Rethinking the Supply Line

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The PCB fabrication industry is older than most of us still working. It is overdue for modernization. We have not seen transformational manufacturing changes in the PCB bare board industry during the past 15 years.

What we have seen is the installed capacity moved to China. It has been reported that 60% of global board fabrication now comes from mainland China or Taiwan. This move created a forced shift in how boards are purchased, and consequently created new demands in communication and logistics. Specifically, language, time zone, and cultural considerations. Bigger companies with China-based feet on the ground could adapt easily; the rest of us had to learn new skills.

I am suggesting that the rest of us modernize and rethink our supply line strategy.

Some may remember the evolution of the electronics component industry. First, component manufacturers sold directly to OEMs. Gradually, customers and component manufacturers found that a better path was through a local distributor. Arrow, Avnet, Future, DigiKey, and many others were born out of this efficiency. Today, it is an exception to buy directly from a component manufacturer.

PCB fabrication is difficult for distributors because every board is custom. Repeat: every board is custom. Custom equals high potential for error, which equals close technical review required.

So, buyers must go to China directly and slog through the variety of China sources. With this come the multiple challenges of accountability, communication, logistics and culture. The most dangerous of the challenges is having picked a supplier that occasionally (or often) sends subpar boards and provides no recourse or no response to your complaint. Do you really want to commit such a critical part of your BoM to the lowest China bidder?

The modernization of the PCB industry is not in processing, but in supply chain. A new category of value-added distributor is evolving in the same way the component distributor evolved … to make things easier. We call it “Managed Manufacturing Services.”

Think of it as a value-added distributor of printed circuit boards. This concept can greatly improve the supply chain for both customer and China manufacturer, but only if they really add value.

What are the important values, and how does this approach add value?

Technical support. The value-added distributor must be your expert design reviewer, capable of counseling you and quickly fixing the errors.

Only technically trained PCB teams really understand the manufacturability challenges of bare boards. With the technology of new IC packages pushing toward smaller geometries, new thinking is required about designing for manufacturability. So, your value added distributor has to be technically trained to provide this service.

Communication. The value-added distributor must be capable of clearly and cleanly communicating with a factory in a different country.

We have been working with offshore factories for a long time. We learned through hard knocks that developing a strong relationship with your counterpart in Asia is critical. I call it “Pitcher-Catcher.” Whether a fastball or a curveball, the two communicate in one cohesive motion. This takes time to develop and not every factory gets it.

Time zones can work to your advantage. We pitch everything to China by 5 pm Pacific and have answers at 6 am the next day. Your distributor must know the factory requirements well enough that only a few questions (EQs) come back, lessening the need for middle of the night conference calls.

Accountability. Your value-added distributor must have carefully vetted and audited the factories they use. They must be US corporations with financial accountability to their customers.

Slogging through a variety of factory options is not a good idea. Jumping from one to the next based on price and email pressure is also not a good idea. It wastes time and invites disastrous quality issues. Customers with little or no knowledge of what makes a solid factory are at particular risk. Yet most customers fall into this category.

If you have someone on staff with experience in this area, you can send them to China to visit multiple factories, but unless this person has in-depth knowledge of what makes the difference between okay and fantastic at the granular level, it is waste of $10,000. It takes deeply experienced people to see the difference. It takes board manufacturing experience.

From the China manufacturer’s side, it is just like the component manufacturers of old. It is much more efficient to deal with a small handful of companies who service the US market than it is to staff and service everyone. The culturally smart ones are beginning to see this and actually do view us as distributors for them. It is a proven supply-chain solution.

Following the model of the component distributors, we can modernize this PCB industry. We can improve efficiency, quickly adopt new technologies, and capture lower costs all by modernizing the supply chain. Welcome the value-added PCB distributor, or as we call it Managed Manufacturing Services.

Thomas Smiley is president, Precision PCBs; [email protected].

Area Ratios for Elongated “D” Apertures

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Folks,

Ismail writes: Dr. Ron, I know that the area ratio for circular and square stencil apertures is 4d/t.  What is it for an elongated “D” aperture?

 

The area ratio of a stencil aperture is the area of the aperture opening divided by the area of the side walls.  It is interesting, as Ismail points out, that the area ratio of a circular aperture is the same as that of a square aperture.  A little 10th-grade geometry will point this fact out.  It ends up that the area ratio of an elongated “D” is a little more complex.  All of these aperture shapes and that for a rectangle aperture are shown in Figure 1.   The area ratio formulas are at the bottom of the figure.

 

Figure 1. The area ratio for several shaped apertures. The elongated “D” aperture is third from the left.

 

 

 

 

 

 

 

 

 

A rule of thumb that still seems to hold is that the area ratio should be 0.66 or greater for the best printing result.  It is possible to do somewhat better (i.e with an area ratio less than 0.66) with a superior solder paste and/or some of the new stencil nano-coatings.

The derivation of the area ratio for the elongated “D” is in Figure 2.

Figure 2.  The derivation of the area ratio for an elongated D shaped aperture.

 

 

 

 

 

 

 

Cheers,

Dr. Ron

 

Hacking the Hacks

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Wikileaks this week released a trove of materials purportedly from the CIA which demonstrate a range of methods used for spying on unwitting individuals. Among the revelations were how-to’s on accessing (read: hacking) most popular operating systems including Android and Apple. The CIA, it is alleged, has figured out how to bypass the encryption on a host of common apps including Signal, WhatsApp and Telegram, and even get around many antivirus programs designed to spy on the spies.

As it turns out, that TV set you have hanging on your family room wall might well be watching you. Worse, it was intimated that a vehicle’s electronics system could be hacked, rendering the car uncontrollable — with potentially devastating consequences.

It doesn’t take much to make the leap from hacking consumer and automotive electronics to overtaking machine language software systems. And that should be of paramount importance to those working on industry standards for Industry 4.0, including IPC’s Shop Floor Communication Standard Subcommittee and Mentor Graphics (OML).

As important as machine-to-machine (M2M) communication is, security should be the priority.

 

 

Let’s Talk about HAL – And Another Thing

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A few days ago, I wrote about HASL PC board surfaces, explaining that it’s not an appropriate choice for small parts.

Look at the same PCB image I used the other day. You might not recognize it because before it was on the right, and today it’s on the left. Getting past the fact that I just insulted everyone’s intelligence, there is something else about this board that we don’t recommend.

I’ll give you 30 seconds to figure it out. I don’t have a stopwatch, so the 30 seconds is on the honor system.

This is a land for a 0.5mm pitch BGA. As I wrote before, HASL is not the right choice for BGAs, especially for those of the smaller pitch variety. The other problem with this board is in the pad layout.

These are solder mask defined (SMD) pads – the solder mask covers the outer part of the pad, so the solderable copper surface is determined by the size of the opening in solder mask, not by the area of the copper pad.

For BGAs 0.5 mm pitch and larger, we (and pretty much everyone else) recommend non-solder mask defined (NSMD). With a NSMD pad, the solder mask opening is larger than the pad. This leaves more copper area to adhere to, including the sides of the copper pad. It tends to be much more reliable.

The image to the right illustrates the difference. 

The left-most pad in the image illustrates an SMD pad, while on the right is an NSMD pad. The NSMD pad leaves a lot more surface area of the copper pad for the solder ball to grip on, including the sides.

BGAs with 0.4mm pitches might need either SMD or NSMD pads, depending on a number of circumstances. Read this blog information for a bit more on 0.4mm. When in doubt, look in the back of the datasheet.

Duane Benson
Question for physicists and mathematicians:
Should the last recursion in the Mandelbrot set land on Plank’s constant?
Show your work.

http://blog.screamingcircuits.com

 

Let’s Talk about HAL – For Big Parts Only

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The board surface names: HAL and HASL (hot air leveling and hot air surface leveling) refer to the same thing. They are interchangeable terms. With that out of the way, I’ll get to my point, which is that HASL is not the right surface for all applications.

Take a look at the photo on the right. This is a 0.5 mm pitch BGA land, using lead-free HASL. Don’t expect good results with this board. It’s a good quality HASL board. Even the bumps on the pads are not out of line for a HASL PC board. It’s not a defect. It’s the HASL works.

The catch is that, while the PC board is perfectly good, it’s not the correct board surface to use for all parts. HASL is fine for larger parts, but for small components, it’s archaic and not reliable.

BGAs require a flat surface (also called a planar surface). With the bumps common on HASL boards, the BGA won’t have a flat surface. The solder paste won’t adhere evenly to the pads. The BGA will probably slide off the pads before reflow. It may end up far enough off that it can’t self-center, as BGAs usually do.

The HASL pads won’t all have an even amount of solder left on the board. Some pads will have more, some less. When added to the solder paste, the pads with more solder may end up bridging.

All of the issues become even more severe as the parts get smaller. Wafer scale parts, 0.4 mm pitch parts, 0201 passives, and other similarly or smaller sized components are essentially incompatible with the HASL surface.

So, what do you do? Order your boards with immersion silver or ENIG. Both give a nice flat surface that BGAs like.

Duane Benson
Open thse Posd Basy Doors Hasl

http://blog.screamingcircuits.com

Milling Madness

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Sometimes, we find things that kind of defy explanation. Fortunately, this didn’t come from Sunstone, our normal board house.

Regardless of who it came from, I’m sure it was a one-off mistake, but, wow. How could anyone miss this?

 

 

 

 

 

 

 

 

 

It just goes to show, it’s always a good idea to take a look at what you get from your board house before sending it on to us.

Duane Benson
Termites, maybe?

http://blog.screamingcircuits.com

Where the Jobs Are

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This news item from the Associated Press cuts to the heart of the matter when it comes to reshoring of manufacturing and why skeptics (including this humble writer) abound over whether Foxconn, among others, truly intend to set up large manufacturing plants in the US:

WASHINGTON (AP) — President Donald Trump brought two dozen manufacturing CEOs to the White House on Thursday and declared their collective commitment to restoring factory jobs lost to foreign competition.

Yet some of the CEOs suggested that there were still plenty of openings for U.S. factory jobs but too few qualified people to fill them. They urged the White House to support vocational training for the high-tech skills that today’s manufacturers increasingly require — a topic Trump has seldom addressed.

“The jobs are there, but the skills are not,” one executive said during meetings with White House officials that preceded a session with the president.

The truth is there are hundreds of thousands of manufacturing jobs available in the US today. The US Census Bureau puts the figure at just shy of one million. In talking with circuit board fabricators and assemblers over the years, the biggest impediment to hiring is not lack of work but rather lack of qualified workers.

My belief is that the demographics of electronics design and manufacturing resemble a bimodal distribution (two humps), whereby workers over 50 years old represent the largest group by age and workers aged 20 to 30 the second largest. Those aged 30 to 50 are the smallest group (the valley in the graph, see below). My thesis is that workers in that segment were coming online right about the time the North American electronics industry cratered — late 2001 to early 2004, leaving them either out of jobs or unable to crack the then much-smaller workforce that was left after the tech recession.

(The graph below illustrates the basic concept, although in reality the right hump would be higher than the left as there likely are more workers over 50 than under 30 in electronics design and manufacturing today. But you get the idea.)

With the older wave starting to retire, coupled with an upturn in the industry’s fortunes starting around 2008, a new wave of workers has entered the industry. And while we often speak of the lack of millennials in manufacturing, a tour of Silicon Valley area shops takes the air out of that conversation. There, workers don’t ask where the young people are; they just look around — they are everywhere. And manufacturers are catering to them, setting up coffee (and more) bars inside their plants, creating workspaces that resemble outdoor atria that offset the traditionally sterile assembly lines.

Moreover, there is some concern that widespread move of manufacturing back to the US will only accelerate the implementation of robots, leaving thousands of operators on the sidelines. In anticipation, robot makers are ramping capacity, in some cases by as much as two times. This is not without precedent. Those of us who were around when PCB fabrication and assembly migrated to China en masse in the late 1990s/early 2000s recall how common semiautomatic machines were then. It was a nod to the Chinese government, which was adamant about protecting employment.

What’s your experience? Is your company weighing a return to the US? If so, will it come with an increase in automation?

(Please, no political comments.)

OEM Markets, Through the EMS’ Eyes

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What can we expect from the OEM markets this year?

While long-term visibility remains cloudy, the outlooks from major ODM/EMS companies give some perspective on the near-term expectations.

Looking at publicly traded EMS and related supply chain (connector suppliers and component distributors), median supply-chain sales came in ahead of implied fourth-quarter guidance, according to data from Deutsche Bank. For the December quarter, sales increased 5.1% year-over-year at the median, almost double that of guidance (2.6% growth).

Likewise, implied first-quarter median sales guidance is 4.3% growth year-over-year which points to continued growth for the supply chain.

“In general, supply chain growth continues to be driven by company-specific new program ramps, although management teams are seeing a more positive demand environment,” DB said.

Two players that just announced quarterly earnings, Celestica and Flextronics, agree that storage and server sales will slump. Another, Sanmina, sees that end-market as stable.

The related communications and telecom sector is seen by Celestica as a big gainer (up 20%), but not so much by Flex (down five to 10%) or Plexus (down 4 to 7%) or Benchmark (down 15% or more). Sanmina called the market stable.

Automotive has, ahem, driven much of the sales growth for many EMS companies for the past eight years. Flex and Fabrinet both expect the surge to continue. So does Kimball, for which automotive makes up 42% of its revenue.

Consumer is expected to take some hits. Flex sees a 20 to 30% drop, Jabil foresees a smaller loss, and Celestica expects flatness.

Medical/healthcare is a mixed bag. Jabil forecasts a 2% drop, IEC also expects it to be lower, while Ducommon and Plexus say flat. Benchmark, Sparton and Jabil see growth, likely in the low to mid single digits.

As for military/aerospace, IEC and Sparton see them as growing, while the larger EMS companies (Celestica, Sanmina, and Ducommon) see them closer to flat. Plexus is most bullish on the segment, at 14 to 16% growth.

Only Flex is bullish on industrial, forecasting 10 to 15% growth. Ducommon sees it as flat to 1% higher, while Celestica, Sparton and IEC don’t expect much either. Plexus predicts a 4 to 7% drop. Benchmark expects sales to fall in the high single digits.

Many EMS companies don’t break out semiconductor, test or instrumentation. An exception is Benchmark, which sees strength there, with anticipated growth or 10% or more.

Finally, remember when computing drove seemingly everything? Benchmark expects that sector to fall 30% or more. It’s a sign of how far computing has dropped in significance among North American-based EMS’s in that many of them now group it as part of consumer.)

Sorry Utica, Foxconn Isn’t Coming There

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Or Broome County, NY. Or Harrisburg, PA.

Despite repeated media reports of an impending Foxconn migration, the company will remain what is has been since its founding in 1974: Chinese.

Sure, there will be satellites in key spots elsewhere: Juarez. San Jose. São Paulo. But not the American countryside, and not in big fashion, as is being widely reported by international media.

If Foxconn were to bring one of its Death Star-like campuses to the US, it would buck not just every single manufacturing trend, but outright common sense. Here’s three quick reasons why to expect that won’t happen.

  1. Incentives. Foxconn routinely holds out for hefty discounts on taxes, favorable access to land, and other concessions (See India, Malaysia, Indonesia, Vietnam, etc.). Given the higher cost of land acquisition, building codes and labor costs, and taxes, among other things, Foxconn would certainly insist on favorable treatment. Even if it were to get it – and unlikely proposition – how would that play with Americans if a Chinese company were to be given such breaks? Such a backlash has already begun in India, by the way.
  1. Access to capital. Founder and chairman Terry Gou is Foxconn’s single largest shareholder. He has been leveraging his own capital, including company stock, to fund recent acquisitions, including the mega-deal for Sharp. Despite (or perhaps because of) being publicly held in Taiwan, getting a clear picture on Foxconn’s assets and true financial worth is exceedingly difficult. Would the company be willing to trade its famously secretive culture in exchange for access to American bankers and financial markets? Or would that be the blow that levels a house of cards?
  1. Access to labor. Foxconn is prone to promoting – or at least failing to dismiss – wildly optimistic forecasts of capital investment in local projects. In the past few weeks alone it has been tied to a nearly $9 billion display manufacturing investment in China and another possible $7 billion version in the US. The latter, the reports say, citing Gou as the source, would create 30,000 to 50,000 jobs. Putting aside the fact that few of these massive new job figures ever are completely realized, even 1/10th of that amount would be three times the workforce of the 6 million sq. ft. battery factory Tesla built in 2014, for which Nevada ponied up nearly $1.3 billion in tax credits and rebates.

Simply put, there aren’t that many qualified engineers and technicians available in and around the American countryside to fill a campus that large. (Even China, which supposedly graduates two to three times the number of students in engineering and related fields each year doesn’t appear to have sufficient manpower to handle those employment estimates.)

The US Census Bureau, which tracks such things, notes there are nearly one million job openings at US manufacturers today. And a single company is going to add 5% more to that figure? Not likely.

There certainly aren’t that many available workers in Utica (population 61,000) or Harrisburg (population 50,000). The latter, famous as home to the Hershey chocolate company, should know to resist Foxconn’s temptations. On second thought, maybe it does:

“One location Foxconn already is familiar with in Pennsylvania is Harrisburg, where the company has a small operation and, in 2013, announced intentions to spend $30 million on a new plant that would employ up to 500. For that project, Havens said, DCED officials met with Foxconn representatives on various occasions and showed them potential locations for the planned site, but the project did not come to fruition.”

As part of the same announcement in 2013, Foxconn said it would invest $10 million for research and development at Carnegie Mellon University in Pittsburgh. When asked whether Foxconn ever delivered on its pledge, CMU spokesman Ken Walters said Wednesday the university had no comment.”

According to my sources, Foxconn is outsourcing, or seeking to outsource, work to other EMS companies in Southeast Asia. That doesn’t sound like a company that intends to take on manufacturing consumer products in North America. Pointedly, Gou himself told Reuters of news Foxconn would expand in the US: “There is such a plan, but it is not a promise. It is a wish.”

So with apologies to Utica, Harrisburg and other fine American cities, we say if you are waiting on Foxconn, don’t hold your breath.

P.S. For a great breakdown see this piece: http://www.livemint.com/Opinion/uzqTrvW0hMxgkSKCnh41dP/US-faces-risk-of-Foxconn-panel-plans-that-dont-add-up.html

Designing for Movement

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What is the difference between electronics in a robot vs., say, a stationary temperature monitor and control device? For one, if the temperature controller goes haywire, you can pull it off the wall and stomp on it, while you might have to chase the robot (or be chased) to deactivate it if it’s gone into world domination mode. More relevant, though, is vibration.

Fixed embedded electronics generally don’t need to worry about vibration induced reliability issues. Mobile robots, however, do. Unsecured connectors can work their way loose. Bolts can back off. wires can brush against stuff. A lot of practices that don’t cause problems in a fixed installation can bite in a mobile setting.

For example, a simple board-to-board ribbon cable. On the left is a common friction-retention cable connector. Fine for a development board, but not for an environment subject to vibration. Instead, use a mechanically captive connector, as shown on the right.

 

 

 

 

Free hanging cables are also a “no” for mobile devices. Cables hanging loose can get caught on edges, or tall or hot components. That can lead to worn or melted insulation and shorts. Instead, use cable ties, insulating grommets, and careful routing.

There are plenty of other considerations, but these are two of the biggest traps to avoid when movement is called for.

Duane Benson
Klaatu barada nikto. Translation: “Spaceman says what”