PCBA generally consists of two parts : SMT and PTH Part : SMT (Surface Mount Technology) is the electronic industry a new industrial technology , its rise and rapid development of the electronic assembly industry A revolution , known as the electronics industry 's " rising stars ", which makes electronic assemblies become more fast and simple , with the attendant
PCBA generally consists of two parts : SMT and PTH
Part I : SMT (Surface Mount Technology Surface Mount Technology)
SMT (Surface Mount Technology) is the electronic industry a new industrial technology , its emergence and rapid development of the electronic assembly industry, a revolution known as the electronics industry 's " rising stars " , it has become increasingly of electronic assembly The more rapid and simple , followed by replacement of various electronic products faster and faster , more integrated , the price cheaper. For the IT (Information Technology) industry has made great contribution to the rapid development .
The first chapter , SMT components
SMT components involved in a wide range of different styles , many have developed common standards for the industry , mainly a number of chip capacitors resistors and so on ; there are many still undergoing constant change , particularly IC parts , the package Changes in the form of endless , dizzying , traditional pin package are going through a new generation of packages (BGA, FLIP CHIP , etc.) the impact of standards in this chapter will be divided into parts and IC parts in detail .
Standard SMT components is evolving development process , mainly for relatively large amount of parts, this section describes only the common standard parts . Present mainly in the following categories: resistance (R), exclusion (RA or RN), inductance (L), ceramic capacitor (C), exclusive content (CP), tantalum capacitors (C), diode (D), transistor (Q) (brackets for thePCB (printed circuit board) on the part code ) , the PCB, according to the type code to determine its parts , in general , part containing the actual code is the corresponding parts .
parts specifications :
(1 )part specification that is part of the form factor , SMT has the development of the industry to facilitate the operation , has become a standard part series, the various parts suppliers are manufactured according to this standard .
Standard part of the imperial and metric sizes have two representations , the following table
Metric representation 1,206,080,506,030,402
British representation 3,216,212,516,081,005
Meaning of L: 1.2inch (3.2mm) W: 0.6inch (1.6mm) L: 0.8inch (2.0mm) W: 0.5inch (1.25mm) L: 0.6inch (1.6mm) W: 0.3inch (0.8mm) L : 0.4inch (1.0mm) W: 0.2inch (0.5mm)
Note : a, L (Length): Length ; W (Width): width ; inch: inch
b, 1inch = 25.4mm
(2 )in (1 ) the thickness of parts not mentioned , at this point varies due to parts in the production should be subject to actual measurement .
( 3) The above-mentioned electronic products mainly for the largest amount of resistance ( exclusion ) and capacitance ( exclusive content ), other such as inductors , diodes, transistors , etc. The dosage of small and diverse shapes , This is not for discussion.
(4)SMT development so far , with the integration of electronic products continued to improve , the standard part of the development phase to the micro , and now the minimum standard parts has reached 0201 .
2 tantalum capacitors (Tantalum)
Tantalum capacitors have been increasingly used in various electronic products , are relatively expensive components , the development has also been a standard size range , with the letters Y, A, X, B, C, D to represent .
The following table correspondence
Type Y A X B C D
L (mm) 3.2 3.8 3.5 4.7 6.0 7.3
W (mm) 1.6 1.9 2.8 2.6 3.2 4.3
T (mm) 1.6 1.6 1.9 2.1 2.5 2.8
Note: The capacitance value of the same model but different size tantalum capacitors can not substitute .
Such as : 10UF/16V "B" type and 10UF/16V "C" type is not another alternative .