Inspection and Design for Testability
I recently spoke with Matthias Müller of Goepel electronic about test and inspection technologies, especially in the automotive industry. In this interview, Matthias also discussed design for testing (DFT) and the benefits technologists can gain from DFT.
Barry Matties: First, why don't you tell us a little bit about your organization and what you do.
Matthias Müller: Goepel electronic is based in East Germany, and founded in 1991. We specialize in test and inspection technologies for the electronics, manufacturing, and automotive industries. This means we have solutions for the development of electronics, electronics production, and even for end-of-line tests of ECUs for cars and the automotive industry. We also have inspection systems for bigger components, like entire car seats.
Matties: For car seats?
Müller: Yes, for car seats. Goepel electronic offers an end-of-line platform called OsCAR which can test, for example, airbags, belt buckles, seat occupancy detection or movement modes. We now have a system that works a little bit like a 3D AOI system for PCBs where you can inspect an entire car seat and find out if there is any fault, failure, or anything that’s not what it's supposed to be.
Matties: What sort of defects? Like stitching defects?
Müller: Yes, or for example, local deformations. But there are also a lot of electronics and motors in the seats of more modern cars with many dynamic functions for increasing security and comfort, such as massage functions. You see, the test system can be utilized across a wide range of requirements. We provide test and inspection solutions from the development of electronics until end-of-line tests of the entire car seat.
Matties: Fantastic. We're here at the electronics show primarily for assembly on the SMT side and you carry a wide range of products for this segment of the supply chain from solder paste to 3D final inspection. Can you talk about your philosophy when it comes to testing? What's your approach here?
Müller: Yes. Our approach is to cover almost 100% test coverage and offer solutions for various requirements. A lot of our customers are mid-sized companies and they may have other test and inspection strategies as a global manufacturer, so we always talk with the customers to find out what they really need. For instance, some customers need X-ray inspection for the PCBs and we have two solutions. Some of them need a 100% X-ray inspection of the PCBs, and others need a selective inspection of just some components. Our approach is to give the customers the best solutions to meet their needs.
Matties: There's a lot of competition in the inspection area in this segment. How do you position yourself to stand out from all the others?
Müller: One point, of course, is that our products are made in Germany. A lot of customers are interested in products made in Germany, and the demand is increasing! Not just because of the good quality of the products, but also, and this is the second point, the good support we can offer. Our philosophy is to give the customers the best support we can give them.
Matties: What kind of support would they need? Is it a process challenge or is there an actual issue with the equipment?
Müller: It depends. For the most issues, telephone support and remote access are the right choice. In the unusual case of a hardware problem we send our engineers.
Matties: Yeah, things do wear out and break down or whatever the case may be.
Müller: Sometimes there is 24/7 production and you know the machines are working non-stop, and sometimes they need to be adjusted or something has to be replaced.
Matties: When I look at the choices people make, not to say your service isn't outstanding, but I think every one of your so-called competitors would say the same thing—we offer great service, we are customer-centric, etc. But from a technological point of view, what sets you apart?
Müller: Yes, the competition is hard. But our systems offer a flexibility for a wide range of inspection tasks, within one machine. For instance, the AOI systems have various illumination techniques, so that the customer can chose between ultraviolet or infrared illumination, depending on the components. But of course, sometimes it's just a decision by the price.
Matties: Price is always a factor.
Müller: Yes, price is always a factor. In Europe, and in Germany, we do not have the lowest prices, and we are not the cheapest, but we aim to give the customer reliable and intelligent products, especially when it comes to networking or smart factories. We want to provide interfaces in our machines that will fit into the production process and into our customers’ smart factories.
Matties: Can you talk about the smart factory?
Müller: At the moment, the Hermes standard is starting here in Europe and in Germany, where a lot of companies, even competitive companies, take part to develop interfaces to allow data transformation between different systems of different suppliers.
Matties: Are the customers coming in and asking for this, or is this a feature you guys are taking to market?
Müller: Both. Sometimes, the customers of our customer (EMS customer) demands traceability. On the other hand, a smart factory makes production processes more efficient. The central multi-line verification that we offer can increase the production throughput significantly. MES connections and interfaces like SMEMA have existed for years, and the new standard is a more-advanced step towards machine-to-machine communication.
Matties: When customers are looking for data, what sort of data are they coming and asking you for? Are there any special requests?
Müller: Yes, of course. Inspection results from different inspection systems need to be stored so that you can trace the product after a long time if there was an SPI or AOI problem before and adjust your printing process. This is the data customers are asking for so they can find out if there is a problem in the printing process, and if so, why and where. This is an example for the quality data of the PCBs in every step of the production.
Matties: And they can find it out in real time so that they can make adjustments?
Müller: Yes, they can find it in real time very easily. They don't have to stand directly on the side of the production lines. Some customers have five, six, or seven production lines. Sometimes it's just enough to sit in your office at your desk on a tablet or mobile device. You can see the status of your production line and every system. You can see how many PCBs are on this system or on this conveyor, so you have an easy way to control your smart factory.
Matties: When it comes to testing, if a fabricator came to you and said, "What's the best advice you could give me regarding testing or inspection," what would that be?
Müller: That's not so easy to say because it depends on the products and what the customer is producing.
Matties: Is there a general approach that people should consider when they're taking testing or inspection into consideration?
Müller: Yes, we would say inspection of the components, like AOI, is a very important factor. 3D AOIs are a very big phrase, but sometimes it's just enough to do a good 2D AOI. After all, it depends if the customer is an OEM or EMS provider. You have to consider the component range and the volumes of production.
Matties: There's a lot of choices out here, from 2D to 3D, types of imaging that you can get from a machine, different approaches you can take, and all the shadowing that you must take into consideration. You’re introducing some new equipment today or this week for large THT, right?
Müller: Yes, through-hole technology. When it comes to high energies, high voltage PCBs, especially for solar energy or electronic cars, for instance.
Matties: Right. The automotive industry for sure.
Müller: There are still big components, huge solder joints, and it's not always getting smaller, so sometimes you need to rely on the bigger issues.
Matties: As we talk about automotive, you mentioned you had an inspection. In the automotive industry, 50% of the value or more is going to be electronics and vehicles are turning into computers with wheels.
Müller: Yes, even more.
Matties: I would think that this sort of testing is becoming more and more critical.
Müller: I think the automotive industry is one of the most important industries in electronics manufacturing because the number of products and the amount of throughput they have is so amazing and huge that they need reliable inspection systems for their production lines. Even in the middle-class cars, the electronics are increasing, and I don’t think that will change in the near future.
Matties: The cost of failure is so expensive and catastrophic. It could lead to the recall of millions of cars. The idea is to avoid this with inspection upfront, right?
Müller: Yes, that is the idea. Goepel not only offers solutions for the test of the PCBs themselves or for the electronics in the car, but we also have a division that just focuses on the automotive industry. Modern cars have hundreds of ECUs in a complex network. You have to test not only whether the ECUs in the car are working, but also if they’re working correctly in the environment. We offer software and hardware solutions to create the environment of a car. This is also a huge market.
Matties: When you're looking at the automotive industry and testing, it really starts with the circuit board design, doesn't it? Do you ever get involved with the circuit designers as they’re designing board?
Müller: Not especially in the automotive industry, but more in the EMS industry. It's always an issue between developers and the production people because the production people want the best possibilities to test their PCBs and the designer wants to make it small. And that's a problem.
Matties: It’s not always aligned.
Müller: Right. When it gets smaller, it's more difficult to test electronics. We help customers in the design process by providing information that can help them design their electronics smarter for the later inspection and test processes.
Matties: Test-friendly designs, basically.
Müller: Design for testability, we call it. There are some things you must think of when you design electronics and PCBs. When you have done this, you can make your inspection and test process easier afterwards.
Matties: A designer with this sort of knowledge becomes far more valuable to the automotive manufacturers or the developers of automotive electronics, or any electronics for that matter, because we should be always thinking of design for testability, right?
Matties: Is testing a value-added process?
Müller: In the first place, not. But recall actions are more expensive, which means, no way without testing.
Matties: For the insurance policy.
Müller: Yes, it’s insurance policy, and it's also important for the traceability. Imagine if there is a problem with the car or even with an entire range of cars. Someone has to find out why and where, so when it comes to the electronics manufacturer, they can say, "Okay, give me the PCB I can find out if there has been anything in the process or not."
Matties: You mentioned solder joints, and I also see you are introducing a new SPI system here. Can you tell us about that?
Müller: Most of the problems in the electronics manufacturing process appear on the soldering, in the paste printing process. It's statistically clear and you have to have 3D SPI because you have to measure the volumes of the printed solder paste. I think every electronics production needs to have an SPI system.
Matties: There's a lot of systems on the market place, so what's new in your system here?
Müller: What’s new is that we have more detailed optics to inspect even the lowest heights for soldering pastes and for PCB substrates. You can have a reliable SPI inspection up to 30 microns, which is getting more and more important because it's not always the big solder paste, it's the smaller ones that are getting important today.
Matties: Right. And when a company uses a system like this, what sort of gains do you think they receive in yield? Is there some empirical data where you've done analysis that says SPI will add a given percentage to your yield, for example?
Müller: What we can say is that a good inspection system lowers the fault calls, and this is an important thing. If the inspection system finds a fault and someone has to go there to verify this fault, and if the system is not working correctly and the PCB is done great, then it's a fault call.
Matties: A lot of wasted of time.
Müller: Yes. They have to go there to look. It's a waste of time. A good inspection system lowers these fault calls. With a smart factory, you can sit in one place and see all the data. You don't have to go there, you just click on a screen, find it, and see if there is a fault or not. It is important to lower these fault calls because it saves time and money.
Matties: Ultimately, it saves defects too, right? Because some are actual faults?
Müller: Yes, some are. You will always have that. That’s normal, but you can save a lot of time.
Matties: Definitely. Is there anything we haven't talked about yet that you feel like we should cover today?
Müller: Earlier, I mentioned the X-ray system is getting more and more important. Some years ago, only a few customers had X-ray inspection because it was expensive, but PCBs are getting smaller. Solder joints are more underneath the components and not just around the components, so there is no way to inspect it via 3D AOI or whatever. You can't see it.
You may have an electrical test that shows it's working fine, but for how long? X-ray inspection is very important for the automotive, military, and aerospace industries. Then we have the two strategies I mentioned before. You can have a complete inspection of the entire PCB, of every solder joint, or you can just quickly inspect some of the components, like processors, VGAs, or FPGAs in high resolution and 3D. You have to have 3D inspection of the X-ray inspection.
Let me give you an example for when I talked about 3D AXI and providing value. We had a customer that had problems with his PCBs. They were broken at the end. He had taken a normal X-ray system and found voids in the bigger components. We didn’t think there was a void between the component and the PCB, so we used 3D AXI where you have layers upon layers. We found out that the void was not inside the solder joint between the component and the PCB, but it was inside the component. There was a component with a package and contact, and the void was inside this package. We called the customer and he said that he had changed his supplier for these components to a cheaper one.
Matties: You get what you pay for.
Müller: It didn't work. We found out that it wasn’t a problem with his production process, so we gave him valuable advice.
Matties: Very valuable. You're revealing a world that's never been seen.
Müller: It’s very interesting to see voids or head-in-pillow defects even in the smaller solder joints where the solder joint isn't correct. This is a big issue.
Matties: I know we don't look at inspection as a value-added process, but there’s no doubt it adds value because it adds data and data is incredibly valuable.
Müller: Yes, data is very important, but you don't just collect data. You have to do something with it.
Matties: You have to interpret it, understand it, and then act upon it.
Müller: Yes, and then you can add value to your entire process.
Matties: Right. And ultimately increase yields, capacity, and capability.
Matties: Thank you so much for sitting down and chatting with us. We appreciate it very much. It's always good to hear from you.
Müller: Thank you. It was great talking with you.