Fiducials and Odd Boards

One of the handy aspects of getting boards assembled at Screaming Circuits is that we don’t require fiducial marks for standard process boards. I would say that we build far more boards without fiducials than with. That’s cool, but there are sometimes when fiducials really are a good idea. In fact, if you’ve got room on the PCB, they’re always a good idea (just because something isn’t required doesn’t mean that it’s not a good idea).

Some boards are more in need of the marks than others. For example, not long ago, we got a rigid flex board in. It had three separate rigid boards connected by flex, designed to be folded into a stack. It looked pretty similar to the mockup in this image:SC_1

The boards didn’t have any fiducial marks. Normally, what we do, is find a via hole, through-hole pin hole, or some similar feature to use as a fiducial. That usually works, but not always. In this case, the length of the flex varied slightly from board to board. The PCB color was also very low contrast, which made it difficult for the machine to consistently recognize any mark we picked.

That meant our machines had a hard time finding the “home” spot, and we had to reset for each of the connected boards. Finding a spot on one board did not guarantee that we’d know where to place parts on the other two boards in the set.

In this case, it would have been far better if the boards were a consistent distance apart, and if each of the three boards had a set of fiducial marks.

What makes a good fidicual?

Most CAD packages have fiducial marks in their components library. Basically, it needs to be a metal dot surrounded by an area without any copper or solder mask. More than one is best. It should be an asymmetrical pattern that can only be oriented one way.

I’ve got some more details in this article here.

Duane Benson
Routed up like a fiducial
Another rigid flex in the night

http://blog.screamingcircuits.com

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Voiding: A Critical Issue in Electronics Assembly

Folks,

Looks like Patty and the team have a new assignment from Mike Madigan. Let’s look in ….

Patty had just waved to her twin boys as they got on the school bus when her mobile phone rang.  The voice was unfamiliar.

“Professor Coleman, this is Mel Ott.  I’m doing some classroom trading for a bunch of Navy Seals and Army Rangers at a location about an hour from Ivy U. I wondered if you could conduct a workshop on critical thinking for these folks?” Ott asked.

Before Patty knew it, she had agreed to do it. As she drove to the university, she kept on thinking,

“Me teaching Army Rangers and Navy Seals!?”

However, a few moments later, an outline for a workshop was forming in her mind. One topic would be: Which animal is implicated in more human fatalities in the US each year?

  1. Bears
  2. Mountain Lions
  3. Horses
  4. Deer
  5. Sharks

A few moments later, Patty was in the Engineering building complex and was rounding the corner to her office. She saw Pete and Rob waiting outside the door.

“By the looks on your faces, I can tell that we must have another assignment from Mike Madigan,” she said with a chuckle.

“This one is a little strange, even for him,” Pete began.

“Yeah! Look at this note he sent us,” Rob chimed in.

Ever since the three of them left ACME to join the ranks of Ivy University, ACME CEO Mike Madigan continued to use their services. They were paid a fair consulting fee, which all agreed more than paid for Christmas presents and vacations. In addition, Madigan convinced the board of directors at ACME to generously contribute to Ivy U’s general fund. In the three times Patty had met Ivy U’s president, he pointed this out to her with his appreciation. So, the bottom line was that the three of them were quite responsive to Mike’s requests.

Together they read his note:

“Team, our biggest customer is concerned with voiding. They claim it to be their number one concern. Since the three of you left, we have drifted a bit in keeping on top of these things. I am away for a week in Eastern Europe and my wife and daughter are joining me after that for a bit of a vacation in Slovakia. My wife’s heritage is from there, steeped in the traditions of the Rusyn peoples. So, she wants to visit the hometown of her great grandfather. Bottom line is that I will be gone for more than two weeks, without reliable Internet access, so I will be out of touch.

I need you to prepare a presentation on voiding that I (with you) will give to the customer’s president the day I get back. The presentation should have recommended actions. The pitch is at 2PM, 20 days from today. Come at 11AM and join us for lunch.”  Mike

“It’s just like Mike to give us an assignment with no details and we can’t ask him any questions and he schedules the meeting without asking if we are available,” grumbled Pete.

“I, for one, think it is great he is going on vacation,” Patty said brightly.

“Good point,” Rob added.  “I can’t recall him ever taking time off.”

“Well, what is our plan?” Patty asked.

“I’m almost certain that they are not interested in champagne voids, Rob pointed out.

“I agree, since they are mostly associated with immersion sliver finish while ACME’s customers mostly use OSP finish,” Pete added.

“I think the big issue today is voiding in quad flat pack no leads (QFN) thermal pads, BGA voiding is sort of passé,” Rob suggested.

A BGA void image, taken by CALCE.

A BGA void image, taken by CALCE.

“Oops! We are supposed to call them bottom-terminated components (BTCs), right?” Patty asked.

“OK. You’re right on that one,” Rob chuckled.

“So, let’s focus on BTC thermal pad voids. But, I think, for completeness, we should cover BGA voids, too,” Patty said.

“Pete, if you can cover BGA voids Rob and I will pull together something on BTC voids.  Let’s put it on our calendars to meet one week from today to review our material,” Patty sort of commanded.

“Yes, ma’am,” Pete and Rob said in unison.

Patty was about ready to get annoyed, but they all burst into laughter as they got up to leave her office.  Even though Patty was now a prof, she still had a lot of manager in her!

Cheers,

Dr. Ron

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TTM Again?

Not quite 18 years ago, a pair of venture capital firms bought a small Washington fab shop named Power Circuits. The following year those two firms, Thayer Capital Partners and Brockway Moran & Partners, added Power Circuits in Santa Ana, CA, to its stable. It renamed the fabricators TTM Technologies.

Today TTM is one of the largest PCB fabricators in the world, with revenues of around $2.5 billion across 25 facilities and 30,000 employees. It made some of the largest acquisitions in industry history, and unlike some of its competitors, made those acquisitions work.

It’s not without some irony, then, that one of the former directors of Power Circuits has teamed with a venture capital fund to acquire a pair of Southern California fabricators this week. 

History repeating?

Shane Whiteside, who was general manager and director of operations at Power Circuits, rose with TTM, eventually becoming executive vice president and COO before departing the firm in 2013.

With his background, Whiteside certainly would know which plants to target on the West Coast of the US. I haven’t been through KCA Electronics, but Marcel Electronics is one of the finest shops PCD&F has had the pleasure of visiting. I’m eager to see how this evolves.

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Manufacturing Loss Costs More than Just Jobs

An ex Photocircuits engineer says the gutting of US manufacturing has led to a huge shift in ownership of US assets, with dire consequences for all Americans.

“With only a very small manufacturing base left, there is a small need to make capital investments in these businesses. Capital investments are what drive productivity,” writes Jason Tillberg.

He’s preaching to the choir, no doubt, but I always find it interesting when folks support their  with details. In this case, Tillberg points to the massive transfer of ownership of US assets to foreign entities — remember Ross Perot’s “giant sucking sound” metaphor? — as a real cost paid by Americans through its inability (unwillingness?) to compete in manufacturing.

I find his thesis a bit incomplete and scattered, but he makes an important observation on capital investment and the disincentives to invest in a shrinking manufacturing base.

(As an aside, Tillberg talks about his experiences at Photocircuits in another piece on productivity written a few years back.)

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Calculating PCB Fabrication Costs (Watch Out!)

We get this question a lot: How much per square inch for a 4-layer board? (or double sided, or 6 layers … same question).  I won’t hold you to it, I promise. Right….

We understand that it is difficult to provide the boss with a project cost roll up if you do not have the board cost estimate. If you do a lot of designs you may have a feel for it or you may refer to a similar board cost from a past project. This actually can be very effective.

I have even seen online cost calculators that presume to give an accurate number.  Knowing what I know about PCB pricing, however, I can say that it just ain’t so.

Here is why calculating PCB cost is tricky and dangerous ground.

The biggest cost drivers for a bare board are:

  1. Who are you? Are you a stranger or newcomer, or do you have established relationships with board vendors? Most of us manufacturers figure the total dollar volume somewhere into the pricing equation.
  1. Board size. Square area of the board, plus the square inches of material remaining on the panel after routing your unique board shape. (You are charged by the processed panel).
  1. Production volumes in the 10 boards to 1000 boards range will have a very steep cost curve. The curve flattens out as the order rises above 1000 and gets very unpredictable at 100,000. Who you are begins to make a big difference at this level, along with your negotiating skills.

All manufacturers have a floor or minimum and it is best to ask how many boards you can get for the minimum charge. Some of the internet guys will sell one or five at a very low seemingly low cost, but your boards will have to fit perfectly into their narrow technical profile.

  1. Delivery days requirement. This can be very steep cost curve in the one to 10 day requirement range. After 10 days, little influence unless the volumes are large. We turn boards from our China factory in 10 working days and small expedite fees for five days. (Yes, we turn boards from China in five days.)
  1. Manufactured location. USA, China, Europe, Taiwan. This is usually a preferential decision, but clearly, China has the edge, followed by Taiwan. Differences can be great.
  1. Number of layers. No surprise here. From double-sided to four layers, costs will go up about 60%. From four layer to six layer add another 50%. For six to eight layers add 30%. Keep in mind that each added layer is the equivalent of a double-sided board added to the stack.  Also, remember that high-layer-count boards are often accompanied by tough technical requirements and buried vias.
  1. Technology stretching requirements, like exotic materials, super small geometries, buried vias, etc. This can be steep or moderate depending upon the manufacturer and the difficulty. Tg requirements will have a moderate impact.
  1. Surface finish, like HASL, ENIG, tin, OSP. If you can handle OSP, it is the lowest cost, followed by HASL, then ENIG. ENIG is so common these days that for low volumes, it can be as low cost as HASL.

Not the following:

  1. Number of drill hits; however, the total number drill tools used can drive costs up. Ten tools is the preferred maximum and usually can do the job.
  2. Presence or absence of a silk screen legend. (Minor influence.)
  3. Always insist on testing at no charge.

So, now think about putting all of this into an algorithm and coming up with a defensible, unchangeable answer. That is a dangerous guessing game.

My best advice is this: Get preliminary Gerbers to your preferred vendors and tell them they are preliminary. If the effort is conceptual, provide a simple description answering the cost drivers above and email your proposed or preferred vendors for a quote. (To make it easy for you, we offer a template. Go to precisionpcbs.com/pcb-manufacturing and click on the “Fab Drawing Template.”)

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60-Minute Simulation

Even for a software company, I’m sure it will be no simple task to analyze customer use and assess the ROI on the so-called “elastic licensing” Ansys just rolled out to enable customers to adjust on-the-fly to meet peak demands. I can’t imagine how crazy life will be for the poor soul who gets the hopelessly thankless task of sorting through all the customers who take advantage of this.

But the one hour rentals, the electronics simulation software company’s latest pay-per-use model, is less interesting for what it allows than for what it might foreshadow.

If I understand Ansys’s offer correctly, this is a bolt-on option for existing licensees, not a standalone offering. Useful? Certainly. Groundbreaking? Not so much.

But could true pay-for-play software be far behind? Reports have surfaced over the years of such licenses being available to certain subsets of users and in certain geographies. I’m unaware of it being rolled out on a wide level, however. It’s kind of like paying for a digital song that then disappears after five or 10 plays.

The emerging legion of new hobbyist/DIY and unconventional startups may be too attractive and otherwise too difficult for the larger players to land, however, unless they try something different. Many of these companies are not interested in paying thousands of dollars for a tool seat. They aren’t designers. They are hardware enthusiasts, and design is just a step in the process (or for some, a hurdle) to realizing their vision.

Even if the margins are weak or, more likely, the revenue elusive, will the sheer size of that audience be too tantalizing for the major ECAD companies to hold fast to their current licensing models?

 

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OEM/EMS Barrier Permanently Cut

For years we’ve been told that EMS companies are in the service business only and would never develop their own products. In one of the first interviews I did, back in late 1991, then IPC director Tony Hilvers — a leading proponent of the then-emerging CM industry (it wasn’t even called EMS then; that term was coined by Sue Mucha the following year) — insisted to me that contract assemblers wouldn’t go down the product development and branding path because it would put them in position of competing with their customers.

We can bury that old saw. With today’s news that Foxconn has, at long last, bought Sharp (for the low, low price of $3.4 billion), the loop between EMS and OEM has been drawn taut.

Not that this is ground-breaking in practice. Certainly, many, many EMS companies have, through acquisition or otherwise, developed and marketed their own products. Our 2009 EMS Company of the Year had a healthy, branded keyboard product line. And we estimated in this space in 2012 that 15 to 20% of the (then) 2,400 companies listed in our EMS directory did some degree of ODM/OEM work.

Going further, we wrote in 2015 we felt the line between EMS and ODM has been “permanently crossed.” But the Foxconn-Sharp marriage takes it to an entirely different scale.

Whether the Sharp name stays on its product lines, which range from Aquos televisions to smartphones to solar panels, and includes the OLED technology so prized by Apple that it compelled Foxconn to write the check in the first place, remains to be seen.

Either way, there’s no going back. EMS is now OEM. Going forward, who is the customer they will serve? And knowing the line keeping their suppliers from their end-customers has been permanently breached, will this spur OEMs  to reestablish their assembly operations?

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Good Talk

The big story out of IPC Apex Expo last week – about the only story, really – was the introduction of an open communications standard by Mentor Graphics’ Valor division, followed by the rapid response by more than two dozen assembly equipment providers and software developers over shared concern that the solution to machine-to-machine communication might end up residing in the hands of a single company.

At the heart of the matter is the so-called Industry 4.0. Also referred to as IIC (US), Made in China 2025 (China), Industrial Value Chain Initiative (Japan), Manufacturing 3.0 (South Korea) and other names, it stands for the capability for different equipment, made by different OEMs, to share bi-directional data over an open, yet secure, platform. Done right, it’s a major step toward permitting manufacturers to pick the best machines for their specific needs, versus being beholden to a single line solution. Fundamentally, it’s at the heart of a fully beating Internet of Things; some feel the fully automated factory can increase production efficiency by more than 30% over time, adding billions or more to national GDPs.

Let’s start with the Mentor specification. Two years in the making and announced just prior to the annual IPC trade show, it was released at the Las Vegas event as OML, which stands for Open Machine Language. Having years of experience writing translators for various assembly line machines, Valor took those translators and installed OML in front of them, and packaged the combination in a black box. Thus, in a relative instant, a solution to a much-discussed electronics assembly problem was at hand; OML satisfied the need for machines to talk to each other, and the box handled any connectivity issues.

Mentor planned to make OML available to any company through a partner program and would retain ownership over the protocol while relying on the partners to help shape the future direction of the specification.

In Las Vegas, of course, everything’s a gamble. Once word got around the show, equipment vendors said “not so fast.”

Mentor’s angle was to multiply the use of IoT through OML, thus exponentially expanding the market for its Valor tools. Perhaps worried by the legalese, or the potential for a single “owner” to license and potentially change or even shut out competitors, roughly two dozen assembly OEMs met over the course of two days to hammer out an agreement that reshapes the trajectory of the specification. Several equipment OEMs PCD&F/CIRCUITS ASSEMBLY spoke with agreed OML is technically sound but felt the business issues inherent in licensing a corporate spec could pose a host of problems. Up against this strong front, Mentor pivoted and offered OML as a starting point for a to-be-determined IPC standard.

In one sense, then, bi-directional communication goes back to the drawing board. Some 15 years ago an IPC committee published a shop floor equipment communication standard labeled IPC-2541 and colloquially known as CAMX. One presenter at the Apex sessions demonstrated how IoT could work using enhanced CAMX. The early take – and this has yet to be finalized, as not even the charter is on paper yet – is the task group will study a combination of OML, CAMX and perhaps other, yet-to-be-written software as part of its IPC mission.

All sides agree there will be an emphasis on speed. If nothing else, OML forced the industry to confront the fact that not only is a standard needed, it was needed yesterday.

Going forward, it will be up to each software company and manufacturer to leverage the IPC standard as they see fit. It remains to be seen if Mentor will ultimately concede OML or whether it will attempt to go it alone.

Some will recall a similar scenario with the data transfer formats for printed circuit board designs. Various specifications sat mostly idle for years, IPC-D-350, IGES and EDIF among them, until the powers behind Valor’s ODB and IPC’s GenCAM formats squared off. Valor donated the XML version of ODB to IPC in 2008, yet continues to maintain its ODB++ format. GenCAM evolved into IPC-2581, and upon Mentor’s purchase of Valor, finally gained traction among worried software competitors and OEMs who feared being shut out of markets or forced to switch tools.

Regardless of the back story, this is where the industry stands today, and a basically workable plan is being formulated. The speed with which the industry moved – and Mentor should be thanked for spurring action – screams the need is present and widespread, and there is general consensus on the solution. That’s a great story. After all, in electronics, how often does that happen.

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Parts Shortage

While assembling SMT PCBs for a customer, the line unexpectedly ran out of 01005 package size resistors during the production run. This was due to an error on the customer’s part; they simply did not provide us with enough. But the customer still expected the finished product in-hand by the due date, and we did not want to disappoint him.

This, of course, created a dilemma. Should we halt production while additional parts were ordered, or simply continue? We placed a replenishment order immediately, and learned that we could not get them until the next day. We asked, “Is it possible to assemble these boards now, and add the part later when they arrive?” We also had to quickly assess the feasibility adding the part later on. How accessible is the site for this tiny part? Can it be done by a skilled soldering technician? We decided that it could.

A parts shortage didn't stop production.

An 01005 parts shortage didn’t stop production.

We proceeded to build the order with the exception of that single 01005 component. The site was accessible, we decided, so that the part could indeed be added individually to each PCB. Sure, it would take some time and hand soldering, but it would not cost us nearly as much time as if we had put the entire build on hold to wait for the parts.

Parts_Shortage02

Once the needed parts arrived, they were hand soldered onto each assembly by a skilled operator using slender soldering iron tips.

When the parts arrived the next day, we were able to employ our best hand soldering people with soldering irons equipped with special slender tips. The job went quickly and easily, and we were able to minimize downtime on the SMT line due to the unexpected component shortage, and keep this job on schedule, much to the relief of our customer. We came through for them despite their mistake, and they appreciated that.

Parts_Shortage03

The 01005 parts were easily and quickly added, and the entire job shipped by the required due date since the rest of the assembly had already been finished.

Efficient use of time, getting whatever can be done while minimizing down time, pays dividends when one is living by tight delivery schedules and expected ship dates. The more that can be achieved without unnecessary delays, the better the chances that a ship date can be honored.

Roy Akber

www.rushpcb.com

Roy@rushpcb.com

 

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Happy St. Patrick’s Day!

SC4And some trivia. You may have noticed that the soldermask used on most PC boards is green, as is the paint used on most steel truss bridges. Why is that? And what do the two things have in common? Why green PCBs and why green bridges?

To answer, I brought in color expert expert Patty O’Patrick O’Dell, who stated: “Many bridges and PCBs are green because they absorb red and blue light, only reflecting the green.”

That wasn’t quite what I was getting at, but close enough. The important thing, is that, generally, in commercial products, the PC boards are hidden, so the color doesn’t matter that much. With prototypes and a lot of the hobby or development boards, that is not the case, so many companies have chosen to use a different color as a part of their identity.

Arduino products are blue, as are most boards from Adafruit. SparkFun makes theirs red. Ti Launchpads are red as well. The Beaglebone uses color, essentially, as a model number; Beaglebone black, Beaglebone green. This is possible because major PC board fab houses have made different colors more economical than they used to be.

I’ve been asked if the color makes any difference electrically. In general, no. If you’re dealing with super high speeds, RF, or other exotic conditions, it’s always best to ask your board house. In those fringe areas, a lot of things have the potential to make a difference. Other than that, if you can afford it, and want to make a statement, go for it. You can often get different color silk screen legend too. Just make sure there’s contrast between the two. White silkscreen on white soldermask would not be the best choice.

Duane Benson
Beware the monsters from Id

blog.screamingcircuits.com

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