What is ENIG Plating Thickness

ENIG coating ratio is important because of its direct impact on the PCB’s dependability and functioning. The recommended ENIG plating thickness on PCBs is usually between 2.5 and 5.0 µm (micrometers) for the nickel film and between 0.05 and 0.15 µm for the gold film. Achieving exact nickel coating thickness creates a sturdy basis for the gold coating and inhibits copper corrosion. Similarly, an accurate gold coating guarantees perpetual dependability, stops gold exhaustion, and preserves solder bond integrity. Building dependable, superior PCBs appropriate for various electronic purposes requires finding the ideal balance between ENIG plating layers.

Impact of Improper Plating Thickness 

Electroless Nickel Immersion Gold plating thickness has an immense degree of impact in direct and indirect ways upon the integrity of the PCB being assembled. As such, not following the established parameters for accurate plating thickness can cause much harm in the short and long term. Some of the consequences of failing to deposit appropriate layer thickness include the following: 

• Depletion of Gold While Soldering: Insufficient enig gold thickness could contribute to gold exhaustion throughout the soldering procedure. Overheating the solder paste during the method of soldering may disintegrate the gold coating within the solder, causing the connection’s electrical properties to be compromised and the joint’s soldering durability to be bad. This behavior, referred to as gold scavenging, may hurt the PCB’s perpetual dependability.
• Imbalances of Surface Coating: Unequal or irregular coverings are examples of surface finishing imperfections that can result from inadequate plating thickness of circuit boards. These imperfections may lead to problems in the soldering paste dispersion and placement of components procedure throughout assembling, eventually compromising the dependability and the standard of the soldered junctions.
• Difficulties in Assembling and Reworking: Problems with printed circuit board assemblage and reworking procedures might arise from insufficient plating thickness of circuit boards. It can enhance the difficulty of applying solder, which raises the possibility of reworking or restoration, reflow problems, and soldered joint faults. 
• Mechanical Sturdiness and Utility: A PCB’s structural endurance may occasionally be jeopardized by insufficient enig plating thickness. Further managing, assembling, or use-related impairment, such as scratches, can cause thinner layers to deteriorate more quickly.
• Issues Regarding Aesthetics and Regulations: An ugly finish may be caused by variations in the level of thickness of the coating. In addition, certain sectors or statutory requirements could stipulate particular criteria for PCB plating thickness; failure to comply with these requirements may lead to PCB rejections for non-compliance
• Problems with Oxidation and Dependability: It is possible that a thinner nickel covering would not be enough to keep the copper lines underneath from oxidizing. The dependability and endurance of the printed circuit boards may be impacted as time passes by this increasing vulnerability to oxidation, particularly in areas experiencing high levels of moisture or corrosive substances.
• Influence on Electrical Efficiency: The discrepancies in enig plating thickness may affect the printed circuit board’s electrical functionality. Changes in thickness have the potential to cause frequency inconsistencies, reliability of signals problems, and weakened conductivity of electricity, every one of which can negatively impact the electrical circuitry’s performance in general.
• Problems with Solderability: A sufficient nickel plating thickness may cause the coating of gold to adhere poorly or lead to exposing the copper layer deposited underneath it to the elements. This may cause the copper material to oxidize and make it more challenging to bond by soldering. When applying a solder, a little layer of nickel could permit gold to seep into the copper material below it, weakening the solder connections and possibly even causing the joints to fail.
• Development of a Black Pad: Erroneous treatment settings or insufficient supervision of enig thickness are capable of causing the development of a fault called a “black pad.” This flaw arises if the protective coating of nickel beneath the gold corrodes or turns permeable, compromising the dependability of soldered junctions and increasing adherence defects.

How to Achieve Precise Electroless Nickel Immersion Gold Plating Thickness

To achieve the correct or accurate level of enig plating thickness, it is essential to know the proper procedures involved and the correct manner in which they must be conducted. The following are the steps in achieving the desired level of enig thickness without errors: 

• Procedure Management and Assessment: Enforce stringent regulation of the ENIG plating thickness technique’s variables, such as temperature, pH, chemical quantities, and agitating speeds. Equality in these aspects guarantees even plating thickness. Employ continuous tracking devices to continually assess and regulate the pace of depositing of nickel and gold coatings throughout the coating procedure. Accurate thickness degree maintenance is aided by automatic surveillance.
• Setting Up and Activating the Surface: Confirm that the copper surface has been adequately cleaned and prepped before plating. Cleansing the surface allows the correct adherence of the following layers by removing impurities, oxidation, and leftovers. Use a dependable activation method with palladium-based catalysts to help the nickel layer stick onto the copper covering. Correct activation is essential to start the electroless nickel depositing process.

Controlling the Gold Deposition:

1. Use an immersion gold coating solvent precisely calibrated in content and strength.
2. Adjust the gold plating solution to get the correct enig gold thickness and homogeneity.
3. Use techniques to regulate the time immersed within the gold plating solution strictly.

Inspect the gold layer’s thickness to ensure uniformity and make any necessary modifications. 

• Screening and Quality Management: While plating, periodically examine and confirm the product’s quality level. Assess and guarantee plating thickness using non-invasive testing techniques such as SEM (scanning electron microscopy) or X-ray fluorescence analysis (XRF). Examine the printed circuit board samples cross-sectionally to determine how well the nickel and gold coatings cling to one another and are consistent. This study assists in locating any thickness irregularities or flaws that could compromise dependability.
• Upkeep and Calibration: To guarantee precision and uniformity in the PCB plating thickness assurance process, recalibrate and service plating machinery on an ongoing schedule. Exact oversight of plating thickness may be attained using well-maintained equipment. Teach staff members engaged in plating to adhere closely to established practices and guidelines. Ongoing instruction guarantees that the procedure stays dependable and regular.

Record-keeping and Streamlining Procedures:

1. Keep exhaustive records of all process variables, bath composition, deposit levels, and quality assurance procedures.
2. Examine the information to spot patterns and make plating process modifications for more accuracy.
3. Get greater control of plating thickness by iteratively improving and fine-tuning your plating procedure using information-driven knowledge.

This also helps in reworking and repairing works by giving a clear initial account.

Conducting the processes involved in PCB plating carefully is the key to consistently achieving the appropriate plating thickness. As such, it is vital for those who supervise and perform the steps to be well acquainted with the proper methods. It is also essential to employ high-quality materials and maintain machinery in top condition to ensure that the functions are carried out seamlessly and without any hiccups.