PCB multilayer board refers to the multilayer circuit board multilayer board used in electrical products uses more single-sided or double-sided wiring boards. Use one double-sided as the inner layer, two single-sided as the outer layer or two double-sided as the inner layer, two single-sided as the outer layer of the printed circuit board through the positioning system and insulating bonding material alternately together and the conductive pattern according to Printed circuit boards that are designed to be interconnected become four-layer and six-layer printed circuit boards, also known as multilayer printed circuit boards.
With the continuous development of SMT (Surface Mount Technology) and the continuous introduction of a new generation of SMD (Surface Mount Devices), such as QFP, QFN, CSP, BGA (especially MBGA), electronic products are more intelligent and miniaturized, so It has promoted the major reform and progress of PCB industry technology. Since IBM first successfully developed high-density multilayer boards (SLC) in 1991, major groups in various countries have also successively developed various high-density interconnection (HDI) microplates. The rapid development of these processing technologies has prompted the design of multilayer circuit boards to gradually develop in the direction of multilayer and high-density wiring. With its flexible design, stable and reliable electrical performance and superior economic performance, multilayer printed boards have been widely used in the production and manufacture of electronic products.
1. Signal Layers
AlTumDesigner can provide up to 32 signal layers, including top layer (TopLayer), bottom layer (BottomLayer) and middle layer (Mid-Layer). Each layer can be interconnected through vias (Via), blind vias (BlindVia) and buried vias (Buriedvia).
(1), top signal layer (TopLayer)
Also known as the component layer, it is mainly used to place components. For double-layer boards and multi-layer boards, it can be used to arrange wires or copper cladding.
(2), the underlying signal layer (BottomLayer)
Also known as the solder layer, it is mainly used for wiring and soldering, and can be used to place components for double-layer boards and multi-layer boards.
(3) Intermediate signal layer (Mid-Layers)
There can be up to 30 layers, which are used to arrange signal lines in multi-layer boards, excluding power lines and ground lines.
2. Internal Planes
Usually referred to as the internal electrical layer; it only appears in multilayer boards, and the number of PCB multilayer boards generally refers to the sum of the signal layer and the internal electrical layer. The same as the signal layer, the interconnection between the inner electrical layer and the inner electrical layer, and between the inner electrical layer and the signal layer can be realized through through holes, blind holes and buried holes.
3. SilkscreenLayers
A PCB board can have up to 2 silkscreen layers, which are the top silkscreen layer (TopOverlay) and the bottom silkscreen layer (BottomOverlay), which are generally white and are mainly used to place printed information, such as outlines and labels of components, and various comment characters Etc., to facilitate PCB component welding and circuit inspection.
(1) The top silk screen layer (TopOverlay)
It is used to mark the projection outline of components, the label, nominal value or model of components and various annotation characters.
(2) Bottom Overlay (BottomOverlay)
Same as the top silkscreen layer, if all the labels are included in the top silkscreen layer, the bottom silkscreen layer can be closed.
4. Mechanical Layers
The mechanical layer is generally used to place indicative information about board manufacturing and assembly methods, such as PCB dimensions, size marks, data files, via information, assembly instructions, and other information. The information varies depending on the requirements of design companies or PCB manufacturers. The following examples illustrate our common methods.
Mechanical1: It is generally used to draw the border of the PCB as its mechanical shape, so it is also called the shape layer;
Mechanical2: We are used to place the PCB processing technology requirement form, including information such as size, board material, board layer, etc.;
Mechanical13&Mechanical15: The body size information of most components in the ETM library, including the 3D model of the components; for the simplicity of the page, this layer is not displayed by default; Mechanical16. The footprint information of most components in the ETM library, in the early stage of the project It can be used to estimate the PCB size; for the simplicity of the page, this layer is not displayed by default, and the color is black.
5. MaskLayers
AITlumDesigner provides two types of mask layers (MaskLayers), solder mask (SolderMask) and tin layer (PasteMask), in which there are two layers, the top layer and the bottom layer, which will not be introduced in detail here.
