Component Footprint Rotation

Before we (or any old assembly house) go about putting surface mount parts on a board, we need to program our assembly robots. I’m oversimplifying, but essentially, the machine program needs to know the X / Y coordinates, relative to the board origin (which is the lower left-hand corner), the part rotation, and the side of the board.

In years past, we needed a centroid file (AKA pick-and-place file) containing all of that information. In some cases, we still need the centroid, but not always. Today, we can get the same information from ASCII CAD files, ODB++ CAD files or Eagle .brd files. You only need a centroid if you send us your board files in Gerber format.

If you do send us a centroid file, you no longer need to worry about rotation. The IPC has defined the zero degree orientation, as well as proper rotation direction, but too many part footprints set the zero degree at different angles. We can’t rely on the data.

While we have to ignore rotation and figure it out with other means, we still do strongly recommend that you follow IPC standards when you make your own footprints. The illustrations below show how footprints are supposed to be oriented.

Duane Benson
There’s no earthly way of knowing
which direction we are going
There’s no knowing where we’re rowing

Package origins

Passives orientation r2

Chip rotation

Quad and BGA

Three-pin parts

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Hats Off to Gary

Congratulations to Gary Ferrari, who last month became the 33d person to gain induction to the IPC Hall of Fame. For printed circuit board designers, this is something of a symbolic victory, as Ferrari is just the third designer (after Dieter Bergman and Vern Solberg) to make it in the IPC Hall.

Ferrari, who has been an occasional contributor to PCD&F over the years, needs little in the way of introduction to the current generation of designers, in the US and abroad. He has his name on all the major industry design and fabrication standards, having led the development of IPC-D-275 and IPC-RB-276 (now IPC-2221/2222 and IPC-6011/6012, respectively). He, along with Bergman, helped found the IPC Designers Council and drove the certification program. Along the way, he has trained or taught several thousand engineers and designers on a variety of topics from layout to heat management to standards to fabrication and assembly. While not the person whose name you will see on a book, Ferrari is still one of the first phone calls anyone with an engineering problem is likely to make.

The timing is bittersweet in that it occurred just months after the death of Bergman, Ferrari’s longtime friend and colleague. Still, it is a long time coming for one of the true iron men of the industry. I am thrilled for my friend.

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Electronics Assembly Process Optimization

Mike Madigan was not used to feeling intimidated.  After all, as the CEO of ACME, a multi-billion US dollar EMS company, he was used to doing the intimidating.  However, he had just finished a meeting with the CEOs of his two biggest customers and it was a disaster.  They asked to “do lunch” with Mike and, after this event, Mike’s stomach was churning.  If Mike was honest with himself, if he was them he would have been tougher.  But, it was their teasing demeanor, punctuated with laughs and jokes, that made it all the worse.

That these gentlemen had some points to make was inarguable.  First-pass assembly yields were down 4%, and Mike’s answer, that it was because the technology was more challenging to assemble, did not fly.  They told him to get that 4% back or they will find a company that can.

Both of these gents had been process engineers when they were younger, so they “knew the ropes.”  In a recent audit of one of ACME’s facilities, they found one process engineer, responsible for the stencil printing process, that didn’t know how to run the stencil printer. And this lad also could not locate the solder paste spec.  Additionally, he could not explain what “response to pause” was.  Another process engineer did not know how to match the reflow profile to the solder paste spec (after they finally located the spec). Mike’s answer, that ACME’s recent growth made it hard to keep the training of the engineers up to snuff, only made things worse.

When asked what percent of his engineers hired in the last two years were SMTA certified, Mike didn’t know.  He expected it was 0.

Then, one of the CEOs said, “Things seemed to be much better when you had that Advanced Processes VP. What was her name? Patty something or other?”  That was a big part of the problem. Patty Coleman was gone and, with her departure, things had gone to h#!!.

Mike thought of asking Patty to fix things, but that would be unfair.  She had only been at Ivy U for a year or so and was still getting established.  Maybe the Professor could help.  Mike hoped so. The CEOs wanted a plan in two weeks.

Ten days later…

Patty had just finished getting ready for a meeting with her husband Rob, Pete, and the Professor.  Ten days ago, the Professor asked if they could help him develop a software tool that would be used by ACME as a self-audit of their practices related to electronics assembly.  The Professor said it was a request from Mike Madigan himself.

Patty had a little time before the meeting, so she decided to check her email.  Suddenly, she was disturbed by a knock at the door.

“Professor, we wanted to ask you a question about probability. Is now a good time?”, a young lad who looked 11 years old asked.

“Sure.” said Patty.  “But tell me your names first.”

“Oh!, Sorry! I’m Henry Finn. But everyone calls me ‘Huck’. And this is Chris Jenkins.  We’re both sophomores.  You spoke about statistics at our Introduction to Engineering Class a few days ago. We’re hoping you can settle an argument,” Finn began.

“What is it?” Patty asked,

“Well, Huck says that since the Patriots are one of 32 teams in the NFL, the chances of them winning 4 Super Bowls is (1/32)^4 = 9.5×10-7, or about one in a million – if they had only an average skill level.  I think it is more than that.  Huck says the rarity of them winning four Super Bowls shows how much above average they are,”  Jenkins jumped in.

“Your analysis is not quite right. You calculated the likelihood of 4 wins in a row. They have won 4 out of the last 14 Super Bowls,” Patty said. Patty was on top of the Patriots stats as she was a big fan.

“To perform the analysis, you have to use the Binomial Distribution.  Let me see if I can calculate it using Minitab 17,” Patty said.

She went to her laptop and, in no time, had a graph that explained the problem.

“So, the chances of a team possessing only average skill winning 4 out of 14 Super bowls is less than 1 in a thousand.  I’ll leave it to you two to decide what that means,” Patty summed up.

Patty chuckled to herself as she saw the two sophomores arguing as they walked away.

She looked at her watch and saw it was time to head to the Professor’s office.

Patty was the last to arrive as Rob and Pete were already there. As she sat down, the Professor began.

“Thank you for coming.  I have incorporated all of your input and am pleased with the results.  I’m hoping that we can review the resulting web application that was developed,” the Professor began.

“Is it in English or one of the 17 other languages you speak?” Pete joked.

“English, Pete. English,” the Professor chuckled.

In reality, Patty, Pete, and Rob were thrilled to help the Professor develop this self-auditing software.  They all knew that it isn’t that often that one can help someone like him.

The Professor was only able to come up with 20 questions for the software.  Patty, Pete, and Rob increased it to 40. Pete was proud that he contributed 8 of the additional twenty questions.

The Professor flicked on his projector and displayed the first page of the self-auditing software.

“This is the first of the four sheets for the software tool.  I think Rob’s suggestion to name it ‘AuditCoach’  is a great idea.  Let’s take a look and see what we think,” The Professor said.

“I think it’s good that you have the questions about the process engineers knowing how to run and optimize the equipment.  It is surprising how many times that is not the case,” Patty commented.

“That was Pete’s idea,” the Professor replied. Pete beamed from the recognition of the Professor.

“I like the idea of making the first question count 3 times as much since it is so critical,” Rob chimed in.

“Agreed,” Patty and Pete murmured.

The Professor pressed on, “I thought it might be best to break the questions in to four categories:

  1. DfM, Processes
  2. Equipment, Materials Supply and Validation
  3. DOE, SPC and CIP, and
  4. Training and Failure Analysis.

Over the next hour the group reviewed all 40 questions on the four sheets of AuditCoach. Some minor improvements were made.

As they were wrapping up, the Professor had one last comment, “I asked Mike Madigan if he would make AuditCoach available to others.  We both thought that doing so was a good idea.”


Dr. Ron



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What Apple’s Latest Supplier Audit Says About Apple

Apple’s annual supplier audit was released today and sure enough critics on both sides are already picking through the core and going at it over whether the company is doing enough to ensure the safety and compensation of the hundreds of thousands of workers who plug away in anonymity daily making Apple the wealthiest company ever.

Apple’s latest stats show a 92% compliance rate with its 60-hour workweek, and says the average workweek was less than 49 hours. Of course, that’s as it should be: Most of Apple’s supply chain is in China, whose laws cap the work week at 40 hours and monthly overtime at 36 hours. Adding nine hours per week over four weeks per month comes to 36, which means Apple suppliers are likely often breaking the local laws.

Indeed, that’s consistent with a separate study of nearly 100 Pegatron workers undertaken by labor rights group China Labor Watch, a constant thorn in Apple’s side, which found that more than half of the its workforce performs more than 90 hours of overtime per month, with some peaking at 132 hours.

Apple essentially ignores this by trying to turn a lemon into lemonade. It now touts its ban — as of October — on its suppliers’ charging workers to obtain jobs. As Apple senior vice president of operations Jeff Williams writes in the report, “You’ll see that we consistently report suppliers’ violations of our standards. … Because of these audits, over $3.96 million was repaid to foreign contract workers for excessive recruitment fees charged by labor brokers. And nearly $900,000 was paid to workers for unpaid overtime.” Williams says that this is proof that the system is working.

I don’t agree, but not because there are violations. I suspect any multibillion dollar company with operations (or contractors) in as many places that Apple has will encounter similar, if underreported, problems.

No, the reason I don’t agree is because the same subcontractors keep getting caught for the same violations. That shows a decided lack of regard for their major customer’s brand and mandates.

I think Apple is taking the problems seriously, but its supply chain is not. And the chain has no real incentive to change. As such, until Apple starts firing suppliers, the problems of what amounts to indentured servitude at its contractors’ factories will continue unabated.

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Should Flextronics Be Broken Up?

The findings of a new study by Boston Consulting Group suggest that, over time, many tech companies are guilty of mission-creep, especially large ones.  And when that happens, those companies do not provide the shareholder value they could if they were leaner and more focused.

As part of its study, BCG analyzed total shareholder return, defined as the bottom-line return from capital gains and cash flow contribution. When it did so, it found little distinction between large-cap and small-cap companies:

“The clear takeaway is that regardless of company size, the more diverse the portfolio, the more difficult it is to generate high TSR—and the greater the set of management skills a company needs in order to handle that diversity. Companies must therefore be more deliberate and more explicit in rationalizing each element of their portfolio.”

BCG likens the strategy to the 3 R’s, in this case, Resize, Reform and Rejuvenate.  Marc Andreessen, the founder of Mosaic (later Netscape), put it this way: “If they’re more than 20 years old, then [companies will] probably benefit from being broken up, and many of them will probably be forced to break up if they don’t do it voluntarily.”

So for the EMS pseudo-conglomerates (Foxconn, Flextronics, Sanmina, etc.), what this means is there are arguments to be made — indeed, being made — that having bare boards, assemblies, design services, box build, ODM products, and a host of other products and services under a single umbrella is not an optimal  strategy.

There’s always been some debate over whether publicly traded EMS firms should be compared to other tech firms like Cisco and Microsoft or to traditional manufacturing companies (say, Caterpillar). It’s tough for a mid-size or larger contract manufacturer to attain repeated organic double-digit topline growth, and their margins are never going to be Wall Street pretty. Dumbing down the peer group makes sense.

But the bigger question being asked is whether their size is actually a hindrance. There must be a point at which that happens. Can the data analysis pinpoint that yet? And will market impatience make all of this moot?


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What is Cicret and Why is It Important?


Let’s check in on Patty …

Patty had to admit that she was getting annoyed. Two of the female engineering students were always going to her husband Rob’s office for help with their homework. At first glance this would seem like a normal thing to do, as Rob was a teaching assistant for the materials science class they were taking as part of his Ph.D. program at Ivy U. But they were there every day. And Patty could tell that they had more on their minds than materials science.

Rob was approaching his mid-thirties now, but had boyish good looks and was in athletic physical condition. He looked just like all of the twenty-something PhD students that were his peers. Patty remembered when she and Rob became engaged, her best friend Jan Curtis said, “Patty you are a lucky girl. In addition to being smart, successful, kind, fun, and interesting, Rob is handsome and cute!”

So it is not surprising that these two engineering females would find Rob attractive. To add insult to injury, these two young ladies just happened to be Justine Randall and Jessica Wu. They were the two students who innocently said to Patty, “Professor Coleman, you are an inspiration for us. We hope, in twenty years, that we can be just like you.”

This quote triggered the beginning of Patty’s relationship with hair dye.

It didn’t help that Rob could not wear his wedding ring, because it was a danger in the experiments he was doing for his research. It had been off for so long that even the tan line had faded.

To Rob’s credit, he was doing nothing to encourage any interest, but Patty wanted to set these two young girls straight. She had purposely not told Rob that she could not pick their twin sons up from daycare. She would do so when Justine and Jessica were in Rob’s office. She would know they were there, as they had to pass by her office on the way to Rob’s.

Just then, they walked by. Patty gave them a few minutes and then she went straight to Rob’s office. She tapped on the open door and stuck her head in.

“Honey, I forgot to tell you that I can’t pick the boys up from day care, I have a meeting with the Dean,” Patty said to Rob.

“No problem. It’s way past my turn to get them anyway,” Rob responded.

Justine and Jessica looked like they just found out spring break was cancelled.

“Justine, Jessica, I believe you have met my lovely wife, Professor Coleman?” Rob said.

After a few pleasantries, Patty left, feeling relieved. However, she decided Rob definitely needed a photo of her and the boys prominently displayed on his desk.

After entering her office, she set her new adjustable desk to the standing position. She then noticed that she had just received an email from Mike Madigan. It read as follows:


The board is considering buying a start-up that has developed a new device called The Cicret. See this video.

They claim they can develop a prototype for $1 million. My gut tells me that they are dreaming. But, if I am wrong, it is too good of an opportunity to pass up.

I’m hoping you can meet with Jan Curtis and Phil Anderson and come to a consensus on what the opportunity is.

Let’s have Anderson write the report to reduce any extra workload on your part.

Your faithful student,


BTW, thanks for helping my son at West Point. Fortunately he has inherited all of my wife’s good points and none of my bad ones!

Patty continued to marvel in the change in Mike Madigan. Much of his aloofness and grouchiness had worn off. Patty then went and looked at the video and was blown away. Her first thought was, “I want one.” Then she went to the company’s website and saw that they had yet to make a prototype. She thought that the company’s request for donations was comically cute, but did not foster confidence.

As she was mulling this over in her mind, Pete came to the door.

“Hey Professor! Jan and Phil are coming to visit!” Pete exclaimed.

As usual, Pete was a step ahead of Patty.

Two days later, Jan, Phil, Rob, Pete, and Patty were in a small conference room at Ivy U. Patty forgot how much she missed them all and got a little misty eyed thinking about it.

“Well Professor Coleman, what do you think about the Cicret Bracelet?” Phil teased.

“I want one!” Patty joked loudly.

“But, I’m not sure I will ever have one,” she continued.


Figure 1. The Cicret Bracelet. Will it look this bright in sunlight?

“It seems a challenge to get all of the electronics into such a small form factor,” Pete chimed in.

There was a murmur of agreement.

“Can you even find an IC with dimensions as small as the width of the bracelet?” Jan asked.

“I did a little checking and the new Apple A8 processor is quite small, a little less than 1 cm on a side. But that is about the width of the bracelet and some margin will be needed,” Rob added.

“Let’s see if we can estimate the dimensions of the bracelet and compare them to an iPhone 6,” Patty suggested.


Figure 2. The Cicret Bracelet teardown.

The team went to different websites to get the answers. As usual, it took a little longer than expected. Within an hour, they had a summary.

The dimensions of the Cicret Bracelet were 20 cm long, by 1 cm wide and 0.5 cm thick for a volume of 10 cc. The iPhone 6’s dimensions are 13.8 cm by 6.7 cm wide by 0.69 cm thick equaling a volume of 63.8 cc, over 6 times the volume of the Cicret.

“I think we might be unfair in comparing the Cicret to an iPhone 6. The video doesn’t suggest it can do all that the iPhone does,” Jan commented.

“Perhaps, but a factor of 6 in volume difference is a lot,” Rob responded.

“The battery seems like a show stopper, the iPhone battery is 9.5×3.8×0.33 cm = 12 cc, more than the entire volume of the Cicret,” Patty said.

While the team hashed all of these issues out, Pete obtained a teardown analysis of an iPhone 6.


Figure 3. The iPhone 6 teardown.

“Look at the teardown of the iPhone 6, it has more than 20 ICs. The Cicret has only about 5,” Phil sighed.

“To make the Cicret in its proposed form factor, one would almost surely have to work with IC and component vendors and have them develop special ICs and components to fit into the bracelet. This would certainly add to the cost,” Jan added.

“Let’s see if we can summarize what we have learned,” Patty suggested.

Since Phil was to write the report, he went to the white board and queried the team. The following summary resulted.

  1. The Cicret, at this time, appears to be a design concept. The videos were clever digital creations, not the viewing of a working prototype.
  2. It is quite a stretch to think that a working prototype can be developed in anything close to the form factor shown in the video. The reasons for this are:
    • The integrated circuits required are likely to be smaller than the width of the bracelet, as some margin will be needed. So, smaller-than-typical ICs will be needed. If this is the case, special ICs must be developed at considerable cost.
    • The volume of the Cicret is 10 cc vs over 60 cc for a smartphone. Although the Cicret may not need all of the function of a smartphone, this volume difference appears to be too much.
    • The volume for a battery, using current technology, will be the biggest challenge. Current battery sizes are greater in volume than the Cicret.
    • The parts list that the Cicret offers appears to us to be too low. There are likely quite a few components needed that may not be listed.
  3. We question that the projector lights will be bright enough to be viewed in sunlight as the video suggests.
  4. One million dollars (US) seems to be a very optimistic cost to develop a working prototype in anything like the form factor shown in the video. Component and (especially) battery sizes will be issues. We think this cost could be off by a factor of 10 or more.
  5. These conclusions may be too negative. It would be helpful if one member of our team could visit Cicret to discuss these concerns.

“Nice summary everyone,” Patty said.

“Who will go to Cicret? It’s in France, right?” Jan asked.

“How about Phil? Maybe he can at last find a girlfriend,” Rob teased.

And with that the meeting ended.

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Using the Newest Gen Arm Microcontrollers

I’ve written a few times about the new Freescale KL03 ARM Cortex M0+ microcontroller. This particular part comes only in very small packages, with the smallest being a 1.6 x 2mm WLCSP (wafer level, chip scale package) 0.4mm pitch, 20 bump BGA. That’s a mouthful — albeit a very tiny mouthful. Maybe just a toothful.

On the left, here, I’ve got a pair of them on a US postage stamp.

For us, it’s not a particularly difficult part to assembly; just a garden variety 0.4mm pitch BGA, as far as we’re concerned. We place loads of them. But, it can be a very different story for a designer. Conventional wisdom says that a PCB designer has two choices with a part like this: a very expensive PCB, or don’t use the part.

Escape routing becomes very difficult (read: expensive) at 0.4 mm pitch. This part only has six connections that need to be escaped, but that can still be a problem. You can’t fit vias between the pads to escape out the back side. You can’t put vias in the pads unless you have them filled and plated over at the board house. That’s expensive in small quantities.

This blog post series is going to examine some possible ways to use these parts with more of a standard fab, such as Sunstone Quickturn. I’ve got three different process blank PCBs, each with four different land patterns.

I’ve been asked about home reflow too, so as a bonus, I’ve done my best to duplicate hobbyist conditions for one of the board sets.

Duane Benson
“Screaming Reflowster” not sold here

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Early Placement Tales

Some comical reminisces on an early (50 years old!) attempt to machine-assemble a printed circuit board. The program was written on punched paper tape and feed into a robotically controlled “placement machine.” Hijinks ensure.

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Polarized Non-Polarized Components: Inductors

We have a number of manufacturing engineers running around here at Screaming Circuits. They’re very good at what they do, as are our operators and technicians. They are not, however, electrical engineers. Our parent company has a big group of electrical engineers, but they’re at a different location.

What that means is, though we endeavor to be experts at building things, we often don’t know what the circuits and components do in your specific application. People tend to send us their difficult projects so we’ve probably seen just about everything possible go through our plant. But, every now and then we see something unfamiliar. It doesn’t happen very often, but it does happen.

Sometimes it’s an exotic new package (like the 0.3mm pitch wafer scale BGAs now
showing up). Other times, it’s something a bit older, but just not clear. Rather than put a job at risk, if we aren’t sure, we’ll always hunt down the designer and ask.

Okay. That was a long-winded intro.

We recently ran across just such an unknown; a “polarized” inductor, without an accompanying “polarity” mark on the PC board. Not only that, but the markings on the inductor were a bit ambiguous. One half is black and the other half is green. The datasheet is in black and white, so there’s more room for interpretation than we’re comfortable with.

SC2At first glance, you might wonder why polarity / direction matters in an inductor. I did. It’s just wire. Right?

Almost: it’s not just wire, it’s coiled wire. In most cases, the direction doesn’t matter, but in cases with multiple inductors, or with super high speeds, it can matter due to the fact that the coil winding direction has an influence on the flux and the actual induction.

I won’t go into all of the theory, but think of walking. In most cases, it doesn’t matter whether you start with your left foot or your right. However, if you’re marching in a coordinated group, you want everyone to start with the same foot.

Look at the two sets of air-core inductors above. When set like this, directionality starts to make a bit of sense. Imagine the electrons being pushed around in theses things and try to picture the resulting lines of flux.

The moral of the story: eliminate ambiguity. If the part is polarized, either mark the board, or make it the direction clear to your manufacturer in build documentation. Do this even if the polarity doesn’t matter to you, ’cause we don’t know that.

After photographing these, I ended up recalling this bit of knowledge. It’s just so rarely needed that it had vanished in to the fog. I put a few more photos after my signature.

Duane Benson
Which way did he go?
Which way did he go?




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The Best-Read PCD&F Articles in 2014

As we did with CIRCUITS ASSEMBLY on Monday, here’s the list of the best-read new articles at this year.

Leading the pack was IMI president Peter Bigelow, whose piece “When ‘Scaling Up’ Leads to ‘Belly Up’ ” received the most hits of his 10-year career as our columnist.

Next up was “A Two-Team Race?” Dr. Hayao Nakahara’s annual list of the largest PCB fabricators.

Coming in third was “Design for Reliability with Computer Modeling.” Dr. Randy Schueller and Cheryl Tulkoff, both with DfR Solutions, explained a new CAD tool that imports design files and quantitatively predicts product life.

They narrowly beat out “Magnification vs. Resolution in Visual Examination Specifications,” by Louis Hart of Compunetics and consultant Robert Simmons.

Coming in fifth was “Design Practices for Panelization and Depanelization,” by Phil Lerma, fabrication manager at NexLogic Technologies.

In sixth was Patrick Carrier’s “Maximizing Capacitor Effectiveness,” the first of multiple contributions from Mentor Graphics.

Next was “Power Electronics Packages with Embedded Components – Recent Trends and Developments,” by Lars Boettcher, Stefan Karaszkiewicz, Dionysios Manessis and Andreas Ostmann, who summed the work of a cross-industry team’s development and testing of a PCB-based embedded chip technology for an under-the-hood automotive application.

They were followed by “Qualification vs. First Article Inspection,” authored by Charles Hill and Karen Ebner of Raytheon.

The ninth most-read piece was “Effectively Managing PCB Design Constraints,” by John McMillan of Mentor Graphics.

And closing out the Top 10 was yet another Mentor offering, “Passing Electrical Signoff,” by Rod Dudzinski and Minoru Ishikawa.

The top written staff articles were “The One-Stop SoCal Shop,” senior editor Chelsey Drysdale’s look inside Murrietta Circuits, and “Good Values in Vegas,” our staff writeup of the 2014 IPC Apex Expo trade show.

We want to thank all our contributors from last year, and especially our loyal readers. Happy new year!

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