Keywords: PCB Assembly China, Printed Circuits Assembly

PCB Assembly

PCB is a circuit board before assembling the electronic components. The board is denoted as PCB Assembly or Printed Circuit Board Assembly or Printed Circuit Assembly after the electronic components are soldered. In this process, various automatic and manual tools for PCB Assembly in China are used.

You must know that PCB Manufacturing Process is not the same as assembling a circuit board. Several processes including creating PCB prototypes and PCB designing are involved in the manufacturing of printed circuit boards. Before using the board in any electronic gadget or equipment, you must get the passive and active electronic components soldered onto the board once a PCB is ready. The purpose of the circuit board, type of electronic components, and type of printed circuit board determines this assembly of electronic components.

Requirements for PCB Assembly in China

For Printed Circuits Assembly, consumables, electronics parts, and Assembly Tools needed are as follows:

• Basic Electronic parts
• Soldering equipment including testing equipment, wave soldering machine, soldering station, inspection, SMT equipment, etc
• Printed Circuit Board
• Soldering flux
• Soldering materials including solder paste, solder wire, solder balls for BGA, solder bar, solder performs. All these depend upon the soldering type to be done.

The assembling process of the printed circuit board starts once the raw materials, electronic parts, and equipment are arranged.

Process of PCB Assembly in China

The addition of solder paste to the board, testing, soldering, picking and placing of the components, and inspection are the different stages involved in the process of PCB assembly. For ensuring that the product is of the highest quality, all these processes need to be monitored and are done efficiently. As all Printed Circuits Assembly these days virtually uses surface mount technology, the PCB assembly process described here takes the use of surface mount components into consideration.

Solder paste:   Before including the components in a board, solder paste is put on the board in the areas where solder is required. These areas typically are the component pads. Using a solder screen, this is achieved.

A paste mix of small solder grains and flux is the solder paste. You can get this deposited into place like you do in some printing process.

A runner is moved across the screen using the solder screen, which is placed in the correct position directly onto the board. This squeezes a small solder paste amount onto the board and through the holes in the screen. It has holes in the solder pads positions as the printed circuit board files generate the solder screen. Thus, the solder gets deposited on the solder pads only.

For ensuring the resulting joints contain the correct solder amount, you must control the deposited solder amount.

Following steps are included in the whole wave soldering Process of PCB Assembly:

• Electronic components Insertion
• Application of Flux
• Preheating
• Wave Soldering
• Cleaning
• Testing

The PCBA undergoes cleaning and testing once the wave soldering is complete. It is taken for rework if any defect in the solder joint or any fault such as blowhole wave soldering or pinhole defect is found, which is generally done by hand.

Picking and placing: The board with the added solder paste is then passed into the picking and placing process during this part of the assembly process. Here the components are picked from the reels or other dispensers and placed onto the correct position on the board by a machine loaded with reels of components.

The tension of the solder paste holds the components placed onto the board in place. Provided that the board is not jolted, this is sufficient to keep them in place.

For securing the components to the board, the picking and placing machines add small dots of glue in some processes of assembly. However, if the board is to be wave soldered, this is normally done only. The presence of the glue makes any repairing difficult, which is the con of this process. However, certain types of glues have been made to get degraded during the soldering process.

The printed circuit board design information offers the component and position information needed to program the picking and placing machine. This simplifies the picking and placing programming considerably.

Soldering: The production process is to pass it through the soldering machine once the components have been added to the board in the next assembly stage. This process is not widely used for surface mount components these days although some boards may be passed through a wave soldering machine. Solder paste is not added to the board if wave soldering is used as the solder is provided by the wave soldering machine. Reflow soldering techniques are used more widely rather than using wave soldering.

Inspection: The boards are often inspected after they have been passed through the soldering process. For surface mount boards, Manual inspection is not an option employing a hundred or more components. Instead, a far more viable solution is automatic optical inspection. For detecting misplaced components, poor joints, and the wrong component in some cases as well as inspecting boards, machines are available.

Testing: Before the electronic products leave the factory, it is necessary to test them. They are tested in numerous ways.

Feedback: Monitoring the outputs is essential to ensure that the manufacturing process is running satisfactorily. By investigating any failures that are detected, this is achieved. As this generally occurs immediately after the soldering stage, the ideal place is at the optical inspection stage. This means that before too many boards are built with the same problem, process defects can be detected quickly and rectified.

Conclusion

In this overview, the process of PCB Assembly in China has been considerably simplified for the manufacture of loaded printed circuit boards. For ensuring very low levels of defects, the production processes and PCB assembly are optimized generally and the highest quality product is produced in this way. For the success of the products that are manufactured, the operation of this process is critical in view of the very high demands placed on quality as well as the number of solder joints and components in today's products.