Tag Archives: SMT

Slow Train a Comin’

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Where are the next generation of good engineers going to come from?

If I had a nickel for every time I’ve been asked this …. well, you can do the math.

A good friend asked me this just today. He has noticed many of the 25 to 45 year old engineers have left the SMT industry, and questioned where the new ones would come from.

My response: The same place they always have — they will be poached from other companies, or trained in house.

Twenty years ago, we had the same problems we face today regarding the availability of qualified process engineers. But we looked at it differently. Then, with the industry in its relative infancy and growing 15 to 30% per year, we accepted that hiring novice engineers and training them was simply part of the cost of doing business. Somewhere along the line (get it?) the mindset changed. We started to expect that experienced yet affordable engineers would always be available, and when they weren’t — especially after the tech meltdown, when many left for greener, less cyclical pastures — we as an industry went into a collective mode of “woe is us.”

What we forgot, however, is that the electronics industry has traditionally been self-reliant. We don’t need universities to send us mechanical and industrial engineers ready minted and prepared for action. We need to get back to recognizing that every industry has its learning curve, and we need look no further than ourselves for the solution.

It’s time to stop worrying about the next-generation of engineers and get back in the business of recruiting, mentoring and shaping the orbs as they exit college, engineering degrees in hand, into insightful and careful process engineers.

Companies that do well in this regard will have a competitive advantage over those that don’t.

And if we are lucky, we may just learn something along the way.

 

 

Surface Mount Technology vs. Workstation Design

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In today’s modern SMT assembly facilities, the design and flexibility of the workstation is critical to maintain quality, workflow and ergonomics. Unlike the old, static, welded frame workbenches and workstations of the past that were never moved or reconfigured, the modern workstations now incorporate a modular, flexible, adaptable design, with a wide variety of options,  that allows the end-user tremendous flexibility in reconfiguring the furniture to meet an ever changing production environment.

Circuit board assembly used to be a fully mechanical process with through-hole components relying on bent leads to secure them to the board before manually applying solder.  Component preparation was also a manual or semiautomated process to form, straighten or cut leads to facilitate assembly. Today, fully automated equipment handles most of those same operations, including x-ray inspection and inline circuit inspection.  As a result, the role of the workstation has evolved to accommodate a production staff that is highly trained to perform multiple high level functions, often at the same workstation.  Productivity is more important than ever to maintain a competitive edge over off-shore manufacturers, so the workstation must be designed to adapt and change as production requirements change. No longer is it acceptable to simply scrap that old workstation and start over just because it no longer meets your current needs. A workstation design that permits quick and easy reconfiguration is the only viable option in today’s competitive environment. Carefully researching the workstation systems on the market, while planning for future needs, will result in substantial cost savings over both the short- and long-term while providing considerable ergonomic advantages.

Workstations that are considered “state-of-the-art” can and will provide more than just a worksurface.  Examples of  features should include: ESD protection, height adjustability, easily add casters for mobile applications,  cleanroom certification, Shelving (solid or wire), overhead task lighting, tool and equipment stands, test equipment carts, mobile maintenance stations,  Overhead mounting options for electric tools, LCD monitor arms, tote bin bars, tool trollies, Material transfer technology (ball transfer, conveyors, Flow racking) and rack mount/enclosures must be part of the overall package for continued adaptability in your changing environment.

 

In a typical SMT assembly facility, these modular workstations can be found in a variety of areas, such as: Machine Programming centers, Solder paste / metrology set-up, Post Process assembly of non-wets and odd form components, In-line inspection, box build assembly, Rework & repair, Product packaging, Quality control, Supervisory or management areas.  With a wide variety of module sizes available, nearly any possible configuration can be provided to meet the often limited footprint available in today’s modern assembly facility.

As SMT assembly trends continue to evolve into the age of nano-electronics, how is the job function of  your people and equipment going to change in the future?  Lean manufacturing, as well as state and federal legislation, may also have an effect on the end users requirements for workstation designs of the future.   While we don’t have the answers to those questions yet, we can be certain that workstation manufacturers will be working closely with the SMT industry to insure the designs will change as the industry dictates.

Will Juki-Sony Talks Get Others Going?

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Industry chatter has long said M&A activity among the major placement companies is inevitable.

Yet throughout the gut-wrenching downturn of 2001-02, the widespread pause in 2008-09, and the subsequent fallout starting last spring, nothing concrete took place.

Sure, a few companies have changed hands — Mydata was bought out by Micronic, Dover divested Universal Instruments to Francisco Partners, which in turn sold it to Patriarch Partners, ASM took Siplace off Siemens’ hands, and H2 Equity Partners did the same for Philips with Assembleon.

But there are more than 25 pick-and-place OEMs around the world, and despite fierce competition the number is actually growing.

Today, Juki and Sony announced the signing of a non-binding memorandum of intent to discuss the possible integration of their respective surface-mount technology equipment and related businesses. Will this finally get things rolling?

Under the MOI, Sony and Juki would integrate their SMT businesses under a newly established company, whose name is yet to be disclosed. Both companies are ponying up cash for the “startup,” Juki presumably providing the lion’s share as stands to receive two-thirds of the shares in the new venture.

The deal could be consummated by September if everything holds up.

It’s unclear what a merged entity’s worldwide market share would be, but I suspect it would be the largest in the world. Juki currently is neck-and-neck with Yamaha and Fuji in Asia, and is probably the current leader for new units sold in the US. Sony hasn’t been able to penetrate the US, but has done well in Mexico, where many Japanese OEMs have or had larger factories. It also sold thousands placement machines to Foxconn, reportedly as part of a an arrangement under which Sony outsourced production of various consumer electronics. Latin Americas is up for grabs. Siplace and Assembleon continue to hold sway in Europe, but others have made inroads of late.

This could also affect Juki’s deals as a full-line distributor for other suppliers. Sony currently makes everything from screen printers to placement machines to AOI. Juki resells printers (GKC) in the Americas and Europe, as well as various soldering equipment lines.

The bigger question, however, is will this spur other M&A? Not many companies align so neatly as Juki and Sony. So while many placement companies have been on the block for some time, and the lure of better share, less competition and — hopefully — greater margins is always on the CFOs’ minds, the merging of differing technology, approaches and cultures (not to mention the acquisition price) haven’t been enough to seal any deals thus far. And we don’t see that changing any time soon.

Talking Cleaning with Mike Bixenman

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Folks,

There is a lot of interest in cleaning PCBs assembled with no-clean solder pastes. Recently I discussed the topic with my good friend Mike Bixenman of Kyzen.

Dr. Ron (DR): Mike, many of the best performing lead-free and lead containing solder pastes today are no-cleans. They have been designed to solve assembly problems like graping and the head-in-pillow defect. For the vast majority of applications, the small amount of residue left by a no-clean is not a problem. However, some assemblers want the performance of no-cleans, but need to clean the no-clean residue as they have extreme reliability or cosmetic requirements. Are there cleaning solutions for these situations?

Mike Bixenman (MB): Absolutely!

DR: Can you tell use a little bit about these cleaning solutions?
MB: Several factors come into consideration when engineering electronics assembly cleaning agents. Design factors include the soil make-up, heat exposure, Z-axis clearance under bottom termination components, material compatibility, and cleaning equipment. Typical process goals require that all flux be removed in one cleaning cycle, shiny solder joints (no chemical attack to the alloy), fast production speed, no material effect to labels and other materials of construction, long chemistry bath life, and low operating concentrations.

Cleaning solutions vary depending on the cleaning equipment. For solvent systems, a solvent cleaning agent is needed – with properties that allow for non-flammability, constant boiling mixture, and being environmentally-friendly to workers and the environment. For solvent cleaning agents that are rinsed with water, the cleaning agent requires a solvent mixture that can be rinsed with water while matching up to the soil and cleaning equipment. For aqueous cleaning agents, the cleaning agent is engineered with properties that provide solvency for the soil, polarity for inducing a dipole and/ or to oxidize and reduce the soil, low surface tension to reduce the wetting angle, buffers to stabilize pH, defoaming to reduce the tendency to foam at high pressures, and inhibitors to widen the passivation range on metallic alloys.

The most critical property is the nature of the soil. As soldering temperatures rise and the time exposed to higher temperatures increase, solder paste material supplies must improve the oxygen barrier and prevent flux burn out. This requires higher molecular weight compositions that may change the nature of the soil and the cleaning solution needed to remove the soil. Other factors such as processing conditions and how these conditions can change the soil’s cleaning properties must be considered. For example, excessive exposure to heat may polymerize the flux residue rending the soil uncleanable. To better understand and plan for these factors, solubility testing and matching the cleaning agent to the soil assist formulators in designing cleaning agents that are effective on a wide range of soldering material residues.

DR: What type of equipment is typically needed?
MB: Two key factors must be matched to clean:
1: Potential energy of the cleaning agent for the soil and
2: Kinetic energy of cleaning machine for delivering the cleaning agent to the soil necessary to create a flow channel needed to rapidly displace the soil.

The cleaning machine requires energy to deliver the cleaning fluid across a distance and create enough force to deflect fluids under the Z-axis. The capillary attraction for moving the cleaning fluid into an out of tight gaps is created by fluid flow, spray impingement pressure and surface tension effects. When cleaning under tight standoffs, cleaning agents that wet (form small droplets) improves capillary action, penetration and wetting of the residue. The solubility rate is dependent on the soil, temperature effects and concentration of the cleaning agent needed to dissolve the soil. Hard soils clean at a slower rate and remove the soil in a concentric (tunneling effect) manner. Soft soils clean at a fast rate and remove the soil in a channeling (multiple tunnels) effect.

The Z-Axis gap height has a direct correlation to the energy required to penetrate and remove the soil under components, time required to clean the soil and wash temperature. The irony is that lower Z-axis gaps increase capillary action of the flux for underfilling the bottom side of the component. When this occurs, flux residue dams up and closes any flow channels under the component. Research findings indicate that high pressure coherent spray jets are needed since energy drop is less and defective energy is higher. The wash time needed to clean under a 1 to 2 mil gap as compared to a 4 to 6 mil gap can range from 4t o 8 times longer. Higher wash temperatures increase the softening effect and aid in penetrating and removing the soil. The net effect is that, as components decrease in size, the Z-Axis gap height reduces and the cleaning factors needed to clean the soil increase. These effects favor spray-in-air cleaning equipment over immersion cleaning equipment.

DR: How are the results of cleaning assessed, so that we know that the boards are truly clean?

MB: The first level that we judge cleaning performance by is the visual presence of the residue post cleaning. Most cleaning processes have no problem with removing surface residue from the assembly. The issue is the residue under the bottom side of the component. This complicates the issue since the residue under a specific component is where most failures occur. These site-specific failures may reduce the confidence in existing IPC standards that correlate anion and cation ionic residues over the entire board surface area. So, when designing the cleaning process, we use test cards with bottom termination components and judge cleaning performance by the level of flux residue remaining under those components. To achieve this value, all components are removed and the surface area of the residue under components is graded and statistically analyzed.
Let me finish by adding that highly dense interconnects assembled onto circuit boards is advancing at a rapid pace. Traditional SMT component spacing between conductors was larger. No-clean post soldering residues posed minimal risks to reliability. The information age has spoiled us in expecting higher functionality in smaller spaces. As assembles reduce in size and increase the levels of functionality, cleaning becomes more important. I hope that the cleaning factors discussed in this interview provide insight into cleaning process design considerations that may be of help.

DR: Mike, thanks. Who should folks contact if they would like more information on cleaning boards assembled with no-clean solder pastes.
MB: Thanks for letting me share with your readers. I would be glad to help anyone with the cleaning challenges they face. Contact me at [email protected].

Cheers,
Dr. Ron

Counting Once, Counting Twice…

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Panel single scLet’s say you have two options: First, you could send in your boards for assembly as individuals. Second, you could send them in a panel. That’s all fine and dandy. For a few, send individuals. For a bunch, panels might make more sense. But, when you do go to quote and order, how do you count the parts?

Let’s take this example. As a single, this board has 32 line items on it’s bill of materials. That’s 32 unique parts. Counting all of the individual part placements, there are 56 total parts: 42 SMT and 14 through-hole. So, naturally, if you quoted the assembly of 20 of this board at Screaming Circuits, you would enter your desired board quantity as 20, 32 total unique parts, 42 SMT and 14 through-hole.

But what do you do if you send it in panel form? How do you count? It’s actually not as difficult as it seems. In this example, it’s in a panel of four. There are still only 32 BOM line items, but there are four times as many placements. That means that if you quoted this, as a panel, you would enter 32 total unique parts, 168 SMT and 56 through-hole parts. If you still need 20 of the final boards assembled, you would enter 5 as your desired board quantity.

In the end, you will have 20 assembled boards. In case you are wondering about the cost, there won’t be a difference. As long as the final number of boards (after the panel is broken apart) are the same, your cost will be exactly the same for panel vs. one up. You don’t save any money by sending in singles. However, if your board is panelized and all of your parts on on reels, full or partial, you can save money by ordering Short-Run production.

Duane Benson
50 Years ago today
Robert Rushworth flew the X-15 to Mach 5.03 at 100,400 feet altitude

http://blog.screamingcircuits.com/

Ambiguity

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P3281577 smIt’s pretty important to have unambiguous polarity markings and pin one markings printed on your PCB. In theory, for SMT parts, it really shouldn’t matter; the centroid would take care of the placement orientation. But, you may have noticed that it’s not a perfect world. It took me a while to figure that out, but I have finally concluded such.

It’s not uncommon for the CAD library part to have the wrong zero degree rotation orientation. The IPC specified location for pin one orientation Quad and BGA for square chips like QFPs, QFNs and BGAs is either the upper left or middle top. Check out our Centroid guide for more detail. If it’s wrong in CAD, the centroid will be wrong as will everything downstream. That’s why markings on the board are still important.

What do you do if your part is ambiguous though? This particular chip has three markings that could be interpreted as pin one indicators. At first glance, I’d assume it’s the dot in the center top. It would match with the text. However, there is a white dot in the lower left that could be pin one indicator which would mean, in this case, the CAD library component had the incorrect zero rotation orientation.

Datasheets aren’t always easy to find. This one is behind a registration wall. If you have a part like this, it’s really helpful if you include some documentation (in electronic form) clarifying. I found the datasheet for this particular part and was able to confirm that it is correct as placed with pin one down in the lower left (90 degrees).

Duane Benson
Via via in the board,
what’s the top on my PCB?

www.blog.screamingcircuits.com

Chatting Away

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We had a great premiere of PCB Chat last week. Eric Bogatin, the signal integrity guru, hosted the nearly two hour session, answering more than 20 questions.

The transcript can be seen here (you must be signed in to Printed Circuit University to view it; registration is free).

The next chat will be Feb. 7 with SMT process consultant Phil Zarrow. Note that you don’t need to make the live session in order to ask a question: questions may be submitted in advance.

If you have recommendations for future moderators, drop me a line or post in the comments. Thanks!

Through-Hole Parts

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Screaming Circuits uses machines to place surface mount parts; even if it’s just one board. Through-hole is a different story, though. Way back in the cobwebby section of the building, we do have a through-hole part sequencing and insertion machine. Our volume manufacturing division still uses it on occasion, but it’s just not efficient for small quantities, which is why through-hole parts get hand-inserted at Screaming Circuits. We have three options for soldering the parts into your prototype. We can hand-solder all the parts, we can send the board through our selective solder machine or we can send it through the wave solder machine. We’ll pick whichever route makes the most sense based on quantity and configuration.

It’s good that we can solder through-hole parts, but how, you might wonder, do we know where to put the through-hole parts? The SMT has the centroid file to tell our machines where to put them. Through-hole locations being more of a manual process, we rely on visual data. If your silkscreen markings are readable, we can use that as a reference. If the parts will only fit one way into one footprint on the board, then it’s not much of a challenge. Regardless, make sure that the polarity is clear for any polarized components.

Sometimes, though, there isn’t enough room on the PCB for clear silkscreen and parts will fit in a number of different places. That’s where the assembly drawing comes in. This illustrates an example of a suitable assembly drawing. It’s got your web order number in the image and all of the parts are clearly pictured and their locations clearly identified. If any of the parts are polarized, make sure you include that information as well. Send the assembly drawing as a .JPG or PDF file format in your ZIP file with the BOM, Gerbers and Centroid.

Duane Benson

It just goes to the back side of the board. It’s not a wormhole going to another galaxy. Or is it?

http://blog.screamingcircuits.com/

How to Build a Footprint

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Well, not really how to build one in a technical sense, but some thoughts on how to better ensure that you get it right. In theory, it shouldn’t be that difficult. You download the datasheet and build the land pattern based on the information in the datasheet. That usually works, but not always.

I had a through-hole battery holder that didn’t match up with any of the land patterns in my library, so I modified one that was close. That worked mostly okay, but there was one measurement in the data sheet that was a little ambiguous. I ended up with the mounting holes being off by a millimeter or so. Not too much, but enough to make the fit difficult.

I went in and shifted the leads over by the same amount, used it again, got another PCB fabbed and discovered that I had shifted the pins the wrong way! Then it hit me. In the first application, I had the battery holder on the bottom side of the PCB but I had looked at it through the mounting holes from the top side of the PCB. D’oh! One reason why I’m not a professional designer.

The other part was a little tiny SMT trim pot. Since there are pretty close to a million different little trim pots, the likelihood of me finding an exact match in my CAD library was precisely zero. I didn’t want to Gieger VR mistake close re-invent the little zig zag resistor symbol, so I just found a part that looked the same. Well, it was almost the same. The footprint I found is for a 4 x 4mm part and the part I ordered is 3 x 3mm. That’s a tiny trim pot. Somehow, when looking at the datasheet, I got the measurements wrong. Once the part came in the mail, it was quite obviously too small.

The pad pretty much ends right at the edge of the trim pot. We won’t be able to reflow that part. No solder paste would be touching the pads on the trim pot. I’ll see if our guys on the floor can figure out how to get the thing soldered on there. If they can’t, I’ll need to look for a larger part to put in it’s place.

Fortunately, I physically looked at the part and the PCB before assembly. Unfortunately, I got the measurements wrong. If at all possible, get some sample parts before you order your PCBs. Then you can print out a 1:1 image of your PCB and lay the parts out on it. That would have saved me in both of the above cases.

Duane Benson
Is it “datasheets” or “data sheets”?

http://blog.screamingcircuits.com/

Electricity Use in Pb-Free

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Folks,

An obvious disadvantage of lead-free electronics soldering assembly is that the oven must be hotter and therefore will use more electricity (versus SnPb37 soldering). But is the extra amount of electricity significant?

KIC’s Brian O’Leary claims that a typical SMT oven uses $7,000 worth of electricity a year at $0.072/Kilowatt hour (Kwh) or about 100,000 Kwh. That number strikes me as about right, as a household uses about 5-20,000 Kwh per year.

In the late 1990s there were 35,000 SMT lines in the world. At a 3% growth rate that would be about 50,000 lines now. So worldwide SMT reflow oven use would be about 5E9 KWhr (50,000 ovens x 100,000 Kwh/per year) worldwide.

With most heat loss be due to convection, the increase in energy use will be approximately proportional to the difference between the oven temperature and the room temperature (25°C). An oven processing tin-lead solder would run at about 210°C versus lead-free’s 250°C. So the added energy for a lead-free oven would be about (250-25)/(210-25), or about 22% more. So if all assembly lines in the world are SMT the added energy use would be about 0.22x 5E9 Kwh = 1E9 Kwh. The cost of this extra electricity would be about $100 million at $0.10/ Kwh. The electronics industry generates about $1.5 trillion in sales. So this added cost would be about 0.0067% of sales. Since world electrical use is about 150,000 E9 Kwhr per year, this increase is about 1/150,000 of all of the electrical use or 0.00067%.

So although more electricity is used, the increase is not significant to the value of the electronics sold or the total world use of electricity.

Best Wishes,

Dr. Ron