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80 SMT Magazine • August 2015 want it to match, so if you're using an electro- form stencil, ideally you should be using an electroform blade, and then you won't have the parts damaging one another as they scrape across. Matties: Do you offer some sort of free evalua- tion, where you go into a shop and look at their systems and see what they're doing, and then make recommendations of how to improve? Weissmann: What we would normally do is take a look at the customer's board or drawing and recommend what they should be using. It's also really important that we talk to the customer and see where they're having challenges. We do often make suggestions for modifying the sten- cil design as well as the stencil type to come up with better results. The thing we need to be looking at is that customers look at their whole process to im- prove it and find the weakest part. A stencil is an awfully easy thing to improve. You don't have to change much of the rest of your pro- cess, if any, and you can get better results by using better stencils in SMT. Study after study shows that the type of stencil makes a differ- ence, and that the quality of the stencil makes a difference in the quality of the print that a customer ends up with. As components get smaller and density in- creases, that's going to become more and more critical to avoid bridging and many of the other defects that you can see. There will always be a need to print materials in the electronics in- dustry, whether it's solder or some of the other alternatives that are out there. You still need to get it in the right place in the right amount, and that's what we can help with. Matties: there's this whole new marketplace that's just emerging where we can start printing circuits on our wallpaper or on our sofas... Weissmann: Or on the side of a building. We have a customer who has worked out how to make lighting on the side of a building that's only visible from one direction, and that's a materials printing process too. There are a lot of amazing material printing applications out there, and they all have to have the right amount of material in exactly the right place and exactly the right quantity. Matties: as far as cleaning and maintaining, what are the issues that people should look at and con- cerns that they should have? Weissmann: The quality of a stencil can make a big difference in the cleanability of a stencil. This affects how often you have a failure, be- cause a failure in cleaning can create a failure in printing, but it also slows the process down, like whether you have to clean every five prints or every ten prints. That makes a big differ- ence, too. A pure nickel stencil, a stencil that has a smoother finish on the contact side sur- face of the stencil, will clean better and need to be cleaned less frequently. This is also one of the benefits of the nano-coating that can be ap- plied to a stencil that helps make that possible. It's important not to have debris introduced in your products by the indirect materials like a stencil or a blade. That's one of the reasons that in our new factory we're going to be doing all of our assembly inside cleanrooms for all of these products. Our semiconductor customers are in cleanrooms now, and as more and more of our SMT customers are moving to clean assembly, STENCILS: WHY THEY STILL MATTER continues IntervIeW