【摘 要】
：
In recent years, intensive studies have been carried out to find an alternative for Tin ( Sn)-Lead ( Pb ) solder alloys with increasing demand over lower temperature solder alloys in current electronic packaging industry. High temperature operational sold
【机 构】
：
Center for Advanced Materials Research and Manufacturing Processes,SEGi University,Petaling Jaya 478
论文部分内容阅读
In recent years, intensive studies have been carried out to find an alternative for Tin ( Sn)-Lead ( Pb ) solder alloys with increasing demand over lower temperature solder alloys in current electronic packaging industry. High temperature operational solder alloys seem to produce drawback to other components on the printed circuit board ( PCB) . Low melting temperature Sn58Bi substrate as a potential replacement was investigated in this paper based on the melting properties, wettability, and shear strength. The Sn58Bi was soldered at a temperature below 200 ℃ on the Cu substrate, and the shear strength and contact angle were calculated. A peak temperature ( melting temperature, TM ) of 144. 83 ℃ was identified. Single lap joint method was performed at a strain rate of 0.1 mm/min and an average shear strength of 23.4 MPa was found from three samples. The contact angle ( wettability ) was calculated to study the solder joint behaviour at reflow temperature of 170 ℃. The contact angle of the Sn58Bi was found to be 32.4 ° and considered to be desired value since the angle is less than 50 ° . The low temperature soldering provides a preliminary result to allow further application on the real PCB.
其他文献
The effect of the pore density of porous copper ( Cu) on brazed Cu/porous Cu was investigated. A filler with a composition of Cu-9. 0Sn-7. 0Ni-6. 0P ( Sn:Tin;Ni:Nickel;P:Phosphorus) and porous Cu with pore densities of 15 pores per inch ( PPI) , 25 PPI, a
车对车(V2V)通信是智能交通系统的重要组成部分.隧道是智能交通系统的一个重要应用场景.考虑到隧道壁反射、车辆衍射以及隧道附属设施布置密而复杂的问题,研究隧道场景下的V2 V信道传播特性对于智能交通系统的设计与测试具有重要意义.本文利用宽带信道探测器对隧道环境下的V2 V信道进行了测量.测量所使用的载波频率和带宽分别为5.2 GHz和120 MHz.根据不同的情况,将测量分为3种类型:可视距(LOS)、部分视距(OLOS)和不可视距(NLOS).基于实际测量数据,建立不同场景的路径损耗模型和接收信号幅值衰
In this paper, battery aging diversity among independent cells was studied in terms of available capacity degradation. During the aging process of LiFePO4 batteries, the phenomenon of aging diversity can be observed. When batteries with same specification
在拉深成形过程中,纤维金属层板常见的失效模式主要有起皱、纤维拉伸断裂以及界面分层.受金属拉深成形测试的启发,经研究,当纤维金属层板以纤维拉伸断裂与界面分层失效为主要的失效模式时,可以将纤维应变引入到成形极限图中.但是,由于用于拉深测试的传统金属条状试样形状会干扰纤维金属层板内纤维应变的计算,因此,本研究设计了一种新型切槽形状试样.通过对比传统的条状试样和新型切槽试样的成形试验以考察玻璃纤维/聚酰胺树脂(Gf/PA)复合材料-铝合金层板的成形性能.研究结果表明:所设计的新型切槽试样可以将纤维计算的应变水平控
针对现有频谱分离方法进行声学场景分类研究时其分类准确率不高的问题,提出了一种基于梅尔频谱分离和长距离自校正卷积神经网络(long-distance self-calibration convolutional neural network,LSCNet)的声学场景分类方法.首先,介绍了频谱的谐波打击源分离原理,提出了一种梅尔频谱分离算法,将梅尔频谱分离出谐波分量、打击源分量和残差分量;然后,结合自校正神经网络和残差增强机制,提出了一种长距离自校正卷积神经网络;该模型采用频域自校正算法以及长距离增强机制来保
Variability of power generation due to the prevalence of cloud cover over solar photovoltaics (PV) power plants is a challenge faced by grid operators and independent system operators (ISOs) in the integration of solar energy into the grid. Solar forecast
为研究新型双箱型空腹圆弧钢拱的平面内稳定特性,采用理论推导与有限元数值模拟相结合的方法,研究其平面内弹性屈曲及弹塑性稳定承载力,分析剪力对拱截面破坏模式的影响,并建立了平面内稳定承载力的设计方法.首先,根据拱截面的剪力分布情况,研究了双箱型空腹圆弧钢拱截面整体剪切变形及弦腹杆剪切变形对平面内弹性屈曲的影响;推导出了考虑双剪切变形影响时,双箱型空腹圆弧钢拱的纯压弹性屈曲荷载公式.然后,参考轴心受压柱设计原理,引入稳定系数及正则化长细比,绘制了纯压状态下的稳定曲线.最后,分析了在几种常见荷载工况下,双箱型空腹
To solve the dead-zone in the output flow curve of the proportional flow valve without displacement sensor, a dead-zone compensation approach is proposed in this paper. Instead of detection and feedback of the valve spool position, the proposed approach a
Heavy metals-polluted water has negative impact on the ecosystem. In Malaysia, minimum discharge limit for Cu2+ and Zn2+ are 1 mg/L and 2 mg/L, respectively. Zeolite is a highly porous adsorbent and its performance is affected by various factors, includin
针对巷道掘进过程中掘进效率低的问题,采用双契形斜眼掏槽方式进行爆破,详细分析爆破工艺参数,设置起爆顺序,通过实际应用,结果表明,在使用双契形斜眼掏槽爆破方案后,平均进尺从试验前的1.2 m增加到1.8 m,炮眼深度从1.5 m增加到2.0 m,炮眼利用率从85％增加到90％,在巷道成型方面有了很大的改善,爆破效果显著.