• 제목/요약/키워드: lead free

검색결과 1,073건 처리시간 0.031초

전자 패키징용 고신뢰성 나노입자 강화솔더 (High reliability nano-reinforced solder for electronic packaging)

  • 정도현;백범규;임송희;정재필
    • 마이크로전자및패키징학회지
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    • 제25권2호
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    • pp.1-8
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    • 2018
  • In the soldering industry, a variety of lead-free solders have been developed as a part of restricting lead in electronic packaging. Sn-Ag-Cu (SAC) lead-free solder is regarded as one of the most superior candidates, owing to its low melting point and high solderability as well as the mechanical property. On the other hand, the mechanical property of SAC solder is directly influenced by intermetallic compounds (IMCs) in the solder joint. Although IMCs in SAC solder play an important role in bonding solder joints and impart strength to the surrounding solder matrix, a large amount of IMCs may cause poor strength, due to their brittle nature. In other words, the mechanical properties of SAC solder are of some concern because of the formation of large and brittle IMCs. As the IMCs grow, they may cause poor device performance, resulting in the failure of the electronic device. Therefore, new solder technologies which can control the IMC growth are necessary to address these issues satisfactorily. There are an advanced nanotechnology for microstructural refinement that lead to improve mechanical properties of solder alloys with nanoparticle additions, which are defined as nano-reinforced solders. These nano-reinforced solders increase the mechanical strength of the solder due to the dispersion hardening as well as solderability of the solder. This paper introduces the nano-reinforced solders, including its principles, types, and various properties.

향상된 SVD 필터를 이용한 Multi-lead ECG에서의 EMG 신호 제거 (EMG Signal Elimination Using Enhanced SVD Filter in Multi-Lead ECG)

  • 박광리;박세진;최호선;정기삼;이경중;윤형로
    • 대한전기학회논문지:시스템및제어부문D
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    • 제50권6호
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    • pp.302-308
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    • 2001
  • SVD(Singular Value Decomposition) filter for the suppression of EMG in multi-lead stress ECG is studied. SVD filter consists of two parts. In the first part, the basis vectors were chosen from the averaged singular vectors obtained from the decomposed noise-free ECG. The singular vector is computed from the stress ECG and is compared itself with basis vectors to know whether the noise exist in stress ECG. In the second part, the existing elimination method is used, when one(or two) channels is(or are) contaminated by noise. But the proposed enhanced SVD filter is used in case of having the noise in the many channels. During signal decomposition and reconstruction, the noise-free channel or the least noisy channel have the weight of 1, the next less noisy channel has the weight of 0.8. In this way, every channel was weighted by decreased of 0.2 in proportion to the amount of the added noise. For the evaluation of the proposed enhanced SVD filter, we compared the SNR computed by the enhanced SVD filter with the standard average filter for the noise-free signal added with artificial noise and the patient data. The proposed SVD filter showed better in the SNR than the standard average filter. In conclusion, we could find that the enhanced SVD filter is more proper in processing multi-lead stress ECG.

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P(인)의 첨가에 따른 Sn-Ag-Cu계 및 Sn-Cu계 솔더의 특성에 관한 연구 (A Study on Characterization of Sn-Ag-Cu and Sn-Cu Lead-free Solders by Adding of P)

  • 김경대;김택관;황성진;신영의;김종민
    • 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.

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실리콘 태양전지용 Ag pastes 에서의 무연 프릿에 따른 Ag, Si간 접촉 형성 (Contact Formation Between Ag and Si With Lead-Free Frits in Ag Pastes For Si Solar Cells)

  • 김동선;황성진;김종우;이정기;김형순
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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    • pp.61.2-61.2
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    • 2010
  • Ag thick-film has usually been used for the front electrode of Si solar cells with the outstanding electrical properties. Ag paste consists of Ag powers, vehicles, frits and additives. Ag paste has broadly been screen-printed on the front side of Si wafer with the merits of low cost and simplicity. The optimal contact formation between Ag electrodes and Si wafer in the front electrode during a fast firing has been considered as the key factor for high efficiency. Although the content of frit in Ag pastes is less than 5wt%, it can profoundly influence the contact formation between Ag and Si under the fast firing. In this study, the effects of lead-free frits on the contacts between Ag and Si were studied with the thermal properties and compositions of various frits. Our experimental results showed that the electrical properties of cells were related to the interface structures between Ag and Si. It was found that current path of electrons from Si to Ag would be possible through the tunneling mechanism assisted by tens of nano-Ag recrystals on $n^+$ emitter as well as Ag recrystals penetrated into $n^+$ emitter layers. These preliminary studies will be helpful for designing the proper frits for the Ag pastes with considering the properties of various Si wafers.

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The Electronic Properties of the $BT-(BaNaK)(TiNb)O_3$ System for Lead Free PTC

  • 이미재;박정묵;정영훈;이우영
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2009년도 추계학술대회 논문집
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    • pp.12-12
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    • 2009
  • We weal know that PbO was poisonous and prone to volatilize, then to pollute the circumstance and hurt to people, so we should dope other innocuous additives instead of lead to increase Tc of composite PTC material. In order to prepare lead-free $BaTiO_3$-based PTC with middle Curie point, the incorporation on $(BaNaK)(TiNb)O_3$ into $BaTiO_3$-based ceramics was investigated on samples containing 0.05, 0.07 and 0.1mol% of $(BaNaK)(TiNb)O_3$. $(BaNaK)(TiNb)O_3$ was compounded as standby material by conventional solid-state reaction technique. The starting materials were $Na_2O_3$,$K_2CO_3$, $BaCO_3$, $TiO_2$ and $Nb_2O_5$ powder, and using solid-state reaction method, too. The microstructure of samples were investigated by SEM, DSC, XRD and dielectric properties. Phase composition and lattice parameters were investigated by X-ray diffraction. Also, we are measure the resistivity of sintered bodies with calcinations condition.

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Sn-Zn계 무연 솔더접합부의 전단강도와 미세구조 (Microstructures and Shear Strength of Sn-Zn Lead-free Solder Joints)

  • 김경섭;양준모;유정희
    • Journal of Welding and Joining
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    • 제21권7호
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    • pp.59-64
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    • 2003
  • Microstructure and shear strength of Sn-Zn lead-free solders and Au/Ni/Cu UBM joint under thermal aging conditions was investigated. The samples were aged isothermally at 10$0^{\circ}C$ and 15$0^{\circ}C$ for 300, 600, and 900 hours. The IMCs(Intermetallic Compound) at the interface between solder and UBM were examined by FESEM and TEM. The results showed that the shear strength was decreased with aging time and temperature. The solder ball with high activated RA flux had about 8.2% higher shear strength than that of RMA flux. Poor wetting and many voids were observed in the fractured solder joint with of RMA flux. The decreased shear strengths were caused by IMC growth and Zn grain coarsening. Zn reacted with Au and then was transformed to the $\beta$ -AuZn compound. Although AuZn grew first, $r-Ni_5Zn_{21}$ compounds were formed with aging time. The layers indicated by $Ni_5Zn_{21}(1)$, (2), and (3) were formed with the thickness of ∼0.7 ${\mu}{\textrm}{m}$, ∼4 ${\mu}{\textrm}{m}$, and ∼2 ${\mu}{\textrm}{m}$, respectively.

PDP용 무연 투명유전체의 Dry Film 개발 (Development of Dry Films of Lead-free Transparent Dielectrics for PDP)

  • 이지훈;방재철
    • 한국산학기술학회논문지
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    • 제6권6호
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    • pp.497-501
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    • 2005
  • Dry film 공정에 의해 PDP(Plasma Display Panel)용 무연 투명유전체를 제조하였다. 여러 슬러리 조성으로부터 고밀도 green sheet를 제조하는데 최적의 조성을 선정하였다. 한편, 슬러리는 양질의 green sheet를 제작하는데 적합한 shear thinning 특성을 나타냈다. 제조한 투명유전체의 열팽창계수는 유리기판인 PD-200과 유사한 $97{\times}10^{-7}/^{\circ}C$로 측정되었다. PD-200에 접합된 투명유전체의 단면 주사현미경 관찰로부터 두 층은 갭이 없이 매우 견실히 접합되어 있음을 확인할 수 있었다.

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Electrical Properties of (Ba,Ca)(Ti,Zr)O3 Ceramics for Bimorph-type Piezoelectric Actuator

  • Shin, Sang-Hoon;Yoo, Ju-Hyun
    • Transactions on Electrical and Electronic Materials
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    • 제15권4호
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    • pp.226-229
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    • 2014
  • In this study, lead-free $(Ba_{0.85}Ca_{0.15})(Ti_{1-x}Zr_x)O_3$ ceramics and a bimorph-type piezoelectric actuator were fabricated using the normal oxide-mixed sintering method, and their dielectric properties, microstructure, and displacement properties were investigated. From the results of X-ray diffraction, the pattern of the specimen has a pure perovskite structure. In addition, no secondary impurity phases were found. The excellent piezoelectric coefficient of $d_{33}=454pC/N$, the electromechanical coupling factor $k_p=0.51$, the dielectric constant ${\varepsilon}_r=3,657$, the mechanical quality factor $Q_m=239$, and $T_c$(Tetragonal-Cubic) =$90^{\circ}C$ were shown at x= 0.085. ${\Delta}k_p/k_p20^{\circ}C$ and ${\Delta}f_r/f_r20^{\circ}C$ showed the maximum value of -0.255 and 0.111 at $-20^{\circ}C$ and $80^{\circ}C$, respectively. The maximum total-displacement was $60{\mu}m$ under the input voltage of 50 V. As a result, it is considered that lead-free $(Ba_{0.85}Ca_{0.15})(Ti_{1-x}Zr_x)O_3$ ceramics is a promising candidate for piezoelectric actuator application for x= 0.085.

무연 Cu-Zn-Sn 청동의 조직과 주조성에 미치는 Bi 및 Sb 첨가의 영향 (Influence of Bismuth and Antimony Additions on the Structures and Casting Properties of Lead-free Cu-Zn-Sn Bronze Castings)

  • 박흥일;박성익;김성규
    • 한국주조공학회지
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    • 제32권2호
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    • pp.91-97
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    • 2012
  • The effects of Bi and Sb additions on the microstructures and casting properties in lead-free Cu-Zn-Sn broze were investigated. (1) When only Bi was added to the bronze, Bi was precipitated on the ${\delta}$ phase of ${\alpha}$ dendrite cell boundary. When Bi and Sb were added together, Bi was precipitated on the ${\delta}_A$ which was the Sb-rich area in the ${\delta}$ phase. (2) The addition of Sb accelerated the formation of ${\delta}$ phase, and when Sb, Bi and Pb were added, Bi and Pb were precipitated as mixed solution in the ${\delta}_A$ phase. (3) The combined addition of Sb and Bi resulted in the suppression of shrinkage due to the complementary effects of the mass feeding of ${\alpha}$-dendrite cluster covered with ${\delta}$ phase and sealing of micro-shrinkage in the ${\delta}$ phase by solidification expansion of Bi.

하소온도변화에 따른 (Na,K)NbO3계 무연 압전세라믹스의 압전 및 유전특성 (Piezoelectric and Dielectric Characteristics of Lead-free (Na,K)NbO3 Piezoelectric Ceramic System according to Calcination Temperature)

  • 류성림;정광현;류주현;이병률;정영호
    • 한국전기전자재료학회논문지
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    • 제18권9호
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    • pp.821-826
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    • 2005
  • In this paper, in order to develop lead-free piezoelectric ceramics, $(Li_{0.04}Na_{0.44}K_{0.52)(Nb_{0.86}Ta_{0.10}Sb_{0.04})O_3$ ceramics were fabricated with the variation of calcination temperature and sintering temperature. The ceramics couldn't be sintered at temperature less than $1110^{\circ}C$ and showed the highest density at calcination temperature of $800^{\circ}C$. Crystal structure of the ceramics showed pseudo-tetragonal phase. At the calcination temperature of $800^{\circ}C$ and sintering temperature of $1110^{\circ}C$, the optimal values of $density=4.64g/cm^3,\;kp=0.45,\;{\varepsilon}r=1336,\;d_{33}=254pC/N\;and\;Tc=335^{\circ}C$ were obtained.