8-layer pcb circuit board proofing process

The process of 8-layer pcb proofing is similar to that of ordinary PCB proofing, but compared with ordinary PCB, there are more pressing processes. Today, Xiaobian will show you the specific process of 8-layer pcb proofing.
Brief introduction of the differences between common double-sided pcb and multilayer Pcb;
The double panel is the middle layer of medium, and both sides are wiring layers. A multilayer board is a multilayer wiring layer, with a dielectric layer between every two layers, and the dielectric layer can be made very thin. The multilayer circuit board has at least three conductive layers, two of which are on the outer surface, while the remaining layer is synthesized in the insulation board. The electrical connection between them is usually realized by plated through holes on the cross section of the circuit board.
The production process of 8-layer pcb proofing is the same as that of pcb multilayer board. Let’s see what processes are available.
First, 8-layer pcb proofing-blackening and browning purpose ① Remove oil stain, impurities and other pollutants on the surface; (2) Increasing the specific surface area of copper foil, thus increasing the contact area with resin, is conducive to the full diffusion of resin, forming a larger binding force; ③ changing the nonpolar copper surface into the surface with polar CuO and Cu2O, and increasing the polar bond between copper foil and resin; ④ The oxidized surface is not affected by moisture at high temperature, which reduces the probability of delamination between copper foil and resin. ⑤ The board with the inner circuit must be blackened or browned before lamination. It oxidizes the copper surface of the inner board. Generally, Cu2O is red and CuO is black, so Cu2O-based oxide layer is called browning and CuO-based oxide layer is called blackening. 1. Lamination is the process of bonding all layers of circuits into a whole by means of B- stage prepreg. This kind of bonding is realized by the mutual diffusion, infiltration and interweaving of macromolecules on the interface. The process of bonding layers of circuits into a whole by prepreg. This kind of bonding is realized by the mutual diffusion, infiltration and interweaving of macromolecules on the interface. 2. Objective: To press the discrete multilayer board together with the adhesive sheet into the multilayer board with the required number of layers and thickness.
(1) Typesetting: Copper foil, adhesive sheet (prepreg), inner sheet, stainless steel, isolation sheet, kraft paper, outer steel sheet and other materials are laminated according to the technological requirements. If the board with more than six floors needs to be pre-typeset. Laminate copper foil, adhesive sheet (prepreg), inner sheet, stainless steel, insulation sheet, kraft paper, outer steel sheet and other materials according to process requirements. If the board with more than six floors needs to be pre-typeset.
② During the lamination process, the folded circuit board is sent to a vacuum hot press. The heat energy provided by the machine is used to melt the resin in the resin sheet, so as to bond the substrate and fill the gap.
③ Lamination For designers, the first thing to consider in lamination is symmetry. Because the board will be affected by pressure and temperature during lamination, there will be stress in the board after lamination. Therefore, if the two sides of the laminated board are uneven, the stress on the two sides will be different, resulting in the board bending to one side, which will greatly affect the performance of PCB. Keyou Circuit specializes in the production of high-precision multilayer circuit boards, and its products are widely used in LCD modules, communication equipment, instruments and meters, industrial power supply, digital, medical electronics, industrial control equipment, LED modules/modules, electric power, transportation, scientific and educational research and development, automobiles, aerospace and other high-tech fields. In addition, even in the same plane, if the distribution of copper cloth is uneven, the resin flow speed at each point will be different, so that the thickness of the place with less copper cloth will be slightly thinner, while the thickness of the place with more copper cloth will be slightly thicker. In order to avoid these problems, the factors such as the uniformity of copper distribution, the symmetry of lamination, the design and arrangement of blind buried holes, etc. must be tested in detail.
Second, 8-layer pcb proofing production-drilling dirt and copper deposition Purpose: Metallize the through hole. ① The substrate of the circuit board is composed of copper foil, glass fiber and epoxy resin. In the manufacturing process, the cross section of the hole wall after drilling the base material is composed of the above three parts of materials. ② Hole metallization is to solve the problem of covering a layer of uniform and heat-resistant copper on the cross section. Hole metallization is to solve the problem of covering a layer of uniform, heat-resistant copper on the cross section. ③ The process is divided into three parts: first, the process of drilling dirt, second, the process of chemical copper deposition, and third, the process of thickening copper (full-plate copper electroplating).
Three or eight layers of pcb proofing-copper sinking and thickening
Metallization of holes involves a concept of capability, thickness-diameter ratio. Thickness-diameter ratio refers to the ratio of plate thickness to aperture. , thickness-diameter ratio. Thickness-diameter ratio refers to the ratio of plate thickness to aperture. When the plate thickness is increasing and the hole diameter is decreasing, it is more and more difficult for chemical yao water to enter the depth of the drilling hole. Although plating equipment uses vibration, pressurization and other methods to make yao water enter the center of the drilling hole, the thinner central coating caused by the concentration difference is still unavoidable. At this time, there will be a slight open circuit phenomenon in the drilling layer. When the voltage increases and the board is impacted under various bad conditions, the defects will be completely exposed, resulting in the open circuit of the board and the inability to complete the specified work.
Therefore, designers need to know the technological capabilities of board manufacturers in time, otherwise the designed PCB will be difficult to realize in production. It should be noted that the thickness-diameter ratio parameter must be considered not only in the design of through holes, but also in the design of blind buried holes.
Four or eight layers of pcb proofing-outer dry film and graphic plating
The principle of pattern transfer in the outer layer is similar to that in the inner layer, that is, the printed circuit pattern is printed on the board by photosensitive dry film and photographing. The outer dry film differs from the inner dry film in that:
① If the subtractive method is adopted, the outer dry film is the same as the inner dry film, and the negative film is used as the board. The cured dry film part of the board is the circuit. The uncured film is removed, the film is etched back by acid, and the circuit pattern is left on the board because it is protected by the film. For more questions about 8-layer pcb proofing and other pcb multilayer boards, please consult Jin Rui Xin Special Circuit. Jin Rui Xin Special Circuit has more than ten years of industry manufacturing experience, which can realize rapid proofing and small and medium-sized batch production of 2-30-layer circuit boards. A team of 300 people specializes in manufacturing, and strictly controls all aspects of quality to ensure product performance.