What You Should Know about PCB Processing
The printed circuit board (PCB) is a vital part of electronic devices; without it, they’re just metals and scraps. At the same time, transitioning from simply prototyping circuits to designing an actual PCB is a long, tasking process. Hence, you must familiarize yourself with this concept and understand the complex process associated with PCB design. Then, you can venture into PCB processing with a good idea of what it is about.
Different types of PCBs are differentiated by their structure and manufacturing process. The higher the steps involved in manufacturing the PCB, the more complex it is. Nevertheless, each step in the PCB manufacturing process is important, and skipping any step could mean a faulty PCB. However, if meticulously and religiously designed, the PCB will do exactly what it is meant to do as a key electronic component.
What Are the Essential Parts of a PCB?
First, you need to understand the four main parts of a printed circuit board. To understand PCB processing, you must first understand the basics and anatomy. They include the substrate, copper layer, solder mask, and silkscreen; let’s look at them one after the other for a better understanding.
The substrate of a PCB is the first and most important part of the board; it is typically made of fiberglass. The fiberglass material used in making this part helps it provide core strength to the board – like a skeleton. The substrate also ensures the printed circuit board can resist breakage.
● Copper Layer
This part of the PCB comes in two forms, depending on the type of PCB you are designing: copper foil or full-on copper coating. However, the form of the copper layer, regardless, performs the same function, which is to transmit electrical signals to and from the PCB. Consider the copper layer as the nervous system and its all-too-important job of carrying signals between the brain and muscles.
● Solder Mask
Next is the solder mask, the polymer layer that protects the copper to prevent short-circuiting upon contact with the environment. The solder mask of the printed circuit board functions like a skin; you could call it the PCB skin.
The silkscreen is the last part of the board and is usually on the component side of the PCB. This part shows logos, component references, part numbers, symbols, switch settings, and test points. It is often referred to as nomenclature or legend.
Before the PCB Design Starts
Now that you have a good idea of the anatomy of the PCB, you have started on the right footing. Next, let’s talk about things you need to know before designing.
- The size of the PCB: The PCB size depends on the product or enclosure size, which is defined during the design process of electronic engineering.
- The layers: PCBs come in different layers, including two, four, and six to eight. The rule is that the more layers, the more complex and expensive the PCB manufacturing process.
- Manufacturer requirements: Before designing your PCB, read the guidelines. In the guidelines, you will find information about file naming, trace size, pacing, and power isolation. Your PCB manufacturer will require information concerning the number of layers, material to use, thickness, color, copper weight, surface finish, and Gerber file.
Now, the PCB Design Process
The PCB manufacturing process starts with its design through the circuit boards’ fabrication. Then, before it is finally packaged and delivered, the completed board must undergo strict testing. Below are the steps involved in the PCB design process:
Step 1: Designing the Circuit
To design the circuit, you must create a schematic – a blueprint describing how components work together and relate to each other. It would help if you had a software tool; you can choose any, including Altium, Quadcept, KiCad, Cadence Allegro, DipTrace, and many more.
After installing the software, you must get component specifications for each component selected to aid in drawing the schematic. Note that each schematic symbol must have an associated PCB footprint defining the components’ physical dimensions and through-holes or copper pads’ placement on the PCB.
Step 2: Designing the PCB Layout
Using the same software tool you used to design your circuit, create a Gerber file in which you will design the PCB layout. In this stage, you allocate the actual components to the exact location on the board. You are also showing the trace to connect the components between the layers. When you’re done designing your layout, you will have a Gerber file, which your PCBA manufacturer will use for finishing the product.
Step 3: Fabrication
When your Gerber file is ready, you can send it to your desired PCB manufacturer, who will print it on the circuit board. The printing will be the basis for further buildup, adding components to the PCB, and manufacturing the Printed Circuit Board Assembly.
Step 4: Preparing the Material
Your components should have been selected; you can do this yourself or have your PCBA manufacturer help. You must know the lead time, packaging, minimum order quantity, and associated losses at this stage.
Step 5: Component Mounting
The next stage is to mount the components on the board, which can be manual (through-hole mounting) or automatic (Surface Mount Technology). Through-hole mounting is the manual fitting of components onto the PCB surface holes using wire leads. Contrarily, SMT is usually used in mass manufacturing; it is faster, cheaper, and more accurate.
Step 6: Soldering
This process involves “sticking” the components to the PCB to permanently connect them to it. The PCBA is taken through an infrared lamp or reflow oven, which is heated until the solder melts. Note that each package has its thermal profile; therefore, be careful not to overheat or damage the components. There are different types of soldering: reflow, wave, and iron soldering, used in different cases.
Step 7: Testing and QA
This is the final stage; the PCBAs are tested for quality and to eliminate mistakes such as unconnected or misaligned components. The most common PCBA tests include in-circuit, Automatic Optical Inspection, and X-ray testing.
High-quality PCB manufacturing and processing are critical aspects of PCB operations in electronics. When you give yourself a diligent study of the process’s complexities, you understand it. You will be able to appreciate better the cost and effort that goes into each PCB processing.