X-Rayted Files: My Favorite BGA Assembly Ever, Part 3

While the novelty may have worn off, let’s take one last look at my favorite BGA image. In part 2, we discussed issues of coplanarity, shorts and head-in-pillow. Now we will review the other common BGA assembly issues, illustrated so well in Figure 1. Whether or not you are fascinated by this, maintaining awareness of these common failure modes of BGAs, and inspecting for them throughout your process, will increase yield, reduce rework and scrap, and result in higher quality, more reliable products.

Cardoso_July_Fig1.jpg
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.

First up: opens. An open circuit, or “open,” occurs when the solder ball fails to collapse and doesn’t touch the pad on the board. Open solder joints on a BGA are an indication of insufficient solder paste, or that the component is not sufficiently coplanar. Opens can also be caused by contamination or an insufficiently clean board. It is another condition that is relatively easy to identify with X-ray inspection and again, if caught early, can usually be addressed with adjustment to your process.   

Solder splatter has a few common causes:

  • Moisture contamination of solder paste can cause rapid outgassing during reflow, resulting in splatter.
  • Splatter can also be an indication that oven profiles are off.
  • Excessive ramp rate during reflow is another common culprit causing solder splatter, as solvents in solder paste need to outgas gradually.
  • Sometimes humidity is the culprit, as moisture in the solder paste can cause it to explode as the gases expand rapidly.

It’s essential to bring solder paste to room temperature prior to reflow to prevent moisture from condensing on the paste. Once again, early inspection during production can help inform adjustment that reduce rework and scrap.  

Properly applied solder mask will prevent oxidation and protect against solder bridging. While it is essential, it can cause problems if it interferes with pads or is too thick. Diagnosing solder mask problems is, in part, a function of the board layout. Design options for BGA and solder mask include designing the mask on the pad—or not. If the solder pad is defined, the edges of the pad are covered with solder mask and proper solder mask adhesion and deposition must be verified. If the solder mask is not defined on the pad, the pad edges are exposed and alignment becomes critical. If the solder mask is not centered on the pad, the trace can be overexposed, thus causing solder run and potentially an open or short circuit.

Voids in the solder balls themselves are common in BGAs and are only problematic when voiding is excessive. Voids occur when entrapped flux from solder paste vaporizes rapidly and resulting gases rise within the molten solder. Due to buoyancy, voids are most often located near the package interface. Excessive voiding can cause individual balls to develop cracks (opens) over time. Void analysis with X-ray inspection allows for quantifying voiding and ensuring that the percent voiding of given components conforms to manufacturers requirements; typically, the higher reliability demanded, the lower the acceptable percent voiding. When caught early in a run, voiding can be reduced by adjustments to ramp and temperature of your reflow oven. 

At the risk of seeming shallow, looks do matter, and solder ball shape is an important indicator of quality. The ideal shape of a solder ball is round. When seen through an X-ray image, there should be a uniform grid of dark circles. The primary cause if misshaped BGA balls is the alignment of the package to the board. If a solder ball does not land directly on top of the board, it can elongate (as a result of surface tension) to make the connection, resulting in an oval-shaped profile. Excessive solder deposition on the pad can also result in misshaped balls, as the excess solder combines with the BGA ball.

Missing balls are easy to identify, but their causes may not be immediately obvious. BGA balls can separate mechanically from the package during placement or in handling of the component. Metallurgical problems can also be a cause if they inhibit the solder’s ability to wet to the pad. Sometimes the problem is with the stencil used in printing the solder balls. A dirty stencil with a clogged opening may not deposit adequate solder on the pad to create a ball. Likewise, if solder paste is too thick, it may not flow properly through the stencil, clean or not.

As inspection techniques and equipment advance, BGA quality assurance becomes more automated. But it’s still important to understand and review these common BGA problems, be aware of the factors that contribute to them, and thus make them rare. Longer lasting, more reliable products, and happier customers will result, as will improved profits from avoiding costly rework and scrap. I hope this review has helped.

Dr. Bill Cardoso is CEO of Creative Electron.

Back

2022

X-Rayted Files: My Favorite BGA Assembly Ever, Part 3

09-07-2022

While the novelty may have worn off, let’s take one last look at my favorite BGA image. In part 2, we discussed issues of coplanarity, shorts and head in pillow. Now we will review the other common BGA assembly issues, illustrated so well in Figure 1. Whether you are fascinated by this, maintaining awareness of these common failure modes of BGAs, and inspecting for them throughout your process will increase yield, reduce rework and scrap, and result in higher quality, more reliable products.

View Story

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.

View Story

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.

View Story

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."

View Story

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.

View Story

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.

View Story

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?

View Story

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?

View Story
Back

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.

View Story

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.

View Story

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.

View Story

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.

View Story

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.

View Story

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.

View Story

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.

View Story

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.

View Story

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.

View Story

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.

View Story
Back

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.

View Story

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.

View Story

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.

View Story

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.

View Story

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.

View Story

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.

View Story

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.

View Story

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.

View Story

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.

View Story

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.

View Story
Back

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.

View Story

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.

View Story

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!

View Story

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.

View Story
Copyright © 2022 I-Connect007. All rights reserved.