干冰表面处理技术在系统级封装的应用

目的电子元器件表面材料的质量是影响电磁屏蔽镀层和封装材料表面结合力的主要因素,封装元件在切割分离过程中侧壁表面粘附的Cu杂质对屏蔽膜的质量有不利影响。为了提高电子封装体的表面质量,提出一种可应用于高精密电子加工领域的新型表面技术——干冰处理技术。方法通过实验设计深入研究干冰技术的关键参量(喷射压力、喷射角度和清洗速度)对电子材料表面杂质去除的影响规律,分析了干冰处理封装材料表面的作用机理,对比了干冰作用与传统去离子水处理所获得的电磁屏蔽膜质量。结果作用机理为干冰的物理冲击和微爆破产生的冲击力将粘附到侧壁上的杂质剥离而去除,实验得到最优作用条件,即在喷射压力为0.2~0.4 MPa,作用速度为40~50 mm/s,喷射角度为40?~70?时,封装元件PCB侧壁表面质量明显改善,表面PCB区域铜杂质的含量由30%降至2%,阻焊层破损率可控,且有效地提高了电磁屏蔽镀层结合力的等级。结论干冰技术工艺操作简单,作业效率高,且在最优工艺参数下无其他不良产生,可作为未来电子元器件制造领域表面处理的技术支撑。

Application of Dry Ice Surface Treatment Technology in System-in-package

The surface material quality of electronic components was the key factor influencing surface binding force between electromagnetic shielding coatings and packaging materials.The work aims to improve the surface quality of electronic package by putting forward a novel surface technology-dry ice treatment technology,which can be applied to high precision electronic processing field.The influencing rule of such key parameters as injection pressure,injection angle and clean speed on surface impurity removal of electronic materials was studied in depth based on experimental design.Function mechanism of treating surface of packaging materials by dry ice was analyzed,and quality of electromagnetic shielding films acquired by using dry ice and traditional deionized water was compared.As a result,the function mechanism was like this:the impact force produced by physical impact and micro explosion peeled off and removed impurities adhering to side wall.Under the optimum reaction conditions obtained from the experiment:injection pressure of 0.2～0.4 MPa,action speed of 40～50 mm/s and injection angle of 40°～70°,surface quality of the potted element PCB side wall improved significantly,copper impurity content of the surface PCB area reduced from 30％ to 2％,breakage rate of the solder mask was controlled,binding force level of the electromagnetic shielding coating was improved effectively.Since the whole process of dry clean is efficient,easy to operate and free from side effects provided with optimum process parameters,it can provide technical support for surface treatment in future manufacturing of electronic components.