With more than two decades of experience, we are familiar with PCB design failure points and how to avoid them. Let’s review some of the most common mistakes and problems encountered during PCB production and their solutions:
High Current Traces are Too Thin
When a PCB trace carries more than the standard multi-hundred milliamps, what minimum trace width will be insufficient? By specifying the acceptable temperature rise for a certain trace, engineers calculate the current carrying capacity to determine the appropriate copper weight. This is critical since trace loss is equal to the square of the current times the trace resistivity. These values as specified in MIL-STD-275 are designed into trace width calculators for quick evaluation by designers.
Incorrect Wireless Antenna Placement
When a product requires wireless technology, the physical location of the antenna on the PCB is vital. However, many design engineers regularly make this mistake. we keep the antenna layout a priority during the designing process to avoid this common error.
Avoiding Acute Angles or Acid Traps
Acute trace angles may trap acid during the PCB etching process, which allows acid to build up at the angle’s corner. This build-up enables acid to dissolve more than intended, compromising the connections and ultimately causing more serious issues down the road. By performing a DFM check, our experienced engineering team uses automated tools and precise checklists to scan for these types of simple human errors that can be easily overlooked throughout design and manufacturing processes.
Decoupling Capacitors Improperly Used
For the best performance, PCB electrical components need a consistent supply of reliable, constant voltage. Therefore, designers place decoupling capacitors on the power supply rail to ensure a stable current. For maximum efficiency, our engineers place the decoupling capacitors as close as they can to the pin and cycle the current through the decoupling capacitor before it reaches the pin. This is reviewed with the temperature rating of the product, ambient temperature, and temperature properties of the capacitors.
For more sensitive components a series impedance is needed to create a low-pass LC filter. This takes the form of an inductor or a carefully specified ferrite bead. For the highest quality PCBs, let the skilled staff at Freedom CAD help choose the right components for your PCB design to guarantee optimal performance.
Not Optimizing the Switching Regulator Layout
Electronic designs use two varieties of voltage regulators: linear regulators and switching regulators:
- Linear Regulators are less energy efficient, but low cost and easy layout can make them appealing in specific PCB designs. In low voltage or low-noise applications, a linear regulator is even more useful.
- Switching Regulators are much more complicated. These regulators are more energy-efficient but require more detailed attention to the design of your PCB. Datasheet guidelines must be followed carefully.
Long High-Speed Traces
High-speed signals need to follow the most direct path available in order to transmit quickly and efficiently. As such, these designs should be focused on high-frequency impedance matched routing. Although many microcontroller-based PCB designs rarely require many high-speed signals, this trace path is vital when using high-speed microprocessors with external data and address buses. For the differential traces used in high-speed communications, the issue is even more critical. Impedance matching, minimization of feed-throughs, and termination to match the chosen substrate material are all mandatory.
Naturally, problems occur which have nothing to do with experienced engineers or faulty PCB design. Instead, these PCB issues are less technical in nature:
Environmental Issues
PCBs and their components typically have little tolerance for the elements. Extreme temperatures, dust, and debris, and moisture and corrosion are well-known for causing failures. Unintentional drops and impact damage, as well as power surges, also cause damage. As a manufacturer, however, the most damaging is premature circuit board failure due to electrostatic discharge at an assembly or during routine handling.
Component Aging
Nothing can avoid the test of time. Everything ages and failures caused by age are unavoidable. Many failures can be predicted by the temperature of the components. For existing designs; replacing worn out parts may be significantly less expensive than creating entirely new PCBs. Freedom CAD offers both thermal simulations or infrared imaging of existing assemblies to reduce failure rates.
Source: freedomcad
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