Contents
1. Material and Components
You must consider the material and components you plan to use for your print on the pertinent details; you must first define the functions the PCB will have to perform, the approximate size of the final product, the PCB’s interconnection with other circuits, and of course, its placement in the product.
Some materials can operate in extreme temperatures, while others may fail, resulting in short-circuiting.
For this reason, consider the working temperature of the final product when choosing the material and components for your printed circuit board.
Finally, consider the cost and availability of the materials. If you settle for hard-to-find materials, they may be expensive and time-consuming to locate, which will eventually delay assembling your PCB.
Consider choosing a PCB supplier that can maintain a steady supply of the necessary components for your PCB.
Other areas to consider include spare parts, repairs, and replacements.
2. PCB Layout Component Placement
Laying out components on the board requires many problem-solving skills and creativity.
Because everyone has a unique design perspective, your component placement will be unique from someone else’s idea.
Consider the manufacturing of the PCB because that is the end goal.
For instance, like-minded components such as transistors should face the same direction when placed for easier installation and inspection by the manufacturer.
Keep in mind the size and height of each component. Some components will be larger than others, which may result in uneven bumps on the circuit board when placed next to each other.
Some taller details may block shorter elements, and when the board is passed through the soldering oven to engrave the parts onto the board, it may return with poorly connected solder joints.
Always consider the height and width of components on the board – details of similar dimensions can be placed towards one side, ensuring the soldering wave reaches the smaller parts without being blocked.
Allow space for routing. If you place components too close together, you will run out of reach when you start routing. Integrated circuits, for example, have lots of pins to be connected around the board. To prevent running out of space and jumping over your design layout again, give enough room for components that require lots of pins to be connected to make the process easy.
3. PCB Layout Stack Up
PCB stack-up forms the foundation of the entire PCB. It involves placing insulating and copper layers.
The stack comprises the various layers within the PCB and allows you to establish the characteristic impedances at each layer.
The more layers the PCB has, the costlier it becomes.
Printed Circuit Boards have layers of different materials laminated with an adhesive.
The top layer is the silkscreen that adds other indicators, such as letters and symbols, to the board.
The bottom layer is the FR4, giving the board its rigidity and thickness.
The next one is the copper layer, followed by the solder mask, which gives the PCB its distinctive green color.
Optimal multilayer stack-multilayer radiation and external noise. It also enhances your design’s electromagnetic compatibility, keeps the cost within budget, and ensures efficiency in the manufacturing technique.
4. PCB layout Via Types
A PCB Via allows interconnections between different layers of the board. Vias may join traces, pads, and other conductive elements and provide the path for electrical and thermal energy moving from one layer to another.
Since we drill holes through the board to create the vias, you must consider each hole’s placement and size in relation to the other PCB components.
Ensure all the vias on the board are the same size to improve efficiency in the manufacturing process.
There are three basic types of vias: Through vias, blind vias, and buried vias. A through via connects two visible exterior layers.
Blind vias connect a visible outer layer with an invisible interior layer. Buried vias connect two hidden interior layers.
Other vias include thermal vias for transferring heat from the top layer to the bottom or internal layers and tented vias enclosed with solder masks to prevent electrical and thermal components leakage.
Be sure to discuss the capabilities of the via types you intend to use with your PCB supplier because different vias have different current-carrying capacities.
5. Power And Thermal Issues
While component placement is crucial to the design, to get those components to work, you also need to consider power routing.
Power and ground planes should be internal to your board, centered, and symmetrical to prevent board twisting or bowing.
Thermal issues affect larger circuit boards with higher density and excessive processing speeds. To avoid such problems, your PCB must allow heat to dissipate.
During the material selection, identify components generating a lot of heat and find ways of diverting heat from them. Surface space around parts quickly becoming hot is a crucial layout design consideration because they’ll need space to cool off.
You may consider including heat sinks, cooling fans, and thermal reliefs.
Some places to add thermal reserves include through-hole vias to slow the heat sinking rating through the PCB layers.
It affects signal integrity. You should expect electrical problems such as electromagnetic interference in electronic devices.
Avoid laying tracks parallel to ensure your PCB doesn’t cause such issues. For records that must crossover each other, ensure they are at right angles to minimize capacitance and mutual inductance.
6. Board Constraints
First, depending on the purpose of the PCB you are designing, you must consider the size and shape of the board.
The board is a primary component of the PCB because it holds all the other parts. Factors determining the size and shape of the PCB include the functionality and size of the destination product.
For example, wearable products such as activity trackers require way smaller PCBs than televisions.
Some products require PCBs with more circuits than the board can hold. In such situations, you may need to use mumultilayerigh-demultilayer connect PCBs(HDI PCBs), which allow packing more functionality into a smaller area.
High-density interconnects increase levels of reliability because they have robust interconnection of stacked vias.
Another advantage of HDI PCBs is ensuring electrical signals take less time to travel because of the components’ proximity.
PCB layout Issues
PCB assembly stage. A well-designed board helps avoid PCB layout issues such as starved thermals, insufficient annular rings, missing solder masks, acid traps, etc.
Starved thermals occur when thermal relief traces and associated copper planes are improperly connected.
Missing solder masks will likely occur in tightly spaced boards during the Bill Of Materials (BOM) of a PCB fitted aboard.
Acid traps can cause open circuits on a PCB board because of disconnection traces from their assigned nets. Missed drill hits cause Annular rings.
It’s crucial to consider that there are high chances of layout failures in manufacturing PCBs, which can go a long way toward negatively affecting the final product’s functionality.
Several PCB layout rules prevent such problems, which can result in losses, bad prototypes, and time wastage.
Conclusion
This article discussed the various issues to consider when designing a printed circuit board and some problems a poorly designed PCB may cause.
Some topics discussed include component placement, board constraints, PCB stack-up, material and components, power and thermal effects, and PCB via types.
To connect the various components of the PCB, we print conductive pathways on the board.
Since the connections are internal, the overall design’s complexity is greatly reduced. Elements such as integrated circuits, transistors, and resistors are mounted into the board through soldering.
PCBs are crucial to the functioning of IoT devices and graphics cards, motherboards, network interface cards, TVs, cellphones, tablets, and more.
As technology advances, the complexity of a PCB layout increases. Getting the design right for production will result in a high-quality printed circuit board.
Your end product should reliably work as expected and stay within the budget. We hope this article helps you achieve a good PCB layout.
