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Pcb basic knowledge

Shenzhen Inno Circuit Co.,Ltd | Updated: May 25, 2018

Pcb basic knowledge


Names of circuit boards are: ceramic circuit boards, alumina ceramic circuit boards, aluminum nitride ceramic circuit boards, circuit boards, PCB boards, aluminum substrates, high frequency boards, thick copper boards, impedance boards, PCBs, ultra-thin circuit boards, ultra Thin circuit boards, printed (copper etching technology) circuit boards, etc. The circuit board miniaturizes and visualizes the circuit, which plays an important role in the mass production of fixed circuits and the optimization of electrical layout. The circuit board may be referred to as a printed circuit board or a printed circuit board, a printed circuit board (PCB), or a flexible printed circuit board (FPC) circuit board (an FPC circuit board is also referred to as a flexible circuit board. The flexible circuit board is a polyimide. Or a polyester film made of a base material with a highly reliable, excellent flexible printed circuit board. Has a high wiring density, light weight, thin thickness, good bending characteristics!) And soft and hard The birth and development of FPC and PCB, reechas, Soft and hard combination plate, gave birth to the new product of soft and hard bonded board. Therefore, the soft and hard bonded board is a flexible circuit board and a rigid circuit board. After the laminating and other processes are performed, the circuit board with the characteristics of the FPC and the characteristics of the PCB is formed in accordance with the relevant process requirements.


When the circuit board is divided according to the number of layers, it is divided into three major categories: single-panel, double-panel, and multilayer circuit board.

The first is a single panel. On the most basic PCB, parts are concentrated on one side and wires are on the other side. Because the wire only appears on one side, the PCB is called a single-sided circuit board. A single panel is usually simple to make and has a low cost, but the disadvantage is that it cannot be applied to products that are too complex.

Double-sided panels are single-panel extensions. When single-layer wiring does not meet the needs of electronic products, double-sided panels are used. Both sides have copper-clad traces, and can pass through the vias to open the lines between the two layers to form the desired network connection.

Multi-layer board refers to a printed board with three or more layers of conductive pattern layers and insulating material between them laminated and laminated with the conductive patterns therebetween as required. Multi-layer circuit boards are the products of electronic information technology to high speed, multi-function, large capacity, small size, thin and light weight.

According to the characteristics of the circuit board is divided into soft board (FPC), hard board (PCB), soft and hard board (FPCB).

PCB board

FR-1: Flame-retardant copper-clad phenolic paper laminate. IPC4101 detail specification number 02;Tg N/A;

FR-4:1) Flame-retardant copper-clad epoxy E-glass cloth laminated board and its bonding sheet material. IPC4101 detail specification number 21; Tg≥100°C;

2) Flame-retardant copper-clad modified or unmodified epoxy E-glass cloth laminates and their bonding materials. IPC4101 detail specification number 24; Tg 150°C~200°C;

3) Flame-retardant copper-clad epoxy/PPO glass cloth laminate and its bonding sheet material. IPC4101 detail specification number 25; Tg 150°C~200°C;

4) Flame-retardant copper-clad modified or unmodified epoxy glass cloth laminates and bonding sheet materials. IPC4101 detail specification number 26; Tg 170°C~220°C;

5) Flame-retardant copper-clad epoxy E glass cloth laminate (for catalytic addition method). IPC4101 detail specification number 82; Tg N/A;




The creator of the printed circuit board was the Austrian Paul Eisler. In 1936, he first used a printed circuit board on the radio. In 1943, Americans mostly used the technology for military radios. In 1948, the United States formally recognized that the invention could be used for commercial purposes. Since the mid-1950s, printed circuit boards have only been widely used.

Prior to the advent of PCBs, interconnections between electronic components were made by direct connection of wires. Today, wires are used only for experimental applications in the laboratory; printed circuit boards have certainly taken absolute control in the electronics industry.

PCB production process:

First, contact the manufacturers

First, you need to contact the manufacturer, then register the customer number, and someone will quote you, place orders, and follow up on the production schedule.

Second, open materials

Objective: According to the requirements of the engineering data MI, on the large sheets that meet the requirements, cutting into small pieces of production board. Small sheets that meet customer requirements.

Process: big plate → cutting board according to MI requirements → seesaw board → beer fillets → edging → out board

Third, drilling

Objective: According to the engineering data, drill the desired hole diameter in the corresponding position on the board that meets the required size.

Process: Stacked Pins → Upper Plate → Drilled → Lower Plate → Inspections → Repairs

Fourth, sink copper

4. Objective : To deposit copper on the wall of insulating hole by chemical method.

Process: coarse grinding → hanging plate → automatic copper sink → lower plate → dip % diluted H2SO4 → thick copper

Fifth, graphics transfer

Purpose: Graphical transfer is to transfer the image on the film to the board

Process: (blue oil process): grinding plate → printing the first side → drying → printing the second side → drying → exposure → shadowing → inspection; (dry film process): hemp plate → laminating → standing → pair Bit → Exposure → Resting → Impact → Check

Six, graphic plating

Purpose: Pattern plating is to plate a layer of copper to the required thickness and the required thickness of gold or tin on the bare copper skin or hole wall of the circuit pattern.

Process: upper plate → degreasing → washing twice → micro etching → washing → pickling → copper plating → washing → pickling → tin plating → washing → lower plate

Seven, film

3. Objective : To remove the anti - plating film by NaOH solution to expose the non - copper layer.

Process: Water film: insert frame → alkali soak → rinse → scrub → over machine; dry film: put plate → over machine

Eight, etching

Purpose: Etching is the use of chemical reaction method to etch away the non-line copper layer.

Nine, green oil

Purpose: Green oil is the transfer of the green oil film to the board, which plays a role in protecting the circuit and blocking the soldering of parts.

Process: grinding plate → printing photosensitive green oil → seesaw plate → exposure → shadowing; grinding plate → printing first side → baking plate → printing second side → baking plate

Ten characters

Purpose: Characters are an easy-to-identify marker

Process: After the end of the green oil → cooling stand-by → transfer → print character → rear

Eleven, gold-plated fingers

Purpose: Plating a layer of nickel/gold with a desired thickness on the plug finger to make it more wear resistant

Process: Upper plate → degreasing → washing twice → micro etching → washing twice → pickling → copper plating → washing → nickel plating → washing → plating

Tinplate (a side-by-side process)

Purpose: Spray tin is sprayed with a layer of lead and tin on the exposed copper surface that is not covered with solder resist to protect the copper surface from corrosion and oxidation to ensure good soldering performance.

Process: Micro-etching → Air drying → Preheating → Rosin coating → Solder coating → Hot air formation → Air cooling → Wash air drying

Twelve, forming

PURPOSE: To use the method of molding or molding the shapes required by the customer by die stamping or numerically controlled crucibles. Organic crucibles, beer board, hand picks, hand cuts

Explanation: The precision of data-board and board is high, followed by hand-rolling. The minimum amount of hand-cutting board can only be done in some simple shapes.

Thirteen, test

Objective: To detect defects such as open circuit and short circuit which are not easily detected by electronic 100% test.

Process: Upper mold → put plate → test → qualified → FQC visual inspection → failed → repair → back test → OK → REJ → scrap

XIV. Final inspection

Objective: Through 100% visual inspection of the appearance of the board defects, and minor defects repaired to avoid problems and defective plate outflow.

Specific workflow: incoming → view data → visual inspection → qualified → FQA spot checks → pass → packaging → unqualified → processing → check OK

Industry Trends

Rapid development of PCB industry

Since the reform and opening up, China’s preferential policies in labor resources, markets, and investment have attracted large-scale transfer of manufacturing industries in Europe and the United States. A large number of electronic products and manufacturers have set up factories in China, which has led to the inclusion of PCBs. The development of related industries within. According to China's CPCA statistics, in 2006 China's actual PCB production reached 130 million square meters, and the output value reached 12.1 billion U.S. dollars, accounting for 24.90% of the global PCB output value, surpassing Japan to become the world's number one. From 2000 to 2006, the average annual growth rate of China's PCB market reached 20%, far exceeding the global average. The global financial crisis in 2008 caused a great impact on the PCB industry, but it did not cause a catastrophic impact on China's PCB industry. In 2010, China's PCB industry showed a full recovery under the stimulation of national economic policies. In 2010, China’s PCB output value reached US$ 19.971 billion. . Prismark predicts that China will maintain a compound annual growth rate of 8.10% for the period 2010-2015, which is higher than the global average growth rate of 5.40%.

Uneven regional distribution

China's PCB industry is mainly located in South China and East China. The sum of these two countries reaches 90% of the country's total, and the industrial agglomeration effect is obvious. This phenomenon is mainly related to the major production bases of the Chinese electronics industry focused on the Pearl River Delta and the Yangtze River Delta.

PCB downstream application distribution

The distribution of downstream applications in China's PCB industry is shown in the figure below. Consumer electronics accounted for the highest proportion, reaching 39%; followed by computers, accounting for 22%; communications accounted for 14%; industrial control/medical instruments accounted for 14%; automotive electronics accounted for 6%; national defense and aerospace accounted for 5%.

Technological backwardness

Although China is now the world’s largest in terms of industry scale, it still lags behind the world’s advanced level in terms of the overall technological level of the PCB industry. In terms of product structure, multi-layer boards account for most of the production value ratio, but most of them are low-end and mid-range products below 8 layers. HDI, flexible boards, etc. have a certain scale but exist in advanced technologies with Japan and other foreign advanced products. Disparity, the most technologically-intensive IC carrier is rarely available in China.