Let us think about a gadget that does not have a printed circuit board. Now let us think about that printed circuit board without electroplating. This is really hard to imagine because the printed circuit board needs electroplating to work with electricity. The printed circuit board relies on electroplating. Without electroplating the printed circuit board would not be able to do its job.
So basically electroplating is a process where we use electricity to add a layer of metal to the surface of the printed circuit board. This electrical current is supplied in the form of DC, typically provided by an electroplating power supply. We also use it to put metal inside the holes that are drilled into the printed circuit board. The printed circuit board really needs electroplating to work.
Electroplating achieves this through three main jobs, carried out in a specific sequence during manufacturing:
Step 1: Plating Up the Copper Traces
Think of a raw PCB as a blank canvas. The canvas itself is an insulating material like FR-4. Onto this, a thin layer of copper is initially bonded, forming the base upon which the circuit will be built.
The pattern we want on our circuit is put onto the copper using a kind of protective ink. The board then goes into a bath for copper electroplating. Electricity supplied by a DC power supply makes copper stick to the exposed copper areas—the future circuit traces. This makes the paths thicker and stronger. The extra thickness is really important. It changes the fragile foil pattern into a wire that can actually carry electrical current.
Step 2: The Magic Step: Wiring Up the Holes
This job is really important. After plating the traces, we take off the protective ink. Then we remove the thin copper foil that we don’t need, leaving only the thick, plated traces.
But what about the holes? We made these holes earlier. They go all the way through the copper layers, which means the holes show the raw laminate underneath. This laminate is not conductive. If we do nothing, a component lead in a hole will not connect to the other side of the board.
The problem is fixed by a special treatment for the holes. The entire board gets processed so that the walls of the holes can carry electricity a little bit. Then the board is put back into the tank where copper is added. As copper builds up on the surface under controlled DC current, it also builds up on the walls of every hole. The result is a copper lining inside each hole.
This lining lets electricity flow easily from the top of the board to the bottom, or to a layer inside. We call this “through-hole plating.” It is this step that makes a functional multi-layer PCB possible.
Step 3: The Final Touch: Surface Treatment
After the copper traces and through-holes are formed, the board receives a protective solder mask, typically the familiar green coating.Then, the exposed copper pads get a final metal finish. Several of these finishes involve adding a layer of metal, or plating.
ENIG: This is a two-part finish. First, a layer of nickel is applied using a chemical process (electroless plating). Then, a thin layer of gold is added on top through a displacement reaction. This protects the copper and makes it easy to solder to.
Gold Finger Connectors: The gold contacts along a board’s edge are electroplated with a durable hard gold layer using stable DC. This finish is built to endure physical wear and prevent corrosion over thousands of mating cycles.
In PCB manufacturing, electroplating ultimately comes down to three critical jobs.
1.It builds up the copper traces to make them functional.
2.It plates the inside of drilled holes to connect different board layers, which is absolutely critical.
3.It applies specialized metal finishes to protect the board and allow components to be soldered. It’s a process that turns a patterned piece of plastic and foil into the sophisticated, interconnected nervous system of every electronic device we use.
