In today’s industrial automation landscape, Human-Machine Interface (HMI) boards play a critical role in bridging operators and complex systems. Found in factory floors, automated production lines, and process control systems, these boards handle both graphical output and sensor input, demanding stability and clarity of signals. However, one of the most pressing challenges in HMI electronics is the issue of noise and electromagnetic interference (EMI). Engineers often turn to Printed Circuit Board Layout Redesign as part of a reverse engineering process to overcome these limitations and ensure consistent performance.
Der Prozess beginnt normalerweise mit dem Extrahieren der Gerber-Datei oder der Rekonstruktion des PCB-Prototyps in ein digitales Format. Anschließend untersuchen die Ingenieure die Verlegung zwischen Hochgeschwindigkeitskommunikationsleitungen, Stromversorgungsnetzen und empfindlichen analogen Signalen. Reverse Engineering kann beispielsweise ergeben, dass überlappende Masseflächen Stromschleifen erzeugen oder dass Entkopplungskondensatoren nicht ausreichen, um hochfrequentes Rauschen zu unterdrücken. Nach diesen Erkenntnissen wird ein Redesign des Leiterplattenlayouts durchgeführt, mit Modifikationen wie verbesserter Leiterbahntrennung, verbesserter Abschirmung oder optimierter Platzierung von Filterkomponenten. Die neu gestaltete Platine kann wiederaufbereitet, reproduziert oder in Prototypen dupliziert und in realen HMI-Anwendungen getestet werden – sei es in einem Bedienterminal an einer Produktionslinie oder in einem Überwachungsdisplay zur Prozesssteuerung. Dieser iterative Zyklus aus Analyse, Redesign und Test ist entscheidend für die Störfestigkeit.
“Noise problem!” – This is the problem that every PCB Board engineer will hear. In order to solve the noise problem, it often takes several hours to carry out laboratory tests in order to find out the culprit, but in the end, it is found that the noise is caused by improper PCB layout of the switching power supply. Solving such problems may require printed circuit board layout redesign, resulting in product delays and increased development costs.
printed circuit board layout redesign
This article will provide guidance on the printed circuit board layout redesign to help designers avoid such noise problems. As an example, the switching regulator layout uses the dual channel synchronous switching controller ADP1850. The first step is to determine the current path of the regulator. The current path then determines the position of the device in the low noise layout design.
Unlike simpler devices, HMI boards combine digital controllers, communication interfaces, and display modules in a compact printed circuit board. Poor grounding, cross-coupled signal traces, or improper shielding in the layout drawing can introduce EMI that disrupts touchscreen accuracy, delays data exchange, or even causes system crashes. By analyzing the original schematic diagram, BOM list, netlist, and cad file, engineers can identify flaws in the design that contribute to interference. Through cloning, replicating, or restoring the layout with optimized grounding strategies and filtering techniques, they achieve significant reductions in noise.
Le processus commence généralement par l’extraction du fichier Gerber ou la reconstruction du prototype de circuit imprimé au format numérique. Les ingénieurs examinent ensuite le routage entre les lignes de communication haut débit, les réseaux d’alimentation et les signaux analogiques sensibles. Par exemple, la rétro-ingénierie peut révéler que le chevauchement des plans de masse crée des boucles de courant ou que les condensateurs de découplage sont insuffisants pour supprimer le bruit haute fréquence. Suite à ces analyses, une refonte du circuit imprimé est réalisée, avec des modifications telles qu’une meilleure séparation des pistes, un blindage renforcé ou un positionnement optimisé des composants de filtrage. La carte repensée peut être remanufacturée, reproduite ou dupliquée en prototypes et testée dans des applications IHM réelles, que ce soit sur un terminal opérateur sur une ligne de production ou sur un écran de supervision pour le contrôle de processus. Ce cycle itératif d’analyse, de refonte et de tests est essentiel pour garantir l’immunité au bruit.
The first step of redesigning printed circuit board layout to reduce the noise: Determine the current path
In a switching converter design, the high current path and the low current path are very close to each other. The alternating current (AC) path carries spikes and noise, the high direct current (DC) path produces a considerable voltage drop, and the low current path is often sensitive to noise. as a result of that, the key to redesign a proper PCB layout is to identify critical paths, then arrange the device and provide enough copper area to avoid high currents from damaging low currents.
Poor performance is grounded bounce and noise injection into the IC and the rest of the system from the ground path.
Below Figure shows a synchronous buck regulator design that includes a switching controller and the following external power devices: high-side switches, low-side switches, inductors, input capacitors, output capacitors, and bypass capacitors. The arrows in Figure 1 indicate the flow of high switching currents. Care must be taken to place these power devices to avoid undesirable parasitic capacitance and inductance, resulting in excessive noise, overshoot, ringing, and ground bounce.
Switched current paths such as DH, DL, BST, and SW must be properly routed away from the controller to avoid excessive parasitic inductance. The high δI/δt AC switching pulse currents carried by these lines may reach more than 3 A and last for a few nanoseconds. The high current loop must be small to minimize output ringing and avoid picking up extra noise.
Low-value, low-amplitude signal paths, such as compensation and feedback devices, are sensitive to noise. These paths should be kept away from the switching nodes and power devices to avoid injecting interference noise.
The process usually begins with extracting the Gerber file or reconstructing the PCB prototype into digital format. Engineers then examine routing between high-speed communication lines, power delivery networks, and sensitive analog signals. For example, reverse engineering may reveal that overlapping ground planes create current loops or that decoupling capacitors are insufficient to suppress high-frequency noise. After these insights, a Printed Circuit Board Layout Redesign is carried out, with modifications such as improved trace separation, enhanced shielding, or optimized placement of filtering components.
The redesigned board can be remanufactured, reproduced, or duplicated into prototypes and tested in real-world HMI applications—whether in an operator terminal on a production line or in a supervisory display for process control. This iterative cycle of analysis, redesign, and testing is key to achieving noise immunity.
El proceso suele comenzar con la extracción del archivo Gerber o la reconstrucción del prototipo de PCB en formato digital. A continuación, los ingenieros examinan el enrutamiento entre las líneas de comunicación de alta velocidad, las redes de suministro de energía y las señales analógicas sensibles. Por ejemplo, la ingeniería inversa puede revelar que la superposición de planos de tierra crea bucles de corriente o que los condensadores de desacoplamiento son insuficientes para suprimir el ruido de alta frecuencia. Tras esta información, se rediseña la placa de circuito impreso (PCB), con modificaciones como una mejor separación de pistas, un mejor blindaje o la optimización de la ubicación de los componentes de filtrado. La placa rediseñada puede remanufacturarse, reproducirse o duplicarse en prototipos y probarse en aplicaciones HMI reales, ya sea en un terminal de operador en una línea de producción o en una pantalla de supervisión para el control de procesos. Este ciclo iterativo de análisis, rediseño y pruebas es clave para lograr la inmunidad al ruido.
In industrial settings, HMIs must deliver flawless performance. On factory floors, EMI can interfere with touch responsiveness, confusing operators. In automated production lines, signal integrity problems may cause timing errors, leading to halted operations. Process control systems, which rely on accurate feedback from sensors, can suffer dangerous delays if EMI is not controlled. By applying Printed Circuit Board Layout Redesign, engineers ensure that HMI boards remain reliable under demanding conditions filled with motors, variable frequency drives, and other noise-generating equipment.
Difficulties in the Redesign Process
While effective, reverse engineering and modifying HMI boards present challenges. One major difficulty lies in balancing signal integrity improvements with space limitations. Many HMI devices are compact, leaving little room for layout changes. Additionally, redesigning may require updating the BOM list to include new shielding materials or filtering components, which can increase costs. Another challenge is ensuring compatibility with the existing industrial environment—too many modifications may disrupt communication protocols or power requirements. Finally, duplicating or replicating boards that integrate both analog touchscreen drivers and digital microcontrollers adds complexity, as noise sources may overlap and interact in unpredictable ways.
O processo geralmente começa com a extração do arquivo Gerber ou a reconstrução do protótipo da placa de circuito impresso em formato digital. Os engenheiros então examinam o roteamento entre linhas de comunicação de alta velocidade, redes de fornecimento de energia e sinais analógicos sensíveis. Por exemplo, a engenharia reversa pode revelar que planos de aterramento sobrepostos criam loops de corrente ou que capacitores de desacoplamento são insuficientes para suprimir ruídos de alta frequência. Após essas descobertas, um Reprojeto do Layout da Placa de Circuito Impresso é realizado, com modificações como melhor separação de traços, blindagem aprimorada ou posicionamento otimizado de componentes de filtragem. A placa redesenhada pode ser remanufaturada, reproduzida ou duplicada em protótipos e testada em aplicações HMI do mundo real — seja em um terminal de operador em uma linha de produção ou em um display de supervisão para controle de processo. Este ciclo iterativo de análise, reprojeto e testes é fundamental para alcançar a imunidade a ruídos.
Printed Circuit Board Layout Redesign through reverse engineering techniques is an essential strategy for mitigating noise and EMI issues in HMI boards used in industrial automation. By carefully reconstructing the schematic diagram, netlist, and gerber data, and then optimizing component placement and grounding, engineers can recover, modify, and remanufacture boards that meet the stringent requirements of real-world factory environments. Though challenges exist—from cost constraints to compact form factor limitations—the benefits are clear: stable, interference-free HMI systems that ensure smooth interaction between humans and machines in critical industrial applications.
