PCB assembly services play an increasingly important role in the industrial control industry, including circuit board design, printed circuit technology, assembly, testing, quality control, etc. Each step requires strict control and efficient management.

1. Industrial Control PCB Assembly Solution Process

● PCB Design

PCB design is to convert the schematic diagram into a PCB layout diagram, ensuring that the design meets the specifications of the PCB manufacturer, including minimum spacing, minimum aperture, number of layers, etc. At the same time, the bill of materials (BOM) is generated, listing the detailed information of all components, including model, quantity, package, etc.

● Component Procurement

Purchase high-quality components and PCB materials, select PCB materials suitable for industrial control applications, such as FR-4, ceramic substrate or metal substrate, considering temperature, electrical performance and mechanical strength

● PCB Fabrication

PCB boards are manufactured through processes such as etching, drilling, gold plating, solder mask, copper coating, and lamination, ensuring that each process meets standard requirements and guarantees the quality and stability of the circuit board.

● PCB Assembly

Various SMD components (surface mount components) will be precisely placed on the printed circuit board. These components include resistors, capacitors, diodes, transistors, integrated circuits, etc. SMT patch is an important part of automated production, which can greatly improve production efficiency and quality. The mounted components are soldered to the PCB through the reflow oven to control the temperature curve and avoid welding defects.

● Testing and Quality Control

Testing can effectively ensure the quality and stability of PCBA, including optical inspection (AOI), functional testing, X-ray inspection and environmental testing, etc., to avoid losses caused by PCBA failure.

Optical inspection (AOI):  Use automatic optical inspection equipment to detect welding quality and component position, and find problems such as misalignment and leaking.

X-ray inspection:  Perform X-ray inspection on invisible solder joints such as BGA to ensure the quality of internal solder joints.

Functional testing:  Perform electrical functional testing on assembled PCBs to simulate the working environment and verify their performance and reliability.

Environmental testing:  Perform ecological tests such as high and low temperature cycles, humidity, and vibration to ensure the stability of PCBs under extreme conditions.

● Finished Product Assembly

The finished product assembly process is assembling the tested industrial control PCBA board into a shell. The finished product surface is scratch-free and then tested. Finally, the electrostatic packaging is completed. Finished product assembly includes cleaning the PCB surface, applying three-proof paint when necessary to prevent moisture, dust and chemical corrosion, and providing detailed industrial control PCB assembly test reports, declarations of conformity and related certification documents, such as RoHS, CE, etc.

2. Selection Tips for Industrial Control PCB Boards

● PCB Board Material

Industrial control PCBs can usually choose FR-4, ceramic substrates, metal substrates, etc. FR-4 has good electrical insulation performance and mechanical strength, and is suitable for most industrial control equipment applications; ceramic substrates and metal substrates are suitable for high-temperature, high-power industrial control working environments. For high-quality industrial control motherboards, the color and gloss of the PCB boards are almost consistent, and most motherboards have 6-10 layers. Multi-layer boards can achieve higher circuit density, better electromagnetic compatibility, and stronger anti-interference ability. Reasonably design the PCB stacking structure to ensure signal integrity and power integrity, and reduce electromagnetic interference (EMI) and electromagnetic compatibility (EMC) problems.

● Power Circuit

The power circuit plays a vital role in industrial control PCBA, especially for the stable operation of CPU (central processing unit). As the core component of industrial control PCBA, CPU requires a stable voltage source. Any voltage fluctuation may cause system instability or damage. Therefore, the power supply design must provide stable voltage output to ensure stable and reliable power supply for the operation of industrial control equipment.

● Capacitor Quality

Capacitors are very important electronic components in industrial control PCBs. They are used to stabilize voltage and current, filter and store energy. Their capacity and quality directly affect the stability and life of industrial control motherboards. Capacitors can be roughly divided into three types: 

Ceramic capacitors (MLCC): commonly used for decoupling and bypassing, with low ESR (equivalent series resistance) and ESL (equivalent series inductance), suitable for high-frequency industrial control electronics

Electrolytic capacitors: suitable for large capacity requirements and low-frequency filtering applications, with large capacity but high ESR, and life limited by temperature and voltage

Film capacitors: have good stability and low loss, suitable for high-frequency filtering and high-voltage industrial control environments.

Capacitors are distributed in different positions on industrial control motherboards according to their respective characteristics and functions.

● Environmental Adaptation

Select high-temperature and low-temperature resistant materials and components to ensure stable operation of PCB in various industrial control equipment. For example, industrial-grade or military-grade components, which have been rigorously tested and can work reliably in a wide temperature range, are used. During the PCB manufacturing and assembly process, environmental tests such as high and low-temperature cycles, humidity, and vibration are carried out to verify the circuit board's performance under various extreme industrial control conditions.