Immersion Silver (ImAg)

This is a method of immersion plating copper with silver. This means that copper atoms are replaced by silver atoms. The process of this method involves immersing the PCB in a solution containing silver ions, which are reduced to elemental silver on the surface of the copper.

Advantages of immersion silver plating of copper:

+     ImAg provides excellent solderability.

+     Bonding wires, for example in medical devices, is no problem for ImAg. On the contrary, this method ensures good performance when joining wires using this method.

+     No hazardous substances or heavy metals. ImAg contains none of these, making it more environmentally friendly.

+     The high surface energy ensures that the components adhere to the PCB surface.

+     If you need to save money, this method is for you. This is because ImAg is relatively inexpensive compared to other surface treatments.

Disadvantages of copper immersion plating with silver:

-       The surface finish is susceptible to the presence of sulphur. This causes darkening of the plates and solderability problems.

-       Since ImAg can degrade over time, it has limited shelf life.

-       ImAg requires careful handling during the manufacturing process to avoid contamination.

-       A thin layer of this coating may not provide sufficient protection against certain types of corrosion or wear.

-       For applications that require greater thickness or a different level of protection, this coating may not be suitable.

Immersion Gold (ENIG)

After applying a thin layer of gold, the circuit board is immersed in a solution containing nickel ions. The nickel chemically displaces the gold, creating an intermetallic compound of nickel and gold.

Advantages of immersion plating copper with gold:

+     Due to the protective nickel layer, ENIG exhibits excellent corrosion resistance.

+     ENIG provides a uniform layer thickness, which is important for SMT surface mount technology.

+     If you need to bond some conductors, ENIG is the right choice because it provides a highly conductive surface that is easy to bond to.

+     ENIG provides a flat surface that is suitable for chip packaging (CSP).

+     If you need to re-melt your board multiple times, ENIG is the right choice.

Disadvantages of gold immersion plating:

-       Cost: ENIG is more expensive than other finishes.

-       ENIG requires careful handling during the manufacturing process. At the same time, nickel is susceptible to oxidation.

-       Beware of thermal shock. Heat shocks can cause cracking and flaking of the nickel layer in the ENIG method.

-       The ENIG nickel layer is difficult to visually inspect.

-       Avoid high temperatures: The intermetallic compound of nickel and gold can disintegrate at elevated temperatures.

Immersion tin (ImSn)

This is a method of immersion plating copper with tin. This means that copper atoms are replaced by tin atoms. The process of this method involves immersing the PCB in a solution containing tin ions, which are reduced to elemental tin on the surface of the copper.

Advantages of tin immersion plating:

+     Suitable for SMT applications due to the flat surface that tin creates.

+     ImSn is well solderable.

+     ImSn has a long shelf life.

+     Price: ImSn is relatively cost-effective compared to other surface treatments.

Disadvantages of tin immersion plating:

-       ImSn is not suitable for applications where wire splicing occurs due to its brittleness.

-       ImSn has limited heat resistance.

-       ImSn is susceptible to tin whiskers formation, which can lead to short circuits.

-       Handling Caution: ImSn is sensitive to handling and requires careful handling.

-       Harsh environments are not conducive to this finish. In fact, ImSn provides only limited corrosion resistance.

Organic Soldering Preservatives (OSP)

An environmentally friendly surface treatment that applies a layer of organic material to copper plates. OSP is a water-based organic compound that forms a protective layer on copper.

Benefits of OSP coating

+     The absence of heavy metals makes this coating environmentally friendly.

+     OSP coating is relatively simple to apply.

+     The cost of this coating is very affordable.

+     OSP provides a flat finish on the circuit board.

+     No extra thickness due to the OSP method.

Disadvantages of OSP surface treatment

-       Over time, the surface finish will begin to degrade.

-       It is easily damaged by handling and can be affected by contaminants.

-       Avoid high temperature applications: OSP can break down and lose its protective properties.

-       OSP is difficult to reprocess because the organic layer can be damaged during reprocessing.

-       OSP provides only limited protection against corrosion.

LF-HASL surface treatment

Full name Lead-Free Hot Air Solder Leveling. Exposed copper surfaces are coated with a thin layer of molten solder, which is then leveled with hot air knives. LF-HASL is a lead-free alternative to the traditional HASL process.

Advantages of LF-HASL

+     Relatively low cost makes this method an attractive choice.

+     LF-HASL offers good solderability due to its thin solder layer.

+     LF-HASL can be stored for a long time

+     LF-HASL is suitable for the use of fine-pitch components

+     The hot air leveling process produces a uniform surface which helps prevent component placement problems.

Disadvantages of LF-HASL

-       High frequency applications can be a problem for the LF-HASL method. This is due to the thick layer of solder that is used in the LF-HASL method.

-       The thickness of the solder layer can vary and cause deviations from design specifications.

-       Despite the absence of lead, the LF-HASL method is not environmentally friendly. It still involves the use of hazardous chemicals such as flux that can be harmful to the environment.

Surface finish HASL (tin-lead)

Hot Air Solder Leveling (HASL) is a common surface treatment used on printed circuit boards. Coating the copper surface with a layer of tin-lead alloy and then leveling with hot air creates a flat and uniform surface for soldering.

Benefits of HASL treatment:

+     Need a strong and reliable solder joint? HASL surface treatment is a good candidate for this application.

+     HASL is a relatively inexpensive finish compared to other alternatives.

+     HASL has a wide range of applications.

+     Long shelf life due to the fact that HASL retains its properties for a longer period of time.

Disadvantages of HASL treatment:

-       The lead contained in HASL is hazardous to the environment and human health.

-       HASL is not suitable for fine pitch components and for SMT technology.

-       The thickness of the HASL surface may vary depending on the size and shape of the PCB.

-       The cost of HASL can be higher than for OSP and ENIG treatment.

-       The use of HASL treatment is not RoHS compliant.

Each of these methods has advantages and disadvantages. When selecting a finish, it is important to carefully consider factors such as solderability, wire bonding, corrosion resistance, durability, and cost.

Image