Simulation Study On Key Process Of Packaging Of Micro-coil CCGA Device

Ceramic Column Grid Array package has been widely concerned by researchers due to its high reliability and excellent thermal and electrical performance.However,CCGA devices often have solder joint cracks due to the residual stress generated in the packaging process,which will have a great potential safety hazard.In order to reduce the hidden danger and improve the reliability of the device,this thesis analyzes the three key processes of column planting,reflow soldering and reinforcement in the packaging process of micro-coil CCGA device.The effects of structure,material and process parameters on residual stress are studied,so as to provide some theoretical guidance for the actual production process of devices.The main work of this thesis are summarized as follows:1.Taking the micro-coil CCGA device as the research object,the column planting process is analyzed.The location of the dangerous point is determined.The influence of welding column size on the residual stress is studied.The research shows that:(1)The dangerous point is located in the welding column at the corner of the substrate,specifically in the contact position between the welding column and the mounting hole.(2)When the outer diameter is 0.5mm,the free height is 1.27 mm,and the diameter of the coil wire is 0.063 mm,the residual stress of the column planting process is the smallest.The reliability of the device is relatively high.2.Based on the principle and process of reflow soldering,the reflow soldering process of micro-coil CCGA device is analyzed.The location of the dangerous point is determined.The effects of the diameter of PCB pad,cooling rate and structural parameters on the residual stress are studied.The research shows that:(1)The dangerous point is located in the welding column at the corner of the substrate,specifically in the contact position between the welding column and the inside of the solder.(2)With the increase of the diameter of PCB pad,the residual stress of the reflow soldering process shows a trend of first decreasing and then increasing.With the increase of the cooling rate,the residual stress shows a trend of first stable and then increasing.(3)The order of the sensitivity of structural parameters to residual stress in reflow soldering process is: PCB thickness>substrate thickness>free height of welding column.The residual stress first increases and then tends to be stable with the increase of the substrate thickness,decreases with the increase of the free height of the welding column,and increases with the increase of the PCB thickness.3.Aiming at the reinforcement process of micro-coil CCGA device,the location of its dangerous point is determined.The effects of filler material,curing curve,filling position and filling amount on the residual stress are studied.The optimal combination of process parameters is selected by orthogonal test.The research shows that:(1)The dangerous point is located in the welding column at the corner of the substrate,specifically in the contact position between the welding column and the solder.(2)Compared with U8410-99 and FP4526,it is recommended to use 3513.With the increase of the cooling rate,the residual stress of the reinforcement process keeps increasing.With the increase of filling amount,both of the residual stress of filling on the substrate and the PCB show an increasing trend,but decreases after complete filling.Under the same filling amount,the residual stress of filling on the substrate is larger than that of filling on the PCB.(3)The influence of process parameter on the residual stress of the reinforcement process is as follows: cooling rate>filling position and filling amount>filling material.The optimal parameter combination of the reinforcement process is: 3513,filling 1/6 of the PCB,and cooling rate of 5℃/min.