环形SrTiO_3双功能元件的焊锡和通流能力研究

采用固相合成法,研究了SiO2含量和收缩温度对环形SrTiO3压敏元件微观组织、气孔率的影响。结果表明:元件在1050℃时开始收缩;通过SEM分析,发现随着SiO2含量的增加,元件的气孔率有减少趋势;当x(SiO2)为0.05%～0.10%时,可以获得良好的微观组织。通过改进工艺参数制备压敏元件。焊锡并通100mA电流后,压敏电压的变化率ΔV·V–110mA为0.95%～3.60%,电容变化率ΔC·C–1为9.6%～16.4%。     

In-situ observation and simulation of the solidification process in soldering a small outline package with the Sn-Ag-Cu lead-free alloy

The formation process of solidification defects in solder fillet of circuit boards with a small outline package (SOP) soldered with Sn-3wt.%Ag-0.5wt.%Cu has been examined primarily by using an in-situ observation system and solidification simulation software. The lead frames of the SOP are two kinds of materials: Cu and Fe-42wt.%Ni (42 alloy). Microstructural observations were made of the SOP solder joints using metallographic cross sections. The β-Sn dendrite structure in the solder fillet of a SOP with 42-alloy lead frames is larger than that of a Cu lead frame. This is attributed to the slower cooling speed of the 42-alloy lead-frame SOP than that of the Cu lead-frame SOP. The solidification of a SOP joint is not uniform and locally time dependent. The solder surface of the slowly cooled region of the 42-alloy lead-frame SOP exhibited shrinkage voids and a rough surface because of the coarsening of the dendrite structure. According to the simulation of the solidification process, the relationship between the solidification process and formation characteristics of solidification defects for a SOP joint can be clarified.     

再流焊工艺技术的研究

随着表面贴装技术的发展,再流焊越来越受到人们的重视。文中介绍了再流焊的一般技术要求,并给出了典型温度曲线以及温度曲线上主要控制点的工艺参数。同时还介绍了再流焊中常见的质量缺陷,并粗浅地讨论了其产生的原因及其相应对策。     

BGA植球工艺技术

BGA(ball grid array)球栅阵列封装技术是20世纪90年代以后发展起来的一种先进的高性能封装技术,是一种用于多引脚器件与电路的封装技术。BGA最大的特点就是采用焊球作为引脚,这不仅提高了封装密度,也提高了封装性能。而植球工艺作为BGA封装中的关键工艺将会直接影响器件与电路的性能及可靠性。影响BGA植球工艺的主要因素有:植球材料、植球工艺及回流焊工艺。文章通过对BGA植球的基板、焊膏/助焊剂、焊球等材料的详细介绍,详实阐述了植球工艺过程,并对BGA后处理的回流焊工艺进行了详细描述,提供了BGA植球工艺的检测方法,对植球工艺的可靠性进行了探讨。     

Shape control of polymer reflow structures fabricated by nanoimprint lithography

Nanoimprinted resist pre-forms were modified using thermal reflow. This post-processing of binary structures enabled us to generate lens-like 3-D structures with different shapes by time- and surface chemistry controlled spreading. The method was extended to feature dimensions down to 100 nm. Surfactant coated line nanostructures were found to be limited by a maximum aspect ratio for imprinted pre-forms. This powerful post-processing method can be used either directly as post-processing step in production or for the fabrication of 3-D stamp copies with the desired shapes.     

小型聚丙烯薄膜电容器在波峰焊接上的改进

该文先从小型聚丙烯薄膜电容器在260C无铅波峰焊接后失效着手,通过失效样品解剖分析中得出原因。是此类材质的直引线小体积产品无法承受260C焊接高温所致。为了寻找改进方法,作者运用详细的原理解释,通过对薄膜原料的材质对比,以及聚丙烯与聚酯薄膜电容器的性能对比,再用这两种材质的薄膜电容器样品做成直引线与引线打弯两种方式,结...     

La对SnAgCu/Cu及Ni界面金属间化合物的影响

利用扫描电镜、能谱分析仪对Sn0.3Ag0.7Cu-xLa/Cu(x=0～0.25)和Ni界面金属间化合物(IMC)形成及长大规律进行了研究.结果表明:微量La的添加使钎焊与时效后焊点/Cu界面生成的Cu<,6>Sn<,5>晶粒明显细化,当X超过0.10时,Cu<,6>Sn<,5>晶粒的上方出现大量的粒状Ag<,3>S...     

无铅药芯焊锡丝用非松香基固体助焊剂的研究

针对现有松香固体助焊剂活性温度低和焊后变色的问题,研制了以十八酸、聚乙二醇和少量耐热松香作为载体,以己二酸和癸二酸复配作为活性剂的非松香基固体助焊剂.此助焊剂常温下为白色膏状,熔点范围110℃～130 ℃,满足Sn-0.7Cu无铅药芯焊锡丝灌芯和拔丝工艺.助焊剂中各成分沸点在300℃左右,满足手工烙铁焊高温要求且大大减...     

导线无铅与有铅搭接焊点抗拉脱力对比实验研究

介绍了导线搭接在工程生产中的应用及特点;简述了无铅焊接在导线搭接中的应用进程;重点论述了无铅搭接与有铅搭接抗拉脱力对比实验的方法,并依据实验方法对制订的样品以及采取的实验设备进行了介绍,然后针对实验数据进行了对比与分析,得出在此实验条件下无铅搭接焊点的抗拉脱力性能明显优于有铅焊点。最后给出了进一步开展抗拉脱力对比实验研...     

Cu镀Au腔体气密性封装工艺研究

Cu镀Au腔体是微波器件常用封装载体之一。在目前应用中,Cu镀Au腔体微波器件的气密性封装一直是工程化技术难题,大幅影响了微波器件的可靠性和使用寿命。对基于Cu镀Au腔体的微波器件进行了气密性封装研究,探讨了Cu镀Au腔体实现气密性封装可能的工艺路线。通过比较激光封焊和真空钎焊等传统气密性封装工艺方法,提出了＂小孔密封...