This is likely one of the distinct benefits of ENEPIG over the ENIG floor end. The immersion gold layer that sits atop the palladium presents nearly-complete board protection by protecting and preserving the palladium beneath. This is a technique of floor plating in which an organic compound bonds over the naked copper surface.
On the other hand, ENIG tends to remain the same across most PCB producers, though quality can range. Hot Air Solder Leveling is a surface end that includes the insertion of the copper into a vat of molten solder. A sequence of compressed sizzling-air knives then take away extra solder and levels the surface finish before the solder solidifies and cools. This creates a strong coating that protects the copper from corrosion and makes for an easy assembly process.
Even the current ENIG (electroless nickel/immersion gold) course of has a restricted life for solderability as a result of the immersion gold is skinny. Immersion coatings are floor finishes employed on printed circuit boards by submerging them in molten states of particular elements. Using a floor end on a printed circuit board is helpful in preventing the corrosion of the conductive board path. Corrosion of the copper traces happens due to the oxidation course of.
OSP can be utilized in conjunction with different technologies too, as it does not work together with gold surfaces. Pretty much all PCBs are designed with copper finishes on their uncooked, unpopulated surface. Copper is a extremely reactive metallic and, if left exposed, the copper surface will oxidize and deteriorate, ruining the circuit board. The end exists to create a protective barrier over the copper circuitry and to offer a solderable floor when assembling the elements onto the board.
Excessive nickel corrosion will dramatically cut back wettability and bonding performance of soldering and solder should face up to bigger stress when it's bonded with corroded nickel floor. Finally, the contact layer for contact between solder and nickel will break with black nickel floor generated, which is called black pad. The difference between ENEPIG and ENIG is the added layer of palladium. The palladium helps defend the nickel layer from corrosion, which helps stop “black pad” from occurring.
In a method, we can say the hot air solder leveling has some specific advantages over the electroless nickel immersion gold and vice versa. However, right here in this part, we would specify every kind of floor finish, the advantages and the disadvantages. It is essential to notice that no surface end has a present with no penalty, and therefore, the selection of any floor finish relies on a particular software. As discussed earlier, the HASL is a kind of floor end with nice solderability, and also offers a wonderful shelf life.
This therapy has also seen an increase in recognition due to the RoHS rules and provides a level exterior for advanced floor components such as BGAs and flip chips. Immersion gold on copper is often skinny and has a degree of porosity which is able to result in oxidation. In addition, if the coating is simply gold over copper, diffusion will continue till all of the gold has gone.
The HASL step, the revealed copper surfaces are covered by immersing the printed circuit board in a container containing molten solder. On the other hand, it'll react with tin, with the era of excellent IMC Ni3Sn4 in order that good assembly solderability may be ensured. Under the motion of catalytic surface, ENP leads to the deposition of nickel layer via redox reaction with NaH2PO2 as reducing agent. During the method of immersion gold in ENIG, black pad tends to be triggered as a result of nickel corrosion beneath bad operation.
This layer supplies related qualities that the opposite surface finishes do. The course of required to achieve OSP finish is fast and price-efficient. The downside is the difficulty to inspect because of its shade transparency. If your objective is to protect uncovered copper in your PCBs mid-production, OSP might be the best choice out there.