Printed circuit boards are used in modern electronics and made from a non-conductive substrate. Copper is laid on the board and unwanted material is removed using milling, screen engraving, or photoengraving. Holes are drilled for mounting and electrical components, and the board is tested for functionality.
A printed circuit board is the structure used for many modern electronic components. These boards are usually green in color with different types of electrical components and computer chips attached. A printed circuit board has extremely high reliability combined with a very low cost. As a result, these cards are common in everything from cellphones to children’s toys to cars.
All circuit boards are made from a non-conductive material called a substrate. This material is the basis of the board. It must be light, strong and completely non-conductive. Most boards are made from a combination of man-made materials, such as polyester or fiberglass, mixed with various plastics.
The next step in creating a printed circuit board is laying it on the conductive rails. To do this, most companies cover the entire board surface with a copper alloy. After the board has been covered, any unwanted material is removed. Other manufacturers lay the circuit paths directly on the board, but this process is more complex and expensive, so it’s rarely used.
To remove unwanted copper, one of three techniques is typically used. Board milling works like most industrial milling, a specialized machine scrapes off unwanted substance down to extremely precise specifications. With screen engraving, the copper that is left behind is protected, either physically or with specialized inks, and the rest of the copper is engraved. Photoengraving is the third method and is similar to screen engraving. Materials and protectors have different properties, but the process is the same.
At this point, holes are drilled into the PCB substrate. Some of these holes are used as anchor points for mounting the board or electrical components. Other holes have rivets inserted; these rings allow electrical signals to travel from one side of the board to the other. After the holes are drilled, the board is covered with a variety of sealants and protectants.
The final step in assembling these boards is connecting the electrical components. Some components are threaded through holes and fixed to the underside of the board. Others are placed on non-conductive pads and work entirely on one side. Typically, the machines make printed circuit boards off-the-shelf. On smaller batch jobs, or when dealing with extremely small components, it’s not uncommon for a printed circuit board to be crafted by hand.
After the board has been assembled, it undergoes an automated test. Test machines flood the board with electricity and verify that all connected equipment is powered as it should be. This process will also highlight any shorts or broken paths.
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