Classification of PCBs from three aspects

PCB Classification

PCB materials, layers, and manufacturing processes are diversified to suit different electronic products and their special needs, so there are many types of PCBs.

The following is a summary of some common differences, to briefly introduce the classification of PCB and its manufacturing process. Then China PCB manufacturer SysPCB will analyze it from three aspects.

I. Material

1. Organic materials:

① Phenolic resin: Phenolic resin is also called bakelite or bakelite powder. It was originally colorless or yellowish-brown transparent material, and it is often sold in the market with coloring agents to be red, yellow, black, green, brown, blue and other colors, in the form of granules and powder.
Phenolic resin is resistant to weak acids and weak bases. It will decompose when exposed to strong acids and will corrode when exposed to strong bases. Insoluble in water, soluble in organic solvents such as acetone and alcohol. It is obtained by condensation polymerization of phenol aldehyde or its derivatives. 

② Glass fiber: Glass fiber (original name in English: glass fiber) is an inorganic non-metallic material with excellent performance. It has a wide variety of advantages. It has good insulation, strong heat resistance, good corrosion resistance, and high mechanical strength, but it has disadvantages It is brittle and has poor wear resistance.

It is made of seven kinds of ores of pyrophyllite, quartz sand, limestone, dolomite, boronite, and boronite as raw materials through high-temperature melting, drawing, winding, weaving and other processes. The diameter of its monofilament is several Micron to more than twenty microns, which is equivalent to 1/20-1/5 of a hair strand, each fiber strand is composed of hundreds or even thousands of monofilaments.

Glass fiber is usually used as a reinforcing material in composite materials, electrical insulation materials and thermal insulation materials, circuit boards and other fields of the national economy. 

③ Polyimide: polyimide resin referred to as PI, appearance: transparent liquid, yellow powder, brown particles, amber particles polyimide resin liquid, polyimide resin solution, polyimide resin powder, polyimide Resin pellets, polyimide resin pellets, polyimide resin pellets, thermoplastic polyimide resin solution, thermoplastic polyimide resin powder, thermosetting polyimide resin solution, thermosetting polyimide resin powder , Thermoplastic polyimide pure resin, thermosetting polyimide pure resin 2. Polyimide PI molding methods include: high temperature curing, compression molding, dipping, spraying, calendering, injection molding, extrusion, die-casting, coating Laminating, casting, lamination, foaming, transfer molding, compression molding. 

And our epoxy resin and BT are all organic materials.

2. Inorganic materials:

Aluminum Substrate: Aluminum substrate is a metal-based copper clad laminate with good heat dissipation function. Generally, a single panel is composed of a three-layer structure.

They are the circuit layer (copper foil), the insulating layer and the metal base layer. Commonly found in LED lighting products. There are two sides, the white side is for soldering the LED pins, and the other side is the natural color of aluminum. Generally, the thermal conductive paste will be applied to contact with the thermal conductive part. Currently there are ceramic substrates and so on. As shown in the figure:

② Copper substrate: Copper substrate is the most expensive kind of metal substrate, and its thermal conductivity is many times better than aluminum substrate and iron substrate. It is suitable for high-frequency circuits, areas with large changes in high and low temperatures, and heat dissipation and architectural decoration of precision communication equipment. industry. As shown in the figure:

There are also ceramic substrates, etc., which are all inorganic materials, as long as they are used for heat dissipation.

II. Rigid and flexible of finished PCB products

1. Rigid PCB board:

Rigid board is a kind of board made of epoxy resin as raw material. epoxy resin rigid board is a widely used product in industry, especially in the chemical anti-corrosion industry.

epoxy resin is a resin resistant to acid, alkali, and salt. Because of its good chemical properties and relatively low price, it is widely used in various industries such as chemical industry, building materials, light industry, and machinery. 

2. Flexible PCB board:

Soft PVC extruded sheets are made by adding plasticizers, stabilizers, etc. to PVC resin through extrusion molding.

It is mainly used for the lining of anti-corrosion equipment such as acid and alkali resistance. It can also be used as general electrical insulation and sealing gasket materials. The operating temperature is -5 to +40℃. It can be used as a substitute for rubber sheets. It has a wide range of uses and is a new type of environmental protection. product. As shown in the figure:

3. Rigid-Flexible PCB board:

The birth and development of FPC and PCB gave birth to a new product of Rigid-Flexible PCB. Therefore, the rigid-flex board is the combination flexible circuit board and the rigid circuit board. After pressing and other processes, they are combined according to the relevant process requirements to form a circuit board with FPC characteristics and rigid PCB characteristics. 

III. According to PCB structure:

1. Single side PCB:
Single-sided board is on the most basic PCB, the parts are concentrated on one side, and the wires are also concentrated on one side. Because the wires only appear on one side, we call this kind of PCB called single-sided.

Because single-sided boards have many restrictions on the design of the circuit (because there is only one side, the wiring cannot cross and must be wired use a separate path), so only early circuits use this type of board. 

2. Double side PCB:
The double-sided board is a printed circuit board with copper coated on both sides including Top (top) and Bottom (bottom). Both sides can be wired and soldered. There is an insulating layer in the middle, which is a commonly used printed circuit board.

Both sides can be wired, which greatly reduces the difficulty of wiring, so it is widely used. 

3. Multilayer board:
The manufacturing method of the multilayer board is generally made by the inner layer pattern first, and then the single-sided or double-sided substrate is made by printing and etching, and incorporated into the designated interlayer, and then heated, pressurized and bonded. As for the subsequent Drilling is the same as the plated through-hole method of the double-sided board. 

The above is the classification of PCBs from three aspects.