• Title/Summary/Keyword: Solder balls

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A Study on Solderability of Sn-Ag-Cu Solder with Plated Layers in ʼn-BGA (ʼn-BGA에서 Sn-Ag-Cu 솔더의 도금층에 따른 솔더링성 연구)

  • 신규식;정석원;정재필
    • Journal of Welding and Joining
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    • v.20 no.6
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    • pp.59-59
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    • 2002
  • Sn-Ag-Cu solder is known as most competitive in many kinds of Pb-free solders. In this study, effects of solderability with plated layers such as Cu, Cu/Sn, Cu/Ni and Cu/Ni/Au were investigated. Sn-3.5Ag-0.7Cu solder balls were reflowed in commercial reflow machine (peak temp. : 250℃ and conveyer speed : 0.6m/min). In wetting test, immersion speed was 5mm/sec., immersion time 5sec., immersion depth 4mm and temperature of solder bath was 250℃. Wettability of Sn-3.5Ag-0.7Cu on Cu, Cu/Sn (5㎛), Cu/Ni (5㎛), and Cu/Ni/Au (5㎛/500Å) layers was investigated. Cu/Ni/Au layer had the best wettability as zero cross time and equilibrium force, and the measured values were 0.93 sec and 7mN, respectively. Surface tension of Sn-3.5Ag-0.7Cu solder turmed out to be 0.52N/m. The thickness of IMC is reduced in the order of Cu, Cu/Sn, Cu/Mi and Cu/Ni/Au coated layer. Shear strength of Cu/Ni, Cu/Sn and Cu was around 560gf but Cu/Ni/Au was 370gf.

A Study on Solderability of Sn-Ag-Cu Solder with Plated Layers in $\mu-BGA$ ($\mu-BGA$에서 Sn-Ag-Cu 솔더의 도금층에 따른 솔더링성 연구)

  • 신규식;정석원;정재필
    • Journal of Welding and Joining
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    • v.20 no.6
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    • pp.783-788
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    • 2002
  • Sn-Ag-Cu solder is known as most competitive in many kinds of Pb-free solders. In this study, effects of solderability with plated layers such as Cu, Cu/Sn, Cu/Ni and Cu/Ni/Au were investigated. Sn-3.5Ag-0.7Cu solder balls were reflowed in commercial reflow machine (peak temp.:$250^{\circ}C$and conveyer speed:0.6m/min). In wetting test, immersion speed was 5mm/sec., immersion time 5sec., immersion depth 4mm and temperature of solder bath was $250^{\circ}C$. Wettability of Sn-3.5Ag-0.7Cu on Cu, Cu/Sn ($5\mu\textrm{m}$), Cu/Ni ($5\mu\textrm{m}$), and Cu/Ni/Au ($5\mu\textrm{m}/500{\AA}$) layers was investigated. Cu/Ni/Au layer had the best wettability as zero cross time and equilibrium force, and the measured values were 0.93 sec and 7mN, respectively. Surface tension of Sn-3.5Ag-0.7Cu solder turmed out to be 0.52N/m. The thickness of IMC is reduced in the order of Cu, Cu/Sn, Cu/Mi and Cu/Ni/Au coated layer. Shear strength of Cu/Ni, Cu/Sn and Cu was around 560gf but Cu/Ni/Au was 370gf.

Reliability Investigation and Interfacial Reaction of BGA packages Using the Pb-free Sn-Zn Solder (Sn-Zn 무연솔더를 사용한 BGA패키지의 계면반응 및 신뢰성 평가)

  • Jeon, Hyeon-Seok;Yun, Jeong-Won;Jeong, Seung-Bu
    • Proceedings of the KWS Conference
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    • 2005.06a
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    • pp.25-27
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    • 2005
  • Sn-9Zn solder balls were bonded to Cu and ENIG (Electroless Nickel/Immersion Gold) pads, and the effect of aging on their joint reliability was investigated. The interfacial products were different from the general reaction layer formed in a Sn-base solder. The intermetallic compounds formed in the solder/Cu joint were $Cu_{5}Zn_{8}$ and $Cu_{6}Sn_{5}$. After aging treatment, voids formed irregularly at the bottom side of the solder because of Sn diffusion into the $Cu_{5}Zn_{8}$ IMC. In the case of the solder/ENIG joint, $AuZn_{3}$ IMCs were formed at the interface. In the case of the Sn-9Zn/ENIG, the shear strength remained nearly constant in spite of aging for 1000 hours at $150^{\circ}C$. On the other hand, in the case of the Sn-9Zn/Cu, the shear strength significantly decreased after aging at $150^{\circ}C$ for 100hours and then remained constant by further prolonged aging. Therefore, the protective plating layer such as ENIG must be used to ensure the mechanical reliability of the Sn-9Zn/Cu joint.

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Thermo-mechanical and Flexural Analysis of WB-PBGA Package Using Moire Interferometry (무아레 간섭계를 이용한 WB-PBGA 패키지의 온도변화 및 굽힘하중에 대한 거동해석)

  • Han, Bong-Tae;Joo, Jin-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.7
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    • pp.1302-1308
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    • 2002
  • Thermo-mechanical and flexural behavior of a wire-bond plastic ball grid array (WB-PBGA) package are characterized by high sensitive moire interferometry. Moire fringe patterns are recorded and analyzed for several bending loads and temperatures. At the temperature higher than $100^{\circ}C$, the inelastic deformation in solder balls become more dominant, so that the bending of the molding compound decreases while temperature increases. The deformation caused by thermally induced bending is compared with that caused by mechanical bending. The strain results show that the solder ball located at the edge of the chip has largest shear strain by the thermal load while the maximum average shear strain by the bending moment occurs in the end solder.

Flip-chip Bonding Using Nd:YAG Laser (Nd:YAG 레이저를 이용한 Flipchip 접합)

  • Song, Chun-Sam;Ji, Hyun-Sik;Kim, Jong-Hyeong;Kim, Joo-Hyun;Kim, Joo-Han
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.1
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    • pp.120-125
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    • 2008
  • A flip-chip bonding system using DPSS(Diode Pumped Solid State) Nd:YAG laser(wavelength : 1064nm) which shows a good quality in fine pitch bonding is developed. This laser bonder can transfer beam energy to the solder directly and melt it without any physical contact by scanning a bare chip. By using a laser source to heat up the solder balls directly, it can reduce heat loss and any defects such as bridge with adjacent solder, overheating problems, and chip breakage. Comparing to conventional flip-chip bonders, the bonding time can be shortened drastically. This laser precision micro bonder can be applied to flip-chip bonding with many advantage in comparison with conventional ones.

Effect of Test Parameter on Ball Shear Properties for BGA and Flip Chip Packages (BGA 및 Flip Chip 패키지의 볼전단 특성에 미치는 시험변수의 영향)

  • Gu, Ja-Myeong;Jeong, Seung-Bu
    • Proceedings of the KWS Conference
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    • 2005.06a
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    • pp.19-21
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    • 2005
  • The ball shea. tests for ball grid array (BGA) and flip chip packages were carried out with different displacement rates to find out the optimum condition of the displacement rate for this test. The BGA packages consisted of two different kinds of solder balls (eutectic Sn-37wt.%Pb and Sn-3.5wt.%Ag) and electroplated Au/Ni/Cu substrate, whereas the flip chip package consisted of electroplated Sn-37Pb solder and Cu UBM. The packages were reflowed up to 10 times, or aged at 443 K up to 21 days. The variation of the displacement rate resulted in the variations of the shear properties such as shear force, displacement rate at break, fracture mode and strain rate sensitivity. The increase in the displacement rate led to the increase of the shear force and brittleness of solder joints.

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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.

Lead-free Solder for Automotive Electronics and Reliability Evaluation of Solder Joint (자동차 전장용 무연솔더 및 솔더 접합부의 신뢰성 평가)

  • Bang, Jung-Hwan;Yu, Dong-Yurl;Ko, Young-Ho;Yoon, Jeong-Won;Lee, Chang-Woo
    • Journal of Welding and Joining
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    • v.34 no.1
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    • pp.26-34
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    • 2016
  • Automotive today has been transforming to an electronic product by adopting a lot of convenience and safety features, suggesting that joining materials and their mechanical reliabilities are getting more important. In this study, a Sn-Cu-Cr-Ca solder composition having a high melting temperature ($>230^{\circ}C$) was fabricated and its joint properties and reliability was investigated with an aim to evaluate the suitability as a joining material for electronics of engine room. Furthermore, mechanical properties change under complex environment were compared with several existing solder compositions. As a result of contact angle measurement, favorable spreadability of 84% was shown and the average shear strength manufactured with corresponding composition solder paste was $1.9kg/mm^2$. Also, thermo-mechanical reliability by thermal shock and vibration test was compared with that of the representative high temperature solder materials such as Sn-3.5Ag, Sn-0.7Cu, and Sn-5.0Sb. In order to fabricate the test module, solder balls were made in joints with ENIG-finished BGA and then the BGA chip was reflowed on the OPS-finished PCB pattern. During the environmental tests, resistance change was continuously monitored and the joint strength was examined after tests. Sn-3.5Ag alloy exhibited the biggest degradation rate in resistance and shear stress and Sn-0.7Cu resulted in a relatively stable reliability against thermo-mechanical stress coming from thermal shock and vibration.

Solder Bump Deposition Using a Laser Beam (레이저빔을 이용한 솔더범프 적층 공정)

  • Choi, Won-Suk;Kim, Jea-Woon;Kim, Jong-Hyeong;Kim, Joo-Han
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.1
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    • pp.37-42
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    • 2012
  • LIFT (laser-induced forward transfer) is an advanced laser processing method used for selectively transferring micron-sized objects. In our study, this process was applied in order to deposit solder balls in microsystem packaging processes for electronics. Locally melted solder paste could be transferred to a rigid substrate using laser pulses. A thin glass plate with a solder cream layer was used as a donor film, and an IR laser pulse (wavelength = 1070 nm) was used to transfer a micron-sized solder ball to the receptor. Mass balance and energy balance were applied to analyze the shape and temperature profiles of the solder paste drops. The transferred solder bumps had measured diameters of 30-40 ${\mu}m$ and thicknesses of 50 ${\mu}m$ in our experiment. The limits and applications of this method are also presented.

Reliability of High Temperature and Vibration in Sn3.5Ag and Sn0.7Cu Lead-free Solders (Sn3.5Ag와 Sn0.7Cu 무연솔더에 대한 고온 진동 신뢰성 연구)

  • Ko, Yong-Ho;Kim, Taek-Soo;Lee, Young-Kyu;Yoo, Sehoo;Lee, Chang-Woo
    • Journal of the Microelectronics and Packaging Society
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    • v.19 no.3
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    • pp.31-36
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    • 2012
  • In this study, the complex vibration reliability of Sn-3.5Ag and Sn-0.7Cu having a high melting temperature was investigated. For manufacturing of BGA test samples, Sn-3.5Ag and Sn-0.7Cu balls were joined on BGA chips finished by ENIG and the chips were mounted on PCB finished OSP by using reflow process. For measuring of resistance change during complex vibration test, daisy chain was formed in the test board. From the results of resistance change and shear strength change, the reliability of two solder balls was compared and evaluated. During complex vibration for 120 hours, Sn-0.7Cu solder was more stable than Sn-3.5Ag solder in complex vibration test.