FS Technology's introduction to the layers of the PCB.

Electronic Design Automation (EDA). It is a software used to design PCB and likewise confirm integrated circuits (ICs). There are different kinds available in PCB single, double-sided, High layer Count (multilayer), control impedance, Aluminum backed PCB and many more. This picture shows a single sided PCB which has four-layer basic layer.  

4-layer base layer single-sided PCB

Designers use EDA Инструменты для проектирования печатных плат to construct the layers of the PCB board and organize with the help of heat and adhesive. That makes many layers into one single object.  More layers complex the design and it develops a difficult route for your connections. A multilayer board have metallic linking with holes that attach to each other with suitable route. FS Technology will explain each layer of the printed circuit board in detail in the following content to help you understand what the PCB board is made of.

Silkscreen layer

The silk screen layer is the text layer, which can be dyed or painted on the board. It contains labels to aids in joining component to the circuit and adds letters, numbers and many signs to make it easier to comprehend. Silkscreen has no restrictions, it can be red, green or black or even none. The designer of FS Technology once saw such a post in a Производство печатных плат forum: “Why do Chinese manufacturers like to mark some messy symbols on the silk screen layer of the circuit board.” If you object to this practice, you can communicate with our sales.

PCB silk screen layer

Solder mask

A solder mask is a thin layer that is applied on a copper layer on a PCB. This is the upper layer which is overhead the copper foil. It is usually in green and black but make sure that it can be in any color. The solder mask plays an important role in the reflow process, and designers can prevent solder defects by reducing the spacing around the pads. The functions of the PCBA solder mask layer include the following:

  • It is used to evade conduction in case of direct touch of any metal or solder. 
  • It is the layer used to create an insulating layer to prevent a short circuit in electronic components and conductive traces.
  • Furthermore, it also prevents soldering on unwanted parts and ensures that solder only goes on the areas intended for soldering.
PCB Solder Mask

Rigid Copper Clad Laminate (Copper Layer)

This is the layer on which conductive traces are formed. These are a slim layer on the copper foil, which will directly affect the properties of the rigid PCB, so customers need to read the PCBA copper thickness guide carefully before choosing a PCB manufacturer. It is coated on PCB board with adhesive and heat. Normally, both sideways of substrate are coated with copper apart from single-sided PCB. When we say different layers of PCB that where we count how many numbers of copper layer PCB has. The copper clad laminates are connected to each other through holes, and we can place different types of objects on it, such as:

  • Tracks
  • Individual pads
  • Vias 

PCB tracks or trace

Tracks are sometimes stated as PCB trace. It is used to join two points in the PCBA, conduct. It spread signals and power to each other. Tracks can be very in thickness and resistance. The bigger the track, the more current it conveys. And if the track is stripper than it would be easy to fit more tracks. 

Pads

PCB pads are commonly exposed area of metal that allows soldering the component to the board. They can be in rectangle, ovel or round shape. A circuit is occupied with many holes if it is a multilayer PCB. Pads should be minimum of 0.25 mm.

Vias

Vias in PCB used to connect different track. It is plated hole that allows the current to pass over the board. The tracks and pads that fits to the lowest layer are visually dimmed so one can distinguish.

Fills

In PCB fills provides shielding in divergent parts and likewise protect the tracks that carries a lot of current. 

FR4 Substrate Layers

Substrate use in PCB is the material which hold the components and trace. Printed circuit board composed of fiber glass that part is recognized as substrate. This layer helps to improve the rigidity of the PCB, generally this layer is made up of FR-4 material.

FR means Flame Retardant and 4 represents epoxy resin. There are many glass epoxy laminates likeFR-5, FR-6, G-10 G-11. But FR-4 epoxy resin is used mostly.  The FR4 fiber glass in now commonly used in today’s PCB. It is durable and available in different types of thickness.

Properties of FR4 substrate

  • Fine Electrical retardant 
  • Flame retardant
  • Low Moisture captivation
 

Although most circuit boards are manufactured using FR-4 as the substrate material, this rigid PCBA has some specific disadvantages:

  • You cannot alter the PCB once you print out the circuit on the PCB
  • Electronic component must be required to connect the with the soldering. 
  • Thermal shock is also required for soldering.
  • Printed circuit have more amount of lead. 
  • In the manufacturing of PCB, the engraving process is harmful.
  • It has rough surface. 

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