依据拼装产品的具体要求和拼装设备的条件选择适宜的拼装方法，是高效、低成本拼装出产的基础，也是SMT贴片加工工艺规划的主要内容。所谓外表拼装技能，上海贴片

According to the specific requirements of assembly products and the conditions of assembly equipment, the selection of appropriate assembly method is the basis of efficient and low-cost assembly production, and is also the main content of SMT chip processing process planning. The so-called surface assembly skills, Shanghai SMT processing refers to the assembly skills of components with sheet structure or small components suitable for surface assembly, which are placed on the surface of printed circuit board according to the requirements of the circuit, and installed by reflow soldering or wave soldering and other welding processes to form an assembly skill of electronic components with certain functions. In traditional tht PCB, components and solder joints are located on both sides of the board, while in SMT SMT PCB, solder joints and components are on the same side of the board. Therefore, in SMT SMT PCB, through holes are only used to connect the wires on both sides of the circuit board. The number of holes is much less and the diameter of holes is much smaller. Therefore, the installation density of circuit board can be greatly improved. The following SMT SMT chip processing and finishing in Shanghai introduces the assembly method of SMT chip processing skills.

1、 The first kind of SMT single-sided hybrid assembly method is single-sided hybrid assembly, that is, SMC / SMD and through-hole plug-in components (17hc) are mixed on different sides of PCB, but the welding surface is only one side. This kind of assembly methods all adopt single side PCB and wave soldering (now double wave soldering is generally used), and there are two specific assembly methods. Paste it first. The first assembly method is called paste first method, that is, SMC / SMD is first installed on the B side (welding surface) of PCB, and then thc is inserted on the a side. Post sticking method. The second assembly method is called post mounting method. Shanghai OEM first inserts THC on a side of PCB, and then SMD on B side.

2、 The second type of SMT double-sided hybrid assembly method is double-sided hybrid assembly. SMC / SMD and t.hc can be mixed and dispersed on the same side of PCB. Together, SMC / SMD can also be distributed on both sides of. PCB. Double sided mixed assembly adopts double sided PCB and Shanghai PCBA processing, double wave soldering or reflow welding. In this kind of assembly method, there are differences between SMC / SMD first or SMC / SMD later. Generally, reasonable selection is based on the type of SMC / SMD and the size of PCB. There are two assembly methods commonly used in this kind of assembly. SMC / SMD and "FHC on the same side", SMC / SMD and thc are on the same side of PCB. SMC / SMD and ifhc have different side methods. SMIC and thc are placed on a side of PCB, while SMC and sot are placed on B side. Because SMC / SMD is mounted on one side or both sides of PCB, and the lead components which are difficult to be assembled on the surface are inserted into the assembly, and PCBA is used as a substitute for material, so the assembly density is quite high.

The assembly method and process flow of SMT chip processing mainly depend on the type of SMA, the types of components used and the assembly equipment conditions. Generally, SMA can be divided into three types: single side mixed assembly, double-sided mixed assembly and full appearance assembly, with a total of 6 assembly methods. Different types of SMA have different assembly methods

加工是指把片状结构的元器件或适合于外表拼装的小型化元器件，依照电路的要求放置在印制板的外表上，用再流焊或波峰焊等焊接工艺安装起来，构成具有一定功用的电子部件的拼装技能。在传统的THT印制电路板上，元器件和焊点别离位于板的两面，而在SMT贴片印制电路板上，焊点与元器件都处在板的同一面上。因此，在SMT贴片印制电路板上，通孔只用来衔接电路板两面的导线，孔的数量要少得多，孔的直径也小许多，因此就能使电路板的安装密度极大提高。下面上海smt贴片加工整理介绍SMT贴片加工技能的拼装方法。

一、SMT单面混合拼装方法第一类是单面混合拼装，即SMC/SMD与通孔插装元件(17HC)散布在PCB不同的一面上混装，但其焊接面仅为单面。这一类拼装方法均采用单面PCB和波峰焊接(现一般采用双波峰焊)工艺，具体有两种拼装方法。先贴法。第一种拼装方法称为先贴法，即在PCB的B面(焊接面)先贴装SMC/SMD，然后在A面插装THC。后贴法。第二种拼装方法称为后贴法，上海oem代工是先在PCB的A面插装THC，后在B面贴装SMD。

二、SMT双面混合拼装方法第二类是双面混合拼装，SMC/SMD和T.HC可混合散布在PCB的同一面，一起，SMC/SMD也可散布在.PCB的双面。双面混合拼装采用双面PCB、上海pcba加工双波峰焊接或再流焊接。在这一类拼装方法中也有先贴还是后贴SMC/SMD的差异，一般依据SMC/SMD的类型和PCB的大小合理选择，一般采用先贴法较多。该类拼装常用两种拼装方法。SMC/SMD和‘FHC同侧方法，SMC/SMD和THC同在.PCB的一侧。SMC/SMD和iFHC不同侧方法，把外表拼装集成芯片(SMIC)和THC放在PCB的A面，而把SMC和小外形晶体管(SOT)放在B面。这类拼装方法由于在PCB的单面或双面贴装SMC/SMD，而又把难以外表拼装化的有引线元件插入拼装，pcba代工代料因此拼装密度相当高。

SMT贴片加工的拼装方法及其工艺流程主要取决于外表拼装组件(SMA)的类型、使用的元器件种类和拼装设备条件。大体上可将SMA分红单面混装、双面混装和全外表拼装3种类型共6种拼装方法。不同类型的SMA其拼装方法有所不同，同一种类型的