hence here a polishing mechanism 5 is used to planarize it so as to form planarized metallic pillar 6 a and 6 b which is as shown in fig1 c and fig1 d in the current embodiment the polishing mechanism 5 used can be polishing and planarization mechanisms such as traditional mechanical polishing or advanced chemical and mechanical polishing cmp step 4 please refer to fig1 e u02dc fig1 h and repeat step 1 u02dc 3 that is coat a second mask layer 7 on the planarization metallic pillar 6 a 6 b and first mask layer 2 then prepare again solder tip structural layer opening 8 a 8 b to be electroplated then electroplating is used again to complete the preparation of solder tip 9 a 9 b similarly polishing mechanism 5 is used again to planarization it to obtain planarization solder tip 10 a and 10 b here the material of second mask layer 7 is the same as that of first mask layer 2 that is they are all photo resists moreover the thickness range of second mask layer 7 depends on the solder tip height to be formed subsequently in addition the shape and size of structural layer opening 8 a and opening 8 b of the solder tip to be electroplated is designed based on the needed electroplating solder volume for obtaining spherical bump height after reflow and through advance design and calculation of solder tip electroplating height for the same.