In the periodic table, nickel gets represented by the symbol Ni. Nickel’s increased hardness, anti-corrosion, wear resistance, and magnetic properties. These are just a few examples of the many ways. So its chemical and physical characteristics lead to use in engineering and sector. To improve corrosion and oxidation resistance. It is typically formulated into alloys like nickel-chromium steel, nickel steel, nickel-copper, etc. In the beginning, it was frequently used to mint coins due to its high oxidation resistance.
Nickel is rapidly oxidized in the environment due to its high oxygen activity. But the substances (NiO, Ni (OH) that it generates on its own are of very high purity. In order to form a video to protect itself. It usually separates itself from prolonged contact with air and avoids continued oxidation. The nickel must first oxidize itself to create a protective film before it can secure it and the bottom steel from further oxidation. When employing this, care must get taken.
Once the metal has oxidized. A protective film forms to stop any further oxidation from happening. This phenomenon gets known as “metal passivation.” In order to prevent the oxidative stress of the metal substrate from air exposure. Nickel plating is commonly used. To provide adequate protection, the plating surface must be “defect-free.” Unfortunately, small holes are common in the early Ni plating process because the procedure is not very advanced, so as an outcome, the bottom metal substance under the covering cannot be sealed up, which leads to oxidation. The modern nickel plating method has evolved to the point where the porous issue can remedy by simply adding an adding agent to the plating solution.
Nickel plating can improve mechanical characteristics. Such as these in addition to avoiding surface oxidation:
- A measure of tensional force
- Length
- Toughness
- Psychological Pressures Within
- Weary of life
- Embrittlement caused by hydrogen
In addition to its aesthetic value. Nickel plating is widely employed in the petroleum, chemical, food, and soft drink industries as it has the ability to resist corrosion. As well as it keeps products free of pollutants and preserves their pristine state. It is important to note, however, that pinhole rust develops when the chloride solution penetrates the nickel oxide protective cover. While nickel plating typically performs well in neutral and alkaline solutions. But the majority of issues arise when exposed to acidic conditions. Corrosion of minerals is inevitable.
Purpose and Benefits of Nickel Plating PCB
Nickel plating on an ENIG circuit board gets used primarily to stop gold and copper from moving around and mixing. Protecting the copper layer from oxidation and breaking of conductivity and weldability. It serves as a protective film and anti-corrosion protective layer. For ENIG nickel plating to serve as intended, it has to be at least three m/118 inches thick. As specified by IPC-4552.Ni3Sn4 Intermetallic Compound gets formed. When nickel combines with tin in solder paste during brazing or SMT reflow. However, the capacity of this layer of IMC is lower than that of the Cu6Sn5, which get produced by the OSP surface coating. But it’s good enough to fulfill the needs of the vast majority of existing products.
Also, instead of using pure copper as the substrate metal. Brass is frequently used to accomplish certain mechanical properties for the wires of electrical parts. However, plating tin directly on brass is not possible due to the metal’s high ZN. So a surface of nickel should get plated as a protective film before welding can be accomplished.
Since brass is a copper-zinc metal, so tin plating would cause the copper to scrape off upon remelting, which creates a false weld.
Is nickel plating an alternative to tin soldering? The response is a resounding “no,” as nickel is susceptible to earth’s atmosphere passivation. And it will have a devastating effect on solderability if left uncoated. Instead, pure tin is typically plated on the surface of the nickel. In order to increase the castability of the portion feet. Once the nickel surface gets oxidized, even if welded. Its welding power will continue to weaken and eventually break unless the wind gets isolated during the wrapping of the finished parts. And the user ensures that now the nickel layer is just not oxidized before soldering.
Some persons choose to pre-plate pure copper as a protective film. And a protective layer against rust in brass gets used. In order to avoid the movement and dispersion of zinc and tin. Then it gets tinned to improve soldering.
After being installed for a while, the tin-plated parts often oxidize. Most of these issues arise. When copper or nickel plating that gets supposed to prevent corrosion. It is either not present or is not heavy enough.
Tinning the solder with the intention of making it stronger. And it is usually done with matte tin plating as opposed to a shiny one.
Circuit Board Plating Process for Surface Finishes
As we’ve seen, copper attributes are a common component of PCB. Soldering requires leaving the pads and gaps exposed. Even though the trace amounts and region fills will be shielded and protected by a solder mask. Because copper oxidizes and degrades if left undefended for any amount of time. This access will be problematic and render the circuit board useless. Because of this, the exposed copper must be protected by applying a surface finish, such as plating.
In order to provide the necessary shielding for a circuit board. Various surface finishes could be applied to the board.
· HASL (Hot Air Solder Leveling)
Until recent times, HASL was the most popular surface finish in the business world. The PCB would be immersed in a vat of molten solder and then subjected to hot air streams. In order to remove any excess. HASL can be performed nearly everywhere at a minimal cost. Simple to prepare and store for later use. However, HASL leaves a rough surface that can lead to solder bridging. And lack the fine detail required for use with fine-pitch parts.
· ENIG (Electroless Nickel Immersion Gold)
In recent years, ENIG has emerged as one of the widely used surface finishes for PCBs. It has two metal coatings. The first of which is a covering of nickel that has been chemically layered to the board. A nickel barrier safeguards the copper, which is then shielded from oxidative stress by a gold film. The superior surface planarity of ENIG makes it well-suited for soldering fine-pitch elements. It’s long-lasting and secure. And it passes the test for RoHS-compliant products. However, it is more costly than HASL and other finishes.
· Immersion Silver
Since silver has limited losses in high-frequency applications, it is frequently used in high-speed PCBs with this finish. Immersion silver gets stored chemically in the copper, which provides excellent surface planarity for the solderability of fine-pitch sections. The silver used in immersions is also RoHS compliant. This finish needs to be kept in sealed containers. In order to avoid tarnishing from airborne or surface-mounted contaminants. It has a shelf life of about 12 months if properly stored. But must get used soon after being exposed to air.
Other plating options for printed circuit boards include hard gold (ENEPIG), organic weldability preservative, and immersion tin. At the same time, all of these have their place. But the most common types of surface finish for PCBs are (HASL), which include electroless nickel immersion plating (ENIG) and immersion silver. How do you know which plating method will work best for your PCB?
Electroless Nickel Plating Advantages
When deciding on a metal plating method. Many businesses are unaware of the many advantages electroless nickel plating offers.
Some of electroless nickel plating’s many benefits are listed below.
The thickness of Nickel Plating
Electroless nickel plating depth can be kept consistently even. Thanks to the special chemical makeup of the plating solution. Industries that rely on precise metal measurements have a vested interest. In order to achieve this level of precision in metal finishing. In contrast, electroplating makes it extremely challenging. If not impossible, to achieve a uniform thickness across a surface.
Corrosion Resistance of Nickel Plating
The chemical composition of electroless nickel plating is particularly protective. Because of the heavy proportion of phosphorous, it contains. When contrasted with electroplating, nickel plating has superior corrosion and wear resistance. Thanks to its protective layer. Because of its protective properties. Electroless nickel plating is useful in many different industrial settings.
Applications of Nickel Plating
It’s easy to see why electroless nickel plating is so widely used. Here are some instances:
- Miniscule-diameter components. Like those found on PCB and semiconductor chips
- Examples include deepwater oil rigs where metals are or will be revealed to acid and brine.
- Fuel injection systems in vehicles are vulnerable to corrosive effects due to many fuel combinations that are burned.
- In highly reactive environments, where components must be used.
- Electroless nickel plating is especially helpful for combustion-powered machinery because it reduces friction and heat.
Cost Efficiency of Nickel Plating
Electroless nickel plating has many advantages in terms of cost. Both during production and during use.
- By eliminating the need for an external source of electricity. The operational expenses can be cut significantly.
- While other plating materials like silver and gold can be quite pricey. Nickel is typically quite affordable.
- Reduces the risk of breakdowns, boosts productivity, and lengthens the life of machinery.
