In Part One of this series, we explained that of all the systems in a SMT/THT assembly line, automated optical inspection systems have the most scope for development and improvement as they are the least mature technologically, the most complex, very software oriented and highly dependent on computer processing power.
Part One introduced the latest addition to the wide range of Mek (Marantz Electronics Ltd.) AOI products; the Mek ISO-Spector M2 full 3D AOI with Artificial Intelligence. A true, full range, no compromises, fast to program 3D AOI system. Using the very latest that modern technology has to offer in terms of both hardware and software, result is a self-learning, high specification, high accuracy AOI machine that is easy to program with programmer independent inspection results. The fact that it is self-learning with Artificial Intelligence makes the M2 particularly special.
Programmability
A flaw of Automatic Optical Inspection systems, including 3D AOI’s, is that the results are strongly dependent on the experience levels of the programmer. Very simply put, an experienced AOI programmer can get more out of the AOI system and that translates into better inspection results. The reason is that during the programming process the programmer needs to make many decisions autonomously as the software does not make those decisions automatically. As well as the inspection results, the programming time also depends on the experience level of the programmer. Long programing times lead to delays in production. But most of the time unfinished, poorly debugged programs are used for production which eventually also lead to production delays.
To overcome this dependency on the programmer skill level, an AOI system needs to minimize the decisions required from the programmer and to do more automatically. The Mek ISO-Spector M2 gives the same inspection results regardless of who is programming it. This is mostly thanks to the Artificial Intelligence of the system, but also because no libraries are needed. Gerber (Pad) data can be imported and most measurements are carried out automatically without telling the system what type of component is being measured. Programing becomes a short and simple process.
What can be inspected?
When we hear the term full 3D it is usually assumed that every aspect, component, solder, lead, pin etc. can be measured. This is incorrect as most of the so called “full 3D” AOI’s are only able to measure regular component body surfaces and in a few cases the solder joint shape of passive chip components and lead heights of IC’s/QFP’s. It is quite a challenge to measure objects that have irregular shapes like “odd” components or components/objects that are shiny and reflective. So mostly only simple co-planarity measurements are possible on component bodies and for solder joints, it will usually rely on the side lights – which is a 2D inspection.
The Mek ISO-Spector M2 can measure any object that has the height dimension in 3D. This includes all types of components, even those with irregular shapes, solder joints of the tiniest components, THT pins and solder joints, foreign objects etc. There are almost no exceptions for 3D measurement – apart from transparent components because light penetrates through them.
So what can be inspected, or rather measured, is every component that is visible to the camera and they can be checked for presence/absence, XYZ offset, XY co-planarity, correct size, correct type, polarity, lifted leads, all solder joint defect types, bridges, foreign materials etc.
IPC?
When creating an inspection program for an AOI system, besides Cad and Gerber data, a finished PCB is required. The tolerance values of for example component offsets and solder joint volumes are then based on that PCB used for the programming. While this is not the wrong thing to do, if the PCB is visually inspected carefully and the results are satisfactory, it is still unknown whether the tolerances meet the IPC standard values. 3D AOI’s should be a great tool for such tasks.
The Mek ISO-Spector can be set to measure and compare against IPC-A-610 Class I, II or III. With literally one press of a button the measurement can be activated after a program is ready.
Foreign Materials
Another flaw of classic 2D AOI’s is in the detection of foreign materials, parts or objects that are not meant to be on the surface of a PCB. While every object has an XY dimension, it is quite a challenge to distinguish a very thin object, like for example something that is written with a marker on the PCB, or a piece of dust. Then 3D measurement with the Z information comes in handy. It’s still a challenge for some AOIs to skip certain areas, for example where components are placed, and include other areas where there are no test frames.
The Mek ISO-Spector features a full range foreign material detection in all 3 dimensions, automatic skipping of unnecessary areas and automatic inclusion of empty areas. Again, it is literally a matter of pressing a button.
Solder Joints
Of all inspection types, solder joints inspection (or measurement) is the most challenging and undergoes the most scrutiny during evaluation phases. Many assume that if this inspection is done properly, then all other inspections will be done well too.
The inspection/measurement itself, while being challenging for the AOI optics and software, is also the most time consuming and most prone to human mistakes during the programming process. Even after programming it can take a long time for debugging and is always considered as one of the top 3 generators of pseudo defects.
At Mek these challenges are known and overcome with the Mek ISO-Spector M2. Solder joints programming is 100% automatic and Artificial Intelligence based.
Artificial Intelligence
Solder joints inspection is completely reliant on Machine Learning, Artificial Intelligence (AI). The system learns from the process tolerances, from the good solder joints, from defective ones, from its own mistakes and keeps learning during production and doesn’t forget the past. It learns the different pad designs of different users. It changes its decision strategy depending on the solder joint shape and component type and still gives the programmer the freedom to change parameters if necessary. The result is a close to zero false calls rate with maximum detection of defects. The ISO-Spector M2 is probably the first AOI in the market with AI capabilities and one of Mek’s most innovative achievements in its 25 years of experience.
AOI Connectivity
Alongside Artificial Intelligence, ‘Smart Factory’ is another buzz term that has captivated the industry in the last few years. Smart factories demand that all systems in the production line are connected not only “horizontally” but also “vertically” through data management centers (servers, cloud etc.) and communicate with each other via MES or ERP systems, to improve operations. As virtually every system has its own import/export file formats and different sets of data they can import/export, it is a challenge to connect them vertically as every system speaks a different language. This issue might explain the emergence of “a complete production line from the same brand” for which suppliers promise seamless connectivity. Whether that seamless connectivity works, we will not comment upon.
Fortunately there is progress with the introduction of standardized formats. Formats like IPC-CFX to aid vertical communication and Hermes to replace the horizontal communication standard are developments which make such connection possible. So-called mid-layer providers, who deliver a solution that connects various equipment in the factory with the MES/ERP systems (instead of direct connection) make life easier as well.
Mek, as supplier of both 3D SPI and 3D AOI systems, has a proprietary solution, called FIBER System, that connects the SPI and AOI for fast track and trace and defect origin analysis. Also, the FIBER system provides feedback to screen printers and P&P systems. It is fully compatible with integrated line management systems such as Panasonic iLNB and FUJI Nexim and Next-Gen Standards support like IPC-CFX and SEMI SMT-ELS, allowing users to analyze information from the inspection machine and entire production line to inform when to perform predictive maintenance.
Find out more about the ISO-Spector M2 Full 3D AOI System
