The quality of Printed Circuit Boards would determine the quality and reliability of the application. Due to the uprising developments trends towards the halogen-free, lead-free environment, using the right inspection techniques is imperative.
If you ignore timely inspection, your PCB is bound to have all sorts of failures such as delamination, crack, wettability, etc. Therefore, to ensure the quality of a Printed Circuit board rigid, rigid-flex or flex PCB manufacturer needs to implement circuit board inspection at different stages.
To detect and eliminate surface defects, inspection processes should be implemented into the assembly procedure as well. In addition, implementing these inspections will help determine the defect in time. You will not have to wait for the electrical test to find the error.
Incorporating different inspection techniques offer effective, efficient and reliable results. Likewise, finding defects on time is valuable for data accumulation for SPC (Statistical Process Control). Since timely defect defection is imperative, therefore, we are going to talk about some effective techniques.
Different Types of Inspection Techniques
Moreover, to ensure that the inspection technique generates effective results, you need to implement them at various stages of the manufacturing and assembling process. Thus, ensuring effective and efficient results.
Above all the inspection techniques, you have a visual inspection technique. You can use visual inspection at different stages of the PCB manufacturing process. In addition, there are different equipment that you can use for visual testing including prism, etc.
However, do bear in mind that choosing the equipment for visual inspection depends upon the position of a target you want to inspect. For instance, you would have to use prism for inspecting the reflow solder joints. When the joints reflect the light rays, this helps the professionals in finding numerous manufacturing defects. With this type of inspection, you are generally able to test 5 joints in one second.
Likewise, experts are able to determine defects with the naked eye after they devise placement and solder paste printing. For instance, the common defects that they find include missing components and solder paste issues.
Visual inspection is an effective technique provided you have experienced and well-trained staff. In addition, its quality depends upon your inspection standards and how well-aware are the inspectors regarding the solder joint’s technical requirements.
After all, each solder joint can have around 8 different types of defect standards and there are about 6 different solders joints present on in PCB. Therefore, we do not recommend a visual inspection of the quantitative measurement of the structure control process.
In addition, we do believe that visual inspection isn’t the best choice for hidden solder joint inspection especially the ones that we have on ultramicro fine flat square devices, J-lead devices, BGA devices or surface array flip-chip.
According to specific rules and uniform establishments, we regard visual inspection at a low cost and easily available technology. Thus, it can be applied to a large number of defect inspections.
Structural Process Test System
You can drastically improve the repeatability and allowance of visual inspection by incorporating automatic video capture and real-time analysis system. The SPTS majorly depends upon some form of emitting light such as X-ray, laser beam or visible light.
Moreover, to find solder joint quality defects, these systems use information gathered via the processing images. Likewise, it is possible to implement a structural process test system for visual inspection without coming in contact with the circuit board.
STPS is effective and efficient. It does differ from the usual visual inspection. Also, it promises result, as it ensures, eliminates subjectivity and ensures high repeatability from defect measurement.
|After the Printing of Solder Paste||Magnifying Glass or Naked eye||汚染と印刷の欠陥|
|After the Placement of Component||Magnifying Glass or Naked Eye||Disoriented components, misplaced components or missing components|
|After Reflow||Light Source, Magnifying Glass or Naked Eye||ツームストーンニング、オープンジョイント、はんだブリッジなど。|
Automatic Optical Inspection
The automatic optical inspection uses a number of light sources in order to find defects. For instance, it might use cameras to throw lights on solder joints or programmable LED library. The objective is to shed some light on the shed joints and take clear pictures.
Although automatic optical inspection techniques are effective in comparison to manual visual, they are expensive. The modern Printed Circuit boards are way more complex and denser instead of their predecessors. Therefore, a smart PCB assembly manufacturer would use X-rays and leaser beams instead of visible light.
After all, the objective is to find as many defects as possible in an effective and effective manner. Incorporating a Structural process test would ensure high repeatability. In addition, it would help remove measuring defects’ subjectivity.
NOTE: Automatic Optical Inspection is an excellent choice for Gull-wing and ICs devices that have a pitch bigger than 0.5mm.
X-Ray Fluoroscopic System
The technology uses a single point of a light source to emit a beam of rays. So, these beams vertically enter the circuit board. There is no denying that X-Ray Fluoroscopic is an effective technique.
However, with double-sided PCB, X-ray Fluoroscopic system might not be able to generate effective results and the reason being, the solder joints weaken the ray’s intensity to a great extent.
Since in double-sided PCB, solder joints are present on both sides, thus the technology fails. Another reason for its failure is the overlapping of X-ray images.
However, when you use this technology on a single-sided Printed Circuit Boards, it produces accurate results. Furthermore, you will be able to determine different solder joint defects including misalignment, bridging, void, insufficient solder, crack among others.
Most of these joints defect take place passive chips, Gull-Wing devices, and J-shape wiring devices. In addition, ALT is an effective inspection technique to find missing components. Similarly, PCB assembly manufacturer can use it for inspecting the reversed tantalum capacitors.
Automatic Laser Test Measurement
To test the height and shape of solder joints and to verify the deposition of solder paste, you would need more a direct technique such as ALT. To measure the reflectivity and height of some components, the technology uses a laser beam and multiple sensitive detectors.
These detectors maintain a certain angle with the laser beam to find defects in an efficient manner. Moreover, Different detectors are responsible for different aspects of a PCB. For instance, the position-sensitive detectors are responsible for measuring the surface height. Likewise, the reflected light beam determines the surface reflectivity.
However, the system can have multiple reflection and shielding which results in a lack of efficiency. To avoid shielding and eliminate multiple reflections, the system should test the reflected beam along an optical path that is independent.
In addition, ALT systems provide real-time accurate data regarding solder paste’s structural process control including cleanliness, viscosity, squeezing speed, alignment, fluidity, and stress.
|Inspection Technique||Types of Defect||Inspection Speed||Inspection Cost|
|Manual Optical||Contamination and Printing Defects
|自動光学||Contamination and Printing Defects
|自動X線||Mult-Layer PCBs’ Internal Defects
At 6pcba, we have the best inspection techniques in place. After all, it is our objective to ensure the highest inspection stands to deliver high-quality, reliable and effective Printed Circuit Boards. Regardless, the type of Printed Circuit Boards, you want, we will deliver only the best.
We excel as a flex PCB manufacturer as well as other types of Printed Circuit Boards. Similarly, our experienced designers and engineers are able to come up with effective, yet inexpensive solutions. We are the leading PCB Assembly manufacturer and we promise to deliver the best.
You can reach out to us:
Phone: +86 (755) 2328-7815
Email: [email protected]