Differences Between PCB Fabrication and PCB Assembly
PCBs are essential for the operation of many electronic devices. Whether they are used in home appliances, industrial IoT technology or mobile phones, the PCB fabrication and assembly process helps ensure these devices work reliably and efficiently. Understanding the differences between PCB fabrication and PCB assembly is important for engineers, manufacturers and designers who produce these devices.
The bare PCB is created through processes like etching and layering. The bare board is then ready for PCB assembly, which includes component procurement, placement and soldering. To ensure a high-quality product, a PCB assembly service must also perform a thorough inspection and testing process before it is released to the market.
Rigid and flex PCBs are both designed for different uses. Rigid PCBs are typically used in equipment that requires structural support, such as motor control boards and power supplies. On the other hand, flex PCBs are often used in smaller and more portable electronics, such as smartphones, tablets, and medical devices.
During pcb fabrication assembly, copper is deposited on each layer to serve as an electrical conductor. A dielectric material is then bonded to the copper, insulating it from other components on the PCB. The insulated copper layers are then coated with a material called solder mask, which protects the exposed copper during assembly and ensures that all soldered connections have a consistent and even height.
The Differences Between PCB Fabrication and PCB Assembly
Next, a mixture of solder alloy and flux is applied to the surface of the PCB. This process is known as solder paste application. Automated machines, called pick-and-place machines, then place the individual electronic components onto the PCB in their designated positions. These machines help to minimize errors, such as misplaced components or shorts, by placing the components with precise accuracy.
Once the assembler has placed all the components, they need to be soldered in place. The plated through holes (PTH) on the PCB provide pathways for connecting the top and bottom layers of the circuit board. The assembler can choose to use through-hole or surface mount technologies to connect the components. A through-hole connection involves inserting small wires, known as leads, into the drilled holes on the PCB. Each end of the lead is soldered to the corresponding component on the board.
The assembler can then add silkscreen overlays to the PCB for identification and troubleshooting purposes. This can include text, logos, and component identifiers. The assembler can also choose to apply surface finishes, such as hot air solder leveling (HASL), electroless nickel immersion gold (ENIG) and organic solderability preservative (OSP). These coatings help protect the copper from corrosion and enhance its ability to conduct electricity. A reflow soldering process then melts the solder paste, forming reliable electrical connections and completing the circuit. Finally, the reflow process needs to be followed by a thermal shock test and a functional test. If the test passes, the reflow process can be considered complete.
