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PCB Assembling: Ways to Go About It

From kitchen appliances to smartphones, electronics play an important role in our daily lives. The heart of every electronic product is a printed circuit board (PCB). You’ll find these little green chips in countless configurations and made of various materials. Today, we will explore PCB assembling in more detail.

PCB understanding

PCB refers to a circuit board that has yet to undergo any assembly involving electronic components. Once the process occurs, it becomes a PCBA (Printed Circuit Board Assembly).

What Is PCB Assembly?

Printed Circuit Board assembly, also called PCBA, is a process that involves the assembling or soldering of electronic pieces onto a PCB board.  To facilitate the assembly, you can use the conductive routes engraved within the laminated pieces of PCB copper sheets inside a non-conductive substrate. The attachment of these electronic components to PCBs eventually leads to creating of a fully operational electrical device. 

PCB vs. PCBA: What’s the difference?

The assembly of a circuit board is different from the PCB manufacturing process. The latter involves numerous processes, including creating a PCB prototype and design. Once you have done this, sell passive and active electrical components onto the board to utilize any electrical component or device. The assembly process also depends on the kind of PCB you plan on using, the different electrical components involved, and the intended purpose of the circuit board.

Things Needed for Printed Circuit Board Assembly

The following are some PCB assembly tools, consumables, and electrical parts required for a PCB assembly process.

  • PCB (Printed Circuit Board)
  • Standard electrical components
  • Soldering materials include solder paste, wire, bar, and balls for BGA. You could also need solder performance depending on the kind of soldering you wish to do. 
  • Soldering flux
  • Soldering equipment such as wave soldering machines, soldering stations, testing and inspection, and SMT tools, to mention a few.

Caption: BGA

PCB Assembly Technologies & Soldering Techniques

Below are some of the PCB assembly technologies and soldering techniques.

Through-hole technology (THT)

The through-hole technology involves the soldering of a pin or leaded-through electronic components to a board to create a circuit. Implant the terminals or leaded pins of the components through the pads or holes found on the PCB, which are then soldered on alternating sides.

Surface-Mount Technology (SMT)

There are two kinds of assembly technology: surface-mount and through-hole. SMDs (surface-mounted devices) need soldering to create the circuit. Solder paste is also helpful during the process.

Mixed Technology

Once a circuit design seems complicated, you can always stick to a single component within a circuit. In the case of PCBs, the aspect of realizing that it is too complex can happen when a circuit has both surface-mount and through-hole devices. These PCBs are often referred to as mixed technology boards, and the assembling process is a hybrid technology PCBA methodology.

Wave Soldering

When employing a wave soldering technique, move the PCB across hot soldering liquid that solidifies and adjoins the components. It is one of the most commonly used techniques in the SMT and THT PCBA process.

Braze Soldering

With braze soldering, you adjoin the metal components together through heat application. However, the technique requires melting the metal at the bottom to allow it to fit in the filler metal. It also uses high temperatures, which leads to the creation of some of the strongest joints. 

Reflow Soldering

Reflow soldering involves the attachment of components to a board via the use of heated soldering paste. This molten state can connect the pins and pads within the PCB. 

Soft Soldering

With the soft soldering technique, the person places a metal space filler made of a tin-lead alloy that’s heated using gas or an electric torch to adjoin components onto the board. It is one of the more popular techniques, particularly when fixing fragile and compact pieces to a PCB. 

Hard Soldering

Hard soldering is typically applied when one combines metal pieces like brass, copper, gold, or silver at temperatures of around 600°F. It also leads to the formulation of stronger joints, unlike soft soldering. 

A Step-By-Step Guide to PCB Assembly

Once you have all the items and technologies mentioned above, the relevant electronic components, and some raw materials, you can commence with the PCB assembly process. The following is a guide to assist you in the assembly of PCB:

Step 1

The first step of the process involves applying the soldering paste on a circuit board. You then take the slim, unmarred steel stencil and place it on the board. You can use mechanical fixtures to ensure to apply the paste is evenly and exactly where required. 

Step 2

The next thing is to pick and set down the machine. This means putting the surface-mount components or  SMDs on an already prepared PCB using robotic devices. After which, you need to solder the components onto the surface of a circuit board. 

Step 3

Now you should give the solder paste some time to solidify so the components can adhere to the PCB. However, the solder paste must also flow and remain in place for a while. 

Step 4

During this step, you should examine the PCB assembly. You can begin once the reflow process is over and the mount components have been properly soldered where needed. Some ways you can test or inspect for functionality are manual checks, automatic optical inspections, and x-ray inspections. 

Step 5

Proceed by inserting the plate into the through-hole component. However, as opposed to using soldering, you’ll need a more specialized method, like manual or wave soldering. 

Step 6

The final step of a PCB assembly involves conducting a complete inspection of the board. You can run simulated signals and power to the board to test some of its electrical traits. A good indicator that things aren’t right is when it begins to display fluctuations of electronic signals during the test. As a result, if the PCB fails its final inspection, you should scrap it and start the process until you have a functioning PCB. 


PCBs are an adaptable solution for many applications across various industries. Qualified and experienced fabricators can create easy-to-manufacture PCB solutions for any application. If you are looking for a quality PCB solutions provider, wellpcb can help. Whatever PCB your company needs, we can handle it. Whether double-sided or single-sided, SMT, through-hole, or hybrid assembly, we can manufacture most cost-effectively.

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Emma Lu
Our professional engineering support saves our customers a lot of trouble and loss. >>>>>> After you place the order, our engineer will conduct technical reviews to make sure the parts can be mounted well/correctly on the boards. We will check if the component packages match well with the Gerber footprints, if the part numbers you provided match well with the descriptions, and if the polarity is clearly marked. >>>>> When your design is ready, please send your Gerber and BOM so we can quote and start!