Issue link: https://iconnect007.uberflip.com/i/1150604
AUGUST 2019 I SMT007 MAGAZINE 23 Ultimately, applicator timing and perfor- mance achieve uniformity and consistency. Accurate programming is also important. If the system does not allow for operators to program well, then your fluid is still not going to go where you intend. Dan Feinberg: What are the most commonly used methods of application? Sybert: That's an interesting question because the answer varies by region. Method of appli- cation largely depends on the type of fluid that's being dispensed. Europe tends to use largely solvent-based instead of silicones. With a lower viscosity, solvent-based type applica- tions lend themselves well to film coating for large board applications as well as some jetting for more precise applications. But in the Amer- icas, we also see silicone-type applications. Silicone applications lend themselves to either an atomized spray or a monofilament process. The monofilament approach creates a path that's about 10 millimeters wide; it's intended to cover a broad area. But as a non-atomized process, it gives you better control compared to a spray process. Feinberg: When you say a film coating, is it a liquid-film coating, a dry-film coating where it would be laminated on or applied to some other way, or are or both being used at times? Sybert: The term "film coat" refers to a specific type of wet coating in which the fluid exits the nozzle in a fan pattern. If you look at the noz- to use the information from one machine to help with another system, similar to the coat- ing system and automated coating inspection (ACI) system. Using the results from the ACI system helps the operators understand what's going on with their process and allows them to make adjustments on their conformal coat- ing programs, for instance, to ensure that areas that need more rework can be addressed. Sybert: One thing I was looking forward to dur- ing this discussion is the equipment used to apply conformal coatings. The process is effec- tive when you have the right pieces of equip- ment applying the materials. When we talk about these pieces of equipment, we're not talking only about the specific conformal coat- ing machine, but also all of the other pieces of equipment that go into the entire process. The objective is not just achieving correct coating requirements but meeting throughput require- ments. Both of those are major concerns for our customers as well. When we talk about equipment, it's important to focus on what the overall result is that you're looking for. Sometimes, we can get distracted by specific mechanics and details. For example, what are the accuracy and repeatability specifications of a system not running fluid? But if we're talk- ing about conformal coating, the application of liquid matters. It comes down to what is the equipment is able to do. In that case, the valve or applicator is critical to fluid dispensing because it's the last machine part to touch the fluid. The start and stop timings of the applicator can signifi- cantly affect placement. In other words, if you have the most expensive mechanics available on a system but incorrect applicator timing, that machine still might not meet the needs of your coating application. As a result, in con- formal coating, we have a number of different technologies that we use to apply the material, including film coating; spray; monofilament, which is a non-atomized process where you take a bead of material and rotate it; jetting; and needle dispensing. Depending on the wide range of fluids that you're placing, each tech- nique has its own nuance.