A computer circuit board is a central hub that connects and allows communication between all of the other components of a computer system. It houses the CPU (Central Processing Unit), RAM, expansion slots for storage devices like hard drives and CD drives, ports for external devices such as keyboards, mice, and speakers, as well as electrical connections for power and data transmission. The motherboard, as it is commonly known, can also be referred to as the “mother” or “father”.
How do circuit boards work are made up of a series of conductive materials that connect and conduct electricity. These materials can be copper or aluminum, but gold is often used to connect smaller electronic chips on a circuit board due to its better resistance to corrosion. These conductive materials can be found in the wires that run across the entire surface of the board, connecting all the different components to each other. These conductive wires are attached to the components using a special type of solder, which is heated up and melts onto the surface. This helps ensure that all of the connections stay in place.
There are two primary ways in which components are attached to a PCB: through hole technology and surface mount technology. Through hole technology was first developed in 1949 by Moe Abramson and Stanislaus F Danko of the United States Army Signal Corps. In through-hole technology, component leads are inserted through holes surrounded by copper PCB traces on one side of the substrate and then soldered to connection pads in the circuits on the opposite side. This method is less expensive than surface-mount technology but is less reliable, and requires hand soldering of each individual component.
On the other hand, surface-mount technology is a much faster and more accurate process that was introduced in the 1960s. With this technique, stubby J-shaped or L-shaped legs on each component are pushed down against a layer of solder paste on the surface of the substrate, where they line up with corresponding conductive pads or “lands” on the surfaces of the circuit boards. The pins on the components then contact and are held in place by the lands, with the component’s packages holding it in place until the solder is melted.
Regardless of which process is used to create a PCB, it’s important that the copper layers are as thin as possible so that the resulting board will have good electrical conductivity. This is accomplished by either etching away the original bare copper substrate with a potassium permanganate based etchant, or by using a semi-additive process where the bare copper laminate has been covered with a mask, and the exposed areas are then plated with copper to the desired thickness.
The final step in making a PCB is to add the legend, which typically includes component designators, switch settings, test points, and other indications helpful for assembling, testing, servicing, and using the finished product. The legend can be printed with epoxy ink, liquid photo imaging, or silkscreening.