• Title, Summary, Keyword: SnPb solder

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A study on the characteristics of low Pb Sn-5%Pb-1.5%Ag-x%Bi solder alloys (저Pb Sn-5%Pb-1.5%Ag-x%Bi계 솔더 합금의 특성에 관한 연구)

  • 홍순국;주철홍;강정윤;김인배
    • Journal of Welding and Joining
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    • v.16 no.3
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    • pp.157-166
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    • 1998
  • Recently as environmental pollution caused by Pb has posed a serious threat to the global environment, the trend to regulate the usage of Pb in electronic industry is one the rise. Currently, the solder alloy with high Pb content, Sn-37%Pb, is utilized in the electronic assembly therefore, the objective of this study is to develop an alternative solder alloy for the existing Sn-37%Pb solder alloy. First thing, this work choosed Sn-5%Pb-1.5%Ag, Sn-5%Pb-1.5%Ag-x%Bi(x=1~5%) for candidate solder alloys, and examined their properties such as melting range, wettability, microhardness, tensile property, oxidation behavior and microstructure. Wettability was on the same level of Sn-37%Pb. Dissolution of Pb ion in Sn-5%Pb solder was 0.46ppm. This solder alloy revealed cellular dendrite microstructure $\beta$-Sn matrix, Pb-rich phase, Ag/Sn, and Cu/Sn Intermetallic compounds. The range of solidification temperature was within 3$0^{\circ}C$. Also these alloy displayed higher tensile strength and lower elongation than Sn-37%Pb. The resistance of oxidation in Sn-5%Pb-1.5%Ag solder alloy was superior to that of Sn-37%Pb solder alloy. But that of Sn-5%Pb-1.5%Ag-5%Bi solder alloy was equal to that of Sn-37%Pb solder alloy.

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A study on the characteristics of Pb free Sn-2%Ag-x%Bi solder alloys (Pb Free Sn-2%Ag-x%Bi계 Solder의 특성에 관한 연구)

  • 흥순국;박일경;강정윤
    • Journal of Welding and Joining
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    • v.16 no.3
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    • pp.148-156
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    • 1998
  • The purpose of this study is to investigate the characteristics of Pb-Free Sn-2%Ag-Bi solder alloys. The solder alloys used in this study is Sn-2%Ag-(3,5,7,9%) Bi It is examined that their properties such as melting range, wettability, microstructure, microhardness, and tensile property. The addition of Bi(3,5,7,9%) lowered the melting point of the solder and the melting range was 196~203$^{\circ}C$. The wettability of the solder as equal to that of Sn-37% Pb solder. The morphology of structure did not change largely by addition of Bi. But the structure of cellular dendrite of linear type displayed. The tensile strength of the solder was superior to that of Sn-37%Pb solder. But the elongation was inferior to that of Sn-37%Pb solder. The hardness of Sn-2%Ag solder was tow times and that of Sn-2%Ag-Bi solder was three times of that in Sn-37%Pb solder. But the effect of increment of Bi content did not change largely.

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A Study on the Characteristics of Low Pb Sn-5%Pb-1.5%Pb-1.5Ag-x%In Solder Alloys (저 Pb Sn-5%Pb-1.5%Ag-x%In계 솔도 합금의 특성에 관한 연구)

  • Hong, Sun-Guk;Ju, Cheol-Hong;Gang, Jeong-Yun;Kim, In-Bae
    • Korean Journal of Materials Research
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    • v.8 no.11
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    • pp.1011-1019
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    • 1998
  • This work designed Sn-5%Pb-1.5%Ag-x%In solder alloy to develop the solder alloy with low Pb content. This solder alloy doesn't cause environmental pollution. and this study reviewed the probability of replacement of Sn-37%Pb solder as evaluation of melting range, wettability. microstructure, microhardne'ss, tensile strength, drossability of this new solder alloys. The level of international regulation in dissolution amount of Pb ion was 3ppm. But dissolution amount of Pb ion in Sn-5%Pb solder alloy confirmed not to threat the global environmental is 0.46ppm. The melting range of this solder alloy was $183-192^{\circ}C$. Also the range of solidification was very narrow within $5^{\circ}C$. The wettability was similar to Sn-37%Pb solder, and the effect of amount of In addition of wettability couldn't be founded. The probability of replacement in the melting range and wettability is very high. And microhardness of this solder alloy was 1.5 times of conventional type solder. Tensile strength of new solder alloys was a little high than that of conventional type solder. With increasing amount of In% addition, tensile strength was increased, but elongation was decreased. The solder alloy of l%In addition revealed AgSn and Pb on dendrite microstructure boundary, and $Ag_3Sn$, $Ag_3In$ and Pb were revealed on it at the solder alloy of 3% In addition. The drossability was superior to Sn-37%Pb solder alloy and the solder alloys of 2% In addition was not generated for 3hrs.

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A Study on Characteristics of Sn-37Pb and Sn-4.0Ag-0.5Cu Solder Joints as Various A:V Ratio (A:V Ratio 변화에 따른 Sn-37Pb, Sn-4.0Ag-0.5Cu Solder 접합부의 특성 연구)

  • Han, Hyun-Joo;Lim, Seok-Jun;Moon, Jung-Tak;Lee, Jin
    • Proceedings of the International Microelectronics And Packaging Society Conference
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    • pp.67-73
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    • 2001
  • To investigate the relationships of solder joint characteristics with solder composition and A:V ratio (solder volume per pad area), Sn-37Pb and Sn-4.0Ag-0.5Cu solder balls with 330, 400, 450 and $457{\mu}{\textrm}{m}$ size were reflowed on same substrate. Sn-37Pb and Sn-4.0Ag-0.5Cu was reflowed at $220^{\circ}C$ and $240^{\circ}C$ respectively by IR-type soldering machine. As a result of reflowed solder- ball diameter(D) and height(H) measurement, D/H was decreased with solder ball size increment in range of 330~450 ${\mu}{\textrm}{m}$. But, D/H was increased in the solder joint for 457 ${\mu}{\textrm}{m}$ size, it was caused possibly by decrement of solder ball height increment compared with solder volume increment. As a result of shear and pull test, joint strength with A:V ratio was high. Joint strength of Sn-4.0Ag-0.5Cu was higher than Sn-37Pb. However, Sn-37Pb had more stable solder joint of small standard deviation. A thick and clean scallop type Ni-Cu-Sn intermetallic compound layer was formed in high A:V ratio and Sn-4.0Ag-0.5Cu solder joint interface.

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Reliability evaluation of Pb-free solder joint with immersion Ag-plated Cu substrate (Immersion Ag가 도금된 Cu기판을 가진 Pb-free solder 접합부의 신뢰성 평가)

  • Yun Jeong-Won;Jeong Seung-Bu
    • Proceedings of the KWS Conference
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    • pp.30-32
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    • 2006
  • The interfacial reaction and reliability of eutectic Sn-Pb and Pb-free eutectic Sn-Ag ball-grid-array (BGA) solders with an immersion Ag-plated Cu substrate were evaluated following isothermal aging at $150^{\circ}C$. During reflowing, the topmost Ag layer was dissolved completely into the molten solder, leaving the Cu layer exposed to the molten solder for both solder systems. A typical scallop-type Cu-Sn intermetallic compound (IMC) layer was formed at both of the solder/Cu interfaces during reflowing. The thickness of the Cu-Sn IMCs for both solders was found to increase linearly with the square root of isothermal aging time. The growth of the $Cu_3Sn$ layer for the Sn-37Pb solder was faster than that for the Sn-3.5Ag solder, In the case of the Sn-37Pb solder, the formation of the Pb-rich layer on the Cu-Sn IMC layer retarded the growth of the $Cu_6Sn_5$ IMC layer, and thereby increased the growth rate of the $Cu_3Sn$ IMC layer. In the ball shear test conducted on the Sn-37Pb/Ag-plated Cu joint after aging for 500h, fracturing occurred at the solder/$Cu_6Sn_5$ interface. The shear failure was significantly related to the interfacial adhesion strength between the Pb-rich and $Cu_6Sn_5$ IMC layers. On the other hand, all fracturing occurred in the bulk solder for the Sn-3.5Ag/Ag-plated Cu joint, which confirmed its desirable joint reliability.

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Effects of Fatigue Strength by Solder Ball Composition (솔더볼 조성에 의한 피로강도의 영향)

  • 김경수;김진영
    • Journal of the Korean Vacuum Society
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    • v.13 no.3
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    • pp.127-131
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    • 2004
  • Package reliability test was conducted to investigate the effect of solder composition on the ball fatigue strength for BGA (Ball Grid Array) packaging. The test pieces are assembled using eutectic composition 63Sn/37Pb, 62Sn/36Pb/2Ag, and 63Sn/34.4Pb/2Ag/0.5Sb solder after pre-conditioning at MRT Lv 3 (Moisture Resistance Test Level) and then conducted under T/C (Temperature Cycle test). For each case, the ball shear strength was obtained and micro structure photos were taken. SEM (scanning electron microscope) and EDX (Energy Dispersive X-ray) were used to the analyze failure mechanism. The growth rate of Au-Sn intermetallic compound in Sn63Pb34.5Ag2Sb0.5 solder was slow when compared to 63Sn/37Pb solder and 62Sn/36Pb/2Ag solder. The degradation of shear strength of solder balls caused by solder composition was discussed.

A study on the implementation of wave soldering process and the solder joint reliability of it using Sn-Cu-Ni lead-free solder (Sn-Cu-Ni계를 이용한 Pb-free wave Soldering의 공정 적용 및 신뢰성에 관한 연구)

  • 유충식;정종만;김진수;김미진
    • Proceedings of the International Microelectronics And Packaging Society Conference
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    • pp.89-98
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    • 2001
  • Pb-free wave soldering process of AC Adapter was implemented by six sigma method using Sn-Cu-Ni type solder. The solder joint appearance, microstructural change, a lift-off phenomenon and reliability were evaluated through thermal shock teal. $(Cu,Ni)_6Sn_5$-type intermetallic compound of which thickness is about 5 micron was found at solder joint between Sn-Cu-Ni solder and copper land. After applying the thermal shock test of as-soldered product up to 750 cycles, no crack was found at the solder joint and the newly developed product was superior to conventions; one in terms of productivity and reliability.

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Phase Transformation of Sn-Pb-Bi Solder for Photovoltaic Ribbon: A Real-time Synchrotron X-ray Scattering Study

  • Cho, Tae-Sik
    • Transactions on Electrical and Electronic Materials
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    • v.15 no.3
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    • pp.155-158
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    • 2014
  • The phase transformation of Sn-Pb-Bi solder for photovoltaic ribbon during soldering was studied using real-time synchrotron x-ray scattering. At room temperature, Sn and Pb crystal phases in the solder existed separately. By heating to $92^{\circ}C$, a new PbBi alloy crystal phase was formed, which grew further up to $160^{\circ}C$. The Sn crystal phase first started to melt at $160^{\circ}C$, and was mostly melted at $165^{\circ}C$. In contrast, the Pb and PbBi crystal phases started to melt at $165^{\circ}C$, and were mostly melted at $170^{\circ}C$. The useful result was obtained, that the solder's melting temperature decreased from $183^{\circ}C$ to $170^{\circ}C$ by addition of a small amount of Bi atoms to the eutectic Sn62-Pb38 (wt%) solder. Our study first revealed the detailed in-situ phase transformation of Sn-Pb-Bi solder during heating to the eutectic temperature. Considering the results of peel strength and hardness, adding 1 wt% of Bi atoms to the Sn62-Pb38 (wt%) solder produced an appropriate composition.

Material Property Evaluation of High Temperature Creep on Pb-free Solder Alloy Joint to Reflow Time by Shear Punch-creep Test (전단펀치-크리프 시험에 의한 리플로우 시간별 Pb-free 솔더 합금 접합부에 대한 고온 크리프 물성 평가)

  • Ham, Young Pil;Heo, Woo Jin;Yu, Hyo Sun;Yang, Sung Mo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.21 no.1
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    • pp.145-153
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    • 2013
  • In this study, shear punch-creep (SP-Creep) at Sn-4Ag/Cu pad the joint was tested by using environment-friendly Pb-free solder alloy Sn-4Ag of electronic components. Pb eutectic alloy (Sn-37Pb) joints limited to environmental issues with reflow time (10sec, 30sec, 100sec, 300sec) according to two types of solder alloy joints are compared and evaluated by creep strain rate, rupture time and IMC (Intermetallic Compound) behavior. As the results, reflow time increases with increasing thickness of IMC can be seen at overall 100sec later in case of two solder joints on the IMC thickness of Sn-4Ag solder joints thicker than Sn-37Pb solder joints. In addition, when considering creep evaluation factors, lead-free solder alloy Sn-4Ag has excellent creep resistance more than Pb eutectic alloy. For this reason, the two solder joints, such as in the IMC (Cu6Sn5) was formed. However, the creep resistance of Sn-4Ag solder joints was largely increased in the precipitation strengthening effect of dispersed Ag3Sn with interface more than Sn-37Pb solder joints.

Microstructure Characterization of the Solders Deposited by Thermal Evaporation for Flip Chip Bonding (진공 증발법에 의해 제조된 플립 칩 본딩용 솔더의 미세 구조분석)

  • 이충식;김영호;권오경;한학수;주관종;김동구
    • Journal of the Korean institute of surface engineering
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    • v.28 no.2
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    • pp.67-76
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    • 1995
  • The microstructure of 95wt.%Pb/5wt.%Sn and 63wt.%Sn/37wt.%Pb solders for flip chip bonding process has been characterized. Solders were deposited by thermal evaporation and reflowed in the conventional furnace or by rapid thermal annealing(RTA) process. As-deposited films show columnar structure. The microstructure of furnace cooled 63Sn/37Pb solder shows typical lamellar form, but that of RTA treated solder has the structure showing an uniform dispersion of Pb-rich phase in Sn matrix. The grain size of 95Pb/5Sn solder reflowed in the furnace is about $5\mu\textrm{m}$, but the grain size of RTA treated solder is too small to be observed. The microstructure in 63Sn/37Pb solder bump shows the segregation of Pb phase in the Sn rich matrix regardless of reflowing method. The 63Sn/37Pb solder bump formed by RTA process shows more uniform microstructure. These result are related to the heat dissipation in the solder bump.

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