder pastes(Sn-3Ag-0.5Cu, Sn-0.2Sb-0.4Ag-37.4Pb) were applied to the QFP solder joints and each specimen was checked the external and internal failures(i.e., wetting failure, void, pin hole, poor-heel fillet) by digital microscope and X-ray inspection. The creep test was conducted at the temperatures of $100^{\circ}C$ and $130^{\circ}C$ under the load of 15$\sim$20% of average pull strength in solder joints. The creep characteristics of each solder joints were compared using the creep strain-time curve and creep strain rate-stress curves. Through the comparison, the Sn-3Ag-0.5Cu solder joints have higher creep resistance than that of Sn-0.3Sb-0.4Ag-37.4Pb. Also, the grain boundary sliding in the fracture surface and the necking of solder joint were observed by FE-SEM.