Issue link: https://iconnect007.uberflip.com/i/1243344
22 SMT007 MAGAZINE I MAY 2020 use the SPI information to keep things like sol- der paste jetting or solder paste application in compliance within tolerances? Welch: To a limit. Our Koh Young Process Opti- mizer (KPO) now has various printers that have opened up the key print parameters so that we can take control of the printer. First, we do it to perform a real DOE to try to optimize the print parameters. Then, we monitor the process via SPI and fine-tune the print parameters in real- time to stay in compliance. There are still other factors, but at least it's trying to keep the pro- cess in control. There's another module in the KPO tool that looks for patterns and variations in volume across the board. We are trying to maintain or achieve some real-time control of the printing process through the three param- eters of print speed and pressure and separa- tion speed. But you still have to practice good, sound printing process practices on the part of the operator. Johnson: Part of your presentation talks about making sure that you're programming your tests appropriately and testing for the right thing. That strongly implies that good test- ing involves a more thorough thought process while programming the tests. How much skill level is involved in that work? What kind of training is required to be a good programmer with the Koh Young SPI equipment? Welch: The level can be a good process tech up to an engineer. It can't be an operator, per se, unless they're a super operator, but a process tech and above. Every customer I've visited has an issue with programs. Often, the peo- ple who were initially trained by Koh Young have moved on. There has to be discipline in the program itself. I usually start by looking at the programs and making sure that the SPI system is set up correctly, so you know you're getting good, valid results. Then, we can talk more about characterizing the process, which plays back into the printer itself. Johnson: Isn't what you described an HR prob- lem? Welch: Sometimes, large organizations have the CAD or test engineering people create the SPI programs, but that person may have no connec- tion with the print process itself. The person who creates the program may never see it on the line, or the people on the line don't under- stand programming themselves, so there's a disconnect. Oftentimes, when I go there, I'll see something on the screen, and I'll say, "Do you see that?" and the engineers or process techni- cians don't even know what I'm talking about. It reveals the sins of the process, which may be the sins of them creating a program or some- thing with the way they're doing SPI. Johnson: It is the operator or technician attri- tion on the floor that I was flagging as an HR department issue. The trained staff are gone, and somebody who's untrained is now in charge. There's where I point back at HR to make sure that that company has the appropri- ate training programs in place for the people taking over the job. Welch: I agree. I've seen places in manufactur- ing where they're short a person or two, and they walk someone in front of a machine and say, "Run this machine," without good train- ing. Otherwise, the person offering the train- ing candidate might not realize the skill or dis- cipline required to run something like an SPI system, and certainly our AOI systems, which are far more complicated than SPI. Sometimes, they give us the wrong person to train. We are trying to maintain or achieve some real-time control of the printing process through the three parameters of print speed and pressure and separation speed.