What is Circuit Design

Circuit Designers try to make connections.

3. Process Overview

3.3. Electroplating

To prevent copper from going onto areas of the board that will later be etched, the panels go through a photo-sensitive lamination process prior to electroplating.

Hot Roll Laminator

A dry-film laminate is placed on either side of the PCB and then light patterns are projected onto the laminate.  The light polymerizes the plastic when it strikes the laminate and that becomes a protected area.  In the spots where the light didn't strike the laminate, the coating will wash away easily, leaving exposed copper.  

Via Formation Proces

This series of images shows an abridged via-formation by electroplating process.

To form VIAs and thicken traces, PCBs are placed in a chemical bath and connected to the cathode of a power supply. Sacrificial copper ingots are connected to anodes of the same power supply and lowered into the tank with the PCB.  Copper ions travel through the liquid to the panel, where they fill the via cavities and increase the overall thickness of the copper layers.  

Ingot in Bag

Copper Ingots are hung from conductive frames that are connected to the anode of a power supply.

Wet Process Tank

Circuit Board panels are connected to conductive frames that are hung on metal bars connected to the cathode of a power supply.

Board out of Eletroplating

Image of a worker holding a PCB Panel in a conductive frame prior to submersion in etching tank.

This process is used to make through-hole vias.  To make buried or blind vias, additional layers would be added to the PCB after the through-hole vias were made.  So buried and blind vias add additional lamination steps to a PCB design.