PCB design basics answers: What is packaging?

What is encapsulation?

Packaging refers to connecting the circuit pins on the silicon chip to external connectors with wires to connect them to other devices.

Component packaging, simply put, is the appearance of the component, or the shape of the component on the PCB board. Only when the components’ packaging is drawn correctly can the components be soldered on the PCB board. Packaging is roughly divided into two categories: DIP plug-in type and SMD patch type.

Package form refers to the housing used to install semiconductor integrated circuit chips. It not only plays the role of installing, fixing, sealing, protecting the chip and enhancing the electrical and thermal performance, but also connects to the pins of the package shell with wires through the contacts on the chip, which in turn pass through the wires on the printed circuit board. Connect with other devices to realize the connection between the internal chip and the external circuit. Because the chip must be isolated from the outside world to prevent impurities in the air from corroding the chip circuit and causing a decrease in electrical performance. On the other hand, packaged chips are also easier to install and transport. Since the quality of packaging technology also directly affects the performance of the chip itself and the design and manufacturing of the PCB connected to it, it is crucial.

An important indicator to measure whether a chip packaging technology is advanced or not is the ratio of chip area to packaging area. The closer this ratio is to 1, the better. The main factors to consider when packaging are the following three points:

1. In order to improve packaging efficiency, the ratio of chip area to packaging area should be as close to 1:1 as possible;

2. The pins should be as short as possible to reduce delay, and the distance between pins should be as far as possible to ensure that they do not interfere with each other and improve performance;

3. Based on heat dissipation requirements, the thinner the package, the better.

Common component packaging

For most electronic components, common discrete component packages mainly include diodes, capacitors, resistors and transistors; common integrated circuits mainly include single in-line and dual in-line.

Diode: The number of the diode component package is generally DIODE-xx, where the number xx represents the distance between the pins of the diode component. For example, the component package number is DIODE-0.5, which means that the distance between component pins is 500mil.

Capacitor type: Capacitive component packaging can be divided into two categories, namely non-polar capacitor type and polar capacitor type. The number of the non-polar capacitor component package is RADxx, where the number xx represents the distance between the component package pins; the number of the polar capacitor component package is RBxx-yy, where the number xx represents the distance between the component pins, and the number yy Represents the diameter of the component.

Resistor: Resistor component packaging can also be divided into two categories, namely ordinary resistors and variable resistors. The package number of ordinary resistance components is AXIAL-xx, where the number xx represents the distance between component pins; the package number of variable resistance components is VRx, where the number x represents the type of component.

Integrated circuits: The number of the single in-line component package is SIL-xx, where the number xx represents the number of pins of the single in-line integrated circuit; the number of the dual in-line component package is DIP-xx, where the number xx represents The number of pins in a dual in-line integrated circuit.