PCBA Tech - Embedded PCB circuit and embedded PCB circuit

With the miniaturization, thinning and high speed of electronic products, the assembly density of components on the PCB is getting higher and higher, and the transmission speed of electrical signals is getting faster and faster. Only by increasing the wiring density and multilayering of the PCB, It is also difficult to meet increasingly high assembly requirements.

The embedded component circuit board can improve the reliability of the package and reduce the cost

By embedding a large number of buried passive components in the printed circuit board, the circuit length between the components can be shortened, the electrical characteristics can be improved, the effective printed circuit board packaging area can be increased, and a large number of printed circuits can be reduced. Soldering points on the board surface, thereby improving the reliability of the package and reducing the cost.

Save product space

If these components are embedded in the PCB, so that the same area of the PCB, the space for mounting surface mount devices (SMD) will be greatly increased, and the need for impedance matching of signal transmission characteristics can also be improved, so in recent years, embedded resistors, The PCB of passive components such as capacitors has developed rapidly.

Although some technologies are not perfect at present, its superiority has been paid more and more attention by the electronics manufacturing industry. It has become one of the development directions of PCB, and it will become increasingly mature and It is widely used.

Types of embedded passive components PCB

Embedded passive component PCBs are divided into the following four types according to the type and method of embedded components:

Embedded resistor PCB (Embedded Resistor PCE), the passive components embedded in the PCB are resistors.

Embedded Capacitor PCI (Embedded Capacitor PCI), the passive components embedded in the PCB are capacitors.

Embedded Inductor PCB (Embedded Inductor PCB), the passive components embedded in the PCB are inductors.

The PCB with various passive components embedded is collectively called Embedded Passive PCB (Embedded Passive PCB).

When two or three of the resistors, capacitors, and inductors are embedded in the PCB, the board can be called a PCB with embedded passive components.

1. Scope of application

Embedded passive components PCB has a wide range of applications. At present, it is mainly used in computers (such as supercomputer computer mainframes, information processors), PC cards, IC cards and various terminal equipment, communication systems (such as cellular launch platforms) at home and abroad. ATM systems, portable communication equipment, etc.), test instruments and test equipment (such as IC scanning cards, interface cards, load board testers), aerospace electronic products (such as space shuttles, electronic equipment on satellites, etc.), consumer base Electronic devices (such as potentiometers, heaters), medical electronic equipment (such as scanners, CT machines), and military equipment (such as cruise missiles, radar unmanned reconnaissance aircraft, shields, etc.) in electronic control systems

2. Advantages and disadvantages

A large number of passive components that can be buried are buried in the PCB (including HDI boards) to make the components of the PCB assembly more compact and lightweight. Embedded passive components PCB has the following advantages:

(1) Increase the degree of PCB density

Since discrete (non-buried) passive components not only have a large number of assembly, but also occupy a large amount of space on the PCB board. For example, a GSM phone contains more than 500 passive components, which account for about 50% of the PCB panel assembly area. If 50% of the passive components are embedded in the PCB (or HDI board) for calculation, the size of the PCB board can be reduced by about 25%, so that the number of vias is greatly reduced, and the connecting wires are also reduced and shortened. . Not only can increase the flexibility and freedom of PCB design and wiring, but also reduce the amount of wiring and shorten the length of wiring, thereby greatly improving the high density of PCB (or HDI board) and shortening the signal transmission path

(2) Improve the reliability of PCB assembly

Embedding the required passive components inside the PCB can significantly improve the reliability of the PCB (or HDUBUM) assembly. Because through this process method, the soldering (SMTAK PHT) points on the PCB board surface are extremely reduced, thereby improving the reliability of the assembly board, and greatly reducing the probability of failure due to soldering points.

In addition, embedded passive components can be effectively "protected" to improve reliability. Because these buried passive components are embedded in the PCB as a whole, unlike discrete (or discrete) passive components with pin soldering (or bonding)

The connection pads on the PCB surface will no longer be corroded by moisture and harmful gases in the atmosphere to reduce or damage the passive components. Therefore, the method of embedding passive components can significantly improve the reliability of PCB assembly

(3) Improve the electrical performance of PCB assemblies

By embedding passive components in high-density PCBs, the electrical performance of electronic interconnections has been significantly improved. Because it eliminates the connection pads, wires and their own leads needed for discrete passive components to form a loop after soldering. Any such a loop will inevitably produce parasitic effects, that is, stray capacitance and parasitic inductance. And this parasitic effect will become more serious as the signal frequency or the leading time of the pulse square wave increases. Eliminating this type of failure will undoubtedly improve the electrical performance of the PCB assembly (signal transmission distortion is greatly reduced). At the same time, because the passive components are buried inside the PCB, the surroundings are tightly protected, and their functional values (resistance, capacitance and inductance) will not be changed due to dynamic changes in the working environment, making it in a very stable state. It is helpful to improve the stability of the passive component function and reduce the probability of the passive component function failure.

(4) Save product manufacturing cost

Using this process method can significantly save the cost of the product or PCB assembly. For example, in the study of the radio frequency circuit (EP-RF) model with embedded passive components, the PCB substrate equivalent to the low-temperature co-fired ceramic substrate (LTCC) (the same passive components are embedded respectively), according to the statistics of the component cost Save 10%, substrate cost can be saved 30%, and assembly (soldering) cost can be saved 40%. At the same time, because the assembly process and sintering process of the ceramic substrate are difficult to control and the PCB substrate embedding passive components (EP) can be completed by the traditional PCB manufacturing process, the production efficiency is greatly improved.