Basics of e-Getting Started: What is encapsulation?

When learning MCU in college, we realized that the MCU may look like the following picture. These two are called 51 MCUs, but the processing chips seem to be different. What should the MCU look like? This is related to a noun called "encapsulation."

It might look like this:

It could also be like this:

1. What is package?

Encapsulation combines the abstracted data with the behavior (or function) to form an organic whole, that is, the data is combined with the source code of the operational data to form a "class" in which the data and functions are class. member. The purpose of encapsulation is to enhance security and simplify programming. The user does not have to know the specific implementation details, but only uses the external interface to use the members of the class with specific access rights.

Simply put, it is the shape of the component, or the shape of the component on the PCB. Only when the package drawing of the component is correct, the component can be soldered on the PCB. Packages fall into two broad categories: DIP in-line and SMD patch formats. For example, the core part of the two 51-chip microcomputers shown above - STC89C51 chip, one is DIP40 dual-row straight-line type, one is LQFP48 patch form.

2. Component package form

The packaging of components is of international standard. The packaging of different components is different. Even the same device can have multiple packages. Therefore, we must clearly explain to the manufacturer when purchasing components. In the form of a package. Let's take a look at the package of several components.

Patch Transistor: SOT23-2

We all know that the triode has three legs, the emitter-base-collector, and its package is the 1:1 projection of the three legs on the PCB, that is, after the patch transistor is placed flat on the PCB, the pad It coincides with the three legs of the triode. The package on the PCB is as follows:

Chip resistor package: 0805

Chip resistors are available in a variety of package sizes, such as 1210, 0805, 0603, 0402, and others. The package of the chip resistor 0805 is shown below:

SCM package: LQFP48

I believe that STC89C51 microcontroller has been seen by everyone, and the package of DIP-40 is also known. Let's look at the package of LQFP-48. This package has 4 sides, each side is 12 pins, a total of 48. Its package is as follows: