Step By Step Process Involved In The Printed Circuit Boards Assembly

By Author: Ryan
Total Articles: 44
Comment this article

Any kind of electrical product's mechanical support requires PCBA China. This comes in the shape of a card or board composed of hard plastic or thin metal, both of which are generally referred to as insulators. On this card or board are attached the electrical gadget chips. The PCB is utilized in everything from little electronics like smartphones to bigger ones like computers and televisions. As it is unfinished, the PCB is referred to as a PCB, but after the electronics components are installed, it is referred to as PCB assembly service.

Process stages for PCBA

Step 1: Solder Paste Stenciling


The first step in PCB construction is to coat the board with solder paste. This procedure is similar to screen printing on clothing, except instead of using a mask, the PCB is covered with a thin stainless steel stencil. Assemblers can now only apply solder paste to certain areas of the potential PCB. The final PCB will include these portions as the locations for the components.

The actual solder, commonly known as solder paste, is a yellowish material made up ...
... of microscopic metal balls. The flux, a substance used in solder paste to assist the solder melt and adhere to a surface, is combined with the solder. A Grey substance known as solder paste needs to be placed on the board in precisely the proper locations and dosages.

A mechanical fixture keeps the PCB and solder stencil in place in a professional PCBA line. The correct amount of solder paste is then applied using an applicator to the desired regions. The paste is then evenly distributed across the stencil by the machine, covering all of the vacant spaces. The solder paste stays in the designated places after the stencil has been removed.

Step 2: Select and Position


Surface mount components, or SMDs, are placed on a prepared PCB by a robotic device after the solder paste has been applied to the PCB board in the PCBA assembly China process. The majority of non-connector components on PCBs nowadays are SMDs. The next stage of the PCBA process involves soldering these SMDs to the board's surface.

Traditionally, assemblers had to choose and put each component by hand while using a pair of tweezers to complete this task. Thankfully, PCB makers now do this procedure automatically. This change has place mostly as a result of robots' propensity for accuracy and consistency over people. Even while humans are capable of working swiftly, working with such tiny components tends to cause weariness and eyestrain after a while. Machines don't become so worn out working nonstop.

Step 3: Reflow Soldering


Surface mount components must stay in place once the solder paste is applied. To adhere components to the board, solder paste must harden. This is achieved during PCB construction via a procedure known as reflow.

The PCB board is put on a conveyor belt following the pick and place procedure. This conveyor belt travels through a huge reflow oven, resembling a commercial pizza oven in several ways. The board is progressively heated in this oven, which comprises several heaters, to temperatures of around 250 degrees Celsius, or 480 degrees Fahrenheit. The solder in the solder paste will melt at this temperature.

The PCB continues to pass through the oven after the solder has melted. The melted solder can cool and solidify in a regulated manner as it goes through a sequence of colder heaters. As a result, the SMDs and PCBs are permanently connected via a solder connection.

Step 4: Quality Control and Inspection


The finished PCBA and completed board need to be checked for operation once the surface mount components have been soldered in place following the reflow process. Movement during the reflow process frequently causes a connection to be lost entirely or to have a poor-quality connection. This movement can occasionally cause parts of the circuit to join that shouldn't be connected, which can result in shorts.

Step 5: Inserting Through-Hole Components


A PCB hole that has plating that extends through the whole board is known as a plated through-hole. These holes are used by PCB components to transmit signals from one side of the board to the other. Soldering paste won't help in this situation since it will pass right through the hole without having an opportunity to attach.

In the subsequent PCB assembly process, PTH components need a more sophisticated type of soldering technique in place of soldering paste:

• Manual through-hole insertion is a simple procedure that requires manual soldering. Typically, one component will be inserted into a specific PTH by one person at a single station. When they're done, the board is moved to the station below, where a different individual is attempting to attach a different component. For every PTH that has to be equipped, the procedure is repeated. Depending on how many PTH components must be placed during a PCBA cycle, this procedure may take a while. PTH components are still frequently used in PCB designs, although most businesses actively aim to avoid using them.

• Wave Soldering: This automated method of soldering is significantly unlike human soldering. The board is then placed on yet another conveyor belt following the installation of the PTH component. This time, a wave of molten solder is applied to the bottom of the board when the conveyor belt passes through a specialized oven. This simultaneous solders every pin on the board's bottom. Because soldering the whole PCB side would render any fragile electronic components worthless, this form of soldering is almost impossible for double-sided PCBs.

Step 6: Final examination and functional test in step six
A final inspection will test the PCB's functioning once the soldering phase of the PCBA process is complete. This examination is referred to as a functional test. The test puts the PCB through its paces and replicates the conditions under which it will typically function. In this test, the PCB is exposed to the power and simulated signals while testers keep an eye on its electrical properties.

The PCB fails the test if any of these properties, such as voltage, current, or signal output, exhibit unacceptable fluctuation or reach peaks outside of a defined range. Following the criteria of the firm, the faulty PCB can then be recycled or trashed.

The final and most crucial phase in PCBA China is testing, which indicates if the procedure was successful or unsuccessful. Regular testing and inspection are crucial all through the assembly process for the same reason that this testing is done.

High Quality PCB Co., Limited is a leading PCB(Printed Circuit Board) Manufacturer in China since 1995. Dedicated to the technologies innovation, being engaged in IC Substrates, High-Density Interconnect PCB, Multi-layer PCB, Rigid Flexible PCB, Flexible, Radiofrequency PCB.