PCB News - Explore the meaning of each layer of the multilayer circuit board

Explore the meaning of each layer of the multilayer circuit board

PCB multi-layer boards refer to multi-layer circuit boards used in electrical products. Multi-layer boards use 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 and two single-sided as the outer layer of the printed circuit board. The positioning system and the insulating bonding material alternately together and the conductive pattern Printed circuit boards that are interconnected according to design requirements 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 becoming more intelligent and miniaturized. Promoted major reforms and advances in PCB industrial technology. Since IBM first successfully developed high-density multilayer (SLC) in 1991, major groups in various countries have also developed various high-density interconnect (HDI) microporous plates. The rapid development of these processing technologies has prompted the design of multi-layer circuit boards to gradually develop in the direction of multi-layer, 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 of electronic products.

1. Signal Layer (SignalLayers)

AlTIumDesigner can provide up to 32 signal layers, including the top layer (TopLayer), the bottom layer (BottomLayer) and the middle layer (Mid-Layer). The layers can be connected to each other through vias (Via), blind vias (BlindVia) and buried vias (BuriedVia).

(1), the top signal layer (TopLayer)

Also called the component layer, it is mainly used to place components. For double-layer boards and multilayer boards, it can be used to arrange wires or copper.

(2), the bottom signal layer (BottomLayer)

Also called soldering layer, it is mainly used for wiring and soldering. For double-layer boards and multilayer boards, it can be used to place components.

(3) Mid-Layers

There can be up to 30 layers, which are used to arrange signal lines in a multilayer board. Power lines and ground lines are not included here.

2. Internal power plane (InternalPlanes)

Usually referred to as the inner electric layer for short, it only appears in multi-layer boards. The number of PCB multi-layer boards generally refers to the sum of the signal layer and the inner electric layer. Same as the signal layer, the inner electric layer and the inner electric layer, and the inner electric layer and the signal layer can be connected to each other through through holes, blind holes and buried holes.

3. SilkscreenLayers

A PCB board can have up to 2 silk screen layers, which are the top silk screen layer (TopOverlay) and the bottom silk screen layer (BottomOverlay), generally white, mainly used to place printed information, such as component outlines and annotations, and various notes Characters, etc., to facilitate the soldering of PCB components and circuit inspection.

(1) Top screen printing layer (TopOverlay)

It is used to mark the projection outline of the components, the label, the nominal value or the model of the component, and various annotation characters.

(2) Bottom Overlay

Same as the top silk screen layer, if all the marks on the top silk screen layer are included, the bottom silk screen layer can be closed.

4. Mechanical Layers (MechanicalLayers)

The mechanical layer is generally used to place indicative information about board manufacturing and assembly methods, such as the outline dimensions of the PCB, size markings, data materials, via information, assembly instructions and other information. This information varies according to the requirements of the design company or PCB manufacturer. The following examples illustrate our common methods.

Mechanical1: Generally used to draw the frame of the PCB as its mechanical shape, so it is also called the shape layer;

Mechanical2: We used to place the PCB processing process requirement form, including information such as size, plate, and layer;

Mechanical13&Mechanical15: The body size information of most components in the ETM library, including the three-dimensional models of the components; for the sake of simplicity of the page, this layer is not displayed by default;

Mechanical16: The footprint information of most components in the ETM library can be used to estimate the PCB size in the early stages of the project; for the simplicity of the page, this layer is not displayed by default, and the color is black.

5. Mask Layers (MaskLayers)

AlTIumDesigner provides two types of mask layers (SolderMask) and solder paste layer (PasteMask). There are two layers, the top layer and the bottom layer, respectively, which will not be described in detail here.