Because electronic products require sophisticated technology and certain environmental and safety adaptability, PCB board electroplating technology has made great progress. In PCB board

electroplating, the chemical analysis of organic and metal additives is becoming more and more complex, and the chemical reaction process is becoming more and more accurate. But even so, PCB

board plating will still appear from time to time edge burning problems occur, so what is the root cause of the problem?

The cause of burning the edge of the PCB board when electroplating is roughly:

(1) Current density is too high

Each bath has its optimal range of current density.

The current density is too low, the grain of the coating is coarsened, and even the coating cannot be deposited. When the current density increases, the cathodic polarization increases, resulting in

dense coating and higher plating speed. However, if the current density is too large, the coating will be burned black or charred;

(2) Insufficient additives

In simple salt electroplating, if the additive is added too much, the additive film generated by adsorption is too thick, and the main salt metal ions are difficult to penetrate the adsorption layer to

discharge, but H+ is a small proton, easy to penetrate the adsorption layer to discharge hydrogen, and the coating is easy to burn. In addition, too many additives have other side effects, so any

additives, brighteners must adhere to the principle of less and more.

(3) The tin lead anode is too long

The anode is too long and the workpiece is too short, and the power line at the lower end of the workpiece is too dense, which is easy to burn; When the distribution of the anode in the horizontal

direction is much longer than the length of the workpiece placed horizontally, the power lines at both ends of the workpiece are dense and easy to burn.

(4) Insufficient tank circulation or agitation

Stirring is the main means to increase the mass transfer rate. By moving or rotating the cathode, there can be relative flow between the liquid layer on the surface of the workpiece and the plating

solution at a distance. The greater the stirring intensity, the better the mass transfer effect. When insufficient stirring, the surface liquid flow is uneven, resulting in scorch of the coating.

(5) Insufficient tin lead content

The metal content is insufficient, the current is slightly larger, H+ is easy to take advantage of the discharge, and the diffusion and electromigration speed of the bath body is low, which leads to the

burning situation.

In addition, the cause of the burning condition is also Organic pollution; Metal contamination; Too much lead in the coating; The anode slime falls into the tank; The hydrolysis of fluoroborate

results in the attachment of lead fluoride particles