About Basics of PCB Design, Let me guess, right now, you’re using an electronic device with a PCB in it.
Surprisingly, almost all electronic devices like smartphones, televisions, cameras, and radios employ basic circuit boards to link components. But do you know how to design a PCB?
Therefore, you’re at the right place if you don’t know how to do a basic PCB design. Sit back, and let’s take you through PCB design basics, classification, composition, and components.
Table of Contents
- PCB Composition
- PCB Components
- Step By Step PCB Design
- Common PCB problems
- PCB Classification
A PCB has alternating layers laminated using heat and adhesive to form a single product. Below are the layers involved:
Substrate or FR4
An FR4 is the base material that comes from fiberglass. Surprisingly, this material is responsible for the PCB’s thickness and rigidity. Additionally, the substrate is flexible and is built on flexible high-temperature plastic.
The substrate is available in different thicknesses, including the SparkFun product’s thickness of 1.6 mm. However, the Arduino Pro and LilyPad boards have a thickness of 0.8 mm.
After the substrate, you’ll find a copper foil. Also, this layer is laminated to your board using adhesive and heat. In most PCBs, copper is on both substrate ends. However, for lower-cost products, the PCB is only on one side.
Generally, thickness varies with the type of PCB. Most PCBs come with one copper ounce per square foot. However, some high-power PCBs might have 2 to 3 ounces of copper.
(A green PCB)
The solder mask layer is found over the copper foil. Generally, this layer is responsible for the green color on the PCB. Its purpose is insulating copper traces to prevent them from getting in contact with solder, conductive bits, and metal.
Therefore, with the layer in place, you can solder the right places and eliminate solder jumpers.
Finally, there is a white silkscreen over the solder mask. We use it to assign numbers or letters to the board for people to understand everything on it.
(A PCB with components)
You’ll find several components on a PCB that offer different functions. However, the components vary based on the electronic device a PCB is designed for.
Therefore, the most common components you’ll find on a PCB include the following:
- Battery: This component offers the voltage required to run the circuit
- Resistors: The function of resistors is to control electric current. Therefore, you can easily determine their value by checking the color codes.
- Light emitting diode: The LEDs allow current to flow through in a single direction. Normally, they light when the current goes through.
- Transistor: Its function is to amplify charge.
- Inductors: These devices will store charge when current flows through them.
- Capacitors: They harbor electrical charge.
- Switches: A switch will allow or block current depending on whether you close or open it.
- Diode: The purpose of a diode is to allow current to pass through in a single direction.
Step By Step PCB Design
(An engineer designing PCB)
Below are steps to follow to design your PCB:
Understanding Electrical Parameters
The first step in a PCB design process is to understand the system’s electrical parameters, including:
- Shielding considerations
- Current maximums
- Capacitance limitations
- Net wire schematic and listing
- Impedance characteristics
- Signal types
- Location and type of connectors and circuit components
Create The Schematic
You must create a schematic referring to your design at the electrical level of the PCB’s function. Here, you don’t have a mechanical representation yet.
Create a PCB Layout
You use software programs like Altium or Allegro to create a PCB layout here. Therefore, the layout will show how the board will function.
Additionally, it shows where you’ll place specific components. Afterward, a mechanical engineer loads the design to determine how it fits in a device.
Design A PCB Backup
The backup helps a mechanical engineer design and fit the board into the intended device.
Define Design Rules
Here, you need to define standards as set by IPC. Generally, following these standards ensures that you design PCB that will not have problems. Consequently, your project won’t face any delays.
Place The Components
When placing components, the PCB provider and customer should discuss and agree. You may encounter some regulations prohibiting the installation of some components next to others.
In most cases, this applies to components that make noise when closer to each other. Therefore, we recommend that you seek approval from the customer before installing components.
Insert Drill Holes
This is mainly determined by connection and components. Again, most circuits come with drill holes on the bottom layer.
Route the Traces
After inserting drill holes and placing components, you can route traces. Generally, it involves connecting path segments.
Include Labels ad Identifiers
This is the time to include identifiers, references, markings, and labels. They’ll help in showing where components will be put on the PCB.
Generate the Design
Finally, generate the layout files. The files have all the information relating to your PCB. After generating the layout files, you can fabricate and manufacture the PCB.
Common PCB problems
(A damaged PCB)
Your PCB won’t always be perfect. There are common defects that might arise either during design or use. Check them out below:
- First there might be solder bridges or shorts during assembly. Therefore, ensure there are no gaps between the stencil and PCB. Also, add some solder masks between pads.
- Second, a PCB might have plating voids, which might affect current flow.
- Additionally, Non-wetting problems that impact solder joint quality.
- Furthermore, acid traps involve solder leaking through the pads.
- Also, physical damage to the PCB thanks to environmental stress.
- Lastly, electromagnetic issues, thanks to some design flaws.
Generally, PCB classification happens in various ways depending on utilization and mounting technology. Let’s check them out below:
Basics of PCB Design: Mounting Technology
This PCBs classification depends on the mounting technology in use. These include:
- Through-hole PCB comes with components having leads connected through the boards. Surprisingly, these PCBs can withstand vibrations, movement, and stress.
- The surface mount PCBs have components connected to the PCB by soldering. Therefore, they’re cheaper and faster to manufacture.
Basics of PCB Design: Number of Layers
Also, PCBs are categorized based on the number of layers and include:
- First, single-layer PCBs have only a single trace layer. Therefore, they’re cheap and simple to produce.
- Second, double-sided PCBs have traces on both sides of the PCB. Therefore, they offer more space for design components and circuitry.
- Finally, multi-layer PCBs come with at least four layers. Therefore, they’re perfect for high-tech applications.
Classification Based on Flexibility
The flexibility of a PCB determines its application. Generally, under this category, we have:
What can you use a PCB for?
You can use PCBs to design electronic devices, including medical devices, LEDs, smartphones, and industrial equipment.
What is a PCB schematic?
This is a functional diagram representing an electronic circuit. Therefore, it has symbols to represent components. Additionally, it shows how these components are connected.
Can a PCB get damaged?
Yes! Your PCB can get damaged as a result of any environmental impact. Additionally, it can naturally get damaged due to aging.
Can you repair a damaged PCB?
Absolutely! You can remanufacture or repair any damaged PCB. However, you should be careful enough to determine the problem before fixing it.
What are the causes of PCB failure?
A PCB can fail thanks to defects, burnt components, or soldering issues. Additionally, failure can emanate from human error, old age, or environmental factors like heat.
Nowadays, at least every electronic device has a PCB inside. Generally, it provides electrical connectivity and mechanical support. Surprisingly, few people understand how to design and handle a PCB.
Luckily we have given you all the information you need about PCB. Should you need additional clarification, remember to keep in touch.