In SMT Assembly, Even 1 Second of Cycle Time Can Affect Profitability


Patty had just returned from SMTAI 2015. It was a sentimental meeting with the retirement of longtime executive administrator JoAnn Stromberg. At one of the technical sessions, Patty was especially interested in epoxy flux being used as an underfill. She couldn’t wait to discuss it with The Professor.

As she drove up to Ivy University’s campus, she was struck by the many hundreds of students walking to class. No one was overweight and no one was smoking. She reminded herself to discuss this topic in her statistics class. Surely Ivy U did not represent the typical 18-22 year-olds in this regard.

Soon, she arrived at her office. After clearing her laptop of emails, she headed to The Professor’s office.

Patty had been working to improve her French. Since French was one of the 18 languages in The Professor’s repertoire, they often spoke it to improve (for Patty) and keep sharp (for The Professor). Patty chuckled to herself that her French was now good enough to hear The Professor’s Quebecois accent. He learned French as a pre-teen, as his parents were missionaries for Wycliffe Bible Translators and worked with some remote Indian tribes in northern Quebec.

Bonjour Professeur, comment allez-vous?Patty dit gaiement.

“Je suis bon Patty, comment étais SMTAI?” Le professeur a répondu.

The remainder of the discussion will be translated into English for our non-Francophone readers.

“It’s too bad that you couldn’t make it this year. The retirement dinner for JoAnn was touching,” Patty began.

“It will be hard to replace her, indeed. Her commitment was extraordinary,” The Professor responded.

After discussing this topic for a few minutes, The Professor changed the subject.

“Were there any interesting papers presented at the SMTAI tech sessions?” he asked.

“That’s why I’m here,” Patty replied. “There was a paper on epoxy flux as an underfill material. It was a great talk comparing epoxy fluxes to standard underfills. The speaker mentioned how using epoxy flux allows the operator to avoid using a separate dispensing process and curing oven that standard underfills require. His point was that the epoxy underfill approach would save a lot of money, as long as the epoxy process only added one second or less to the cycle time. This one second was the time it took to dip the flip chip or BGA into the flux.”

Patty immediately saw the troubled look on The Professor’s face.

“Professor, I sense you are thinking the same thing that I was,” Patty said.

“Yes, one second is a long time,” The Professor replied. “One second is 5% of a 20-second cycle time, so your production is reduced by 5%. Not a trivial amount.”

“My sense is that this one second would be a greater cost than paying for the dispenser and curing oven in a standard underfill process that keeps the cycle time at 20 seconds,” Patty said.

The Professor nodded his head in agreement and then went to his laptop. In just 3 or 4 minutes, he had calculated four different scenarios using ProfitPro software.

“Well, in most cases, the cost of that 1 second/cycle lost by the epoxy flux process costs the operator somewhere between a few hundreds of thousands of dollars to more than one million dollars per line per year,” The Professor explained. “This estimate even considers the fact that the standard process already needs a dispenser and curing oven.”

“You know what I always say.” The Professor started.

“It never pays to reduce productivity,” Patty chimed in, always the faithful student.

“Take a look at this one example. A large ESM manufactures a product with a 3-shift, 5-day/week operation on a state-of-the-art SMT line. The default, as shown in the figure, is the financial result for one year of production, using a typical underfill, assuming $200K for a dispenser and curing oven and a 28 second cycle time.

“The second run shows the financial results using an epoxy flux that requires a one second longer cycle time (29 seconds), but saves capital cost in that the line does not need a dispenser or reflow oven.”

“Wow, the company loses over $100,000 per year with the epoxy flux!” Patty exclaimed.

“Precisely,” The Professor responded.

“But, this doesn’t mean that people shouldn’t use epoxy flux as an underfill,” Patty stated.

“Right, they just need to avoid losing the one second.” The Professor agreed. “Where do you think the one second can be found?”

“Probably in line balancing,” Patty responded. “About the closest you can balance a line is within a second or two. It could be as simple as having the epoxy-fluxed part placed by the fastest placement machine.”

“And if there are many components that use epoxy flux?” The Professor asked.

“It would likely pay to get another placement machine,” Patty answered quickly.

“As always, there is never one right or wrong way to address a problem like this,” The Professor pointed out. “But, we should always perform the calculations to determine which approach makes the most sense.”

“Yes, and always remember that it never pays to reduce productivity,” Patty joked.

They both smiled as Patty left The Professor’s office.


Dr. Ron

Solder Defects Causes and Cures Webinar

If you missed the SMTA International preshow webinar supported by CIRCUITS ASSEMBLY you can view it online here.

Printing solder paste or other conductive material requires zero defects printing if a high first-pass yield is to be achieved when using fine-pitch components. Monitoring and control of paste height and volume are becoming the norm in many markets, but what capability can we expect?

Correct printer setup, good stencil design and manufacture plus consistent printing materials are key to successful manufacture but inspection and monitoring the performance makes a process more robust. The same three-dimensional inspections are required in other AOI applications like solder joint analysis. There are common process defects during printing and reflow, Willis says, and the webinar shows causes and cures to help yield improvement.

The webinar is presented by Bob Willis and covers:

  • Solder paste inspection standards
  • Soldering yield impact with poor printing
  • Common solder paste defects
  • Impact on reliability based on paste thickness
  • Solder joint inspection defects
  • Common process defects causes and cures

Results of survey of 98 engineers from last week’s webinar on process defects.

Peter Biocca, RIP

Peter Biocca, the longtime face of Kester Solder in the southern US and Mexico, passed away Monday from cancer.

I knew Peter for more than 15 years, dating back to his time with Multicore, when he was one of the regulars at the J-STD-004 and J-STD-005 meetings. Besides contributing to the standards, Peter could always be counted on to prepare papers at all the various technical conferences, participate in road shows, and fill whatever role was needed whenever anyone asked. More than that, he was simply a super nice guy, with nothing but good things to say about other people.

I knew Peter was really ill when he starting missing conferences over the past year. I filled in for him with his old friend Ray Chartrand on a session on alloy selection at SMTAI in 2013.  It didn’t occur to me at the time that I wouldn’t see him again. Knowing that now makes me very sad.

Condolences may be sent to Peter’s wife, Sandy, at:

Sandy Biocca
203 Fairfax Drive
Allen, TX 76013

RIP, Peter.

Low-Temperature Solders: Niche No More?


It surprises many people that the foundation metal of almost all solder alloys is tin. Alloy elements such as lead, silver, copper, indium, etc., are extremely important, as they lower the solder melting temperature below tin’s relatively high 232°C and often improve wetting and other process or performance properties.

Figure 1. Bismuth metal. (Source: Indium)

As an example, tin-bismuth near-eutectic solders have a melting range around 140°C with a processing temperature of about 170°C, putting tin-bismuth solders 50°C or so below most common lead-free solders such as SAC 305. A while ago, I posted on tin-bismuth solders, asking if their time had come. This post generated follow-on questions that were answered in a second post.

iNEMI predicts that low-temperature solders, such as these tin-bismuth solders, may become main stream as soon as 2017. In light of this situation, my colleague and friend, Dr. Ning-Cheng Lee, is presenting a workshop on “Properties and Applications of Low Temperature Solders” at SMTAI on Sept. 29, from 8:30-12 noon in room 54.

The course summary is: Since the dawn of the electronic industry, the soldering process has encompassed mainly component manufacturing and printed circuit board assembly, with a hierarchic solder melting range. Components are made using solder alloys with melting temperatures around 300°C, which will not melt in the subsequent PCB assembly process, where the solders typically melt around 200°C. Low-temperature solders, with melting temperatures less than 170°C, are currently used mainly for niche applications. However, the iNEMI roadmap predicts low-temperature soldering to become a mainstream processes by 2017. Low-temperature soldering is greatly desired for assemblies such as heat-sensitive devices, systems with more hierarchic levels, parts with significant differences in their coefficients of thermal expansion, components exhibiting severe thermal warpage, or products with highly miniaturized design. This course will cover several varieties of low-temperature solders with an emphasis on lead-free alloys, their physical, mechanical, and soldering properties, and the applications involved with those alloys.

And the topics covered will be:

· Design of low-temperature solder alloys.

· Indium-bearing solder systems and their properties.

· Bismuth-bearing solder systems and their properties.

· Recent development in bismuth-bearing low-temperature solder alloys.

· Mechanisms of reliability enhancement of new bismuth-bearing solder alloys.

· Applications of low-temperature solders.

Be sure to add this workshop to your list of things to do at SMTAI.


Dr. Ron

The Weakest Link: Musings from SMTAI

Due to an illness, I jumped in to co-chair a session at SMTAI yesterday. In doing so, I had the pleasure of spending a little time with a longtime industry machine designer. Afterward, he asked an interesting question:

Talking to all these (industry veterans), I’ve seen a common thread. Almost all are unhappy and hoping to make it to retirement while continuously looking over their shoulder and waiting for the shoe to drop. Perhaps it’s a function of have been through too many downturns. Almost all say they are working harder than ever for less money than ever. Staff reductions of years ago have never been replenished.

Griping aside, they are all keenly aware that there is no one to step in to fill their shoes, be it process engineers, quality managers, field service, you name it. They all state they’re on their own with no replacements in sight. What’s your take on this and if they’re correct, will the industry grind to a halt?

Great question! I agree with the sentiment expressed — small/no raises, more work, no bench from which to develop new engineers. These have been problems for the past 10 years.

That said, I see some underlying trends that make me more bullish than some. For starters, there’s never been more entrepreneurs at the college level. I have been spending time researching tech incubators and have come away stunned at the level of talent and energy. The so-called hobbyist market is booming: 140,000 attendees at the Maker Faire event in San Mateo this year, and they all come to see innovation in action. In researching open source pick-and-place software earlier this year, I learned that there are some 2,000 desktop placement machines out there, and an engineer is behind every one.

There is an abundance of talent designing and building electronics hardware and related tools these days. They just aren’t doing it at the usual places like IBM or HP. It’s more under the radar, but it’s there. Google, for instance, has 5,000 workers doing box build and test in Mountain View. There is a lot of hiring going on at growth companies; it’s just no one talks about it.

During the SMTAI Keynote this week (a really interesting, if a bit inflated, talk on the F-35 warfighter by retired US Navy General Bob DuLaney), I asked whether he saw a way we could better leverage such state-of-the-art technology in order to get more engineers interested in the industry. His response was that he couldn’t see how any engineer wouldn’t be excited to work on such a project. Point, DuLaney, but if I had it over, I would have asked the question this way: How could a company like Lockheed Martin ensure product builds come in on time and on budget when the supply chain it depends on for materials, bare boards, assemblies and so on is struggling mightily to recruit and retain top engineering talent?

For my bigger concern is really the lack of interest by new engineers in the smaller companies that supply the big ones. The Lockheed Martins and Raytheons will always attract talent. But they buy much of their bare boards and assemblies from companies that are considerably smaller, local and less well known. Those firms are the ones having trouble recruiting and keeping talent. For those who do it well, it’s become a strategic advantage. And as long as the Tier 1s have to outsource, their ability will always be limited by the weakest links of their supply chain.

SMTAI-IPC Midwest Pact a Long Time Coming

John Mitchell is putting his money where his mouth is.

As the new IPC president, installed just this spring, had made clear in multiple conversations we’ve had, he takes adding value for customers seriously, and he looks for ways various associations can coalesce.

That vision became reality yesterday when Mitchell took to the dais at the SMTA International trade show to announce the two groups would colocate their respective fall shows starting in 2013.

Under terms of the agreement, which remains to be signed, IPC will hold its semiannual standards committee meetings at the SMTAI show in Ft. Worth, TX, next October. IPC will retain its IPC Midwest brand, but the decision effectively tables, for now at least, the Chicago area trade show IPC has sponsored for the past several years.

It’s a welcome change from the past decade, during which something of a Cold War formed between the two dominant North American industry electronics trade groups as each competed for the minds (and bodies) of assembly engineers.

While acknowledging that some wrinkles could still remain, most of the folks we spoke with in Orlando this week are supportive of the move. Many IPC committee members are also regular presenters at the much-lauded SMTAI technical conference, and this allows them to reduce their fall travel. Moreover, it will cut costs for some exhibitors that have tried to pull double duty in the past.

It says here SMTA, which has been burned by colocation arrangements in the past, deserves a mountain of credit for putting aside any bad feelings for the good of its members. And IPC, in particular Mitchell, should be lauded for recognizing that success is not a zero-sum game, and that win-win relationships are possible even among trade associations.

Making the Rounds

We will be at several events over the next six weeks.

On Thursday, senior editor Chelsey Drysdale will attend IMAPS’ annual symposium in Long Beach, CA. There’s a number of EMS companies focused on medical electronics exhibiting and it will be interesting to hear what the latest trends are.

The following week, I will be at SMTA International, covering it for the magazine and cochairing (with CIRCUITS ASSEMBLY columnist Sue Mucha) the session “Global Strategies for Lowering EMS Costs” on Oct. 18 from 10:30-1 pm. CIRCUITS ASSEMBLY also is taking part as an exhibitor (booth 528).

On Nov. 8, I am honored to be speaking at Zuken’s US ZDAC users group meeting. We also will be out in force in mid November at Productronica, the biennial trade show to end all trade shows.

Looking forward to seeing you … somewhere.

A New Trend in Assembly Shows?

Years ago, three major events dotted the US electronics assembly trade show landscape. They included Nepcon East, Surface Mount International, and the mother of them all, Nepcon West.

While Nepcon West was the undisputed champ, all three shows were worth attending, and exhibitors often made new product announcements at each one.

Interestingly, and for reasons too detailed to get into here, none of those shows exist today. And for much of the 2000s, the place to roll out new products became IPC’s Apex. Other events were relegated to regional status, and traditionally were staffed as much by distributors as by OEMs.

There’s a few small signs that trend may be shifting again. While IPC Midwest, taking place this week in the Chicago suburbs remains a local show (and honestly, could they make seeing the exhibitor list any more user-unfriendly?), SMTAI is at long-last beginning to fill the niche for a seasonal alternative to Apex. To wit, we’ve received numerous press releases of late reporting new products to be introduced at SMTAI. That’s evidence suppliers see the venue as a viable place to make product launches.

Also at SMTAI, on Oct. 18, I am cochairing (with CIRCUITS ASSEMBLY columnist Sue Mucha) a panel titled “Global Strategies for Lowering EMS Costs” at SMTAI in Ft. Worth, TX. Topics include EMS in Eastern Europe; networking technical trends; improving quality, delivery and cost in high mix manufacturing; and vapor phase technology, and feature speakers from Kimball, Tailyn, Fabrinet and IBL Technologies. We conclude with a panel on building an EMS cost model.

I can’t mention these events without touting our own. Next week marks the 20th annual PCB West conference and exhibition at the Santa Clara (CA) Convention Center. Traditionally the industry’s leading conference for printed circuit board design and fabrication, we have beefed up the electronics assembly side (with a big assist from the Silicon Valley SMTA Chapter). Highlights include papers on low silver solder alloys, advanced packaging, new plasma-based PCB surface finishes, and lead-free electronics risk reduction, presented by such leading companies as Hewlett-Packard and Amkor. Check out the program at  We really hope to see you there.

Hot Seat

I’ll be blogging from SMTAI in Orlando next week, where I’m chairing/co-chairing a couple of sessions on contract manufacturing.

On Tues. Oct. 26, from 2:00pm – 3:30pm is Outsourcing Strategies: Niche Requirements and EMS Best Practices, featuring

  • ODM or EMS: Which Choice is Best for Your Project?
    Jim Chen, Tailyn Communication Company, Ltd.
  • How Efficient Is Your High Mix EMS Supplier
    Dave Cesar, The Parkland Group and Roy Starks, Libra Industries
  • Outsourcing LED PCB Manufacture
    Scott Mauldin, LEDnovation, Inc.

    Then from 4 – 5:50pm is EMS Segment Focus: Aerospace/Defense:

  • Understanding Differences Between Defense OEM/CEM and Traditional CEM Business Models
    Allan B. Day, TEAM Technologies, Inc.
  • ITAR Compliance – Challenges and Benefits in an Outsourced Relationship
    Joe O’Neill, Hunter Technology Corporation
  • Practical Issues and Solutions for Handling Plastic Encapsulated Microcircuits (PEMs)
    Rick Iodice, Raytheon Integrated Defense Systems
  • Tighter Ratio Rules Ahead?

    The long-held area ratio rule (the ratio of aperture size and stencil foil thickness) of 0.66 is under attack from all sides, it seems.

    Writing this month in CIRCUITS ASSEMBLY, columnist Clive Ashmore explains that  improvements to the shear thinning capability of the print stroke can reduce the area ratio to 0.40. This is an important development because tighter ratios offer greater latitude in stencil design. The rule today is that, since a larger component generally requires more paste volume than a smaller one, one or the other suffers: Optimize for the larger part and print quality suffers on the small aperture; optimize for the smaller ones and the larger parts are starved of paste. With the lower ratio however, as Ashmore notes, 0.3 mm CSPs could be placed beside large tantalum capacitors without penalizing one or the other.

    Next week at SMTAI in Orlando, Rockwell’s Kevin Liticker will present his work evaluating several stencil technologies including “PhD,” fine grain stainless and nickel stencil, and aperture forming methods like pulsed YAG laser, fiber optic laser (with and without electropolish) and electroform as they relate to paste transfer efficiencies for small apertures. I’m not going to give away the store, but he found some evidence that the release characteristics of fine grain material may be superior as apertures shrink.

    I strongly suggest checking out both engineers’ work.