Since PCB boards are in nearly every electronic device on the market today, it’s easy to ask yourself, what are PCB boards made of? After all, not just computer geeks are interested in knowing all about the inner workings of these boards, but if you belong in this category, knowing what a PCB board is made of can help you figure out how to make one yourself one day, and this is truly an invaluable skill.
Just the Facts: What Are the Parts of a PCB Board?
As you likely already know, printed circuit boards, or PCB boards, are made in layers, having different components made out of different materials in each of those layers. Although the materials can change somewhat depending on the board’s function and the device it’s going in, most PCB boards include the following types of materials:
- Fiberglass or resin (derived from paper)
- Solder mask
These are the four main materials used in most PCB boards. The first layer usually uses fiberglass, most commonly the FR4 type. FR stands for fire retardant, and this layer is what provides the foundation of the PCB board. Also called the substrate layer, this is usually the thickest part because it is what provides the board’s rigidity and firmness.
Sometimes, however, other materials are used instead of fiberglass, including epoxy resin or phenolics. These are more cost-effective than fiberglass, but often have sensitivity to heat. Also, using these materials means the components must be soldered onto the board.
The Next Few Layers
The second layer is a copper layer that is bonded with either heat or some type of industrial adhesive. The copper can be located on one side of the PCB or both sides. These copper layers are thinner than the substrate, naturally. The amount of copper varies depending on what you use, but most PCB boards use copper with a content of one ounce of copper per square feet.
The solder mask layer is usually green in color and is applied over the copper layer. This is done so that the copper and the electrical parts don’t come in contact with one another. The fourth and final layer (provided four layers is all the board has) consists of silkscreen, which is placed over the solder mask so that marks can be made to know where all of the components should be placed.
Sometimes, PCB boards can have more than four layers, but the information listed above is for boards with only four layers to them.
Knowing what the different layers of a PCB board are made of is beneficial for many reasons, but it is especially useful if you love to make circuit boards yourself so that you are guaranteed to get what you need. Fortunately, these materials are usually easy to find and easy to afford, and with a little help from websites, e-books, and free software, you can get all the help you need to make sure your PCB board comes out perfect in the end.