The features of rigid PCB assembly mainly include the following aspects:
Mature processing flow
The processing flow for rigid boards is relatively mature and standardized. Processes such as etching, drilling, and component insertion can be efficiently completed using conventional equipment.
Stable structure
Rigid boards have a stable structure and excellent electrical performance. They can carry a large number of chips, resistors, capacitors, and other components, providing a reliable installation and operating environment and ensuring the stable operation of the equipment.
High precision requirements
As the precision requirements of electronic products continue to increase, the manufacturing processes for rigid boards are also constantly improving and upgrading. For example, in the production of high-precision multilayer boards, control over interlayer alignment and through-hole quality has become increasingly strict.
Wide application
Rigid boards play a dominant role in the core components of consumer electronics such as motherboards, graphics cards, and sound cards. At the same time, they are also indispensable in key parts of automotive electronics, such as engine control systems, in-vehicle computers, and braking systems.
Assembling process
The process of rigid PCB assembly mainly includes the following steps:
Preliminary preparations
Component inspection:
Ensure that the quality and specifications of the components meet the requirements, including checking the coplanarity and solderability of the pins. Qualified components are placed in feeders or trays for use by the Surface Mount Technology (SMT) machine.
PCB preparation:
Ensure that the surface of the PCB is clean and free of oil stains. At the same time, prepare the solder paste printer, SMT placement machine, reflow oven, and other equipment, as well as the necessary auxiliary tools.
Solder paste printing
Use a solder paste printer to evenly apply an appropriate amount of solder paste onto the solder pads of the PCB. The amount of solder paste and the uniformity of its application directly affect the quality of the subsequent component mounting and soldering processes.
After printing is completed, the quality of the solder paste printing is inspected using an SPI (Solder Paste Inspection) device to ensure the uniformity and accuracy of the printing.
Component mounting
According to the specifications of the components and the PCB, set the parameters of the SMT machine, including component specifications, positioning methods, and solder paste locations.
The pick-and-place machine automatically picks up components according to the preset program and places them precisely in the corresponding positions on the PCB. This process requires high-precision equipment and technical support.
Reflow soldering
The PCBs that have been surface-mounted are sent into the reflow soldering oven. By controlling the temperature and time profile, the solder paste melts and forms strong solder joints with the component pins. The temperature profile setting for reflow soldering has a significant impact on soldering quality and component reliability.
Quality inspection
The AOI (Automatic Optical Inspection) system is used to check soldering quality and component placement, quickly identifying soldering defects and placement errors to ensure product quality.
Faulty boards identified during inspection are manually repaired to fix defective solder joints or misaligned components.
Final board separation and cleaning
To separate multiple PCBs from the panel (mother board), V-cut machines or punching machines are usually used for the board separation process.
PCBs that have undergone the separation process are then ground and cleaned to remove any excess burrs and residues, ensuring that the board surface is clean and smooth.
Company capability
Our company has more than 50 automatic PCB assembly production lines imported from Japan and Germany. We can provide automatic PCB assembly, advanced PCB assembly, and rapid PCB assembly services.
Fast PCB assembly means a 1-day lead time for prototypes, which helps our customers save significant time in new product development.
Quality assurance of PCB Assembly
PCB Assembly quality inspection mainly includes the following aspects:
Component Placement Accuracy
Check whether components are placed accurately on the designated pads.
Verify that there is no offset, misalignment, or rotation.
Ensure that components are properly aligned and not tilted.
Component Polarity and Orientation
Inspect whether polarized components (such as diodes, electrolytic capacitors, ICs, etc.) are mounted in the correct direction.
Prevent reverse installation or incorrect orientation.
Missing or Incorrect Components
Check for missing components.
Verify that the correct components are used according to the BOM.
Ensure there are no wrong parts or incorrect specifications.
Soldering Quality
Inspect whether solder joints are full, smooth, and uniform.
Check for common soldering defects such as:
Cold solder joints
Solder bridges (short circuits)
Insufficient or excessive solder
Solder balls
Component Condition
Check whether components have defects such as:
Tombstoning
Component standing or lifting
Damaged components
Bent leads
PCB Surface and Pad Condition
Ensure that the PCB pads are clean and undamaged.
Check for contamination, oxidation, scratches, or foreign particles on the PCB surface.
Inspection Equipment
In SMT production, the following equipment is commonly used for quality inspection:
SPI (Solder Paste Inspection): Checks the quality of solder paste printing.
AOI (Automatic Optical Inspection): Detects placement errors and soldering defects.
X-ray inspection: Used for hidden solder joints such as BGA and QFN packages.
Visual inspection: Manual inspection to confirm assembly quality.
Electrical and Functional Testing
In some products, additional testing may include:
ICT (In-Circuit Test) to verify electrical connections.
FCT (Functional Test) to ensure the assembled PCB operates correctly.
In summary, SMT placement quality inspection focuses on component placement, polarity and orientation, soldering quality, component condition, PCB surface condition, and electrical functionality to ensure the reliability and quality of PCB assembly.
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