Cos'è il PCB elettronico22-09-2020
Cos'è il PCB elettronico
The electronic printed circuit board (Russian abbreviation-PP, English-PCB) is a plate-like panel on which interconnected microelectronic components are placed. Printed circuit boards are used in various electronic devices, including simple apartment bells, home radios, studio radio stations, and complex radar and computer systems. Technically speaking, the manufacture of printed circuit boards for electronic products involves the combination with conductive “film” materials. This material is applied (“printed”) on an insulating board, the name of which is-substrate.
1 Historical path of printed circuit boards
2 Electronic Printed Circuit Board-Manufacturing
2.1 Substrate material
2.2 Perform binding operations
2.3 Design of electronic printed circuit board
3 Industrial production of electronic printed circuit boards
3.1 Make a good foundation
3.2 Drilling and tinning holes
3.3 Production of printed circuit board drawings
3.4 How is the addition process?
3.4.1 Industrial production technology of electronic boards
The history of printed circuit boards
The electronic printed circuit board marked the beginning of the development and evolution of the electrical connection system developed in the mid-19th century.
Metal straps (rods) were originally used to connect bulky electrical components mounted on wooden bases.
Gradually, metal strips have replaced conductors with screw terminals. The wooden base has also been modernized, with a preference for metal.
Electronic Printed Circuit Board-Manufacturing
The general vision of the process: a single electronic part is distributed over the entire area of the insulating substrate. Then solder the installed components to the circuit.
The so-called contact “fingers” (pins) of the electronic board are placed along the outer area of the substrate and act as system connectors
By touching the “finger”, you can organize the communication with the peripheral printed circuit board or the connection of the external control circuit. Electronic PCBs are designed to accommodate circuits that support one function or multiple functions at the same time.
Three types of electronic printed circuit boards are produced:
The characteristic of single-sided printed circuit boards is to place parts only on one side. If the entire circuit component cannot be mounted on a single panel, use the double-sided option.
The substrates traditionally used for printed circuit boards are usually made of glass fiber and epoxy resin. One or both sides of the substrate are covered with copper foil.
Phenolic paper-based electronic circuit boards are also coated with copper foil and are considered economically viable. Therefore, compared with other variants, it is more used to equip household appliances.
Wire connections by coating or by etching the copper surface of the substrate. The copper wire is plated with tin-lead compound to prevent corrosion. The contact pins on the printed circuit board are coated with a layer of tin, and then nickel and gold are coated on the surface.
Electronic PCB design
Each individually purchased printed circuit board (batch of circuit boards) of electronic products has a unique function. Designers of electronic printed circuit boards turn to design systems and specialized “software” to lay out circuits on printed circuit boards
The gap between conductive traces is usually measured at a value not exceeding 1 mm. Calculate the hole position of the component conductor or contact point.
All this information is converted into the format of the computer software that controls the drilling machine. Use the same method to program the automatic soldering iron used to manufacture electronic printed circuit boards.
After laying out the circuit diagram, the negative (mask) of the circuit diagram will be transferred to the transparent plastic board. The areas of the negative image not included in the circuit image are marked with black, and the circuit itself remains transparent.
Industrial manufacturing of electronic printed circuit boards
Electronic PCB manufacturing technology can provide a clean environment. The atmosphere and objects of the industrial plant are controlled by automatic equipment to prevent pollution.
Many companies that manufacture electronic printed circuit boards are doing unique production. In the standard form, the manufacture of double-sided printed electronic circuit boards usually includes the following steps:
Build a base
The glass fiber passes through the process module.
Impregnation (dipping, spraying) with epoxy resin.
The glass fiber is rolled on the machine to the required substrate thickness
The substrate is dried in the oven and then folded onto the large panel.
The panels are arranged in a pile, alternately arranged with copper foil and back glue.
Finally, put the stack under the press, and press the stack for 1-2 hours at a temperature of 170°C and a pressure of 700 kg/mm 2. The epoxy is hardened, and then the copper foil is crimped onto the backing material.
Drilled and tinned holes
Take out several boards of the base plate, stack one on top of the other, and fix them firmly.
The folded paper stack is placed in a CNC machine, and holes are drilled in it according to the schematic diagram.
Clean up excess material in the hole.
The inner surface of the conductive hole is coated with copper.
The non-conductive holes remain uncoated.
Production of printed circuit board drawings
Create a sample PCB circuit using the principles of addition or subtraction. In the case of additive type, copper is coated on the substrate according to the desired pattern. In this case, the parts outside the circuit are still unprocessed.