Selective Soldering Tips: Negative Z to Adjust For Board Warp

This is just one article in a series of articles discussing tips and tricks for using a selective soldering machine. Here at Worthington Assembly Inc. we have a selective soldering machine manufactured by RPS Automation. Our particular model is a 2010 Rhythm model. These article are written by the same person who's used this machine every day for years. From time to time, we come cross assemblies that are quite large (16" x 16") and quite flexible. They may be a standard 0.062" board but they're loaded with a lot of large heavy parts. When you put a lot of heavy parts over a large area, it's a perfect recipe for board warpage.

We recently had a job with just these conditions. We have supports on our fixture to try to help with this phenomenon. They're aluminum bars that are self supporting on the fixture, with a spring loaded hook that tries to pull up a heavy board so that it remains flat and does not bow down. But even with these aluminum support bars, the board still wanted to bow down. The only solution was to adjust the height of the nozzle by changing the "Z-Height" in our program.

Example of negative z to adjust for board warp

This can be tricky though because if you lower your z-height all the way across the whole assembly, the areas that are well supported by the edges of the fixture or the aluminum bars may have very poor hole fill or just plain not get soldered at all. So you will need to identify areas on your assembly where the board is going to warp so far down that there's a risk of the leads of the components coming into contact with your nozzle. As you can see in the image above, we start out with no offset on our z-height. But as our path gets closer and closer to the center of the board, where we experience the worst warpage, we decrease our z-height by as much as 1.25mm. This may not sound like much, but we often find even a quarter millimeter can make a huge difference in consistent hole fill.

It's been suggested that we reduce the z-height over the whole assembly and just increase the pump speed. The reasoning is "If you just increase the pump speed, the solder will flow high enough to fill the plated holes properly." This may be true in some circumstances, but you'll be making compromises. In most cases, when your pump speed is too high, you'll experience more bridging, increased dross build up, not to mention that your contact surface area may increase considerably, potentially causing contact with adjacent surface mount components. Yes ladies and gentlemen, selective soldering is a process that will challenge your creativity.

As always, if you have any questions, feel free to give me a call at (413) 624-6879 or send me an email at cdenney@worthingtonassembly.com.

Selective Soldering Tips: Start Where You Finish

This is just one article in a series of articles discussing tips and tricks for using a selective soldering machine. Here at Worthington Assembly Inc. we have a selective soldering machine manufactured by RPS Automation. Our particular model is a 2010 Rhythm model. These article are written by the same person who's used this machine every day for years. Sometimes a person can populate a board much quicker than a machine can solder the board. So if you find that you're piling up boards waiting for the machine to finish, there are a number of different things you can do to reduce the throughput time. I will address just one of the ways with this article.

When drawing a path for the machine to follow, it's important to begin your next path as close to where your previous path stopped. If the machine needs to travel a long distance, criss-crossing back and forth around the board, you'll dramatically increase your cycle time and decrease efficiency.

Example of finishing where you start

I know this sounds obvious, but by being diligent with this practice, we have decreased cycle times by as much as 50%. How does this happen? Well, when you first program your board, you may not have thought about every little detail. Once you've run a couple of boards for the first time, you notice issues such as missing a part or coming into contact with a surface mount part on the bottom. So you go into the program and add a couple new paths. But each time you do this, you're adding complexity, and if you're adding complexity without considering where your machine needs to travel, you'll ultimately end up wasting a lot of time with the nozzle traveling all around the board with no thought put into it.

As always, if you have any questions, feel free to give me a call at (413) 624-6879 or send me an email at cdenney@worthingtonassembly.com.

Request A Quote

Today, we're excited to announce that we have added a new page to our website that should make it easier for customers and potential new customers to request a quote from us. The URL is http://www.worthingtonassembly.com/request-a-quote/

We even have a customized shortened URL http://bit.ly/WAiRFQ

This page will describe all the details of the quoting process and what's required. This is most important for potential new customers, or customers who have not done business with a contract manufacturer before. For existing customers, they mostly know the drill already. You'll also find on that page a link to a Microsoft Word form that will help speed up the quoting process and answer almost any question we might have regarding your assembly. So check it out and let us know what you think.

Westek Orbi Wash for Sale

We recently found that we no longer needed our Westek Orbi wash and are offering it for sale. We would like $6,000 for the unit but are willing to listen to offers. Below, you will find a number of images of the machine. If you would like the full resolution, original images, we have those available as well. It is in working condition and already disconnected and ready to ship. If you have any questions please feel free to contact us at wai@worthingtonassembly.com or call us at (413) 397-8260.

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Published in Circuits Assembly Magazine

Recently, Mike Buetow, Editor-In-Chief for Circuits Assembly, approached us about contributing to his magazine. He had expressed interest in our series of articles regarding selective soldering. We were thrilled with the opportunity and are happy to announce that today our first article has been published. You can find it on Page 50 of the February edition of Printed Circuit Design & Fab / Circuits Assembly. This magazine, with a reported circulation of 32,000 copies, is one of, if not the, largest publication in our industry, with an estimated 60,000 readers per month.

Vitronics Soltec Customer Testimonial

Recently, Worthington Assembly participated in a customer testimonial with Vitronics Soltec. This appeared on their website and many print publications. We were happy to do it. We've been very pleased with Vitronics Soltec's XPM3i reflow oven. What we said back in May, still holds true. Well, recently VS contacted us again. They were very pleased with the written testimonial we provided them and they wanted to now create a video testimonial. We didn't hesitate to say yes. This sounded like an exciting opportunity and it turned out to be. (Though it was also thoroughly embarrassing for me (Chris Denney), who's not accustomed to being on camera)

On November 8th, 2012, a crew came out and transformed our office for the video shoot. Here are a few pictures from the day.

It was a strange experience to be sure. But we were pleased with the results. Everybody from Next Step Communications and eTown Videos was wonderful to work with. You can see the results of our customer testimonial here at Vitronics Soltec's YouTube channel. And for your convenience, we've embedded the video right into this page. Just click the play button on the video below.

Is Outsourcing Losing Its Appeal

Came across this interesting article from Tam Harbert writing for EBN - "Is Outsourcing Losing Its Appeal" Her thesis is basically that if companies like Google and Lenovo are looking at building their own products again, then maybe other large OEM's are looking into building their own products as well. It's well written and worth the read.

Obviously, WAi has a vested interest in companies outsources their manufacturing. I thought this might be a good opportunity to explain why we think outsourcing can be a good idea for many companies.

Primarily, it affords the company greater flexibility. They no longer have to concern themselves with questions like "Do we have enough employees to build as many products as we need?" or "Do we have too many employees and not enough sales to sustain them?". Not to mention the fact that since they build only their own products, they might not be exposed to greater manufacturing challenges that might push their skills to a higher level. Or, for many of our customers, they simply cannot afford the hundreds of thousands of dollars worth of equipment that would assemble the advanced circuitry that their engineers want to build.

When people think of outsourcing production, they often think of dirty, dark sweatshops in Asia where children slave away, tied to workbenches and rationed crumbs of bread to sustain them. This is not what outsourcing is like. Especially considering a lot of outsourcing is outsourced to domestic manufacturers like us. Outsourcing should be viewed more like a coop farm. In a coop farm, the farmer has more land and grows more food than he and his family can eat themselves. He really enjoys the farming process and taking care of his fields. He takes great pride in watching his crops grow and even greater pride knowing he's doing it without pesticides and artificial fertilizers. But then there's that pesky problem of too much food. So what does he do? He invites his neighbors to buy his extra food. Now his neighbors get to enjoy all of the benefits of fresh organic food, without all of the effort. They know the farmer well, they trust him and are happy to support him. They make requests of specific food items and this invigorates the farmer to try new farming techniques. You see where I'm going with this?

When you build your own products, you need to size your plant according to how much you're going to sell. Trouble is, you probably have little idea of how much you're going to sell. So sizing your plant properly is very difficult. Just like it would be a challenge for people trying to farm their own food. They're not quite sure how much to grow for themselves. Whereas if you outsource your manufacturing, your manufacturing partner can have a very large plant with lots of sophisticated equipment, because he shares that manufacturing capacity with many other OEM's. Those OEM's are greatful because they could never afford a machine sophisticated enough to place 0.3mm pitch micro BGA's. Just as a homeowner might struggle to grow an exotic plant that the farmer is probably already familiar with.

Let's take this analogy a little further. That farmer takes great pride in growing his crops without pesticides and artificial fertilizers. A good manufacturing partner has similar pride. He cares about his employees and does not want to expose them to harsh chemicals. He's going to make sure that he's given his employees the necessary tools to make sure they don't expose themselves to the harsh chemicals that are used in manufacturing. Additionally, when byproducts are produced, he'll make sure that hazardous materials are disposed of properly. As an example, WAi produces large amount of solder dross. This is solder that has been exposed to oxygen and is no longer useable. You can't just throw this stuff out, it could be very dangerous. So we've worked with a local company that comes by on a semi-annual basis, picks up our waste material, and then recycles or disposes of the material properly. This can be a lot to manage, but you as the OEM should never be exposed to this, because you've hired a reliable manufacturing partner that worries about those details for you.

Don't get me wrong. I understand there are other benefits to building your own products in house. But I wanted to take this opportunity to state that WAi firmly believes in outsourcing and takes great pride in delivering a quality product to their customers, just as a coop farmer takes great pride in bringing his neighbors fresh fruits and vegetables right to their door.

Manufacturing Can Be Beautiful

I firmly believe that manufacturing can be a beautiful form of art. Even as a child I remember watching how things like crayons were made and being absolutely mesmerized. This probably explains the phenomenon of the television show "How It's Made". Today I watched this video about how baseballs are made. One thing stood out to me more than anything else. Baseballs are mostly hand made. Unbelievable.

How baseballs are made.

Coffee

Here at WAi we like coffee. In fact a couple of us have a little tradition called "Fine Coffee Friday". Every Friday we rotate who will bring in their favorite coffee and we brew it for everybody to enjoy. Typically it's our favorite Starbucks blend. We keep it pretty simple. The coffee is ground for a drip coffee maker, we clean our coffee maker pretty well, then we just go ahead and brew what we brought. We drink it black. But some people can take it to a whole new level. Check out this review of Tonx Coffee. This guy is serious about his coffee.

Assembled in USA

Interesting piece of news from the NY Times. Looks like Google is attempting an experiment that I can't help but feel thrilled about. They're actually assembling their Nexus Q in the United States. I think it will be a success. Truth is, assembling the product in the US will cost them more initially. But it's likely that it will give them much greater flexibility and speed. Plus, they can just drive down the road and figure out any issues that might be happening. No waiting on "the slow boat" or paying hundreds of dollars to overnight packages. There are major benefits to assembling your product close by where you design the product. This inspired us here. So just 10 minutes ago we ordered 1,000 "Assembled in USA" stickers. These will go on every one of the packages we ship out. Hopefully it will inspire our customers too.

Link: Built To Not Last

Built To Not Last I really enjoyed this article by Kyle Baxter.

This was a rebuttle to the argument made by some that insist that technology products should last a decade, and faults manufacturers for not building products that will last that long. But Kyle makes the point that that sounds more like dystopia rather than utopia. It's a short read but wonderful. I especially liked his last paragraph.

I don’t think purchasing a new tablet every couple years is a concern. I do think, though, that purchasing a new one without rationally considering why is. To benefit from new technology, we have to cooly think through its use and how it will improve our lives. Otherwise, it’s just another gizmo that does little tricks and is put away in the closet after it stops amusing us. And otherwise, technology is something that isn’t used for the betterment of our lives. Technology is not inherently good. It’s amoral. How we use it defines whether it’s good or not.

Manufacturing Apple Products in the US

The WSJ had a short article the other day regarding Apple manufacturing parts for their products in the US. Truth is Apple makes quite a bit for their products in the states, including the processors and the glass that covers the front of all of their iOS devices. (and the back of the iPhone) They point out that one of the biggest problems with manufacturing their products in the US is that their just aren't enough manufacturing engineers.

I don't totally buy this as a reason, and I don't necessarily think Apple believes it either. They don't need an army of engineers to help them manufacture their products here, just a handful. They're Apple, they could find the best engineers in the country, and many of them would come out of the woodworks to be a part of that.

The bigger issue is that the assembly of their products is just incredibly labor intensive. Their finally assembly for the iPhone has somewhere in the range of 100+ screws. Those don't get inserted by machine. And believe me, you cannot pay American wages for that kind of manual assembly, for 30-40 million devices a quarter.

But sub assemblies on the other hand, this is where American can knock it out of the park. In addition to the processors, American companies could be making the flash memory, the circuit boards, the circuit board assembly, all of these various sub assemblies that are heavily automated. I know Apple is proud to be an American company. The late Steve Jobs even said so during their "Antennagate" press conference. I think it's very likely that Apple is looking to find ways to produce more of their sub assemblies here. I hope they look at WAi for help! (I'm not holding my breath)

Slight of Hand

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Notice the very creatively designed display for Starbucks cup sizes. They're designed to encourage you to order the large (Venti) drink. They burry the bottom of the small (tall) and medium (grande) so that the large looks enormous. Kind of smart if you ask me.

CBS News: Bringing Manufacturing Jobs Back

http://www.cbsnews.com/video/watch/?id=7406166n Nice short clip regarding Buck Knives and their need to return their manufacturing operations back to the US. Their customers we upset that they no longer manufactured in the United States. But on top of that, the cost to manufacture overseas was just too expensive compared to domestic manufacturing. Looks like companies like GE and Caterpillar are joining in as well.

Selective Soldering Tips: Drag Off Angle

This is just one article in a series of articles discussing tips and tricks for using a selective soldering machine. Here at Worthington Assembly Inc. we have a selective soldering machine manufactured by RPS Automation. Our particular model is a 2010 Rhythm model. These article are written by the same person who's used this machine every day for over a year. When soldering a double row header, or similar part, the solder can easily bridge at the end where the solder nozzle comes off. I don't know the technical term for this but I call it the drag off. There are multiple arguments for the way you can drag off the end of the double row header. The most common recommendation is to drag off at a 45 degree angle.

I don't necessarily agree with this. I found greater success dragging off parallel with the double row (in other words, straight). The key here is the speed you drag off at. The slower the better. (You can go too slow though, so be careful. If you go too slow you'll melt the header you're soldering.) More importantly, you need to use that same speed across the entire header. The trouble is, when the nozzle changes speeds or angles, it stutters. Not much though. It's almost imperceptible but if you look closely you'll see it. I don't know that this is necessarily what causes the bridging but I suspect it is. So what we do more often than not is to drag straight off the double row headers at 0.200" per second.

Selective Soldering Tips: Drag Off Angle

Now after explaining all of that, I must point this out. Sometimes it is still necessary to drag off at a 45 degree angle. Take a look at the above picture. You'll see 2 double row headers. The one on the left we drag off at a 45 degree angle. The one on the right we drag off straight.

You'll notice that on the double row header where we drag off at a 45 degree angle, the pivot point is right at the last 2 pins, while still barely touching the previous 2 pins. What's happening here, as best I can understand, is that we change all of the surface tension of the solder wave. We now have 4 pins all tugging at the solder as it's dragging off. This causes the solder to want to adhere just to the pins and not to fall back onto itself. That having been said, I've still had better success dragging off at a straight angle, without "stutter stepping" on the last four pins.

To sum up, try dragging off at a straight angle, making sure to go nice and slow over the whole double row header. We find 0.200" per second works best. If you get inconsistent results with that technique try dragging off at a 45 degree angle, making sure your pivot point is adhering to the last 4 pins to use them as tension against the solder bridging itself.

As always, if you have any questions, feel free to give me a call or send me an email.

Selective Soldering Tips: Dwelling for Better Hole Fill

This is just one article in a series of articles discussing tips and tricks for using a selective soldering machine. Here at Worthington Assembly Inc. we have a selective soldering machine manufactured by RPS Automation. Our particular model is a 2010 Rhythm model. These article are written by the same person who's used this machine every day for over a year. Some of the parts our customers ask us to solder can absorb a lot of heat. And I mean a LOT of heat. One particular part that we solder has 16 solder joints, is made completely of metal (not sure what but it seems like a tinned copper), and nearly every pin sits on an enormous ground plane. Not to mention, the holes are by no means oversized to make this any easier. Needless to say, it gave us some trouble.

We tried using a local spot preheat. This helped a little but at the end of the day, that solder still did not want to flow up through that ground plane. So we thought, why not just sit there with the nozzle. Turns out, that was the trick.

It's fairly simple really. Using RPS's software we just added an extra point at the four pins that absorbed the most heat. Then we just add a couple seconds of dwell at each point.

Selective Soldering Tips: Dwell for Hole Fill

Click here for the full size image

This worked like a charm. You can actually watch from the top of the machine as the solder climbs up the joint. It happens slowly, but once it makes it all the way through you can see a beautiful solder joint remains.

Dwelling on specific points will add to your cycle time obviously. But in an effort to make the best product possible, it's a small price to pay.

As always, if you have any questions, feel free to give me a call or send me an email.

Selective Soldering Tips: Using the Machine for Preheat

This is just one article in a series of articles discussing tips and tricks for using a selective soldering machine. Here at Worthington Assembly Inc. we have a selective soldering machine manufactured by RPS Automation. Our particular model is a 2010 Rhythm model. These article are written by the same person who's used this machine every day for over a year. Heat helps. Anytime you're soldering anything, the more heat the better. Even when soldering board by hand with a soldering iron, having the board a little warm before you start can help a lot, especially for boards with large ground planes.

One of the boards we run quite often here has just a couple of small connectors. It's a lead-free board but it was a real challenge to get it to solder consistently without bridging. We couldn't figure out what the issue was but after some experimentation, we discovered that heating the specific area we were about to solder helps for just a few seconds made all the difference.

As you can see in the image below, there is a small dot of orange in the middle of where we drag solder across the connector.

Selective Soldering Tip: Preheat using the Machine

Click here for the full size image

When we program the machine, we edit that specific point to dwell for about 3 seconds. We also add a negative z offset of about 5mm. What will happen is the machine will drive to that specific location, raise the nozzle as if about to solder there, but then never come into contact with the board. Heat will just pour out of the nozzle and the nitrogen shroud and get what whole area nice and warm. Right after that we just go ahead and drag solder across the connector and it comes out beautiful every single time. Since we've implemented this one change to this assembly, we have never had a single bridge. Ever.

Preheating is always helpful. We recommend using a hot air preheater before you even put the board inside the machine. But these are rather pricey. So why not just use your machine instead? (unless of course you need your machine to run as absolutely fast as possible)

As always, if you have any questions, feel free to give me a call or send me an email.