PCB Tech - Are PCB boards different from integrated circuits

PCB board is different from integrated circuit? What's the difference?

PCB manufacturer's composition of PCB board

The current circuit board mainly consists of the following:

1. Circuit and pattern (Pattern): The circuit is used as a tool for conduction between the originals. In the design, a large copper surface will be additionally designed as a grounding and power layer. The route and the drawing are made at the same time.

2. Dielectric layer (Dielectric): used to maintain the insulation between the circuit and each layer, commonly known as the substrate.

3. Hole (Through hole / via): The through hole can make the lines of two levels or more connect to each other. The larger through hole is used as a part plug-in. In addition, there are non-through holes (nPTH) usually used as Surface mount positioning, for fixing screws during assembly.

4. Solder resistant /Solder Mask: Not all copper surfaces need to be tinned parts, so the non-tin area will be printed with a layer of material that isolates the copper surface from eating tin (usually epoxy resin), To avoid short circuits between non-tinned circuits. According to different processes, it is divided into green oil, red oil and blue oil.

5. Silk screen (Legend /Marking/Silk screen): This is a non-essential composition. The main function is to mark the name and position frame of each part on the circuit board, which is convenient for maintenance and identification after assembly.

6. Surface Finish: Because the copper surface is easily oxidized in the general environment, it can not be tinned (poor solderability), so it will be protected on the copper surface that needs to be tinned. The protection methods include HASL, ENIG, Immersion Silver, Immersion TIn, and OSP. Each method has its advantages and disadvantages, which are collectively referred to as surface treatment.

PCB board features

1. High-density: For decades, the high-density of printed boards has been able to develop along with the improvement of integrated circuit integration and the advancement of mounting technology.

2. High reliability: Through a series of inspections, tests and aging tests, the PCB can work reliably for a long time (usually 20 years).

3. Designability: For PCB performance (electrical, physical, chemical, mechanical, etc.) requirements, printed board design can be achieved through design standardization, standardization, etc., with short time and high efficiency.

4. Manufacturability: With modern management, it can be standardized, scaled (quantified), automated, etc., to ensure product quality consistency.

5. Testability: A relatively complete test method, test standard, various test equipment and instruments have been established 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. At the same time, PCB and various component assembly parts can be assembled to form larger parts and systems, up to the complete machine.

6. Maintainability: As PCB products and various component assembly parts are standardized design and large-scale production, these parts are also standardized. Therefore, once the system fails, it can be replaced quickly, conveniently and flexibly, and the system can be quickly restored to work. Of course, there can be more examples. Such as miniaturization and weight reduction of the system, and high-speed signal transmission.

Integrated circuit characteristics

Integrated circuits have the advantages of small size, light weight, few lead wires and soldering points, long life, high reliability, and good performance. At the same time, they have low cost and are convenient for mass production. It is not only widely used in industrial and civilian electronic equipment such as tape recorders, televisions, computers, etc., but also in military, communications, and remote control. The use of integrated circuits to assemble electronic equipment can increase the assembly density by tens to thousands of times compared with transistors, and the stable working time of the equipment can also be greatly improved.

Application examples of integrated circuits

1. 555 touch timer switch

The integrated circuit IC1 is a 555 timing circuit, which is connected as a monostable circuit here. Normally, because there is no induced voltage at the P terminal of the touch pad, the capacitor C1 is discharged through the 7th pin of the 555, the output of the 3rd pin is low, the relay KS is released, and the light does not light up.

When you need to turn on the light, touch the metal piece P with your hand, and the clutter signal voltage induced by the human body is added from C2 to the trigger terminal of 555, so that the output of 555 changes from low to high. The relay KS pulls in and the light turns on. Bright. At the same time, the 7th pin of 555 is internally cut off, and the power supply charges C1 through R1, which is the beginning of timing.

When the voltage on the capacitor C1 rises to 2/3 of the power supply voltage, the 7th pin of 555 is turned on to discharge C1, so that the output of the 3rd pin changes from high level to low level, the relay is released, the light goes out, and the timing ends.

The timing length is determined by R1 and C1: T1=1. 1R1*C1. According to the value marked in the figure, the timing time is about 4 minutes. D1 can choose 1N4148 or 1N4001.

2. Single power supply to dual power supply circuit in PCB design

In the circuit of the figure, the time base circuit 555 is connected as an astable circuit, and the output frequency of pin 3 is 20KHz and a square wave with a duty ratio of 1:1. When pin 3 is high level, C4 is charged; when low level, C3 is charged. Due to the existence of VD1 and VD2, C3 and C4 are only charged but not discharged in the circuit, and the maximum charging value is EC. Connect B terminal to ground, and a +/-EC dual power supply is obtained at both ends of A and C. The output current of this circuit exceeds 50mA.

The difference between PCB board and integrated circuit

Integrated circuit generally refers to the integration of chips, like the north bridge chip on the motherboard, the inside of the CPU is called integrated circuit, and the original name is also called integrated block. And the printed circuit refers to the circuit board we usually see, as well as printing solder chips on the circuit board.

The integrated circuit (IC) is the CB version soldered on the PCB board is the carrier of the integrated circuit (IC). The PCB board is a printed circuit board (PCB). Printed circuit boards appear in almost every electronic device. If there are electronic parts in a certain device, the printed circuit boards are all mounted on PCBs of different sizes. In addition to fixing various small parts, the main function of the printed circuit board is to electrically connect the upper parts to each other.

Simply put, an integrated circuit integrates a general-purpose circuit into a chip. It is a whole. Once it is damaged internally, the chip is also damaged. The PCB can solder components by itself, and if it is broken, components can be replaced.

The above are the characteristics and differences of PCB board and integrated circuit in PCB layout design