In the production process of batch processing of high-precision circuit boards, in order to avoid the problem of rejection and material replenishment of FPC boards caused by too many open and short circuit faults, or the reduction of rough processing problems such as punching, injection molding, laser cutting, etc., and to evaluate how to select materials to achieve the best practical effect of customer application, prenatal preparation seems to be particularly important.
There are three levels that must be solved in prenatal preparation, all of which are carried out by technical engineers. First of all, the FPC board project evaluation, mainly to assess whether the customer’s FPC board can be manufactured, and whether the production capacity of the enterprise can consider the customer’s plate-making process regulations and product costs; If the project evaluation is based on, then the materials must be prepared immediately, and the balance between supply and demand of raw materials in each production and manufacturing stage should be considered. Finally, the technical engineer will solve the engineering documents such as the customer’s CAD frame diagram and gerber route materials, so as to suit the working environment and manufacturing specifications and models of the production line equipment. Then, the manufacturing engineering drawings and MI (Project Step Card) and other materials will be distributed to the production technology department, document control, purchase and other departments, and the basic production process will be carried out.
The general “stacking design” is actually the design of the cumulative arrangement method of wiring layers and plane layers.
1. Foil lamination method is strongly recommended for PCB lamination.
2. Minimize the application of PP sheets and CORE models, specifications and types in the same stack (no more than 3 PP sheets are stacked in each layer).
3. The thickness of the PP material in the middle of the double layer does not have to exceed 21MIL (the thick PP material is difficult to process, and generally a blockboard will be lifted, resulting in the increase of the total number of specific laminates, which will further increase the production cost).
4. The PCB surface layer (Top and Bottom layers) generally adopts 0.5OZ thin thick copper foil, and the inner layer generally adopts 1OZ thin thick copper foil. double sided circuit board
The results show that the thickness of copper foil is generally determined according to the current size and wiring size. For example, 2-3OZ copper foil is generally used for power board, 1OZ copper foil is generally selected for general data signal board, and 1/3QZ copper foil will be used for thin wiring to improve the product qualification rate. In addition, blockboard with inconsistent thickness of double-sided copper foil is prevented from being applied in the inner layer. (Manufacturing of double-layer circuit board)
5. The wiring layer of PCB board is spread all over the whole surface layer, and it is stipulated that it is symmetrical from the axis of PCB board stack (including the number of superimposed layers, the distance from the axis, the copper thickness of wiring layer and other main parameters).
It shows that the PCB stacking method needs to choose symmetrical design, which means that the cable sheath is thin and thick, the type of semi-dry solid sheet, the copper foil is thin and thick, and the patterns (large copper foil layer, route layer) are as symmetrical as possible relative to the axis of PCB. (Manufacturing of double-layer circuit board)
6. Sufficient capacity must be reserved in the design of graphic boundary and material thickness to prevent design problems such as SI caused by insufficient capacity. Dingding has fifteen years’ experience in plate-making process, and has been committed to making double-layer PCB for years.
In the design and production of a small amount of PCB, the switching power supply is wired in the ground plane layer or the switching power supply and the ground network are wired in the wiring layer, which is called the data signal layer for this kind of mixed design. Manufacturer of double-layer differential signal characteristic impedance circuit board,
Etching machine of PCB
The wood board flows directly under the roller.
Why is the etching method of PCB inner surface different?
Layer: development → etching → detachment
Surface layer: developing → electroplating tin with copper → stripping → etching → stripping tin.
Why did you do that? Isn’t surface etching like that a lot of technological processes?
Generally, the boundary line distance of the inner layer is very large, so the Ring ring is enough; Generally, the surface route is dense and the indoor space is insufficient. Therefore, at this time, we must find a way to make the route in the insufficient indoor space. The working ability of alkali etching can be 1~1mil ring, but acid etching must be 5mil, so it is necessary to apply tin to maintain the necessary route first. Don’t do it as much as possible in areas where alkali etching can be avoided, because the cost of alkali etching is higher than that of acid etching. Etching factor is the working ability of a processing factory, which can’t be improved according to the technological process. It’s just that the etching ability of acid and alkali etching is different.
Double-layer circuit board is a necessary material for the development trend of electronic information technology towards high-speed operation, intelligence, large space and small volume. With the continuous development trend of electronic information technology, especially the scale and deep application of integrated circuit chips, double-layer printed circuits are rapidly developing towards the digital orientation of high-density, high-precision and high-rise residential buildings, and technologies such as ultra-fine wire frame, small-diameter surrounding, buried hole and buried hole with high thickness-diameter ratio appear to consider the necessity of sales market. Because of the necessity of high-speed power supply circuit in the production of electronic computers and aerospace industries, double-sided circuit boards are required to further increase the relative density of packaging, and the trend of the rapid development of microelectronics and the smaller size of separated components, the smaller forward volume of electronic products and the lower quality of electronic products. Because of the limitation of indoor space, single-sided and double-sided pcb boards are unlikely to complete the further improvement of installation relative density. Therefore, it is necessary to consider the application of printed circuits with more layers than double-sided circuit boards. This has created a standard for the emergence of double-layer circuit boards.
Which problem should we pay special attention to when designing the wiring of 4-layer PCB?
First, connect the wires at least 3 o’clock, and try to make the wires successively according to each point, so as to facilitate the detection. Before the pins, there is no need to pay off the wires, especially in the middle and periphery of the pins of the integrated circuit chip. The lines in the middle of different levels do not have to be parallel to each other, so as to prevent actual capacitors.
Second, when designing a 4-layer circuit board, the wiring design should be parallel lines or 45-degree curves as far as possible. The reason for that is that it can prevent electromagnetic radiation. The grounding wire and power plug should be at least 10-15mil above, and the paving multi-purpose wires should be connected together as much as possible to improve the total area of grounding devices, and the wires should be as neat as possible. High precision double-sided circuit board
Three, should pay attention to the components of sewage symmetry, easy to install, software, practical operation of electric welding is more convenient. Reasonable layout of text drainage parts, pay attention to prevent blocking, in addition, the structure should be taken into account when discharging components, and whether the SMD components are positive or negative should be marked in the package and finally to prevent the contradiction of indoor space.
At present, 2mil wiring and 2mil wire moment can be printed on the 4th and 4th layer circuit boards. When wiring, more consideration should be given to the hazards such as the amount of injected current. The functional block elements should be put together as much as possible. The LCD peripheral elements such as Banma Bar should not be too close, and the pads should be painted with green oil (set to negative double value).
5. Resonant circuit components shall be as close to IC as possible, and the resonant circuit shall be protected from vulnerable areas such as wireless antenna as much as possible. The solder layer of grounding device shall be placed on the crystal oscillator circuit. After the final wiring is carried out, every connection shall be carefully made to ensure that there is indeed a connection.