Electrodeposited via posts are important elements in wafer level CSP. Cross sections of these via posts were observed for the via-posts with less than 100 mum cathode length. Heights of via-posts become non-uniform with the narrower via-post pitches. Via-posts become the higher fur lower portion of electrode and lower for the upper portion of electrode. The uniformity increases for wider via-post pitches. The uniform height via-posts form via-post pitch of for longer than 700 mum at 100 mum cathode length. Uniform height forms for pitch of longer than 400 mum at 75 mum cathode length, longer than 250 mum at 50 mum cathode length and longer than 100 mum at 25 mum cathode length. The solution becomes dilute because of consumption of copper ion at the cathode via. This dilute solution emerges from the via and becomes upper stream flow, which travels along the resist surface and flows into the vias at upper portion of the electrode. The upper stream flow mixes with bulk electrolyte along the resist surface and recovers its concentration. With longer resist surface distance, the flow mixes more with bulk electrolyte and increases recovery. This concentration recovery along the resist surface causes the height of via-posts as uniform.