X-Rayted Files: My Favorite BGA Assembly Ever, Part 2

One of the most notorious component failures in manufacturing is a faulty ball grid array (BGA). Any line manager or engineer will tell you that there are too many things that can cause a BGA to fail.  When a BGA is installed on a circuit board in a factory, it is visually checked for proper alignment. If it passes this simple test some might assume all is well. However, even a board that passes a cursory exam can still be terribly flawed. Because the BGA is a bottom terminating component, examination for quality of the connection cannot be seen with optical tools. To make sure there is a good connection between the BGA and the board, an X-ray inspection is essential. We’ll revisit my favorite X-ray image of a BGA that I shared in my last column and dig into the details of how to address its many problems. 

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Figure 1: This BGA assembly is both the best and worse assembly ever: Worst because it has so many defects; best because it allows us to exemplify, in one image, most defects encountered in BGA assembly.

 Quite honestly, I never get tired of this image (Figure 1), and at the same time, I hope I never come across another like it again. With experience, and advancements in inspection tools, the industry has gotten increasingly better at avoiding these types of defects. Conversely, with packages getting increasingly smaller, these challenges do still exist. So, let’s review some of the problems we see in Figure 1 and how best to address them. 

We’ll start with coplanarity. Imagine two planes, like two sheets of paper, perfectly flat. Now imagine you place these two sheets of paper on top of each other. The four corners of the top sheet will touch the four corners of the bottom sheet. That means they are coplanar; they’re perfectly parallel to each other. Now gently lift one of the corners of the top sheet. You have just created a coplanarity problem, a common issue in BGA assembly caused by either assembly misalignments or by popcorning due to trapped moisture in the plastic BGA package. 

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Figure 2: X-ray image in Figure 1: Emphasis on the four corners and middle of the part.

Coplanarity is one of the trickiest problems to diagnose because it requires the inspection of the whole BGA. A single area of the component will not tell you the whole story. However, as we analyze the X-ray images of all four corners and the center of the BGA, the story starts to clarify, as we can see in Figure 2. The solder balls in the top right corner are elongated, also called hourglass-shaped. As we move to the bottom of the BGA, the solder balls are barely touching the board—and some are not. These X-ray images in Figure 2 show that the BGA is not parallel to the board, requiring it to be reworked. 

cardoso_fig3_0822.jpgShort circuits, or “shorts,” are identified by a solder bridge between two or more solder balls. This defect is easily identified in the X-ray image, as seen in Figure 3. The root cause of this problem is diverse. One common cause is incorrect solder deposition, either too much solder deposited or located in the wrong place in between the pads. Another can be misalignment between BGA and board which can cause solder balls to short. Defective solder mask can also cause shorts if the mask is not properly deposited on the board. I know, I’m a broken record, but all these issues can be caught and addressed early with inspection, avoiding rework and scrap.

cardoso_fig4_0822.jpgPerhaps the most challenging BGA assembly problem to identify—head in pillow (HIP)—has haunted engineers since the early days of the BGA history. Under special circumstances, as seen in Figure 4, the solder ball collapses, but not entirely. This partial collapse allows the solder ball to rest on top of the pad (like a head on a pillow) and to make electrical contact. However, since the contact between solder ball and board pad is mechanical and not metallurgical, the integrity of this electrical contact will depend on how the board is flexed. That’s the case you’ve experienced where the finished board passes all electrical tests in your facility, but it fails at the customer’s site. Temperature differences, for example, can cause the BGA to move, even slightly, and cause the solder ball to open.

One of the most common questions we get asked is how to find HIP. Although we keep improving our algorithms to allow you to find this defect automatically and unequivocally, it is still a manual process in the industry. To attain an image like the one in Figure 4, you need an X-ray inspection machine with high magnification, resolution, and geometric maneuverability. A wide range of geometric maneuverability will allow you to capture profile acquisitions (side view) as well as a tilted view of the BGA assembly. Some call it 2.5D inspection, which is the perspective view you see in Figure 1.

I hope you find this review useful. I’ll cover the remaining issues with this particular BGA in my next column. Stay tuned and stay well. 

Dr. Bill Cardoso is CEO of Creative Electron.

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2022

X-Rayted Files: My Favorite BGA Assembly Ever, Part 2

08-10-2022

One of the most notorious component failures in manufacturing is a faulty ball grid array (BGA). Any line manager or engineer will tell you that there are too many things that can cause a BGA to fail. When a BGA is installed on a circuit board in a factory, it is visually checked for proper alignment. If it passes this simple test some might assume all is well. However, even a board that passes a cursory exam can still be terribly flawed. Because the BGA is a bottom terminating component, examination for quality of the connection cannot be seen with optical tools. To make sure there is a good connection between the BGA and the board, an X-ray inspection is essential. We’ll revisit my favorite X-ray image of a BGA that I shared in my last column and dig into the details of how to address its many problems.

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X-Rayted Files: My Favorite BGA Assembly Ever

07-06-2022

In the early 1980s, Motorola and IBM introduced a novel package that allowed a high number of input and outputs with a large pitch in a small area, thus providing large savings in board real-estate. The ball grid array (BGA) was born. Initially in ceramic, by the late 1980s Motorola—and this time Citizen—brought to market the plastic BGA. This was the pivotal step needed to drop the cost of this packaging technology and to enable the electronic miniaturization wave that soon followed.

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X-Rayted Files: Smart vs. Intelligent SMT Factory

06-01-2022

Amazon currently employs over 200,000 robots across 175 fulfillment centers around the world. The robot ranks at Amazon grow every year, and in some facilities, they outnumber the humans. As the lights out concept rapidly grows with the giant retailer, automation adoption still finds resistance in the SMT manufacturing world. I don’t know what the future holds for surface mount technology (SMT) manufacturing, but I’m certain it depends on our intelligence. As a community, we spend a lot of time discussing the Smart factory. Instead, we should aim higher to the "Intelligent factory."

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X-Rayted Files: X-ray Everything!

04-27-2022

It should be clear by now that my enthusiasm for X-ray knows no bounds. From fighting counterfeits, inventory management, solder inspection, and quality control for an endless array of manufactured products, the usefulness of X-ray inspection tools is seemingly limitless. So, forgive me for not setting my bias aside, but when it comes to X-ray imaging, you probably fall into one of the following categories: you don’t need X-ray and you know it, you need X-ray but don’t know it, you have X-ray but are underutilizing it, or you are the rarest of birds who has X-ray but just doesn’t need it.

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X-Rayted Files: What’s That Noise? Is it Your Data?

04-05-2022

We are in the era of data, big data, and that should be a good thing. But the sheer volume of data we are collecting can be overwhelming; its meaning and usefulness can become a burden, just more noise. All data is noise until it can be contextualized into actionable information. From that perspective, our goal with data collection should be to reduce the noise and organize data in ways that generate meaningful information that can be used to improve our processes. Take this short quiz to gauge where your organization stands.

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X-Rayted Files: Should I Stay or Should I Go? The Future of Trade Shows

03-02-2022

I’ve heard the question repeatedly over the last couple of years, “Is the trade show dead?” It’s a valid question, and I’m not sure what the answer is, should be, or even what I wish it was. With a couple years under our belts now with canceled live events, some limited in person events, and an absolute tidal wave of virtual events and webinars, I am developing an opinion. Informing this opinion is also the fact that we have experience, and in some cases, success in finding effective alternatives to fill the void left by years of shows being on life support. On the whole, it has me scratching my head on another question. Is there a valid purpose for trade shows?

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X-Rayted Files: Nine and a Half Facts About Unknown Radiation

01-26-2022

As we kick off 2022, we thought it would be a good idea to give you a break from another column, talking about “what’s next” after COVID. Yes, the pandemic still here, inflation is kicking in, labor shortages are an issue, supply chains are still disrupted. But let’s take a break from all that and have some fun with X-rays. How about going over some facts that you may (or may not) know about X-rays?

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2021

X-Rayted Files: 2022's Word of the Year is... Resilience

12-29-2021

On balance, this last year goes down as a pretty good one. While we are not as far along in putting the pandemic behind us as we might have hoped, the progress is promising. The economic recovery has been remarkable, despite persistent supply chain woes and (transitory?) inflationary pressures. With consumer demand high, and signs of relief regarding the supply chain, the coming year and its prospect of a return to “normal” will likely offer substantial opportunities, though we must also be mindful of risks.

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X-Rayted Files: Three or More Intriguing Thoughts on Reshoring

11-29-2021

The ground beneath us is always shifting, and while the term “unprecedented” can be somewhat overused, it does seem to be a little tougher to keep our balance these days. For almost every economic disruption, there emerges some argument for how reshoring can mitigate it. This time around, though, there’s a bit of a tug-o-war between the disruptions that are shaping the manufacturing landscape and the broader economy. I’m no economist, but as a dyed in the wool entrepreneur I’d like to share three thoughts about the future of manufacturing with a focus on reshoring, the talent pool, and the joy of making things.

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The X-Rayted Files: Was CS Model 101 Built on Industry 4.0?

10-27-2021

While smart devices like sleep trackers that monitor the quality of our ZZs are exciting to some, for others it induces the fear of becoming subject to robot overlords. Regardless, the age of IoT is upon us, and as manufacturers, IoT is just one facet of the broader Industry 4.0.

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X-Rayted Files: Radiation’s Effects on Electronic Components

09-22-2021

Whether it’s from naturally occurring sources or induced by modern human ingenuity, electronic components, like everything else, are subject to regular exposure to radiation. It is vital to understand the various sources of radiation exposure as well as their likely effects on today’s microelectronics and the devices they make possible.

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X-Rayted Files: Semiconductor Shortage—Avoiding Counterfeit Components

08-11-2021

From bicycles to sundries, from consumer electronics to automobiles, shortages and supply chain issues have hampered an otherwise strong economic recovery much of the world emerge from the pandemic. Among these challenges, none has received more media attention than the semiconductor shortage.

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X-Rayted Files: Tales from the Files of Lithium-ion Batteries

06-23-2021

Lithium-ion batteries have, in part, enabled the continued miniaturization of the devices we love. They have also played an important role in making practical electric cars a reality. But like other approaches high density energy storage, they do present risks.

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X-Rayted Files: Genius, Evil, or Evil Genius?

05-20-2021

Apple dominates its market in many ways. Is this genius for the consumer, or does it effectively rule out any competition? Columnist Bill Cardoso debates its merits—and disadvantages for other players.

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X-Rayted Files: Crafting Our ‘Next Normal’

04-20-2021

As profound an experience as it has been to lead an enterprise through the pandemic, what’s to come may make every bit as much of an impression. So many things that we took for granted as practices and behaviors etched in stone, were interrupted, suspended, or eliminated entirely. As we exit the tunnel into the light of the post-pandemic, we will be challenged collectively in crafting the next normal.

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X-Rayted Files: The Bright Side of the Chip Shortage

03-17-2021

In his previous column, “The Dark Side of the Chip Shortage: Counterfeits,” Bill addressed one of unanticipated outcome of the crisis: the shortage of electronic components and predictable wave of counterfeit components likely to flood the market. Combating that tsunami of fakes may also accelerate the adoption of advanced techniques for detecting counterfeit components.

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X-Rayted Files: The Dark Side of the Chip Shortage—Counterfeits

02-17-2021

It’s February 2021, and as the world slowly recovers from the COVID-19 pandemic, another problem plagues the global economy: the electronic component shortage. What some economists have deemed to be a decade of immense prosperity and growth, the “roaring ‘20s” started with a hiccup.

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2020

X-Rayted Files: Solving for the Limits of Human Visual Inspection

12-16-2020

Because a key element of quality control in manufacturing is still good old-fashioned visual inspection, it’s important to understand the ability of operators to sustain their focus and what we can do to support their success. And while the fallibility of human inspection presents challenges, Dr. Bill Cardoso details how there are many ways to address shortcomings.

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X-Rayted Files: iPhone Transparency—A Window Into SMT

11-17-2020

Though we don’t do them just for fun, teardowns are fun, but they have also taught us more than we could have imagined. Modern teardowns provide critical insights into the nature and construction of these devices. As an example, Dr. Bill Cardoso details the history of the iPhone as told through X-ray.

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X-Rayted Files: A Century of X-Rays in the Automotive Industry, Part 2

10-28-2020

As one of the main users of X-ray inspection, the automotive industry has been one of the main drivers for the development of higher power and higher resolution X-ray imaging systems. Dr. Bill Cardoso continues with Part 2 of this column series.

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X-Rayted Files: A Century of X-Rays in the Automotive Industry, Part 1

09-29-2020

If you have read any of Bill Cardoso's previous columns, you know that he is passionate about X-rays, cars, and electronics. In this column series, he talks about some of his idols, including Curie, Roentgen, Marconi, Galvin, and Ford.

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X-Rayted Files: Is Quality Really Priceless?

08-19-2020

In a day and age when we can learn virtually anything online, manufacturers still manage to be opaque about pricing, especially when it comes to specialty equipment. Some may say, “Quality is priceless,” but Bill Cardoso explains how it isn't.

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X-Rayted Files: Marching Toward 2021, 20 Miles at a Time

07-29-2020

We’re only at the halfway mark, and 2020 has been a real challenge. Our best-laid plans have been cast in doubt by the COVID-19 pandemic. During this transformational time, Dr. Bill Cardoso looks back a century for a bit of inspiration from Norwegian explorer Roald Amundsen.

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X-Rayted Files: E-Commerce Boom Fraught With Risk—X-Rays to the Rescue

06-17-2020

It’s not news that online sales are increasing dramatically during this global pandemic. However, with increased sales comes the increased risk of return fraud and abuse. Dr. Bill Cardoso explains how X-ray can help detect dummy and counterfeit merchandise.

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X-Rayted Files: Why Do We Break Stuff? Intelligence From Teardowns

05-20-2020

The impulse to break a new gadget to "see what's inside" and to “learn how it works” is often the first sign someone will become an engineer. We’ve learned a lot in over a decade of teardowns, which have helped us to understand how the SMT industry has changed over these years. Bill Cardoso investigates.

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X-Rayted Inspection: Manufacturing in the Eye of a Pandemic

04-08-2020

Dr. Bill Cardoso usually writes about X-ray inspection, artificial intelligence, machine learning, and how it all connects to Industry 4.0. This month, however, he shifts gears and shares some of the things Creative Electron has been doing during the COVID-19 outbreak.

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X-rayted Files: X-ray and AI—A Match Made In Heaven, Part 2

03-18-2020

In Part 1, Dr. Bill Cardoso covered the basics of the relationship between X-ray inspection and artificial intelligence (AI). In Part 2, Cardoso takes a step forward to cover some of the practical ways we use AI to improve the efficiency of our X-ray inspections.

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2019

X-Rayted Files: Will Radiation Damage My Electronic Component?

12-17-2019

Before I start talking about radiation damage on electronic components, let me warn you: if you are looking for a simple “yes” or “no” answer to the question, "Will radiation damage my electronic component?" stop reading now. Things will get complicated. You may feel like I did not answer the question at all, and you would be correct. There are whole conferences dedicated to this question (check IEEE’s Nuclear and Space Radiation Effects Conference), so the goal of this column is to give you some background to guide you to the right answer for your specific situation. Ultimately, the best way is to ask an expert.

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X-Rayted Files: The Currency of Technology

11-11-2019

In the ever-moving tide of technology, the need to innovate requires a constant shift in vision, and this need has never been more evident than in PCB manufacturing. In fact, innovation has become so valuable that PCBs are quickly becoming the currency of technology. Dr. Bill Cardoso explains.

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X-Rayted Files: The Risk of Installing Counterfeit Parts

10-02-2019

In high-tech manufacturing, the use of sub-standard components can be catastrophic. There is no greater need for quality control than in PCBs, as they are only as good as the components installed on them; therein lies the problem. Some components shipped to manufacturers are counterfeit!

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X-Rayted Files: Just Because You Can't See the Problem Doesn't Mean It's Not There!

08-20-2019

In this new column, Dr. Bill Cardoso will cover everything related to X-rays from cool historical facts to the latest in technological advancements, starting with the discovery of X-rays in 1895.

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