Advantages: high assembly density, small volume, light weight because of high assembly density, the connection between components (including components) is reduced, so the reliability is improved; The number of wiring layers can be increased, thus increasing the flexibility of the design; Can form a circuit with a certain impedance; Can form a high-speed transmission circuit; The circuit and magnetic circuit shielding layer can be set, and the metal core heat dissipation layer can be set to meet the needs of shielding, heat dissipation and other special functions; Easy installation and high reliability.
Disadvantages: high cost; The period is long; High reliability detection means are required. Multilayer printed circuit board (PCB) is the product of electronic technology to high speed, multi-function, large capacity and small volume. With the continuous development of electronic technology, especially the extensive and in-depth application of large-scale and ultra-large scale integrated circuits, multilayer printed circuits are rapidly developing to high density, high precision, high level digitalization direction. t appears micro-line, small aperture through, blind hole buried hole, high plate thickness aperture ratio technology to meet the needs of the market.
Circuit board factory - Method of improving short circuit caused by etching
Short circuit to circuit board factory caused considerable harm, etching is an important cause of circuit board short circuit, to find a way to improve the etching process to reduce short circuit is the circuit board factory must go through the process, especially in the process of printed circuit board manufacturing, etching process requirements are more and more fine.
Short circuit to circuit board factory caused considerable harm, small to burn components, large to scrap PCB. We only try to avoid short circuit, must grasp every step of production, inspection does not let go of every point of doubt. In the etching process, usually cause circuit board short circuit aspects are: improper control of the parameters of the etching potion, the whole plate plating copper coating thickness is not uniform, resulting in unclean etching. The quality of water parameter control of etching yao directly affects the quality of circuit board to etching. The following is the specific analysis of etching liquid of Shenzhen circuit board factory:
1.PH value: Control between 8.3 and 8.8, if the PH value is low, the solution will become sticky, the color is white, corrosion rate decreases, this situation is easy to cause side corrosion, mainly by adding ammonia water to control the PH value.
2. Chloride ion: Controlled between 190 and 210g/L, mainly through etching salt to control the chloride ion content, etching salt is composed of ammonium chloride and supplements.
3. Specific gravity: The specific gravity is controlled mainly by controlling the content of copper ions. Generally, the content of copper ions is controlled between 145~155g/L, and it is tested every hour or so to ensure the stability of specific gravity.
4. Temperature: Control at 48~52℃, if the temperature is high, ammonia volatilizer fast, will cause pH instability, and most of the cylinder of the etching machine is made of PVC material, PVC temperature limit of 55℃, beyond this temperature is easy to cause cylinder deformation, or even cause the etching machine scrap, so it must be installed automatic temperature controller to effectively monitor the temperature, Make sure it's under control.
5. Speed: Generally adjust the appropriate speed according to the thickness of the plate bottom copper.
In order to achieve the stability and balance of the above parameters, it is recommended to configure automatic feeding machine, in order to control the chemical composition of the child liquid, so that the composition of the etching liquid in a relatively stable state. Keyou fast production of high precision double-sided/multi-layer circuit board (1-26 layers),LED aluminum substrate, thermoelectric separation single-side/double-sided copper substrate, foldable metal substrate, industrial circuit board, power pcb board, medical circuit board, security PCB board, communication PCB board, automotive circuit board, instrument circuit board, military circuit board
A method of improving the uneven thickness of electroplating copper on the whole plate, resulting in unclean etching.
1. When electroplating the whole plate, try to realize automatic production, and adjust the current density per unit area (1.5~2.0A/dm2) according to the size of the hole area, and try to keep the plating time consistent to ensure full load production. At the same time, add negative and anode baffles, and formulate the use system of "electroplating edge" to reduce potential difference.
2. If the whole plate plating is manual line production, then the plate needs to use double clamping stick plating, as far as possible to keep the current density of the unit area a, at the same time to install a timing alarm, to ensure the consistency of plating time, reduce potential difference.