PCBAs are present in every single electronic device used today. These finished boards are responsible for the functionality of these electronic devices. The printed circuit board is the framework of electronic devices. From smart speakers to intelligent thermostat, PCBs are available in even the smallest electronic devices. The manufacturing of functional electronic devices goes beyond putting together a bunch of resistors and components.
Manufacturing PCBA process is very critical. A single mistake in this process could cause malfunctions, components failure or accidents. In this article, we’ll discuss some steps Involved in manufacturing PCBA.
What is PCBA Manufacturing?
PCB manufacturing is different from manufacturing PCBA. A printed circuit board assembly (PCBA) is the finished circuit board after attaching all electronic components on a bare board. A PCB is a bare circuit board with no electronic components.
When manufacturing PCBA, the assembler uses the conductive pathways in the laminated copper sheets of circuit boards within a non-conductive substrate. The process of mounting the electronic components to the PCBs creates a functional electronic device.
The PCB manufacturing process is completely different from PCBA manufacturing process. The process of PCB manufacturing involves several stages such as PCB designing and PCB prototyping. Manufacturing PCBA involves soldering passive and electronic components. The outcome of this process is what makes it possible to manufacture electronic devices.
Electronic devices can’t function without PCBA. There are different techniques of mounting electronic components on a bare board. These techniques include surface mount technology and through hole technology.
PCB Assembly Technologies
Manufacturing PCBA doesn’t only require the use of more than just the raw components, but also needs the integration of the right technology. There are two major technologies integrated in PCBA manufacturing. Each of these technologies has its weaknesses and strengths.
While one technology may be integrated in PCB assembly processes, some PCB assembly processes need the combination of the two technologies. This assembly technique is known as mixed technology. For instance, some circuit boards require the combination of surface mount technology and through-hole technology.
However, it is crucial to understand when and how to integrate each of these technologies. Also, the steps Involved in these various technologies differ.
Surface mount technology
This is the most common technology integrated in PCB assembly process. Surface mount technology involves the use of automation during PCB assembly. In SMT, the electronic components are directly attached on the surface of the PCB. These components comprise both passive and active components.
The SMT process involves the use of a pick and place machine to place electronic components on the board. Also, this assembly technique is faster than through-hole technology since it integrates automated machines. Surface mount doesn’t involve the drilling of holes unlike through hole technology.
Through hole technology
Before the advent of SMT Manufacturing , THT was widely integrated. The through hole technology involves the creation of leads. Also it involves mounting of electronic parts that have leads. Assemblers can use mechanical or manual method to achieve through hole technology.
This PCB assembly technique is highly suitable for some particular scenarios. THT involves inserting the leads of an electronic component on a circuit. Also, this technology allows assemblers to attach the details of a circuit to the inner layers of the circuit.
Steps Involved in Manufacturing PCBA
There are crucial steps Involved in the manufacturing PCBA. Each of these steps must be rightly followed to achieve a functional circuit board assembly.
Apply solder paste
The first step in manufacturing PCBA is the application of solder paste on the PCB surface. The assembler applies the solder paste which is usually a mixture of solder and flux where the components will be placed.
Pick and place components
The next step is to pick and place components. This involves the use of an automated pick and place machine. Although component placement can be manually done, the integration of machine helps in achieving accurate results.
THT process involves the placement of components by hand. This usually requires precision. The automated placement of components is much faster and more precise than manual placement.
Reflow Soldering
Once the solder paste is applied and the components are placed at the right spots, the next step is reflow soldering. The solder paste must solidify properly to adhere to the components of the board. During reflow soldering, the solder goes through a melting stage before it resolidifies. In this step, the circuit board passes through an oven. The oven then heats the solder to ensure proper connections and then the board goes into a cooler.
Perform Inspection and Quality Control
After reflow soldering, the assembler needs to inspect the board to ensure quality control. Proper Inspection helps to evaluate the functionality of the circuit board. In this step, the board is thoroughly evaluated to detect any defects.
Final Inspection & Functional Tests
These tests are necessary in any PCM assembly process. They help in identifying any errors with a board, before mass production begins. Also, these tests are solely carried out to prevent any costly mistakes.
Failures that Could Occur During PCB Assembly Manufacturing
PCB Bend or Crack
Physical and mechanical stress can make a PCBA to crack or bend. Also, if a rigid circuit board is exposed to continuous vibrations or thermal shocks, this could result in a bend or crack. Also, flexible circuit boards are more likely to crack if they go beyond their bending strength. To prevent this from happening, pre-bake and store your circuit board in an humidity-controlled place.
Joint Solder Fracture
Solder joint fracture happens as a result of differences in thermal coefficients of the PCB or manual soldering. A board could fail when exposed to high temperature environments. Integrate specialized automatic equipment to avoid these failures.
Short Circuits
Short circuits occur during PCBA manufacturing. High current spikes, solder bridges, and moisture can cause short Circuits. Short circuits can cause damage to the electronic board.
Conclusion
Manufacturing PCBA process is very critical. A single mistake in this process could cause malfunctions, components failure or accidents. In this article, we’ll discuss some steps Involved in manufacturing PCBA. The best way to prevent this problem is to carry out electrical testing.
