‘Testing’ a Strategy

Estimated reading time: 3 minutes

To get a front-line perspective on test and inspection, we spoke with Raj Vora, manufacturing engineer, and Darren Carlson, operations manager, at San Diego-based VAS Engineering, a company that has been paying careful attention to operational efficiencies. “All roads lead to Rome,” they say, so it seems any operational efficiency work ultimately leads back to data and analysis. In this conversation, Raj and Darren share how test and inspection equipment is vital to the efficiency of the entire manufacturing structure. 

Nolan Johnson: When you consider your overall business operations, where does test and inspection fit, and what challenges do you see in inspection? 

Raj Vora: Inspection is the bane of our existence, yet it’s so crucial to the whole operation. We run in-line AOI on every single board on all three lines. If there's any add-on work—whole mechanical assembly, for example—we do a 100% final manual inspection as well. 

One of the challenges is the false calls on some of our machines in SMT. We are trying to alleviate that issue by replacing all our inspection equipment. 

Barry Matties: What is the strategy when you're looking at equipment? How are you looking to the future to influence the decisions you're making today? 

Vora: One big piece of the puzzle we want to solve is MES software. Real-time feedback is key. Let’s say we're running a job; a reference designator sets off a couple defect conditions and, hopefully right then and there, MES-related real-time software can lock the line and correct the mistake before we start making more of that mistake. We're headed there very quickly; we're already in the RFQ process for MES software. 

We have a lot of good software, but much of that data is just not wrapped into one nice suite. That’s one big problem we have. The second problem was that we want better shop floor control, so we’ve digitized our inventory. Now our inventory management system acts like a database, and that has been a big quality improvement for many reasons. 

Now we're going after quality and all the data that is tied together to understand it. Quality could have many different pieces to it. We've already built some custom in-house software, but we want to become an advanced facility. 

We don't do solder paste (SPI) or pre-reflow inspection because we've haven't found the need for it. The post-reflow data tells us that our process is in good condition. We attribute that to high levels of continued maintenance and the knowledge level of our in-house staff. Almost 95% of all maintenance on equipment is done by our in-house crew. 

Matties: Regarding your SPI, will the finer features coming in result in you changing your strategy? 

Vora: We'll let the data tell us. We are producing boards with 01005s already. For example, we have one board that has 25-line items that are 01005 with 40–50 placements out of a total of 185 placements, just on a board the size of a dime. 

Matties: Is this with stencil or jetting? 

Vora: Stencil. In this case, we have a lot of tech inside the stencil. While the stencil normally costs $200, this is a $1,000 stencil with a few tricks built into it. We've been wildly successful with it. 

Matties: Are you looking at jetting as well? 

Vora: We don't find a need to make that investment in jetting. Jet printing is not useful to us because we want to be able to run any job on any of our three lines. Stencil printing does such a great job already and we're really a production house; we have the time to make stencils. We also have a stencil house nearby that can give us a same day response if we need it. 

Matties: Is your in-line AOI where you're getting your real-time feedback to control your process? 

Darren Carlson: Yes. Right now, we are using the operator. Whomever is running the AOI will flag the line instead of having a software data collection system flag it. It's semi-automatic; there is still a lot of operator intervention. 

Vora: We go over that data to understand the defect rates and causes. What are the reasons for the defects and how many defects are there? For example, why is this suddenly tombstoning?

Continue reading the rest of this interview in the October issue of SMT007 Magazine.