Pcb Design and Optimization

How I Solved a "Mysterious" 5000V PCB Problem That Stumped Everyone Else Have you ever faced a technical problem that made you question your skills as an engineer? Three years ago, I was working as a contract engineer on a 5000V circuit board that kept failing mysteriously. Every calculation said it should work. Every simulation showed perfect results. But in the real world, the exact same spacing issue my manager warned me about on the PCB resulted in complete failure. I spent HOURS staring at my design, checking and rechecking every trace spacing and clearance. The pressure from my manager was mounting with each passing hour. "If I can't solve this," I thought, "they'll think I didn’t follow instructions, or worse - think I don't know what I'm doing." What happened next taught me the most valuable lesson in my entire engineering career... After exhausting every conventional troubleshooting method, I logged into Altium 365 to review my design one more time. All the clearances were perfect. All the traces were properly spaced. Then my eyes drifted to two test points with leads hanging in the air. That's when it hit me - the fundamentals of physics I'd learned years ago suddenly clicked. The 5000V potential was arcing through the AIR between these points, not through the board itself! I grabbed some plastic bubble wrap, placed it between the test points, and the 5kV circuit relays worked PERFECTLY. My supervisor was amazed and surprised because at first he didn’t believe I followed the spacing rule (I had no choice because I set the clearance in Altium already). But most importantly, I realized something crucial: The most powerful tool any engineer has isn't fancy software or expensive equipment - it's the fundamental principles we sometimes take for granted. Today, I've helped dozens of engineers overcome similar "impossible" problems by returning to basics rather than chasing complex solutions or complex examples. Here's what I learned that might help you too: 1. Trust your engineering foundation - those basic principles you learned will save you when cutting-edge tools can't 2. Some real-world electronics scenarios are too complicated (or the time budget is too tight) to be captured in simulations - physical phenomena like arcing don't just show up in your schematic (however, in Altium you can set up component classes and clearance rules to fix this) 3. The process of elimination never fails - systematically rule out possibilities until only the answer remains If you've ever felt stuck on a technical problem or doubted your abilities as an engineer, remember: you already have the knowledge you need. Sometimes the solution isn't adding more complexity - it's seeing the simplicity hiding in plain sight. Have you ever faced a technical challenge that made you question your EE skills? Comment below and let me know - I'd love to hear any war stories. #HardwareEngineering #PCBDesign #EngineeringMindset #ProblemSolving

High-current DC/DC regulators are often plagued by EMI issues due to high dv/dt and di/dt switching transients during MOSFET commutation. These transients lead to both conducted and radiated EMI, which can severely affect system performance, especially in industries such as automotive and communications, where EMI compliance is crucial. To address this, optimizing the PCB layout is one of the most effective ways to reduce EMI at no extra cost. By carefully designing the power stage layout, engineers can minimize the parasitic inductance of the switching loop, thus reducing voltage overshoot, ringing, and overall EMI emissions. For instance, placing input capacitors close to the MOSFETs, and using a vertically oriented power loop in a multilayer PCB structure can significantly reduce the parasitic loop area. This optimization results in improved EMI performance, lowering the overshoot by up to 4V compared to conventional designs. In this white paper from Texas Instruments, we dive deeper into how specific layout changes can help mitigate EMI for high-current regulators. By leveraging best practices, such as minimizing switching loop area and using high-frequency decoupling capacitors, engineers can enhance system stability and comply with stringent EMI standards more easily.

⚡️Cap Placement, Return Paths & Twisted Pair – DC-DC Converter EMI (Part 2) Following a lot of great feedback on my last post about decoupling capacitor placement and its impact on EMI, I ran a follow-up experiment many of you asked for. This time, I looked at how the return path influences EMI, especially when using: ✅ A twisted pair cable ✅ using a return plane 📍Why does this matter? In the first test, we saw how placing input caps too far from the converter caused significant EMI due to longer, radiating current loops. In this test, I kept a similar setup but added: A twisted pair to keep forward and return currents close together A plane under the cap to provide a nearby return path 🎯Result? The radiated magnetic field from the cable drops significantly. Why? Because the return current flows close to the outgoing current, cancelling out the loop area and minimizing the magnetic field. 🔍 Still, placement and low impedance paths remain critical. A short, direct connection between the cap and the converter input is still the #1 priority. But this shows how smart layout and routing choices can help reduce EMI, even in sub-optimal situations.

Fresh PCBs are exciting. They are also where the most expensive mistakes tend to happen. After a recent bring-up failure of my own, swapping the plus and minus 15V rails of op amps due to rotated devices during assembly, I decided to stop and rethink how I do first power up. I realized that up to now, probably around 50% of my boards had some kind of assembly issue in the first batch. So instead of rushing to power up a new board full of confidence, I should probably be more cautious and a bit more pedantic. I took the advice many of you shared with me, added some additional practical tips I found along the way, and put together a step by step procedure for myself to catch problems as early as possible. Here is my current summary. Did I miss anything? 𝟭) 𝗦𝗹𝗼𝘄 𝗱𝗼𝘄𝗻 𝗮𝗻𝗱 𝗹𝗼𝗼𝗸. No power. No excuses. Magnification, good light, and patience. Check orientation, polarity, pin 1 markings, solder bridges, tombstones, cracked parts, missing parts. Even if the PCB markings are perfect. Even if the assembly house is professional. Even if you have done this a hundred times. Assume the board is guilty until proven innocent. 𝟮) 𝗠𝗲𝗮𝘀𝘂𝗿𝗲 𝗯𝗲𝗳𝗼𝗿𝗲 𝘆𝗼𝘂 𝗲𝗻𝗲𝗿𝗴𝗶𝘇𝗲. A multimeter already starts telling you a story before you ever apply power. Measure every power rail to ground. Use ohms mode, then diode mode. You are not looking for exact numbers. You are looking for surprises. A rail that feels too low, clamps in diode mode, or behaves differently from the others is a good reason to stop. If you can inject a tiny current and see where the voltage settles, even better. It is surprising how many problems show themselves quietly at this stage. 𝟯) 𝗙𝗶𝗿𝘀𝘁 𝗽𝗼𝘄𝗲𝗿 𝘂𝗽 𝗺𝘂𝘀𝘁 𝗯𝗲 𝗰𝘂𝗿𝗿𝗲𝗻𝘁 𝗹𝗶𝗺𝗶𝘁𝗲𝗱. 𝗔𝗹𝘄𝗮𝘆𝘀. Current limit is not just protection. It is an early warning system. Set the current limit low before connecting the board. Ramp the voltage slowly and watch what happens. If the supply immediately hits current limit and the voltage collapses, the board is already telling you something is wrong. A board that tries to start and then shuts down over and over again, especially at human time scales, is almost never RF instability. That smell is thermal protection, overload, or a clamp path conducting somewhere it should not. 𝟰) 𝗿𝗲𝗮𝗱 𝘁𝗵𝗲 𝗯𝗲𝗵𝗮𝘃𝗶𝗼𝗿, 𝗻𝗼𝘁 𝗷𝘂𝘀𝘁 𝘁𝗵𝗲 𝗻𝘂𝗺𝗯𝗲𝗿𝘀. Fast oscillations smell like electronics. Slow cycling smells like physics and heat. If something is getting hot quickly, stop. Fingers are still a valid sensor. 𝟱) 𝗦𝘁𝗮𝗴𝗲 𝘁𝗵𝗲 𝗽𝗼𝘄𝗲𝗿 𝘁𝗿𝗲𝗲. Do not power the entire board and hope for the best. Power regulators first. Validate rails unloaded. Then connect loads gradually. Jumpers, zero ohm links, or removable supply paths are bring-up insurance.

IMPEDANCE INTUITION. Achieving signal integrity (SI) in high-speed PCBs requires matching the impedance of physical structures. As data rates increase, the structures we care about become smaller – even down to several mils. Here, I’ll provide a simple way to increase your impedance intuition. The secret is understanding capacitance. Memorize this capacitance approximation equation: C = ƐA/d. These parameters directly translate to items in your PCB:  A (Area) is the size of your structure, d (distance) is the distance to ground/metal, and Ɛ is the dielectric constant of the material between the metal (sometimes called Dk or Ɛr). Next, understand that capacitance is inversely related to impedance (because Impedance=Z=sqrt[L/C]). ‘Inversely related’ means if capacitance goes up, impedance goes down. When you reduce capacitance, impedance goes up. In practical terms, if you make your trace wider, then A (Area) and hence capacitance get larger causing impedance to get lower. Move your trace further from ground, and d (distance) goes up thus lowering capacitance and increasing impedance. Use lower Dk material, C goes down and impedance goes up. See how this works? While understanding impedance guides design decisions, you can also use the concepts to grasp manufacturing changes. For example, if PCB fabrication substitutes a thinner core or presses your pre-preg layers thinner than plan, d (distance) becomes smaller, and impedance gets lower. Or, if traces are imaged or etched thinner, A goes down and impedance goes up. Though fab notes try to protect against these changes, cross-section images and/or measurements may reveal these problems. And what about vias? Think of vias as traces in the Z direction, where drill size defines A (area) and via barrel distance to antipad (metal) is d. Use a smaller drill, A and C go down, so impedance goes up. Widen your antipads and d goes up making C go down, also increasing your impedance. Because we typically have to raise via impedance, both these ideas are often deployed. Keep these concepts in mind, and you can expand into SMT pads, connector styles – you name it. Failing to match the impedance of relevant PCB structures causes impedance discontinuities, the #2 reason high-speed serial links fail. Impedance matters. While your 2D/3D design and simulation tools can help you get the impedance right, per Bogatin’s Rule #9, to believe what tools are telling you it’s important to grow your impedance intuition. Are my design changes having the effect I expect? For more concepts and guidance, be sure to check out both my ‘Signal Integrity, In Practice’ book and LIVE class: Book:  https://lnkd.in/guhndNJG LIVE Class:  www.siguys.com/training #siforees (filter using my name ‘Donald Telian’) #signalintegrity

High Current PCB Design: Practical Layout Tips 📍 Designing high-current circuits is not just about increasing trace width. In real projects, current capability depends on layout strategy, copper distribution, and thermal design, therefore PCB layout becomes critical for reliability. Here are some practical approaches: 🟠 Parallel MOSFETs for Higher Current Using multiple MOSFETs in parallel can significantly improve current capacity in half-bridge designs. This allows current sharing and reduces stress on a single device. 🟠 Multi-Layer Copper Distribution For high-current paths: • place MOSFETs on the top layer • use copper pours + vias to connect multiple layers • replicate power copper on inner layers This creates parallel current paths across layers, greatly improving current capacity and reducing resistance. 🟠 Minimize Distance in Half-Bridge Layout In half-bridge design: • place high-side and low-side MOSFETs as close as possible • reduce loop area This improves: ◽ current efficiency ◽ switching performance ◽ EMI behavior 🟠 Use the Right Power Plane Strategy When routing high current: • use power planes (e.g. VM) instead of GND planes for main current paths • maximize copper area connected to the power source The goal is to provide a low-resistance path to the supply 🟠 Increase Copper Thickness Copper thickness directly affects current capability. Typical values: • 1 oz ≈ 35 μm • 2 oz ≈ 70 μm For very high current (e.g. 100A): • use 4 oz copper • increase trace width (e.g. ≥15 mm) • use multi-layer routing + thermal design 🟠 Consider Busbars for Extreme Current For very high current applications: PCB traces may not be enough. In industrial designs (e.g. power systems, servers): • copper busbars are often used • or thick copper / plated structures 🟠 Don't Ignore Return Path Design Current always flows in loops. • low-frequency current → prefers low resistance path • high-frequency current → follows closest return path (minimum inductance) Poor return path design can lead to: ◽ EMI ◽ unstable switching ◽ signal integrity issues 📌 DFM notes High current PCB design is not only about electrical capability. From a manufacturing perspective: • copper balance • via reliability • thermal distribution all affect long-term stability. Small layout differences can lead to significant temperature variation in production. High current design is not just make it wider. It's about: current path + copper distribution + thermal + layout working together #PCBDesign #PowerElectronics #HardwareEngineering #DFM #HighCurrent #ElectronicsEngineering #KnownPCB

🚨 STOP Before You Route That Trace You might be thinking layout… But your MCU schematic isn’t ready yet — and it’s about to cost you. Over the years, I’ve reviewed dozens of embedded hardware designs and mentored engineers. One pattern keeps repeating: ⛔️ Rushing to layout with a half-validated schematic = costly PCB respins and debug nightmares. Let’s break it down 🔍👇 💥 1. Power Rail Assumptions Kill Boards “I connected VDD and GND — good enough.” 👉 Nope. Did you size your bypass caps correctly? 👉 Are analog and digital domains isolated or at war? 👉 Did you verify power-up sequencing, brown-out thresholds, and inrush limits? Use the datasheet AND the reference manual. Some MCUs require sequencing that’s not obvious from the block diagram. ⚡️ 2. Decoupling: Not Just a Checkbox Slapping a few 100nF caps on VDD pins? Try again. 📏 Calculate placement by pin inductance. 💡 Add bulk caps based on load step current. 🛑 And NEVER daisy-chain supply lines across multiple ICs without local decoupling. 🔄 3. Reset, Boot, and Clock Configuration = The Heartbeat Your MCU won’t even wake up if: Reset is floating or bouncing BOOT0 is misconfigured Your crystal doesn’t meet ESR or load cap requirements And yes, I’ve seen engineers debug for days just to realize… a missing pull-up. 😬 🧰 4. Programming & Debugging Interfaces: Design for the Future You Don’t trap SWD, JTAG, or UART lines under BGA balls. ✅ Use test points or edge headers ✅ Leave space for scope probes ✅ Add 1k series resistors on debug lines to avoid contention You’ll be grateful when your firmware misbehaves just before a client demo. 🛡️ 5. Real-World Protection = ESD + EMI Defense Your lab is calm. The field is not. TVS diodes on USB, UART, GPIOs PTC fuses on power inputs RC filters for noisy ADC pins Ferrites on analog power 🌐 And yes, common-mode chokes for Ethernet! 📐 6. Think Layout Before You Even Start 💡 Ask yourself: Will this schematic allow a clean ground plane? Can I route clocks short and shielded? Are high-speed interfaces length-matched and impedance-controlled? A layout-aware schematic saves you DAYS later. 🎯 Golden Rule: Your schematic isn’t just a functional diagram. It’s the blueprint for signal integrity, power stability, manufacturability, and sanity. 📌 Respect it. Simulate it. Review it. Challenge it. Then — and only then — click “Switch to PCB.” Till next post 😉 👇👇👇👇 🔜 Formation en Conception de PCB avec Altium Designer Pro: De la Conception à la Fabrication 📆 limite d'inscription: 30 mai 2025 🔗 Lien d'inscription: https://lnkd.in/dEwR3eX4 © Thamer HW-Expert

The classic advice? "Split your ground planes. Create an 'analog ground' and a 'digital ground,' and connect them at one single 'star' point." Well, that advice holds true for low-speed designs. However, When high-speed signals are involved, however, this logic is a disaster. At high frequencies, current doesn't follow the path of least resistance. It follows the path of least inductance, which is always directly beneath the signal trace. So, when your signal crosses that 'moat', the return current can't follow as there’s no continuous reference plane directly under the trace. It's forced to travel all the way around the split, to the "star" ground point, and all the way back. This path creates a massive current loop, turning your board into a broadcast antenna for EMI noise. Let's put numbers to the formula V= L. di/dt > 🌀L the new detour might add about 50nH of Inductance, & > ⚡di/dt (Rate of Current Change), if the signal is 20mA switching in 1ns. Plugging this into the formula, V = 50nH X ( 20 x 10^6 A/s) = 1.0V 👉 You just hammered a 1.0V spike into your "quiet" analog ground. The real solution? Use a solid, unbroken ground plane. The return currents will isolate themselves by staying tightly coupled under their traces. #ElectronicsEngineering #HardwareDesign #PCBDesign #SignalIntegrity #EMC #EM #CircuitDesign #Circuit #MixedSignal #MythBusting #SplitGround

🔵 Embedded Tuesday #24 — Why Is There a Capacitor Next to Every IC? Open any PCB schematic. You’ll see the same thing every time tiny capacitors (usually 100nF or 10uF) sitting right next to an IC’s power pin. Almost everyone places it. But why. Here’s the simple truth: A microcontroller does not draw current smoothly. It pulls current in short, sudden bursts when switching states, toggling GPIOs, or executing instructions. Now here’s the problem: Your power trace is not ideal. It has: resistance and more importantly inductance Inductance does not like sudden changes in current. So when the MCU suddenly needs current: The power trace can’t respond instantly. Result? A small voltage drop right at the VCC pin. Small but enough to: cause random resets corrupt communication create “ghost bugs” that are extremely hard to debug This is where the decoupling capacitor comes in. Think of it as a tiny local battery placed right next to the IC. When the MCU demands current instantly, the capacitor supplies it before the power trace can react. But here’s the part many people miss: Placement is everything. If the capacitor is not very close to the VCC pin: If it’s not very close to the VCC pin, the trace adds inductance and the capacitor becomes almost useless. Typically: 100nF → handles fast, high-frequency transients 10µF (bulk) → handles slower, larger variations You need both. They solve different problems. It’s a tiny component. If place it wrong and your system becomes unpredictable in ways you won’t see in simulation only on real hardware. #EmbeddedTuesday #EmbeddedSystems #PCBDesign #HardwareDesign #PowerIntegrity #Electronics #EmbeddedEngineering

Sharing my new Thermal PCB Design Guideline, created to help engineers design reliable, high-performance boards for modern power electronics. This guideline highlights the critical elements of thermal design—identifying high-heat components, selecting suitable PCB materials, applying smart component placement, optimizing high-current traces and copper areas, using thermal vias effectively, and meeting IPC/UL thermal standards. It also includes practical methods for improving heat spreading and cooling in SMPS, motor drivers, EV chargers, LED systems, and embedded hardware. A valuable reference for anyone focused on building cooler, safer, and more efficient PCBs. #PCBDesign #ThermalManagement #PowerElectronics #HardwareDesign #EmbeddedSystems #HighPowerDesign #EngineeringDocumentation