Acidic copper plating additives are a combination of various organic compounds. During the electroplating process, they can effectively increase cathodic polarization through characteristic adsorption, refine crystallization, and improve brightness and leveling. Without any additives, the copper plating solution cannot achieve a bright, leveled coating with excellent mechanical properties. The consumption of additives mainly occurs through anodic oxidation, high-temperature decomposition, cathodic reduction, and adsorption removal during the electroplating process. The role of additives in the plating solution is similar to that of traditional Chinese medicine formulas; the various components must be used appropriately to maximize efficacy. Overuse can lead to toxicity, so it is crucial to control the balance of additive consumption during the electroplating process. Since the consumption of additives is significantly affected by process conditions, it is relatively challenging to maintain the balance of various components in production. The relationship between additive consumption and process conditions is summarized below for reference by various branches.
 

1. The impact of cathodic current density:
If the cathodic current density is too low, the overpotential during the electroplating process will be low, leading to a reduction in the consumption of certain components in the additives, causing them to accumulate in the plating solution. If the accumulation exceeds the upper limit, quality issues will arise. Therefore, it is essential to strictly control the current density within the process range. It is also recommended that non-half immersion plating tanks accurately calculate the plating area to ensure that the current density does not drop too low.
 

2. The impact of anodic current density:
The size of the anodic current density directly affects the anodic polarization potential. A high anodic polarization potential results in a greater amount of additives being oxidized. However, the antioxidant capacity of all additive components varies, leading to disproportionate consumption. Therefore, the anodic area should not be too small, and copper balls should be replenished in a timely manner to avoid increased consumption of certain components due to excessive anodic current density, which could lead to quality issues.
 

3. The impact of the anode-cathode area ratio:
The previous two aspects highlight the importance of the anode-cathode area ratio. If the ratio is too imbalanced, even if the cathodic current density is well controlled, the current density on the anode will deviate from normal process requirements, causing some components in the additives to be consumed excessively or to accumulate, resulting in an imbalance.
 

4. The impact of temperature:
Temperature is a crucial control factor for additive consumption. High temperatures can cause certain components in the additives to decompose too quickly, increasing consumption.
Low temperatures will reduce additive consumption, but not all components decrease synchronously due to differing high-temperature resistance, which can easily lead to the accumulation of certain components. Therefore, using lower temperatures to reduce additive consumption is not advisable.
 

5. The impact of plating solution composition:
The composition of the plating solution is fundamental to achieving a good coating. Without normal plating solution components, even the best additives will not be effective. A low concentration of copper sulfate in the plating solution will increase cathodic polarization, causing the additive components that are prone to reduction and transformation on the cathode surface to be consumed too quickly. Therefore, it is particularly important to ensure that the composition of the plating solution remains within the process range.
 

6. Immersion area:
This issue directly determines the actual current size. If the actual current calculation is not accurate enough, it will naturally affect the consumption of additives. Therefore, it is recommended that customers either use a half-immersion process or a full immersion; otherwise, the stability of the plating solution cannot be guaranteed unless the equipment is equipped with relevant programs that can accurately calculate the plating area.
 

7. The impact of rotation speed:
Excessively high rotation speeds can make it difficult for additives to adsorb on the cathode surface. Additionally, strong agitation can reduce the polarization of the cathode, leading to a decrease in additive consumption.
In summary, there are many factors that affect the consumption of additives, and the consumption pathways for each component during the electroplating process are not entirely the same. Some are primarily consumed through anodic oxidation, some through high-temperature decomposition, and others through cathodic reduction and transformation. Therefore, the combination of intermediates in the additives should have a certain range of use, but it is not unlimited. Thus, during production, efforts should be made to stabilize the composition of the plating solution and production conditions within the required process range to ensure stability and smooth production.
At the same time, it is recommended that all plating manufacturers pay attention to the control of the following process parameters, which are crucial for stabilizing the electroplating process:
 

1. Current density requirements:
The standard half-immersion process should not be lower than 18A/dm2; for non-half-immersion (exceeding half-immersion) processes, the actual immersed area in the plating solution should be accurately calculated, and the current density should not be lower than 14A/dm2; otherwise, it will cause an imbalance in additive consumption and lead to quality issues.
 

2. Plating solution temperature requirements:
The temperature of the plating solution should be strictly controlled between 39-41°C; excessively high temperatures can cause additive decomposition, while excessively low temperatures can lead to additive accumulation, both of which can cause an imbalance in additive components.
 

3. Plate roller rotation speed requirements:
The linear speed of the plate roller should be controlled between 0.8-1.5m/s; due to discrepancies between the displayed speed and the actual speed, calibration should be performed.
 

4. Liquid supply pump flow rate requirements:
The flow rate of the liquid supply pump should not be less than 10 tons/H; clogging of the filter core can reduce the flow rate of the filter machine, so it should be replaced regularly and promptly, with a cycle not exceeding 30 days.
 

5. Anode-cathode distance requirements:
The distance between the anode and cathode should be controlled between 40-80mm, which can effectively save energy consumption without affecting the quality of electroplating.
 

6. Anode area requirements:
Ensure that the anode area is within the range of 1.5-2:1 relative to the cathode area; a too-small anode area will increase the consumption of related components in the additives and disrupt the composition of the plating solution. Generally, the copper balls should be kept level with the liquid surface; the anode should be regularly rinsed to prevent poor conductivity of the copper balls and avoid contamination of the plating solution by falling anode impurities, with a cycle not exceeding one week.
 

7. Power-on time requirements:
The plate roller should not be soaked for too long after entering the tank, as the current nickel layer is relatively thin. It is recommended that the power-on time be 10-20 seconds after the plate surface contacts the liquid surface.
 

8. Initial current requirements:
The initial current should be set within the range of 0.5-0.6 to prevent the plate surface from turning black during the initial power-on stage.
 

9. Requirements for plating solution composition:
The concentration of copper sulfate in the plating solution should be controlled within the range of 180-230g/L; sulfuric acid content should be controlled within the range of 50-60g/L; chloride ion should be controlled within the range of 80-120ppm; it is recommended to add water to the plating solution at least once a day, and to test the plating solution twice a week, making timely quantitative adjustments.
 

10. Requirements for additive replenishment:
The replenishment amount for additive #1 should be 70-80ml/KAH, and for additive #2, it should be added at 65-75KAH while ensuring the flatness of the surface; the hardness of the rollers in each plating tank should be tested daily to grasp the state of the plating solution in a timely manner, summarize the patterns, and choose a suitable additive consumption amount for your company; the additive pump should be calibrated once a week, and the scale should be marked on the additive storage tank, checking daily whether the consumed AH amount and the additive replenishment are balanced.

Dongyun Chemical Technology Department
2010-9-30