MCU entry guide series (5) integrated circuit and encapsulation knowledge

This article is original by purplesword (jzj1993). For more information, see. Original web site http://blog.csdn.net/jzj1993

We have seen pictures of integrated circuits in the previous article, and there are many shapes. What really works on these chips is the transistor integrated into the silicon wafer. What we can see is that it is encapsulated with an external shell. Wire the circuit pin on the silicon wafer to the external connector to facilitate the connection of other devices. Encapsulation has the following functions: installation, fixation, sealing, protection chip, and enhanced electric heating. Silicon wafers must be isolated from the outside to prevent the electrical performance from decreasing due to the corrosion of the circuit caused by impurities in the air.

　　

ATMEL AT89C51 microcontroller

　　

Wang Jing company's Single Chip Microcomputer

We call this shell of electronic components such as integrated circuits as encapsulation. The two single-chip microcomputer in the figure are also integrated circuits, and their packages are the same. They are all 40-foot wide dip-40 packages. As a matter of fact, there are other forms of packaging, such as the 44-foot LQFP-44 package ,.

　　

Lqfp44 chip package of fig +

The above dip-40 package has a long pin. In actual use, the pin will pass through the circuit board and be welded on the other side of the circuit board. It is a direct-insertion package. While LQFP-44 encapsulation, welding pin solder joints and chip in the same surface of the circuit board, is pasted on the surface of the circuit board, we call it a SMD Package. Direct insertion and encapsulation generally have a large pin spacing (the most common is the standard 2.54), which is convenient for manual welding. However, the size of the patch package is greatly reduced, so no drilling is required on the circuit board during welding, it saves a lot of space and costs, and it is easy to achieve automated machine welding. It is widely used in practice (for example, the circuit of small digital products such as mobile phones, almost all of them are in full SMD design ). Because direct plug-in encapsulation is easier to use, we usually choose the direct plug-in dip-40 encapsulation microcontroller for learning (if not specified in the following article, single-Chip Microcomputer refers to the directly inserted package of FIG ).

Other chips may also use the same encapsulation as single-chip microcomputer. For example, the ISD4004 voice chip is often packaged with a wide dip-40. When recognizing a chip, you only need to look at the printed letter.

How should I identify so many integrated circuits with so many pins? For the dip encapsulation above, its pins are arranged in double rows. Careful readers may have observed that one end of the chip has a semi-circular gap, which is exactly what we need to pin. The gap is facing up, starting from the upper left corner and turning a circle clockwise, the PIN number is increased from 1 ,. Some dual-line integrated circuits, especially the patch dual-line packages, have no gaps. The dots at one end shall prevail. This method is applicable to all integrated circuits in double-row encapsulation. For encapsulation similar to LQFP-44, we can see that there is a small dot in the corner (or there is a small triangle gap, both chips in the figure ). Turn the circle around the dot counter-clockwise and the pin number increases from 1.

　　

　　

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MCU entry guide series (5) integrated circuit and encapsulation knowledge