Packaging types and selection of field-effect transistors

1、 Packaging type

1. Plug in packaging

• Transistor outer packaging (TO): Early packaging specifications such as TO-92, TO-220, TO-252, etc. Among them, TO-252, also known as D-PAK, is a surface mount package. TO-263 (D2PAK) is also a surface mount package and a variant of TO-220, mainly used to improve production efficiency and heat dissipation.

Dual in line package (DIP): There are two rows of pins that need to be inserted into a chip socket with DIP structure. Its derivative is SDIP (Shrink DIP), which is a compact dual input package with a pin density six times higher than DIP.

Pin Grid Array Packaging (PGA): There are multiple square shaped pins inside and outside the chip, and each square shaped pin is arranged at a certain distance along the periphery of the chip. According to the number of pins, it can be surrounded in 2-5 circles.

2. Surface mount packaging

D-PAK package: There are 3 electrodes, gate (G), drain (D), and source (S). The pin of the drain (D) is cut off and not used. Instead, the back heat dissipation plate is used as the drain (D) and directly soldered onto the PCB.

SOT package: It is a chip type low-power transistor package, such as SOT23, SOT89, etc., with a smaller volume than TO package.

SOP packaging: In Chinese, it means "small form factor packaging", with pins leading out from both sides of the packaging. There are two types of materials: plastic and ceramic. Common ones include SOP-8, SOP-16, SOP-20, SOP-28, etc. The number after SOP represents the number of pins.

QFN package: In Chinese, it is called a four sided no lead flat package and is one of the surface mount packages. However, it should be noted that QFN packaging is mainly used for integrated circuit packaging and is not commonly used for MOSFETs.

QFP packaging: It refers to a flat packaging with four plastic wrapped pins, where the distance between the pins of the packaged chip is very small and the pins are very thin. It is generally used in large-scale or ultra large integrated circuits.

2、 Selection of encapsulation type

When choosing the packaging type of field-effect transistor, the following factors need to be considered:

1. Heat dissipation performance:

Different packaging types have different heat dissipation performance. The D-PAK package uses the heat dissipation plate on the back as the drain electrode, which is directly soldered onto the PCB and has good heat dissipation effect.

When selecting the packaging type, it is necessary to choose a packaging with appropriate heat dissipation performance based on the actual application scenario and system heat dissipation conditions.

2. Installation convenience:

Plug in packaging (such as TO, DIP) requires pins to pass through the mounting holes on the PCB board and be soldered onto the PCB board, making the installation process relatively cumbersome.

The pins and heat dissipation flanges of surface mount packaging (such as D-PAK, SOP) are soldered onto the solder pads on the surface of the PCB board, making the installation process easier.

3. Electrical performance:

Different packaging types may have different electrical properties, such as maximum current, maximum voltage, etc. When selecting the packaging type, it is necessary to ensure that the selected packaging type can meet the electrical performance requirements of the system.

4. Cost:

The cost of different packaging types may vary. When choosing a packaging type, it is necessary to comprehensively consider the cost budget of the system and the cost of the packaging type to select a packaging with appropriate cost-effectiveness.

5. Packaging size:

The size of different packaging types may vary. When choosing a packaging type, it is necessary to consider the layout and space constraints of the PCB board and select a packaging type with appropriate dimensions.

6. Working environment:

• It is also necessary to consider the impact of the work environment on packaging types. Adverse environments such as high temperature, high humidity, and strong electromagnetic interference may have adverse effects on certain packaging types. When choosing a packaging type, it is necessary to ensure that the selected packaging type can adapt to the requirements of the working environment.

In summary, there are various types of packaging for field-effect transistors, and when selecting, multiple factors such as heat dissipation performance, installation convenience, electrical performance, cost, packaging size, and working environment need to be considered. By considering these factors comprehensively, the most suitable packaging type for system applications can be selected.