A printed circuit board (PCB) is a physical circuit design that is durable and highly reliable. Due to these qualities, it has become an essential part of any electronic device.
Made of a skinny substrate board, PCB is embedded with electronic components interconnected using a thin layer of interlinking copper traces. The substrate of this printed circuit board is usually fiberglass composite epoxy or other laminate materials.
Additionally, it contains both active and passive components. One could say that it can accommodate substantial and challenging courses in a small PCB design due to the availability of smaller and more advanced features.
Types of PCB
When it comes to the types of PCBs, there are essentially three types:
- Single-side added: These are the most basic types of MCBs in the market, containing only one layer of base material or substrate, thinly covered with a metal such as a copper.
- Double-side added: This type of PCB has both sides of its base material covered in a layer of conductive metal. It also has holes, allowing these metal parts to be connected
- Multi-layered boards: As the name suggests, these involve more than two copper layers, such as 4L, 6L, and 8L, etc., giving them a high level of design flexibility.
Major Advantages of PCB
PCBs come with several advantages, which is why they’re in-demand in the market! Some of these advantages are:
- Smaller and Thinner in size with a compact design
- Highly customizable in design and application so that you can choose single-layered, double-layered, or multi-layered with 4L, 6L, and 8L, depending on your need.
- Durable and reliable
- Easy to repair and debug
- Affordable and budget-friendly
- Double-layered and multilayered PCBs allow a wide range of applications such as power monitoring, mobile phone, amplifiers, test equipment, and many more
Various Steps in PCB Design and Manufacturing
After knowing about PCBs, you must wonder how you design and manufacture a PCB, right? If you have all the tools, let’s simulate a PCB step by step in order of design rules!
Step 1: Requirement analysis and Component selection
First off, you would have to analyze what your requirements are and then select the appropriate components. These components include things like power supply and processor etc. Keeping these requirements in mind, you must create a blueprint accordingly.
Step 2: In-System front-end design
Next up, you would have to devise the in-system front end design or the PCB layout, which is constructed with PCB design software. Some commercially available software are EAGLE, Autodesk, Altium Designer, CAD, and KiCAD EDA. Additionally, the output of the design we put in comes in the form of a PCB schematic Gerber file. This file is what encodes all the design information, such as the drill drawing, component notations, copper tracking layers, and other parameters.
Step 3: Photo tool initiation
Moving on, you would have to run the Design for Manufacture check before you start the board fabrication. This tool helps you avoid any contradictions in its design. Once checked, a laser printer makes a photo film to image your PCB design. These photo films are layered and aligned using precise holes in each movie to create a figure of the copper path.
Step 4: Printing the inner layers
Once the outer shell has been printed, you move on to the inner layers, being the substrate. This substrate usually comprises an epoxy substrate that is cut, cleaned, and dried. On both sides of this substrate, you would have to pre-bond copper.
Next up, the copper should be coated with a layer of photoresist cured with UV light to get hard. Once hardened, we take the film from the previous step, align the pin positions and place it over these internal components.
After this, you need to treat this entire panel with UV again to harden the areas with copper wiring.
Step 5: Etching out the unwanted copper
Once assembled, you would have to wash this panel with an alkaline solution to eliminate any unhardened copper. The needed copper layer would be safe beneath the hardened photoresist layer.
After the unhardened layer is removed, the photoresist layer is removed to leave us with the required copper.
Step 6: Register punching for layer alignment
Once all the layers and components are aligned, they must be optically punched.
Step7: Automated optical inspection
After getting punched, this automatic optical inspection should detect any errors within the inner layers.
Step 8: Layer up and bond
This step uses an aluminum plate for laminating all the layers together. Double and multilayered PCBs just get lined with insulating layers within each press.
Step 9: Drilling
Once laminated, these layers get drilled to create holes 100 to 150 microns wide for electronic components.
Step 10: Copper deposition and platting
Next up, the whole piece is covered in a layer of copper to bond the panels and make the entire article conductive. This plating is done through electrolysis.
Step 11: Outer layer imaging and copper etching
Like step 3, a photoresist material is applied over this, and any unwanted copper has scraped away. After this step, the PCB connections are established.
Step 12: Solder mask application
Once the board is clean, a solder mask is applied to protect it from damage, corrosion, or copper oxidation. Additionally, epoxy is used to give it a green color, and an unwanted solder mask is scraped away.
Step 13: Gold or Silver surface finish
Next, you plate this PCB with silver, gold, or lead-free HASL so the pads created can be soldered, and copper is protected.
This is a process where you print all the crucial information to the PCB, such as the company name, manufacturer’s ID, debugging points, and component numbers.
Step 15: Electrical test
A probe tester would be used for this step to perform open and short circuit, electrical, and functional tests to ensure durability and reliability.
Step 16: V-Scoring
This manufactured panel is what will give us the actual PCB. For that, V-cuts are made on the sides of the board according to what shape and size we need, and the PCB pops out.
Step 17: Final inspection and packing
Lastly, the PCB should go through a final visual and quality inspection. Once approved, it is to be vacuum sealed for protection.
PCB design process and PCB manufacturing is a requirement-driven and highly customizable process that enables us to produce specific circuit functions, whether complex or straightforward. So, you can create one depending on your requirements. Remember that precision and cleanliness are the essential precautions in Arshon Technology.
Fatima Hanjani R&D Engineer at Arshon Technology Inc.