PCB is the most important of the electronic components, there is no one. Usually in the insulating material, according to a predetermined design, made of printed lines, printed components or a combination of the two into a conductive graphic called a printed circuit. And in the insulating substrate to provide electrical connections between components of conductive graphics, known as printed circuit boards (or printed circuit boards), which is an important support body of electronic components, able to carry the carrier of components.
I think we usually open the computer keyboard will be able to see a flexible film (flexible insulating substrate), printed with a silver-white (silver paste) conductive graphics and Ken bit graphics. Because the general screen leakage printing method to get this kind of graphics, so we call this printed circuit board for flexible silver paste printed circuit board. We go to the computer city to see a variety of computer motherboards, graphics cards, network cards, modems, sound cards and home appliances on the printed circuit board is different.
It uses the substrate is made of paper-based (commonly used in single-sided) or glass cloth-based (commonly used in double-sided and multi-layer), pre-impregnated with phenolic or epoxy resin, surface layer on one side or both sides of the copper-clad book and then laminated and cured. This circuit board copper clad book sheet, we call it a rigid board. Then made of printed circuit boards, we call it a rigid printed circuit board.
Single-sided printed circuit graphics we call single-sided printed circuit boards, double-sided printed circuit graphics, and then through the holes in the metallization of double-sided interconnections formed by the printed circuit board, we call it a double-sided board. If a double-sided for the inner layer, two single-sided for the outer layer or two double-sided for the inner layer, two single-sided for the outer layer of the printed circuit board, through the positioning system and insulating bonding material alternating with the conductive pattern according to the design requirements for interconnecting the printed circuit board becomes four, six-layer printed circuit board, also known as multilayer printed circuit board.
PCBA is one of the basic components of electronic components, PCB it through the surface assembly technology (SMT), and DIP plug-in insertion of the whole process, known as the PCBA process. In fact, it is the PCB that has been pasted. one kind of finished board and one kind of bare board.
PCBA can be understood as a finished circuit board, that is, all the processes of the circuit board are completed, can be counted as PCBA. due to the continuous miniaturization of electronic products with the refinement of the majority of circuit boards are used to attach the etching resist (film or coated), after the exposure of the development, and then etching to make the board.
In the past, the knowledge of the cleaning is not enough, because the PCBA assembly density is not high, there is also the view that the flux residue is non-conductive, benign, will not affect the electrical performance.
Nowadays, electronic assemblies tend to miniaturize, even smaller devices, or smaller pitch. Pins and pads are getting closer together, and today's gaps are getting smaller and smaller, and contaminants can get stuck in the gaps, which means that relatively small particles, if left between the two gaps, may also cause short-circuiting of the undesirable phenomenon.