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Oct 12 2018

Differences Between IC and PCB: Composition,Characteristics and Application Examples


This paper will finally summarizes the differences between integrated circuit (hereinafter referred to as IC) and printed circuit board (hereinafter referred to as PCB) by first introducing the composition, characteristics and application examples of them. 



Ⅰ PCB Basics

1.1 Composition of PCB

1.2 Characteristics of PCB

1.3 Application Example of PCB

Ⅱ IC Basics

2.1 Composition of IC

2.2 Characteristics of IC

2.3 Application Example of IC

Ⅲ The Difference Between PCB and IC

Ⅰ PCB Basics

1.1 Composition of PCB

  • Wiring and Pattern: the wiring is a tool to conduct the components, and a large copper surface is additionally designed to ground and as the power. The wiring and pattern are made at the same time.

  • Dielectric: commonly known as substrate, is used to maintain insulation between the wiring and layers.  

  • Through hole / via: can make the wiring above the two layers switch on each other, the larger ones are used as part plugins, and the non-plating through hole (nPTH) are usually used as surface mounting positioning and fixing screws for assembly.  

  • Solder resistant /Solder Mask: not all copper surfaces are welded the parts by tin. Therefore, in areas without tin, a material (usually epoxying) is printed to avoid short circuit. According to different processes, it is divided into green oil, red oil and blue oil.

  • Legend / Marking/Silk screen: not necessary. its main function is to mark the name and position frame of each part for easy maintenance and identification after assembly.

  • Surface Finish: copper surface in the general environment is easy to oxidize, leading to poor soldering, so it is necessary to make a copper surface protection. The methods of protection include HASL, ENIG, Immersion Silver, Immersion TIn, and OSP, which have their advantages and disadvantages, and all of them are generally called surface treatment.

PCB board 

1.2 Characteristics of PCB

  • High density. For decades, PCB high density has developed with the development of integrated circuit integration and installation technology.

  • High reliability. Through a series of inspections, tests and aging tests, the PCB can be reliably operated for a long period of time (usually 20 years). 

  • Designability. For requirements based on the PCB performance (electrical, physical, chemical, mechanical, etc.), the PCB design is standardized with short time and high efficiency.

  • Productivity. With modern management, it can ensure product quality consistency by standardization, scale, automation.

  • Testability. Complete test methods and test standards are established, and various test equipment and instruments are used, to test and evaluate the PCB product eligibility and service life.

  • Assemblability. PCB products can not only be easy to assembly various components standardized,but also can be assembled with various components into larger parts components , systems, and even the whole machine.

  • Maintainability. Because PCB products and components are manufactured in a standardized design and scale, these components are also standardized. Therefore, once the system fails, it can be quickly replaced, and the system be recovered conveniently and flexibly. Of course, more examples can be given, such as miniaturize and lighten the system and speed up signal transmission and so on.

1.3 Application Example of PCB

A Relatively Stable Solution for Dual-Output Flyback Circuit

Figure 1. A Relatively Stable Solution for Dual-Output Flyback Circuit

Dual-Output Flyback Circuit with relatively stable output

Figure 2. Dual-Output Flyback Circuit with Relatively Stable Output

This kind of circuit is generally used in low power supply. In order to ensure better cross-over adjustment of the two windings. We need to pay attention to problems below. 

        ●In this example, If the dual sampling cross-adjustment rate is low, even cannot handle with problems of no-load and independent load, we generally solve the problems by setting the sampling feedback end as 5V. But this method is not suitable for the application where the two sets of voltages are far from each other, which will use one more transformer foot. 

        ●The optocoupler for feedback uses 12 V power supply, and the sampling point is better in front of the rear filter inductor. Because the wave in front of the filter inductor can reflect the modulation state of the front-end PWM more quickly, even if the TL431 is open to a certain degree, the 12V wave can make the feedback current of the optical coupling slightly different. In the case of the feedback loop, The selection of the sampling point of the optically coupled power supply is more favorable to the dynamic response and the balance control of the adjustment rate. 

        ●The 12 V winding should be placed closer to the primary winding. This makes it more effective to ensure that the voltage variation ratio of 12V is smaller because the feedback sampling is 5V, so it is difficult to control the 12V winding. 

        ●The template described on the previous is basically within an error of an acceptable range of 5%. 


Ⅱ IC Basics

2.1 Composition of IC

IC is a micro electronic device or component. The transistor, diode, resistor, capacitance and inductor needed in a circuit are interlinked with each other in a certain process, and are fabricated on a small semiconductor chip or dielectric substrate, then encapsulated in a shell, finally become a micro structure with the required circuit function; all of the components are structurally integrated to be a IC.  

Integrated Circuit



2.2 Characteristics of IC  

  • Simple circuit. Because of the use of integrated circuits, the design, debugging and installation of the whole machine circuit are simplified, especially after the adoption of some special integrated circuits, the whole machine circuit appears more simple. 

  • Cost-effective. Compared with discrete electronic component circuits, the overall circuit performance of the integrated circuit is higher,and the cost and price are lower.The high gain of the integrated operational amplifier circuit and the small zero drift are unmatched by that of discrete electronic components.  

  • High reliability. The integrated circuit has the advantage of high reliability, which improves the reliability of the whole circuit and improves the performance and consistency of the circuit. In addition, with integrated circuit, the solder joint in the circuit is greatly reduced, and the possibility of virtual welding is decreased, which makes the whole circuit more reliable.  

  • Less energy consumption. Integrated circuits also have the advantages of small power consumption, small volume,low price and so on. Circuits with the same function consume much less power with integrated circuits than with discrete electronic components.

  • Low failure rate. The failure rate of integrated circuit is lower than that of discrete circuit, so the failure rate of whole circuit is reduced.

In short, the integrated circuit has the advantages of small size, light weight, less lead wire and welding joint, long life, high reliability, good performance, and low cost, which is convenient for mass production. When electronic equipment is assembled by an integrated circuit, its Assembly density can be increased by tens to thousands of times than that of transistors, and the stable working time of the equipment can be greatly increased. 


2.3 Application Example of IC

 555 Touch Timing Switch

IC1 is a 555 timing circuit, here connected to a monostable circuit. Usually, because there is no inductive voltage at the P end of the touch chip, the capacitor C1 completed the discharge through the 7th pin of 555, the output of the 3th pin is low level, the relay KS is released, and the lamp is not on.  

When it is necessary to turn on the lamp, touch the metal sheet P with your hand. The triggered voltage of the human body induced clutter signal is increased from C2 to 555, so that the output of the 555 is changed from low to high level, relay KS pulls in and the electric light illuminates. At the same time, 555 7th pin internal cutoffs, the power through R1 to charge C1, this is the start of the timing. 

When the voltage on the capacitor C1 rises to 2 / 3 of the supply voltage, the 555 7th pass causes C1 to discharge, and the output of the 3th pin changes from high level to low, the relay releases, the light off, and the timing ends.

The timing is determined by R1 and C1:T1=1.1R1*C1. According to the figure, the timing time is about 4 minutes. D1 can choose 1N4148 or 1N4001.


Figure 3. 555 Timing Circuit

Ⅲ The Difference Between PCB and IC

Integrated circuit is a kind of miniaturized electronic circuit, the chips inside are very small and are difficult to connect directly to PCB, but IC can be easily connected to PCB. The main board of the North Bridge chip and CPU internal are called IC, whose original name is also called integration block.

PCB used in almost every electronic device. If there are electronic parts in a device, PCBs are mounted on PCB of all sizes. Besides fixing small parts, the main function of PCB is to connect each other.

IC is welded to PCB, where is the carrier of IC. In short, an IC is a common circuit integrated into a chip, it is a whole. And once it is damaged inside, the chip is damaged. The aim of the PCB is to connect the IC and the discrete components to form a larger operating circuit. PCB can weld the components itself, and when it breaks down, it can replace the components. Prior to using PCB, the components were connected together by wires, using a scheme called "point-to-point" wiring, which is confusing and unreliable compared to PCB. Get a deep info, you can visit the following video.

IC Board: How to Install an Integrated Circuit into a Circuit Board

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