PCBA – Printed Circuit Board Assembly





What are PCBA and each stage of PCBA Manufacturing?

Table of Contents

Printed Circuit Board Assembly (PCBA) – a semiconductor for any electronic product, is the process to connect electronic components like Resistors, Capacitors, or Integrated Circuits (IC) to the circuit board. A complete PCBA has to go through many stages. The detail information below will help you comprehend more clearly about PCBA production in general and Trung Nam EMS’s PCBA manufacturing process in particular:

1. Components Checking.

     Components Checking will be implemented as soon as components are received. Purchased components will be reviewed by Quality Control Department to determine whether or not their quality meet the approval criteria, allowing us to minimize issues during production. This procedure entails:

  •          Package Checking

  •          Ordered Quantity Counting

  •          Confirming Quantity

  •          Error Components Checking

  •          Sorting SMDs

  •          Confirming Quality

2.    Solder Paste Printing

      Solder Paste or Solder Cream is the mixture of soldering iron and flux solution, used to adhere components to the board. In the process of the professional PCBA line, the first step is to put stainless steel stencils on the PCB before moving it into the Solder Paste Printer. After that, the machines will hold the circuit board that is correct with the solder pen position so that it can apply on the surface an exact amount. The mixture will be applied evenly to all exposed areas then removing the stencil layer, we have solder cream placed on the designated positions.

3.    Pick & Place Assembly

     By inserting the board that has printed solder paste into the Pick and Place machines, we have started the next step of the PCBA’s progress. During this, the components will be attached automatically and then have been put in the right position on the PCB’s surface which has been prepared with an amount of solder cream before. High precision help to mount everything together. Check-up each thing again to ensure that there are no defects before starting the reflow soldering process.

4. Reflow Soldering

       To get the PCBA finished, it needs to go through a stage known as “reflowing” by using the reflow oven to create a permanent solder joint to connect the SMDs to the PCB. When the circuit board enters the drying chamber that has a series of heaters gradually heat the board with a temperature of about 250°C or 480°F, the solder cream activates and melts due to the effect of the heat. PCBs continually transfer to the cooling down part which allows the molten solder becomes solidify in a controlled manner. The permanent weld in PCBA has shaped when this procedure gets to the endpoint.


5.   Quality Checking and Verification

       Automated Optical Inspection (AOI) is performed to ensure that no defects exist by evaluating the quality of Pick & Place components on PCBA and often used for large batches. To confirm that there are no errors, the AOI machine compares the PCBA to the Extended Gerber design, which serves as the manufacturer’s model by using a wide range of high-power cameras. Those things have been arranged at various angles to analyse welded connections. The high-speed and short-time evaluation can help technical staff discern which solder has lower quality by showing different weld quality connections reflect light in different ways.

For complex or multilayer PCBs, the board will be X-rayed to check the latent problem. The inspection process includes the following criteria:

  •          Examine the IC packaging for flaws

  •          Measurement of the Circuit Board Dimensions

  •          Examine the PCB Manufacturing Process

  •          Solder Ability Test, and so on

Technical staff is checking PCBA product by using AOI machine
Technical staff is checking PCBA product by using AOI machine

6.    Wave Soldering

     Depend on the type of PCB in PCBA that causes different elements beyond conventional SMDs, including through-hole, plated components, or PTH components. In these cases, solder paste will be struggled to bond to hole, as the glue will run straight through the hole without a chance to approach. That is why wave soldering helps to resolve this issue. In the Wave Soldering process, components are placed on the PCBA to form an electronic assembly using waves of molten solder. A mechanical and electrical connection will be made by wetting the exposed metal portions of the board that are not covered by a solder mask.

7.    Cleaning

     After all the above stages, PCBA product needs to be cleaned. Some acidic flux residues left on the board and may cause PCBA damage over time shall be removed. Although some “no-clean” fluxes do not require cleaning after application, they can reduce the stickiness of conformal coatings. Furthermore, during PCBA progress, the product surface can have saved oil and dirt from fingers and clothes by human manipulation, which more or less affects the aesthetics of the product.  So cleaning PCBs is especially important when dealing with this issue during PCBA manufacturing. After that, the finished PCBs are ready for packaging and shipping.


If you are having trouble finding a place that delivers excellent PCBA and satisfies your needs, Trung Nam EMS is the ideal option. With our careful research and investment in each stage, Quality and customer satisfaction are always our top priority.



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