Hard PCBs consist of different layers that are bonded together using adhesives and heat to provide a solid shape for the board material. The next few layers are used to develop rigid pcb.
Substrate layer – rigid pcb material
The base layer, also known as the base material, is made of fiberglass.
FR4 is mainly used as base material. The most common glass fiber is glass plate, which can provide rigidity and rigidity for the plate.
Phenolic and epoxy resins are also used as base materials, but they are not as good as FR4, but they are cheaper and have a unique odor.
The decomposition temperature of phenolic resin is too low, if the solder is placed for a long time, it will lead to delamination.
At the top of the substrate layer, there is a copper foil, which is laminated on the plate by means of additional heat and adhesive.
In common use, both sides of the circuit board are made of copper laminate, but some cheap electronic products only have a layer of copper material on the circuit board.
Different boards have different thicknesses and are described in ounces per square foot.
The solder mask is located above the copper layer.
The layer is added to the board to add insulation to the copper layer to avoid any damage in the case of any conductive material in contact with the copper layer.
The screen printing layer is located above the solder mask layer.
It is used to add characters or symbols to the board to better understand the board.
White is usually used for silk screen printing, but other colors can also be used, including gray, red, black and yellow.