What is black pad?

Black pad is a term that usually refers to nickel corrosion on electroless nickel and gold immersion (ENIG) surface finishes on PCBs. The defect is not seen as part of normal QC procedures as the immersion gold masks the appearance of the nickel under the gold.

Is Black Pad still an issue for ENIG?

Is Black Pad Still an Issue for ENIG? As long as nickel and gold are used in the ENIG finishing process, black pad can still be a potential issue.

How does ENIG work?

ENIG creates a highly solderable surface that won’t discolor or tarnish; it provides exceptional electrical continuity. The nickel component forms a barrier against copper diffusion and guards against contamination of the solder during soldering and re-work. ENIG also contributes EMI shielding.

What is delamination of PCB?

Delamination is partial separation of the layers of the base material (PCB, multilayer). Their appearance (though smaller) is similar to that of blisters. Delamination is caused by humidity which the laminate has absorbed or which has been added during the production process.

What is OSP finish?

OSP (Organic Solderability Preservative) OSP is a water-based, organic surface finish that is typically used for copper pads. It selectively bonds to copper and protects the copper pad before soldering. OSP is environmentally friendly, provides a coplanar surface, is lead-free, and requires low equipment maintenance.

What is Enepig?

ENEPIG is a type of surface finish done on copper layer to protect it from oxidation and corrosion in printed circuit boards. This surface finish improves the solderability of copper and is also RoHS compliant.

What is hyper corrosion?

It should be noted that for purposes of this writing, I define hyper-corrosion as a spike or fissure in the nickel deposit evident after immersion gold plating. Finally the root causes of such attack on the base nickel will be presented along with strategies to mitigate these effects.

What does the gold do in ENIG?

The gold is added to act as a protective barrier to safeguard the nickel plating from oxidation. The prevention of this chemical reaction is why ENIG plating has become widely popular for preserving the nickel layer prior to soldering.

Is ENIG a Rohs?

ENIG PCB finish is a double layer metallic coating with nickel that acts both as a protective barrier to the copper circuits and a surface on which the components are welded. A layer of gold protects nickel during storage. … Enig is Rohs compliant and people tend to use the tersm together.

How thick is ENIG?

The ENIG specification was amended in 2012. The lower limit for thickness was reduced from 0.05 m to 0.04 m (1.6 in), however some restrictions were added like ability to measure, and limited time from manufacturing to assembly as well as demonstrating the consistency and reproducibility of the plating process.

How do you repair a delaminated PCB?

Procedure

1. Clean the area.
2. Drill into delamination blister with the Micro-Drill and ball mill. …
3. Bake the circuit board to remove any entrapped moisture. …
4. Mix the epoxy. …
5. Pour the epoxy into the epoxy cartridge.
6. Inject the epoxy into one of the holes in the delamination.

What causes delamination?

Delamination is caused by matrix cracking, bending cracks, and shear cracks. Delamination can affect the compression strength of composite laminate, and it will slowly cause the composite to experience failure through buckling.

How do you stop delamination in PCB?

How can PCB delamination be avoided?

1. PCB Drying (baking) before assembly of electronic components. Double-layer PCBs are not typically dried unless they have copper planes that do not have a grid pattern. …
2. If PCBs will be stored indefinitely, they are properly treated with nitrogen before being sealed in a dry bag.

What is ENIG plating?

Electroless nickel immersion gold (ENIG or ENi/IAu), also known as immersion gold (Au), chemical Ni/Au or soft gold, is a metal plating process used in the manufacture of printed circuit boards (PCBs), to avoid oxidation and improve the solderability of copper contacts and plated through-holes.

What is hasl with lead?

HASL / Lead Free HASL HASL is the predominant surface finish used in the industry. The process consists of immersing circuit boards in a molten pot of a tin/lead alloy and then removing the excess solder by using ‘air knives’, which blow hot air across the surface of the board.

What are castellated holes?

Castellated holes are plated holes that are cut through with a router bit as the individual PCB is separated from the panel. Castellations are manufactured by creating ordinary plated holes and then running a sharp router bit across them, leaving half the hole in place.

What is plating in PCB?

Plating on a PCB refers to the electrochemical process by which a metal is deposited onto the surface of the circuit board, and inside the plated through-holes. The most common plated metal in PCB fabrication is copper.

What is immersion gold plating?

Immersion Gold Plating is a process that applies a very thin layer of gold by displacement of the surface atoms. This means the coating is not very thick, typically between three and eight micro inches. It offers some corrosion resistance and is used to extend the shelf life of parts waiting for soldering operations.

What is the difference between ENIG and Enepig?

ENEPIG is similar to ENIG in both utilize electro-less nickel on top of copper plating; the difference is while ENIG has gold deposited directly on top of nickel, ENEPIG has an additional layer of palladium between the nickel and final gold layer (see below Fig. 1).

Can you solder to hard gold?

Use a solder with high gold content, even though it is higher to melt. That is if you have a large repair to make. Go for hard, medium or plumb solder. You can also go for a solder that has 14 karats or more.

Is ENIG conductive?

excellent electrical conductivity, anti-oxidation & anti-rust, good heat dissipation, higher surface thickness.

How tough is gold plating?

Appearance of Hard Gold Plating vs Soft Gold Plating Soft gold plating has a hardness of 90 HK₂₅ maximum which by comparison is consistent with the hardness of a human fingernail.

What are tented vias?

Tenting a via refers to covering via with soldermask to enclose or skin over the opening. A via is a hole drilled into the PCB that allows multiple layers on the PCB to be connected to each other. A non-tented via is just a via that is not covered with the soldermask layer.

Does PCB contain gold?

A printed circuit board contains metals such as copper, tin, silver, and lead along with minute quantities of gold. … The PCB can be broken into very small pieces of sizes around 140 mm.

Is gold plating RoHS compliant?

Restriction of hazardous substances (RoHS) compliant plating services. Plating materials include gold, silver, nickel, copper, electroless nickel, electrolytic nickel and palladium. … Capabilities include testing, plating, cleaning and heat treating.