PCB Tech - Professional PCB circuit board

Basic manufacturing method of circuit board

Panel method

1. Full PCB plating

2. Add a resist to the place to be kept on the surface (to prevent it from being etched)

3. Etching 4. Remove the barrier layer

Pattern method

1. Add a barrier layer on the surface where you don't want to keep it

2. Surface required for electroplating to a certain thickness

3. Remove the barrier layer

4. Etch until the unnecessary metal foil film disappears

Completely additive method: 1. Add a barrier layer where no conductor is needed. 2. Use electroless copper to form the circuit

Partial addition method: 1. Cover the entire PCB with electroless copper 2. Add a barrier layer where no conductor is needed 3. Electrolytic copper plating 4. Remove the barrier layer 5. Etch until the electroless copper disappears under the barrier layer

ALIVHALIVH (Any Layer Interstitial Via Hole, Any Layer IVA) is a layer-added technology developed by Matsushita Electric. This is using Aramid fiber cloth as the base material. 1. Dip the fiber cloth in epoxy resin to become "prepreg" 2. Laser drilling 3. Fill the hole with conductive paste 4. Stick copper foil on the outer layer 5. Use etching method on the copper foil Make the circuit pattern 6. Paste the semi-finished product that has completed the second step on the copper foil 7. Laminate into layers 8. Repeat the fifth to seventh steps again and again, until the professional PCB circuit board is completed

Testability
A relatively complete test method and test standard have been established. Various test equipment and instruments can be used to detect and appraise the eligibility and service life of PCB products.

Assemblability
PCB products are not only convenient for standardized assembly of various components, but also for automated and large-scale mass production. In addition, by assembling the PCB and various other components as a whole, larger parts and systems can be formed to the complete machine.

Assemblability
PCB products are not only convenient for standardized assembly of various components, but also for automated and large-scale mass production. In addition, by assembling the PCB and various other components as a whole, larger parts and systems can be formed to the complete machine.

PCB has other advantages, such as miniaturization and light weight of the system, and high-speed signal transmission. Futian multilayer PCB processing

Circuit board function distinction
The position of the components should be grouped according to the power supply voltage, digital and analog circuits, speed, current size, etc. to avoid mutual interference. When the digital circuit and the analog circuit are installed on the circuit board at the same time, the ground wire and power supply system of the two circuits are completely separated. If possible, the digital circuit and the analog circuit are arranged in different layers. When fast, medium-speed and low-speed logic circuits need to be arranged on the circuit board, they should be placed close to the connector; and low-speed logic and memory should be placed far away from the connector. In this way, it is beneficial to reduce the reduction of common impedance coupling, radiation and crosstalk. Clock circuits and high-frequency circuits are the main sources of radiation interference and must be arranged separately and away from sensitive circuits.

Both thermal and magnetic heating
The components should be as far away as possible from the thermal components, and the influence of electromagnetic compatibility should be considered.

PCB board wiring principles
1. The wires used for the input and output terminals should try to avoid being parallel adjacent to each other. It is better to add ground wires between wires to avoid feedback coupling.

2. The minimum width of the printed circuit board conductor is mainly determined by the adhesion strength between the conductor and the insulating substrate and the current value flowing through them

When the thickness of the copper foil is 0.05 mm and the width is 1 to 15 mm, the temperature will not be higher than 3°C through a current of 2 A, so a wire width of 1.5 mm can meet the requirements. For integrated circuits, especially digital circuits, a wire width of 0.02 to 0.3 mm is usually selected. Of course, as long as possible, use as wide a line as possible, especially the power line and the ground line.

The minimum spacing of wires is mainly determined by the worst-case insulation resistance and breakdown voltage between the wires. For integrated circuits, especially digital circuits, as long as the process permits, the pitch can be as small as 5-8 mm.

3. The bends of the printed conductors are generally arc-shaped, and the right angle or angle will affect the electrical performance in the high-frequency circuit. In addition, try to avoid the use of large-area copper foil, otherwise, the copper foil will easily expand and fall off when heated for a long time. When a large area of copper foil must be used, it is better to use a grid shape, which is beneficial to eliminate the volatile gas generated by the heating of the adhesive between the copper foil and the substrate

PCB is classified according to the number of layers
Classification according to the number of circuit layers: divided into single-sided, double-sided and multi-layer boards. Common multi-layer boards are generally 4-layer boards or 6-layer boards, and complex multi-layer boards can reach dozens of layers. PCB board has the following three main types of division

Single-Sided Boards (Single-Sided Boards) On the most basic PCB, the parts are concentrated on one side, and the wires are concentrated on the other side. ). Because the wires only appear on one side, this kind of PCB is called a single-sided (Single-sided). Because there are many strict restrictions on the design of the single-sided board (because there is only one side, the wiring cannot cross and must go around a separate path), only early circuits use this type of board. Guangzhou PCB circuit board quick proofing

PCB Industry Chain
Classified according to the upstream and downstream of the industry chain, it can be divided into raw materials, copper clad laminates, printed circuit boards, electronic product applications, etc. The relationship is as follows:

Fiberglass cloth: Fiberglass cloth is one of the raw materials for copper clad laminates. It is woven from glass fiber yarn and accounts for about 40% (thick board) or 25% (thin board) of the cost of the copper clad laminate. The glass fiber yarn is calcined into a liquid state from raw materials such as silica sand in a kiln. It is drawn into a very fine glass fiber through a very small alloy nozzle, and then hundreds of glass fibers are twisted into a glass fiber yarn. The construction investment of the kiln is huge, usually hundreds of millions of funds, and once it is ignited, it must be produced 24 hours a day, and the cost of entry and exit is huge.

Copper foil: Copper foil is a relatively large raw material for the cost of copper clad laminates, accounting for about 30% (thick plates) or 50% (thin plates) of the cost of copper clad laminates. Therefore, the price increase of copper is the main driving force for the price increase of copper clad laminates.

Copper clad laminate: The copper clad laminate is a product made by pressing glass fiber cloth and copper foil together with epoxy resin as a fusion agent. It is the direct raw material of printed circuit boards and is made after etching, electroplating, and multi-layer board pressing. Into a printed circuit board. Professional PCB circuit board

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