Almost every electronic device, from small electronic watches and calculators to large computers, communication electronic equipment, military weapon systems, as long as there are integrated circuits and other electronic components, in order to their electrical interconnection, the use of printed boards.
In the larger electronic product research process, the most basic success factor is the product's PCB design, documentation and manufacturing.The quality of PCB design and manufacture directly affects the quality and cost of the whole product and even leads to the success or failure of commercial competition.
Printed circuits provide the following functions in electronic equipment: Provide mechanical support for fixing and assembling various electronic components such as integrated circuits.Realize wiring and electrical connection or electrical insulation between various electronic components such as integrated circuits.Provide required electrical characteristics, such as characteristic impedance, etc.Provides soldering resistance pattern for automatic soldering and identification characters and pattern for component assembly, inspection and maintenance.
Some basic terms related to the printed board are as follows: on the insulating substrate, according to the predetermined design, made into printed circuits, printed components or a combination of the conductive graphics, known as printed circuits.On an insulating substrate, a conductive pattern providing electrical connections between elements and devices is called a printed circuit.It does not include printed components.The finished board of printed circuit or printed circuit is called printed circuit board or printed circuit board, also known as printed circuit board. According to the substrate used in the printed circuit board is rigid or flexible can be divided into two categories: rigid printed circuit board and flexible printed circuit board. This year has seen the emergence of rigid - flexible combination of the PCB.
According to the number of layers of the conductor pattern can be divided into single-sided, double-sided and multi-layer PCB.The entire outer surface of the conductor figure and the substrate surface are located in the same plane of the printed board, known as the plane printed board. For terms and definitions of printed circuit boards, please refer to the national standard GB/ t2036-94 "printed circuit terms".
After the adoption of PCB in electronic equipment, due to the consistency of the same kind of PCB, the error of manual wiring can be avoided, and the electronic components can be automatically inserted or stuck, automatically soldered and automatically tested, which ensures the quality of electronic equipment, improves labor productivity, reduces costs and facilitates maintenance.The development of PCB from single layer to two - sided, multi - layer and flexible, and still maintain their own development trend.
Due to the continuous development to high precision, high density and high reliability, and constantly reduce the volume, reduce the cost, improve the performance, so that the printed board in the future electronic equipment development project, still maintain a strong vitality.
For the printed circuit board (PCB) with double-sided and multi-hole metallized PCB, it means that the number of wires can be arranged between two welding pads at the intersection of 2.50 or 2.54mm standard mesh in the mass production of the double-sided metallized PCB.
A wire is arranged between the two pads, which is a low-density printed board, and its wire width is greater than 0.3mm.Two wires are arranged between the two pads, which are medium density printed boards, and the wire width is about 0.2mm.hree wires are arranged between the two pads, which are high-density printed boards, and the wire width is about 0.1-0.15mm.Four wires are arranged between the two pads to calculate the ultra-high density PCB. The wire width is 0.05-0.08mm.