Interfaces for RFID and robots in SMT lines

(image: copyright ASM)

I covered the subject of interfaces for robots and operators in a previous blog post. After raising many questions in this regard during several presentations, I would like to talk about a few details today.

Interfaces

Most IoT discussions of interfaces are limited to data interfaces. Unfortunately, this excludes many challenges on the road to the smart SMT factory. Networking the hardware in the smart factory requires the standardization of interfaces in many different areas. Here are some examples:

• Machines and systems from different manufacturers must be able to talk to each other. This requires uniform data protocols and standards (whether the connections are wired or wireless).
• Individual workpieces must be identifiable. This requires technologies and interfaces.
• Materials must be recorded, transported to specific points on the line, and assigned to workpieces in a manner that’s traceable.
• Machines and system must have ergonomic mechanical interfaces for operators, whether they are humans or robots.

This short list already shows that interfaces involve more than data standards.

Human-machine or robot-machine interface?

I had mentioned in my earlier blog post that today’s SMT lines are designed for human operators. The splicing process demonstrates this perfectly. People have repeatedly asked me about auto-load feeders and their role in the factory of the future. It is true that this technology can extend reloading times and reduce the likelihood of material-related line stops. On the other hand, auto-load feeders automate only a single splicing interval and are still designed for human operators. Steps during refilling such as unlocking and locking, cutting, punching, inserting the tape into the feeder and removing waste are a cinch for humans, but herculean tasks for robots. In short, auto-load feeders aren’t suitable for advanced automation tasks in the smart SMT factory.
The new SIPLACE BulkFeeder with its tapeless component supply is much more advanced. Replacing cartridges with loose components is much easier for a robot and therefore much more easily automated. Even single steps in the BulkFeeder’s workflow like the refilling of cartridges can be automated.

RFID is not problem-free on SMT lines

A few words on employing RFID technology for identifying workpieces or circuit boards. At its core, RFID technology seems well-suited for the PCB identification, but the devil is in the details.

• Metal everywhere:
  On SMT lines, circuit boards run through printers, placement machines, ovens, inspection systems and other machines. They are surrounded by metal everywhere, making life difficult for RFID.
• Conveyors, clamps and pin supports:
  As the boards travel through the SMT line, they must frequently be clamped in place and mechanically supported (during printing, placement, etc.). This limits the locations where RFID components and antennas can be positioned.
  
• Reader ranges and component heights:
  Today, many connectors and odd-shaped components are placed in SMT machines. The potentially tallest component (and the room in the machine) controls the minimum distance between the reader and the circuit board. As a result, readers and transponders are quite far apart in some products/applications and must be fairly powerful to make the read process work.
• Panels and two-sided placement:
  For efficiency reasons, many small modules are frequently manufactured as a single large panel that cut apart after the placement process.
  
  This graphic shows the problem: The read/write antenna captures multiple RFIDs from different modules quasi simultaneously. As a result, the system may have trouble determining which RFID belongs to which module. For traceability reasons, however, the system would have to be able to know exactly which module was populated with which components and where faults were found.

Don’t get me wrong. This is no rejection of RFID technology, but merely a detailed look at the challenges involved in electronics production. Only someone who is aware of them can resolve them.

Next steps

We in the ASM development departments are working continuously on matters involving robot interfaces and RFID. Our experience with ongoing customer projects shows that the use of RFID requires close coordination between the electronics manufacturer with his specific process requirements and the machine supplier. Our teams can provide lots of help and expertise in this regard.
As far as robot interfaces are concerned, we are running several evaluations to determine in which areas of warehousing, setup, production, testing, etc., robots make economic sense and which interfaces can be adapted and put to use. These assessments are happening in addition to the “abstract” activities and tests in our development departments as well as in concrete customer projects in cooperation with robot manufacturers. The standardization of robotics-compatible interfaces for electronics manufacturing applications is still far off, but in specific projects they make a lot of sense – both technologically and economically. See also the post by Alessandro Bonara.