The purpose of this paper is to investigate and minimize the printing-related defects in the surface mount assembly (SMA) process.,This paper uses an experimental approach to explore process parameter and printing defects during the SMA process. Increasing printing performance, various practices of solder paste (Ag3.0/Cu0.5/Sn) storage and handling are suggested. Lopsided paste problem is studied by varying squeegee pressure and the results are presented. Unfilled pads problems are observed for ball grid array (BGA) and quad flat package (QFP) which is mitigated by proper force tuning. In this paper, a comparative study is conducted which evaluates the manifestation of printing offset due to low-grade stencil. The input/output (I/O) boards were oxidized when the relative humidity was maintained beyond 70 per cent for more than 8 h. This pad oxidation problem is overcome by proper printed circuit board (PCB) handling procedures. When the unoptimized line is used, the paste wedged in the stencil and influences the performance of the screen printer, for this reason, an optimized line is proposed that minimize the printing defects.,The key findings are as follows: in the SMA process, printing quality is directly associated with solder paste quality. Experimentally, it is observed that a considerable variance in solder deposition occurred when the front and rear squeegee have different configurations. High-grade and unsoiled stencil results in superior paste deposition and less distinction. Insufficient solder paste and bridge problems also occur in printing when PCB pads are oxidized. Optimized line resolves solder paste clog issues, associated with stencil’s aperture. The cooling arrangement on the conveyor, after reflow, explicates hot jig problem. Control environmental conditions minimized static charges and printing defects.,The preceding studies emphasis mostly on the squeegee pressure, while other important parameters are not completely investigated. Moreover, it is very imperative to concurrently measure all parameters while varying the environmental conditions. This study highlights and provides an experimental approach to various PCB printing defects, and a comparative study has been conducted that concurrently measure all process parameters.

中文翻译：

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SMT 无铅锡膏印刷中的缺陷最小化和工艺改进：一项比较研究

本文的目的是调查和最小化表面贴装组件 (SMA) 工艺中与印刷相关的缺陷。本文使用实验方法来探索 SMA 工艺过程中的工艺参数和印刷缺陷。为了提高印刷性能，建议采用各种焊膏 (Ag3.0/Cu0.5/Sn) 储存和处理方法。通过改变刮板压力研究了不平衡的糊料问题，并给出了结果。对于球栅阵列 (BGA) 和四方扁平封装 (QFP)，观察到未填充的焊盘问题，这可以通过适当的力调整来缓解。在本文中，进行了对比研究，评估了低等级模板印刷胶印的表现。当相对湿度保持在 70% 以上超过 8 小时时，输入/输出 (I/O) 板就会被氧化。正确的印刷电路板 (PCB) 处理程序可以克服这种焊盘氧化问题。当使用未优化的线时，锡膏会楔入模板并影响丝网印刷机的性能，为此，提出了一条优化线，以最大限度地减少印刷缺陷。主要发现如下：在SMA工艺中，印刷质量与焊膏质量直接相关。通过实验，观察到当前后吸水扒具有不同的配置时，焊料沉积会发生相当大的变化。高级和未污染的模板可实现卓越的糊剂沉积和更少的区分。PCB焊盘氧化时，印刷时也会出现焊膏不足和桥接问题。优化的生产线解决了与模板孔径相关的焊膏堵塞问题。回流后，传送带上的冷却装置说明了热夹具问题。控制环境条件，最大限度地减少静电荷和印刷缺陷。之前的研究主要侧重于刮板压力，而其他重要参数并未完全研究。此外，在改变环境条件的同时同时测量所有参数是非常必要的。该研究强调并提供了一种针对各种 PCB 印刷缺陷的实验方法，并且已经进行了一项同时测量所有工艺参数的比较研究。而其他重要参数没有完全调查。此外，在改变环境条件的同时同时测量所有参数是非常必要的。该研究强调并提供了一种针对各种 PCB 印刷缺陷的实验方法，并且已经进行了一项同时测量所有工艺参数的比较研究。而其他重要参数没有完全调查。此外，在改变环境条件的同时同时测量所有参数是非常必要的。该研究强调并提供了一种针对各种 PCB 印刷缺陷的实验方法，并且已经进行了一项同时测量所有工艺参数的比较研究。