2014_07_27 _ encapsulation form

1.The two most common packages are as follows:Pin-style component encapsulation and SMT (Surface Mount Technology ).

Dip dual-row direct insert Encapsulation

Chip Carrier encapsulation SMT component Encapsulation

2. Number of the component package

Component type + pad distance (number of PAD) + component shape size.

3. helper and Solder Mask

Soldering film: topsolder is coated on the pad to improve solderability. It is a light circle slightly larger than the pad on the green panel.

Solder Mask: Bottom paste mask, in order to make the board to adapt to wave soldering, etc., the non-welded copper foil of the Board must not be dipped in tin, and a coating must be applied to all parts except the pad, block these parts from tin.

4. PCB structure

A general PCB consists of copper-plated resin glass material or a layer of copper foil bonded with the resin material.

5. Through-hole tin pad

6. In pads logic, there are four types of libraries by content.

Component Library (parts). P: graphical display of components in the schematic diagram, including related attributes of components, such as pins, doors, and logical attributes;

Package Library (decals). D: The PCB encapsulation image of the component;

Graphics Library (lines). L: the library stores general graphics data, such as company logos;

CAE logic. C: Schematic representation of a component, such as a function unit such as a gate or a non-gate.

7. Active crystal oscillator and passive Crystal Oscillator

Source Crystal Oscillator: oscillator. The active crystal oscillator has four pins and is a complete oscillator. In addition to the Z crystal in vitro, it also has a transistor and a resistance element, so it is large in size. There are many source crystal oscillator models, and the pin definitions of each model are different, and the connection method is also different. There is a point marked as one foot, and the values are 2, 3, and 4 counterclockwise (pin down. Common usage: one pin is suspended, two ends are grounded, three ends are output, and the four ends are voltage.

Passive Crystal Oscillator: Crystal. A passive crystal oscillator is a non-polar element with two pins. It uses a clock circuit to generate an oscillating signal and cannot oscillate itself. The oscillator in the DSP must be used to generate the oscillating signal, and the passive crystal oscillator cannot oscillate itself. The recommended connection method is available on datasheet. The passive crystal oscillator has no voltage problem, and the signal level is variable. That is to say, it is determined by the starting vibration circuit. The same crystal oscillator can be applied to various voltages, it can be used for a variety of DSPs with different clock signal voltage requirements, and the price is usually low. Therefore, for general applications, if the conditions permit, it is recommended to use crystals, which is particularly suitable for large producers with rich product lines.

2014_07_27 _ encapsulation form