what is multilayer pcb board？

Multilayer pcb board refers to the multilayer pcb used in electrical products, Multilayer pcb uses additional single-panel or double-panel wiring boards,It uses a printed circuit board with one double-side as the inner layer and two single-side as the outer layer or two double-side as the inner layer and two single-side as the outer layer,A printed circuit board (PCB) in which the positioning device and insulating bond material are interconnected according to design requirements is composed of four-layer and six-layer printed circuit boards, also known as multilayer circuit board.

With the continuous development of SMT technology and the continuous introduction of a different generation of SMD (surface mounted device), such as QFP, QFN, CSP, BGA (especially MBGA), electronic products are more intelligent and miniaturized, thus promoting the significant reform and progress of PCB industrial technology. The rapid development of these processing technologies. The design of PCB has gradually developed in the direction of multi-layer and high-density wiring. Multilayer pcb board has been widely used in the multilayer pcb fabrication of electronic products due to its flexible design, stable and reliable electrical performance and superior economic performance.

Multilayer pcb board status

Since the middle and late 1980s, the output value of multilayer pcb board has increased by more than 10% every year. Due to the rapid development of components to light, thin, short and small,multilayer pcb board is bound to become the most influential and vibrant category in the printed circuit board industry, and become the leading product. Multilayer pcb construction will be diversified, thin and high-rise, while McM-l structure will develop faster. Multilayer pcb board requires high investment in equipment and technology. In the future, high-level multilayer pcb board will focus on the development and production of pcb manufacturers with strong strength.

Multilayer pcb board development trend

High density reduction

Thin and high layered

Multilayer pcb construction diversified

Thin base material for thin copper boxes with high performance

High flatness and surface coating technology

Flexible multilayer pcb and multilayer rigid flexible pcb

Multilayer pcb board features

The biggest difference between multilayer pcb board and single panel and double panel is the addition of internal power layer and grounding layer. The power supply and grounding network are mainly routed on the power layer. However, multilayer pcb board wiring is mainly based on the top and bottom layer, supplemented by the middle wiring layer. Therefore, the design method of multilayer pcb board is essentially the same as that of double panel. The key lies in how to optimize the wiring of the inner electrical layer, so that the wiring of the circuit board is more reasonable and the electromagnetic compatibility is better.

Multilayer pcb board process description

This paper mainly introduces the production process of single and double panel, multilayer pcb board, and the role of each layer of the circuit board, let's take a look!

Single and double panel: According to the size of design optimization, cutting → polishing → drilling → pressing circuit board → blind plating hole → outer circuit → line oil printing → oven drying → smooth processing → exposure machine exposure (film positioning)→ darkroom development machine development → etching → green oil printing → baking → Printing white words and characters → Gong edge → opening short circuit function test → entering FQC→ final inspection and visual inspection → vacuum packing after cleaning.

Multilayer PCB board: Pressing before the need for automatic light inspection and visual inspection to enter the pressing machine for typesetting pressing (in a vacuum environment)→ row in the fixed size of the die → 2 hours of cold pressing, 2 hours of hot pressing → segmentation and removal of edge → according to the size of the design optimization for cutting → grinding processing → drilling → pressing circuit board → plating blind hole → outer line → Line oil printing → oven drying → smooth processing → exposure machine exposure (film positioning)→ darkroom developing machine development → etching → green oil printing → baking → white characters and characters printing → Gum-edge → opening short circuit function testing → entering FQC → final inspection and visual inspection → vacuum packaging after cleaning.

The function of each layer of pcb circuit board is introduced:

Signal layer: mainly used for placing components or wiring, middle layer used for laying signal cables, top and bottom layer used for placing components or copper.

Protective layer: It is mainly used to ensure that the parts of the circuit board that do not need to be tin plated are not tin plated, so as to ensure the reliability of the circuit board operation. The Top Paste and Bottom Paste are the top welding resistance layer and the bottom welding resistance layer respectively. Top Solder and bottom Solder are solder coating and bottom solder coating, respectively.

Screen printing layer: It is mainly used to print the serial number, production number, and company name of components on the circuit board.

Inner layer: mainly used as signal wiring layer.

Other layers: There are four main types of layers. The Drill Guide is mainly used for drilling positions on printed circuit boards. The Keep-Out Layer is used to draw the electrical border of the circuit board. The Drill Drawing layer is mainly used to set the shape of drilling holes. Multilayer pcb is mainly used to set up multifaceted layers.

This is the introduction of the multilayer pcb manufacturing process. If you have additional questions related to pcb, you can consult Huihe Circuit for free. Huihe Circuit specializes in R&D and production of all kinds of high-end pcb circuit boards, providing pcb proofing and mass production, mainly serving high-precision pcb circuit boards, soft and tough combined boards, Rogers high-frequency board, FPC, multilayer pcb board, etc.

Four key points of the multilayer pcb manufacturing process

Multilayer pcb board is commonly defined as 2-20 or more multilayer circuit boards, which are more difficult to produce and process than the traditional multilayer pcb board, printed with high quality and credibility strictly specified. The multilayer pcb manufacturing process is used in communications equipment, high-end web servers, medical electronics, aerospace, industrial control systems, and equipment products in the defense industry. In recent years, the market demand for multilayer pcb boards in communications, communication base stations, airlines, defense and other industries continues to increase.

With the rapid development of our communication equipment sales market, the multilayer pcb board industry has broad prospects. At present, multilayer pcb manufacturers that can mass-produce multilayer pcb boards in China come from foreign companies or a few domestic enterprises. The production of multilayer pcb manufacturing process must not only have strong technical and machine equipment project investment, but also must have the accumulation of professional and technical personnel and operators' work experience. In addition, the customer verification process of multilayer pcb board is also strict and complicated. Therefore, multilayer pcb manufacturers introduce steep threshold, industrial development production and manufacturing time. The following production processing points encountered in the multilayer pcb manufacturing process are for reference only.

Compared with traditional pcb products, Multilayer pcb board has the characteristics of thicker board, higher stacking layers, wire frame aggregation, additional buried holes, large unit size, thin material layer and so on. It has higher requirements on indoor space, virtual beam pointing, characteristic impedance manipulation and credibility.

Virtual beam pointing to the problem

Because the multilayer pcb board control panel in the number of strong levels, the customer on the pcb layer correction requirements are increasingly elevated. Typically, the pointing dimension tolerance in the middle of the layer is operated at 75μm, Taking into account the large size of board units in high-rise residential buildings, elevated temperature and humidity in the natural environment of the drawing transformation production workshop, dislocation coincidence caused by the inconsistency of joinery boards, and precise positioning method of virtual beams, the centering of multilayer pcb board is also difficult.
Internal power supply circuit fabrication problems

High-speed multilayer pcb board selects high tg, high frequency, thick copper, thin material layer and other pcb materials, and obviously puts forward high regulations on the internal power circuit manufacturing and drawing specification manipulation. For example, the consistency of characteristic impedance data signals increases the difficulty of manufacturing in-house power circuits. The total width and line interval is narrow, lead and short circuit fault, short circuit fault, low standard rate; with additional data signal layers, the inner AOI leakage test probability is improved; the inner core plate is thin, easy to wrinkle, poor exposure, easy to roll when the etching machine, and the product damage cost is higher.
Reduce manufacturing difficulties
Numerous inner core plates and semi-dry curing plates are accumulated, and it is extremely easy to appear in the production and manufacture of stamping dies, such as double warping plates, layers, epoxy resin gaps and bubble remnants. In the design scheme of the laminated structure, the temperature resistance, impact resistance, glue content and electric polarization thickness of the raw materials should be taken into account to formulate an effective multilayer pcb board pressing plan. Due to the large number of superimposed layers, the swelling and closing control and specification index compensation can not maintain consistency, and the inter-layer cable sheath is highly easy to cause the failure of the reliability test of the virtual beam.

Drilling manufacturing difficulties

The selection of high tg, high speed, elevated frequency, thick copper unique plate can improve the surface roughness of drilling, burr edge of drilling and the difficulty coefficient of removing drilling dirt. The number of stacking layers, the total copper thickness and thickness, drilling easy to cut; the CAF is ineffective due to the large number of accumulated BGA and narrow hole edge spacing, and the inclined drilling problem is extremely easy to be caused due to the thickness of the plate.

The above are the four key points about multilayer pcb manufacturing process. There are numerous manufacturers that can produce multilayer pcb, but few manufacturers can truly make a pcb board.

How to choose multilayer pcb manufacturers?

With the development of the electronic information age, pcb circuit boards, which constitute part of electronic products, have been profoundly penetrated into numerous people's daily lives. Now the pcb market is mixed with fish and pearls. How to choose a multilayer pcb manufacturers with superior cost performance has become a perplexing problem for numerous buyers. Here's how to choose a genuinely cost-effective multilayer pcb manufacturers.

First of all, the wiring of multilayer pcb board should pay attention to the unique places of high density, light size and weight. Thus far, electronic facilities are more and more inclined to tiny, high-density circuit board products. Huihe circuit multilayer pcb manufacturers can meet the needs of short scale progress of electronic facilities, and at the same time, it is more convenient.

Secondly, flexible multilayer pcb board is flexible and accurate. This special property is suitable for extreme precision spectrographs such as cameras, mobile phones and cameras, so as to ensure the accuracy of each part.

Select a high quality service multilayer pcb manufacturer that has high quality and high rate of service. Multilayer pcb manufacturers are equipped with advanced semi-automatic production equipment and facilities, and have rich industry experience, strictly follow the industry production standard process, can provide high-quality products and services for users, sincerely let customers experience the trouble, time saving, less worry and labor-saving service.

I hope the above points can help friends who are choosing multilayer pcb manufacturers.

Get Introduction of multilayer pcb

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