【作者】 张建华；

【导师】 张元良； 孙大超；

【作者基本信息】 大连理工大学 ， 机械工程（专业学位）， 2018， 硕士

【摘要】 选择性无铅浸焊是近些年兴起的一种新型表面贴装技术,与传统选择性波峰焊相比,这种工艺技术更加灵活,适合于柔性化生产的需要。同时,浸焊设备操作更加简单,设备维护保养成本较低。选择性无铅浸焊技术正在逐渐被大量电气元件制造商使用,用于生产片式化与通孔类元器件共存的印刷电路板。然而,由于新工艺技术应用时间较短,经验积累不足,对于生产过程中产生缺陷的根本原因缺少分析,也没有指导性的改善方法。实验设计(Design of Experiment,简称DOE),是一种科学的统计方法,它可以通过较少的实验次数、较短的实验时间,分析出各个因子对于响应的影响。同时,通过最优化处理,计算出响应的最优因子组合和响应预测值。本文将采用DOE中部分2~k析因设计方法,以我司无铅浸焊工艺过程中的两类缺陷:填充不足和漏焊为响应,选取助焊剂喷涂量、预热温度、浸焊温度、浸入时间、浸出速度、浸焊夹具高度六个因子,设计6因子2水平,分辨度为Ⅳ的部分析因实验,进行分析研究,找出产生缺陷的主要原因并对工艺参数及生产过程进行优化。实验结果表明,影响填充不足和漏焊的主要因子是:浸焊温度、浸入时间以及浸焊夹具高度,其余因子对于缺陷的作用不显著。浸焊温度、浸入时间以及浸焊夹具高度对于缺陷的影响是负效应,即在设定的工艺参数窗口范围内,浸焊温度越高、浸入时间越长、浸焊夹具高度越高,生产过程中的缺陷率越低。此外,因子间的二阶交互作用也不显著。通过多元回归拟合,得出填充不足和漏焊与各个因子间的线性回归方程。对方程求解后,找出降低缺陷率的最优因子组合:助焊剂喷涂量:20个脉冲(每个焊点约0.5g助焊剂),预热温度:200℃,浸焊温度:310℃,浸入时间:3s,浸出速度:4mm/s,浸焊夹具高度:98mm。重新按照最优因子组合安排实验,验证了回归方程的有效性,进而得出无铅浸焊工艺的最优参数组合,为降低产品缺陷率奠定了基础。同时,通过测温样件、卡尺及辅助工装等,确保浸焊温度、浸焊夹具高度的参数应用准确,使生产过程更加稳定。更多还原

【Abstract】 Selected lead-free dip soldering is a new kind of surface mount technology,which is generated in recent years.It’s better for flexible production compare with traditional selected wave soldering.Meanwhile,due to dip soldering machine is easier to operate and equipment maintenance cost is less,it’s applied to produce PCB with both SMD and hole mounted electronics by more electronic parts manufacturers gradually.However,due to the new technology application period is short,there are less of experience and guideline on products failure root cause analysis and process modification.Design of Experiment(DOE)is a statistics method,which is used to analysis factor impact on result via less experiment and times.At the same time,the best factor combination and predictive value could be calculated with optimization.The paper would use part 2~k factorial experiment design to analysis two main kinds of failure mode,solder filling insufficient and solder hole in our company.The factors are flux spray amount,pre-heating temperature,soldering temperature,soldering time,soldering speed and height of soldering fixture.The experiment is based on 6 factors with level 2 and the resolution isⅣ.The root cause of parts failure and method of process optimization would be found out after experiment and analysis.The experiment indicates the main factors of soldering filling insufficient and soldering hole are soldering temperature,soldering time and height of soldering fixture.If we want to decrease the failure rate,the three factors must be controlled.And other factors impacts on failure are not significant.The impact of soldering temperature,soldering time and height of soldering fixture to failures are negative effect that means higher soldering temperature,longer soldering time and higher soldering fixture would result in lower failure rate.Besides,the 2 level interaction of factors effect are not significant.Through multiple fitting,we could calculate the linear regression equation of soldering filling insufficient and solder hole with these factors.After calculate the equation,the best factor combination with lowest failure rate are as below:flux spray pulse amount is 20(about 0.5g per solder hole),pre-heating temperature is 200℃,the soldering temperature is 310℃,soldering time is 3s,soldering speed is 4mm/s,height of soldering fixture is 98mm.Arrange another sets of experiment plan with the best factor combination,the equation is verified correct and the best factor combination is fixed,which is the base of decreasing parts failure rate.Meanwhile,use temperature testing sample and caliper with auxiliary jig to make sure the soldering temperature and fixture height are implemented precisely and the process is stable.更多还原