MLCC表面贴装中墓碑现象的研究

墓碑现象是MLCC与PCB板焊接过程中一端离开焊区而向上方斜立或直立。主要原因是在焊接过程中MLCC两端的不平衡的润湿力。而不平衡润湿力产生的主要因素是:(1)MLCC两端不能同时熔融;(2)焊盘设计不合理。根据力学机理提出了保持MLCC的表面清洁,注意合理的焊盘设计、避免焊膏的活性减弱和确保MLCC两端同时熔融的解决措施。该措施能有效防止墓碑现象,并在实际生产中取得了良好的效果。

Study on Tombstoning in MLCC Surface Mounted

Tombstoning is one of the disfigurement which was used in the soldering period between MLCC and PCB board, it means one of the termination was leaning or standing from the soldering area. The main reason of these disfigurement is the imbalance wetting force of two sids during the soldering period. The main factor which results in imbalance wetting force is:1)Both of the sides melting at the different time; 2) The unreasonable design of the soldering board. Were analyzed the reason and mechanical mechanism formed tombstoning. It is put forward the avoiding way that keep the surface of the MLCC clean, the reasonable design of the soldering board, avoid to changing the characteristic of the flux and insure both of the sides melting at the same time, it can avoid tombstoning, have already achieved good results in the production.