- Treatment before immersion copper
1) . Burring
The drilling process of the substrate before copper sinking is easy to produce burr, which is the most important hidden danger to the metallization of inferior holes. It must be solved by deburring technology. Usually by mechanical means, so that the hole edge and inner hole wall without barbed or hole blocking phenomenon.
1) . Degreasing
2) . Coarse processing:
It mainly ensures good bonding strength between metal coating and matrix.
3) Activating treatment:
The main “initiation center” is formed to make the copper deposition uniform
- The cause of the hole wall coating cavity:
1) Hole wall coating cavity caused by PTH
(1) Copper content of copper sink cylinder, sodium hydroxide and formaldehyde concentration
(2) the temperature of the tank
(3) Control of activation liquid
(4) Cleaning temperature
(5) the use temperature, concentration and time of the whole pore agent
(6) Service temperature, concentration and time of reducing agent
(7) Oscillators and swing
2) Pattern transfer caused by hole wall coating holes
(1) Pretreatment brush plate
(2) residual glue of orifice
(3) Microcorrosion of pretreatment
3) Figure plating caused by hole wall coating holes
(1) Graphic electroplating microetching
(2) tin plating (lead tin) poor dispersion
There are many factors causing the coating hole, the most common is the PTH coating hole, by controlling the relevant process parameters can effectively reduce the production of PTH coating hole. But other factors cannot be ignored, only through careful observation, to understand the cause of the coating hole and the characteristics of defects, in order to solve the problem in a timely and effective manner, maintain the quality of the product