Print circuit boards are manufactured in a process that is complicated and rigorous. From the fabrication to the assembly of PCBs, a thorough quality check is done every step of the way. These verifications are essential as any mistake can make the PCB inoperable.
There are various ways to check for faults in PCBs. A few common ones are –
- Manual PCB Inspection: In this kind of inspection, inspectors look at individual boards and assemblies to inspect them for errors. It is an expensive approach involving large manpower, but it still yields poor results as physical inspection tends to overlook a lot of errors.
- X-ray Inspection: As PCBs have more and more IC mounting technologies added to them, some solder joints aren’t visible on the surface. In such scenarios, X-ray inspection helps an inspector see under chips for solder joints. This is also an expensive process and is prone to human errors while the inspection is done.
- AOI PCB Inspection: It is the most widespread PCB Inspection technique.
What is AOI Technique?
AOI stands for Automated Optical Inspection. It captures a collection of images using high-resolution cameras coupled with LED illumination sources. Sometimes micron resolution laser scanning in X, Y, and Z axes is also performed to capture such images. Depending on the system, either of the above processes is used. For instance, solder paste inspection uses a laser scanner for volume detection while assembly verification will use imaging to detect solder components.
How does it work?
The PCB is first manually inspected for defects. Once it has passed the first quality check, the PCB is run through an AOI system. The AOI system then refers to the images predefined in its system and compares them with the images of the PCB clicked. It then identifies any difference between the two images, for a more thorough check. The AOI system inspects the circuit board in various phases of its life cycle, starting from fabrication to assembly. AOI systems primarily validate the manufacturing process used with the help of specifications provided to them. It checks if the designated components are positioned, installed, and soldered correctly.
What are some disadvantages of AOI?
- Even though AOI is the most efficient technique when compared with manual inspection or X-ray inspection, it still is a rigid and inflexible system where predefined and generalized images are compared with the pictures of the PCBs taken. They leave no room for customized PCBs that might be company-specific.
- APIs are coupled with manual inspection, which is expensive and shows that AOIs cannot work independently and need human intervention to perform properly.
A new and emergent technology, called Machine Vision, can fix all the issues that AOI has.
What is Machine Vision?
Machine vision is the capability of a computer to understand and perceive its environment. Machine vision takes the help of video cameras to capture useful information and then send the data into the computer where artificial intelligence algorithms process the data. Such data can also be used to operate a controller or a robotic limb so that it performs a certain task based on the commands it has been given. Machine vision can perform object recognition, pattern recognition, material inspection, and so on.
How does Machine Vision help in PCB Inspection?
Machine vision uses cameras with high frame rates and resolution to capture detailed and precise images of the PCB. This data is then compared with the training data provided to the machine vision model. The training data can be customized according to the needs of the company and the kind of PCBs they make. Deep learning algorithms will use this training data to learn, detect, and even name various components inside the PCB. Depending on the complexity of the pattern, a machine vision model will require a varying size of datasets to correctly inspect any PCB. As the model starts working, it also begins learning more and gradually improving its accuracy over time.
How is Machine Vision better than AOI for PCB Inspection?
- Machine vision models are fully customizable, giving the company a wide range of choices and flexibility over how they design and inspect PCBs.
- Machine vision works with the least human intervention and a large number of manual operators will not be required on the field.
- Machine vision improves the accuracy and efficiency of the inspection process and helps reduce production time.
- Machine vision is self-learning and as more data is provided to it, the efficiency and accuracy keep on increasing.
How to find machine vision technology in India at low prices?
Qualitas EagleEye is a visual inspection system that uses AI and deep learning to develop powerful visual inspection solutions that are backed by cloud computing technology. It decreases false positives and increases error detection rates. It stores training data in the cloud and hence doesn’t require onsite infrastructure. This lowers the price of this model. It also has a lightweight and modular design that cuts costs without sacrificing the efficiency of the model.
The resultant technology in turn optimizes costs by reducing the delay caused because of errors and long inspection hours. All these features make Qualitas EagleEye Platform a low-cost and high-performing machine vision model.
Thus, PCBs are complex structures that require inspection at every stage for their proper functioning. There are a lot of existing inspection methods, and the best among them is Automated Optical Inspection. Errors are handled better with AOI. However, this technique takes the help of manual operators, which increases the cost without reducing the time.
Machine vision technology accounts for all the shortcomings in AOI along with providing a customizable palette of PCBs suited for each company’s needs. Such a visual inspection model results in increased production and turnover in any company.