How to Properly Clean the Surface of PCB Board?

Preparing the surface of the hole for metallization is a crucial stage of production, on which the fate of the further production of printed circuit boards depends.

Cleaning the surface of the workpiece ensures the cleaning of the ends of the copper contact pads from the coating of resin, which inevitably forms during the drilling of mounting and vias.

Without such surface preparation, it will be difficult to obtain a reliable electrical connection.

Methods for Preparing the Surface of Printed Circuit Boards before Metallization:

1. Cleaning with non-woven nylon fiber brushes;
2. Blasting or brushing with abrasive materials such as pumice;
3. Permanganate cleaning;
4. Variable plasma-chemical etching for specific fluoroplastic materials.

Types of Equipment for Permanganate Cleaning:

1. Vertical cleaning machines;
2. Horizontal cleaning machines.

Horizontal permanganate cleaning machines are becoming more and more popular with PCB manufacturers. The productivity of horizontal plants exceeds vertical technology.

Key Features of Horizontal Permanganate Cleaning Machines:

1. The PCB blank floats in the solution;
2. Faster renewal of the solution at the phase boundary due to the pressure of the solution that is supplied to the nozzles;
3. Higher gravity;
4. Faster reaction speed.

All the same stainless steel elements of the modules are used, pumps, filters, regenerator, ultrasonic modules are now present not only in swelling but also in permanganate.

Important Features for Permanganate Cleaning of PCBs Using Horizontal Cleaning Machines:

1. While Potassium can be used for vertical equipment, sodium is better for horizontal equipment;
2. The neutralization module should be installed for cyclic flushing: the first flush after the neutralizer module is connected to the last flush before the neutralizer. This way the workpieces are cleaned better and the concentrate consumption is reduced.

Advantages of Using Permanganate Cleaning with Horizontal Equipment:

1. Intuitive interface;
2. Simple and convenient software;
3. The presence of automatic dosing over the covered area of ​​workpieces reduces the labor costs of laboratory technicians.

Cases of Using Plasma-chemical Etching:

1. For materials with a fluoroplastic filling or with other inert material;
2. For flexible multilayer printed circuit boards or flexible-rigid printed circuit boards where an adhesive layer is used: it does not withstand the highly alkaline reaction of the medium, as in the swelling of permanganate cleaning.