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Cores Foil & Prepreg for PCBs


Prepreg is an abbreviation for "pre-impregnated" material, which is a dielectric material made of a combination of glass fibers and a resin binder that is sandwiched between two cores in a PCB or between a core and a copper foil to provide the required insulation. It either combines two cores or a core and a copper foil. This plays a vital role in PCB design and manufacturing. You can imagine a hamburger and the prepreg is a slice of cheese placed between the bun and the ham. The bread and ham can be a core or a copper foil.


Prepreg is a kind of special dielectric material that can be modified to suit our needs. Through a combination of certain additives and catalysts, specific portions of the prepreg can be transformed into electrically onductive regions during a chemical process. This is known as selective conductivity. This phenomenon occurs when holes are drilled in the prepreg to connect the top and bottom layers. However, the rest of the prepreg remains an insulator, protecting the board from short circuits, which is its basic function.

PCBWay has the following FR4 prepregs in stock

PP TypeThickness(Brand difference)

Rogers Prepregs

PP TypeThickness/Dk
Rogers 4350B0.1mm/Dk=3.48 ±0.05
Rogers 4450B0.1mm/Dk=3.54 ±0.05
Rogers 4450F0.1mm/Dk=3.52 ±0.05


PCB core is the foundation of PCB. It is an important part of every type of PCB. Whether it is a single or double-side board, they all have a core as a substrate. One or both sides are coated with copper.

The core is also known by different names such as FCCL or laminate. Usually, the core consists of FR4 material.

PCBWay can provide clear soldermask and black core PCB, when you place a PCB order, you can check Black FR4 (black core) in Customized Services and Advanced Options in the PCB Specification Selection, as the below picture shows.


Note: This material is not available and needs to be purchased. It would be a lot more expensive and take a long time to produce. You can make an inquiry for the price and delivery time.

Circuit boards cores are pre-pressed layers according to the pattern: copper foil – prepreg – copper foil. PCBWay also manufactures PCBs with metal cores.


PCBWay normally has the following circuit boards cores in stock

Finished Board ThicknessCore ThicknessCopper thickness
0.6mm0.2mm18μm/18μm; 35μm/35μm
0.8mm0.5mm18μm/18μm; 35μm/35μm
1.0mm0.8mm18μm/18μm; 35μm/35μm; 70μm/70μm;
1.2mm1.0mm18μm/18μm; 35μm/35μm; 70μm/70μm;
1.6mm1.2mm18μm/18μm; 35μm/35μm; 70μm/70μm;
2.0mm1.6mm18μm/18μm; 35μm/35μm; 70μm/70μm;
2.4mm2.0mm18μm/18μm; 35μm/35μm; 70μm/70μm;

Copper foils

Copper foil is the base copper thickness coated on the outer and inner layers. It can be pre-attached to the substrate core by the laminate manufacturer, or it can be introduced as copper foil into the multilayer board prior to pressing. On inner layers, the final copper thickness is still that of the base copper foil. On the outer layer, we deposit an additional 20-30μm copper on the tracks during plating to allow plating through the holes. PCBWay has copper foil of 12μm,18μm,36μm, 54μm, 90μm and etc. in stock.

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