摘要
随着欧盟RoHs法令从2006年7月开始实施,印制电路板装配不得不随之无铅化,传统已使用超过50年的63Sn/37Pb焊接材料被SnAgCu(Sn96.5%/Ag3.0%/Cu0.5%)代替,熔点由原来的187℃提升到217℃,相应的焊接温度由220℃～230℃提升到240℃～260℃,印制电路板必须经历熔点以上的焊接时间多出了50多秒,印制电路板吸收热大增,印制电路板必须提高耐热性能与之配合。在过去的一年中,印制电路板分层问题一直困扰着电路板制造商。印制板分层的机理是电路板吸热后,不同材料之间产生不同的膨胀系数而形成内应力,如果树脂与树脂,树脂与铜箔的粘接力不足以抵抗这种内应力将产生分层,所以解决分层的思路是:1.生产流程控制尽可能保证板子有最佳的抵抗内应力的能力;2.使用性能优越的材料减少内应力。文章希望通过研究,在成本和品质双重约束下,找到最佳的解决方案,用最低的成本来解决分层问题。思路是从研究分层的原因着手,通过实验设计的方法,对分层的因素从材料选择、印制电路板制造过程控制到电路板装配的整个过程,进行系统分析。本研究项目耗费25万元的试验材料成本,历时三个多月,最终从成本和品质控制,提升公司竞争力的角度,提出解决分层的三套方案。在将实验结果运用到A公司的实践中后,产生了良好的经济效益,每月减少客诉成本约30万元,减少成本浪费约80万元,取得超过预期效益。
Because EU Rolls instruction became effective, the solder paste of printed circuit board assembly must be lead-free material. The solder paste of 63Sn/37Pb that had used about 50 years had been replaced by SnAgCu （Sn96.5%/ Ag3.0%/Cu0.5 % ）. The Melting point is increased from 187 ℃ to 217 ℃, accordingly, the temperature of PCB A had to be increased from 220 ℃ -240℃ to 240℃-260℃, and the time of PCB over melting points is long about 50 seconds, so PCB wiU absorb thermal mass more and more. The resistance of printed circuit board to thermal shock must be improved and matched with it. In pass one year, the delamination of printed circuit board occurred in PCBA still became a big trouble of PCB manufacturer. The root cause of PCB delamination is that the sticking strength between prepreg and prepreg or prepreg and copper couldn＇t withstand the thermal stress due to different material with different elongation in high temperature. So the solution to delamination is shown as below：
1.By controlling the PCB process, to ensure the sticking strength could get over the thermal stress
2.By choosing suitable material, to reduce the thermal stress as low as possible.
In this thesis, by considering the cost and quality at the same time, we hope could look for the best solution to delamination. With the method of DOE, it try to study the root cause of delamination by analyzing complete process flow from PCB raw material, PCB manufacturing to assembly process.
It took about 3 months and 250 000 yuan material cost, lastly, it had gave three sets of solution to delamination based on cost and quality control, improving company competitive postion.
Great profit was gained in a company after applying the optimized solution by reducing customer complaint cost about 300,000 yuan each month and material cost about 800 000 yuan each month.
出处
《印制电路信息》
2008年第4期31-56,69,共27页
Printed Circuit Information
关键词
分层
无铅焊接
实验设计
印制电路板
delamination
lead-Free soldering
DOE
printed circuit board
