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99 problems but a switch ain’t one: how we solder switches, and other production changes

Today, a note from Kris, doer of many things here at NE, in charge of hardware.

We’ve gotten a few emails recently with customers asking about module components: new jacks that are a bit tight, parts that look like they are not soldered. Have no fear: they actually are soldered, we’ve just changed a bit of our manufacturing process. 

Surface mount: it’s not just for surface mounting anymore

When we talk about how we build our products, we have two processes / types of parts: surface-mount components sit on top of a circuit board (often abbreviated SMT) and are machine soldered. Through-hole (PTH) components have little metal legs that go through holes in the circuit board and are soldered on the other side, usually by humans (but not always). 

Boards ready for SMT

The switches and potentiometers (pots) we use on our modules are through-hole. They have legs that go through the circuit board. Normally, they would be soldered by hand after the boards have had their surface-mount components attached. The problem there is that humans are human, and humans are error-prone. Mistakes happen: solder joints get missed (the older version of the BIA had 80 hand-soldered joints!) or not fully soldered, and modules end up not working to spec.

So, we decided to let the robots take a crack at this: we did some redesigns and now, even though switches and potentiometers are designed as through-hole parts, they go through the same soldering process as the other SMT components on the board. And coming soon, our encoders will be SMT.

Wait, how and why SMT soldering? 

SMT soldering is pretty simple: a circuit board is designed with pads. We use a stencil overlay and smear solder paste (tiny pieces of solder suspended in a gluey, sticky fluid) on it, and then send it to the Pick and Place machine which is a large, sedentary robot with wild arms programmed to put all the right parts in the right spots. The paste is sticky and holds them there until the whole circuit board gets passed on a conveyor into a special oven programmed to melt the paste and make the parts stay in place. From there, it heads on to its next step in becoming a real module.

BIAs after SMT part placement

How does SMT work for switches and pots? 

We use a stencil to control where solder is smeared on the board for parts that will be baked on. For PTH parts, it doesn’t put any on the contacts for switches and pots because it doesn’t need to: solder is normally applied by humans later. But we changed the stencil for the top of the board (where the parts are placed) so that it does. This requires special parts that can go through the oven and be baked: most pots would melt, but we sourced pots for this purpose. Now we drop them in (a technique called pin-in-paste, but we sometimes shorthand it to SMT since the process is largely the same), they go into the oven, and are baked just like all the other SMT parts. And now we have parts that are perfectly soldered, every time. 

This process means that when viewed from the back of the module, the solder joints look different from modules that are human soldered: they don’t seem to have any solder on them, because the solder paste is on the top of the module. Have no fear: these joints are just as sturdy as hand-soldered joint are. 

Still unconvinced that something is soldered? Just test whether the product works!  If you turn the pot or flip the switch and it works, your product is soldered. Without solder, it would be intermittent, at best. 

The back of a module, zoomed in on two switches. No solder is visible on the switches, because they were soldered on the other side of the board.

What about those new jacks?

Even before the pandemic, we realized that our biggest point of failure in production was human error. PTH jacks are soldered by humans. It's easy for a solder joint to get missed in soldering, but that should theoretically get caught in test...but again, 80 points on the BIA makes it easy to miss one! The more nefarious error is the joint that is poorly soldered but corrodes quickly. This joint passes test, but by the time it gets to the user, it no longer works. And then you open your pretty new module, and instead of joy, you get disappointment and we are sad that we made you sad. So, in collaboration with our manufacturing partners, we sought a solution.

That solution came in the form of new surface-mount jacks. When we got samples, we tested the crap out of them for durability to make sure they indeed stand up to what we're going to throw at them as modular users. They seemed a bit harder to insert at first, but they loosened up pretty fast, so none of us were terribly worried about it.

Now fast forward to March of 2020, right around the time we happened to be getting these approved. 

To use the new jacks, I had to redesign all of our products. We considered it worth it because we knew it would be a better product in the end. And you may recall that 2020 was a heck of a year. California, where we build, was hit pretty hard with Covid, and our factory was running on a skeleton crew—when it was running. It turned out to be pretty lucky that we had moved to the SMT jacks, because we simply didn't have the people power to hand solder all the joints.

Contrary to what some posts  have espoused on the forums, these are actually more expensive than the standard jacks! That said, as outlined at the beginning of this blog post, SMT jacks do have the advantage of keeping costs down by decreasing error rates. But it’s never been about saving a few cents in parts, but rather working to provide you with the best, most reliable product we could. 
But we heard from some of you that the new jacks are too tight. And while they do loosen up over time and we’ve mentioned this in a couple of places, we have neglected so far to say this in a blog post: we are listening to your feedback, and we’ve been actively working with our manufacturer to make the jacks less grabby with your plugs. It turns out there are some complicated measurements needed to determine what changes need to be made, and there's still this global shortage/delay thing happening that is slowing everything down. But this is indeed in the works. Future modules will have less stiff jacks, and for those of you with the current ones, just rest assured that they do break in over time.

This all leads us to the last update...

aka the supply chain ain’t what it used to be

Yep, things are moving slowly. We fill orders as fast as humanly possible. A perk of all the surface-mount parts is that they are way faster to build and fail less often, so things get out the door faster. That’s been great. 

Less great has been the supply chain of late. We get loads of questions about when we will release things and why we haven’t released X, Y, or Z. As one of the owners of the company, I (Kris) promise we didn’t tease you just to leave you hanging. We aren’t sitting on a mountain of modules built, tested, and ready for you but just not telling you. It turns out that we really do want to release things, but parts are just...disappearing?! You’ve probably seen news about processors not being available for the auto industry, or any other industry for that matter. Sound on Sound mentioned in the September issue. It turns out that some of those are the same parts we use. Some parts are going on 52+ week lead times at the moment. Some are parts with no realistic substitution out there.

What does this mean? It means we are working hard to get the things we need, but products will be slow to release. We’re still working on all the products we have already announced, and way more. We will continue to build all the modules in our current lineup (at least for the foreseeable future!). We’ll get the new and improved jacks on as soon as we can. But some of the new stuff won’t be out for a while because we just don’t have the parts. On occasion, we’ll sub in a part that may look slightly different (a different LED color, for example, because it’s that or not build a product). This is just where we are right now: get a different color fader or leave orders unfilled for months. But know this: we will never, ever compromise quality. Anything we substitute goes through rigorous testing before we approve it.

TL;DR: don’t worry, and we’re #workinonit

We’ve made a few changes here as we try to roll with all the things that 2020/2021 threw and continues to throw at us. However, we promise that your module works exactly the same way it would if it were manufactured in the old way with the old parts, even if it looks a little different than what you would expect. We like to be up front about this stuff so that you don’t have to think about it, and can get on with the business of making awesome patches with them. If you have any questions at all, we always want to hear from you! Drop us a line on our contact form here.

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