Technical Analysis of High Thick Copper PCBA for New Energy Vehicle Three-Electric System

　　As the core power system of new energy vehicles, the three-electric system (power battery, drive motor, electronic control system) bears the key functions of energy storage, power conversion and drive control. With the industry developing towards high power, long range and fast charging, the three-electric system faces increasingly severe challenges of high current, high heat generation and harsh working environment. High thick copper PCBA (Printed Circuit Board Assembly), as the core carrier of the three-electric system, plays a decisive role in improving current-carrying capacity, enhancing heat dissipation efficiency and ensuring long-term reliable operation. Compared with conventional PCBA, high thick copper PCBA (copper layer thickness ≥3oz) has significant advantages in low resistance, high thermal conductivity and anti-vibration fatigue, which can perfectly match the working requirements of the three-electric system under high load, high temperature and frequent vibration conditions. Leveraging its profound accumulation in precision manufacturing and automotive-grade electronic component technology, Szchaopin has built a full-chain high thick copper PCBA solution for new energy vehicle three-electric systems, covering design, material selection, manufacturing and testing, providing reliable core support for the safe and efficient operation of new energy vehicles.

　　Core Requirements of High Thick Copper PCBA for New Energy Vehicle Three-Electric System. The working environment of the three-electric system is complex and harsh, and the core requirements for high thick copper PCBA are mainly reflected in four aspects: First, excellent high-current carrying capacity. The drive motor controller and OBC (On-Board Charger) in the three-electric system often need to transmit hundreds of amps of current. High thick copper PCBA must have low line resistance to avoid excessive voltage drop and power loss, ensuring efficient energy conversion. Second, superior high-power heat dissipation performance. High-current operation will generate a lot of heat, and the ambient temperature of the three-electric system can reach 125℃-150℃. PCBA must quickly dissipate heat to control the junction temperature of power devices (such as IGBT, SiC MOSFET) within a safe range, preventing performance degradation or thermal runaway. Third, strong anti-vibration and fatigue resistance. New energy vehicles will face road bumps and vibrations during driving, requiring PCBA to have excellent structural stability, avoiding solder joint fatigue, copper foil peeling and other failures under long-term vibration conditions. Fourth, long-term reliability in harsh environments. It needs to resist moisture, salt spray, chemical corrosion and other factors in the vehicle environment, and ensure stable operation for more than 10 years or 200,000 kilometers, which is far higher than the reliability requirements of ordinary industrial PCBA.

　　Szchaopin's Full-Chain Implementation Path for High Thick Copper PCBA for Three-Electric System. Aiming at the strict requirements of the three-electric system for high thick copper PCBA, Szchaopin has constructed a full-chain quality control and technical implementation system from design to delivery, integrating thick copper technology characteristics into every link to ensure product reliability:

　　1. Thick Copper-Oriented Refined Design. In the PCB design stage, Szchaopin integrates the DFMEA (Design Failure Mode and Effects Analysis) concept to conduct risk assessments for potential failure points such as thick copper thermal expansion and contraction mismatch, solder joint fatigue and high-current thermal effects. According to the current requirements of different components of the three-electric system, a graded thick copper design is adopted: 3oz-5oz thick copper is used for the high-current power loop of the drive motor controller, and 2oz-3oz thick copper is used for the signal and control circuits, balancing performance and cost. The layout adopts a "thermal separation + current optimization" design, separating high-power heat-generating devices from sensitive signal components, and optimizing the high-current path to minimize line length and reduce parasitic inductance. For the heat concentration area, a large-area thick copper heat dissipation zone is designed, and array thermal vias (0.3mm-0.4mm aperture) are densely arranged under the heat pad of power devices to form a vertical low-resistance heat dissipation channel, which can quickly conduct the heat generated by the devices to the heat sink. In addition, in order to avoid copper foil peeling caused by uneven thermal expansion and contraction of thick copper, grid copper cladding is adopted in the large-area copper cladding area, and uniform via arrays are added to connect the ground planes of each layer, ensuring uniform copper distribution and improving structural stability.

　　2. Strict Selection of High-Performance Matching Materials. All core materials of Szchaopin's high thick copper PCBA are selected for high compatibility with thick copper technology and automotive-grade reliability. The PCB substrate adopts high-Tg (≥170℃) ceramic-filled copper-clad laminate with excellent thermal conductivity and dimensional stability, which can withstand the high temperature generated by thick copper high-current operation and avoid substrate deformation. The thick copper foil adopts high-purity electrolytic copper foil with low resistivity and high mechanical strength, ensuring good current-carrying capacity and thermal conductivity. All power devices, integrated circuits and passive components are selected from automotive-grade products that can stably operate in the -40℃~150℃ temperature range and meet AEC-Q certification requirements. The PCB surface is treated with ENIG (Electroless Nickel Immersion Gold) process to improve the oxidation resistance and mechanical strength of solder joints, ensuring reliable soldering quality after thousands of thermal cycles. In addition, professional automotive-grade three-proof coating is applied to the PCBA to resist moisture, salt spray and chemical corrosion in the vehicle environment. For high-density packaged components such as BGA/QFN, high-temperature resistant underfill epoxy resin is used for reinforcement, which has excellent shear strength and can effectively prevent solder joint cracking caused by thermal expansion and contraction of thick copper.

　　3. Precision Manufacturing and Process Control for Thick Copper Characteristics. To ensure the reliability of high thick copper PCBA, Szchaopin builds a precision manufacturing system compliant with IATF 16949 standards, focusing on solving key process difficulties of thick copper. In the thick copper plating process, a high-current density pulsed plating technology is adopted to ensure uniform copper layer thickness, and the hole wall copper thickness is strictly controlled to ≥25μm, enhancing z-axis anti-expansion capacity and avoiding hole wall breakage. Relying on advanced SMT equipment, micron-level precision control of component placement is achieved, and 3D AOI and X-Ray inspection technologies are used to strictly inspect solder joints, ensuring that the BGA void rate is ≤5% to avoid heat accumulation. In the soldering process, a high-precision reflow soldering process with real-time furnace temperature curve monitoring is adopted, using SAC305 lead-free solder balls with high solder joint shear strength (≥45MPa), which can still maintain good connection performance after 1000 high and low temperature cycles. A full-process traceability system is established, integrating component batches, thick copper plating parameters, soldering data and inspection results of each PCBA into the MES system, realizing full-life-cycle traceability. For the assembly of high-power devices, laser soldering technology is adopted to ensure welding quality and reduce thermal damage to components.

　　4. Comprehensive Reliability Testing for Three-Electric System Application Scenarios. Szchaopin has built a professional automotive-grade reliability testing laboratory, implementing a full-cycle testing system simulating the actual working environment of the three-electric system to fully verify the performance of high thick copper PCBA. Key tests include: High-accelerated Life Test (HALT) to explore the extreme operating limits of PCBA, including high-temperature and low-temperature stepping stress tests (-40℃~150℃) and rapid temperature change cycle tests (temperature change rate ≥25℃/min), verifying the adaptability to extreme temperature changes; Vibration testing (10~2000Hz, 30g acceleration) to simulate road vibration conditions, ensuring no solder joint fatigue or copper foil peeling; High-current load testing to verify the current-carrying capacity and thermal stability of thick copper circuits, ensuring that the line temperature rise is ≤40℃ under rated current; High-voltage withstand testing and EMC testing to ensure electrical performance robustness in the high-voltage and strong electromagnetic environment of the three-electric system; In addition, a 48-hour full-load functional aging test is conducted under high-temperature conditions (125℃) to simulate the actual operation of the three-electric system, ensuring stable performance of PCBA. All tests meet the IPC-A-600J Class 2 or higher standards, ensuring product reliability.

　　Practical Value and Industry Empowerment. In a drive motor controller project of a leading new energy vehicle enterprise, the high thick copper PCBA customized by Szchaopin has achieved excellent performance in practical applications. Test data shows that the PCBA adopts 4oz thick copper design, the high-current loop resistance is reduced by 60% compared with conventional PCBA, and the maximum current-carrying capacity reaches 300A. Under full-load operation, the temperature rise of the power device junction is controlled within 35℃, and the controller conversion efficiency is ≥98.8%. After 2000 high and low temperature cycles (-40℃~150℃) and 1000 hours of vibration testing, no solder joint failures, copper foil peeling or performance degradation occurred. This solution not only helped the customer solve the problems of high heat generation and poor reliability of the drive motor controller under high load, but also reduced the volume of the controller by 15% through optimized thick copper layout, and shortened the product development cycle by 40%. It has been widely applied in pure electric passenger vehicles and commercial vehicles, providing solid technical support for improving the power performance and reliability of new energy vehicles.