Issue link: https://iconnect007.uberflip.com/i/1379105
12 SMT007 MAGAZINE I JUNE 2021 assembly goes on to a new life—whereas sur- face prep is associated with making the parts and the pieces on the way to that assembly. Johnson: I like your distinction in that. e pri- mary concern—and I know the contract man- ufacturers are going to tell me I'm oversimpli- fying—is making for a good solder joint. Forsythe: Right. Step one is we're making elec- trical devices that are supposed to turn on and do something. If we don't have a good solder connection, obviously it's tough to hit that goal. Now, how long everything is sup- posed to work is a different story. What are the risk factors? Medical and military all use no- cleans. ey clean them all because their prod- crew put up a warning sign that read, "Milling operations this week." I don't think I've ever seen that on a highway sign before. What were they doing? ey were scraping down the surface so they could build it back up again, and that's exactly what plating and chemi- cal etch people do when they roughen a surface. Sometimes chemical milling can create depres- sions in certain areas of the surface. In essence, surface prep is changing the surface. Cleaning doesn't have that notion of changing anything. We get in trouble when we change things. We're supposed to clean the table; we're not supposed to take out a saw and shave it down a little bit. e table is supposed to be what it was before that contamination got there. Johnson: It's more than cleaning. Forsythe: It's a different thing. at's why sur- face prep tends to be more of what happens in a fab—making components and boards. Cer- tainly, in the metal business, it's used in many ways, like pre-plating, pre-painting, pre-coat- ing, and so forth. It's not a word that you find a lot in your bona fide assembly land. Surface prep doesn't come up all that much. Johnson: Where does it come up? Forsythe: When we talk about cleaning, we are not really talking about surface prep. For example, automotive guys love con- formal coating, but they generally don't clean because if your car has a problem, you don't die. at actually defines the whole spectrum of cleaning. If life is at risk, everybody cleans. If it's a nui- sance, nobody cleans. Everybody in between has a decision to make. Where are you on that spectrum? We're not fabricating; we're sticking stuff together that mostly stays the same. Sol- der is probably the one thing that changes, and that Tom Forsythe