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Mislabeled passive components (reels of resistors and capacitors) are surprisingly common in the supply chain. Testing SMT passives first can be the best option.
Once placed on boards, the wrong part is very hard to detect and expensive to correct. We buy reels of SMT passives by the thousands for our contract manufacturing business, usually through major distributors. Several times a year we get a mislabeled reel, so that the true value of the component is different from what the label says. If we don't discover this error before placing the parts, at 5,000 parts per reel, that's a lot of bad boards.
Worse, normal production tests are unlikely to catch this type of error once it occurs. Most surface-mount technology (SMT) passives we use today are 0603 (0.06″ x 0.03″) and smaller, and not individually marked due to their small size. One hundred percent automated optical inspection could confirm that a passive with the right package size is placed in the right location, but its value cannot be determined: a 10-ohm resistor looks exactly like a 10K-ohm resistor to a camera.
In-circuit testing could catch this type of error in perhaps half of the cases. However, most boards for commercial and industrial products aren't subject to the extensive level of testing that would be needed. Consider a few examples:
- A board with hundreds of ICs, each with a decoupling capacitor. All the capacitors are connected in parallel to the power and ground. In-circuit testing would show the sum of all the capacitors but not the individual values. With values ranging from nano-farads to tens of micro-farads, it would be impossible to know whether a 1nF capacitor was used instead of a 10 nF. The board would also work fine in functional testing. But it would probably fail for EMI, which is not a production test.
- A coupling capacitor of the wrong value on a microprocessor. This could cause a slight delay before the microprocessor turns on, but it would turn on and the board would pass a flying probe test. It may then exhibit erratic behavior in the field, such as race conditions in the timing or failure to turn at certain temperatures.
- A board with the wrong pull-up resistor in a circuit. The device may function properly, but draw too much current. This would most likely show up as end user complaints about short battery life.
How does the wrong part get onto a board?
Occasionally, the manufacturer labels reels with the wrong part number. More often a distributor makes an error when creating a barcode label for inventory control and tracking through the supply chain. Sometimes, we make an error when we enter the part number in receiving. Occasionally an SMT pick-and-place operator loads the wrong reel into the machine. All are human errors, either making typos or misreading a long number (often from a long list of numbers). All are very hard to avoid.
Ask any manufacturer when they last built a board with the wrong part, and the answer will probably be within the past than six months. Ask what procedures they have put in place to prevent it from happening again, and the answer will probably involve more human intervention: checking and double-checking the data entry and barcodes and machine setup.
This is not inherently a bad thing, but human intervention is usually the most expensive and least reliable solution to this sort of problem.
A better solution is to set up automated testing to verify the component value before placing them. At Z-AXIS we use pick-and-place machines from MyData that have the option to test passives for correct value — and for diodes, also the correct polarity. By enabling this option and checking several components every time a new reel is loaded, we avoid placing wrong parts without adding a lot of labor cost or significantly effecting throughput.
Indeed passives are the most ignored components, even during development stage, not to mention production stage. How dangerious it is to have a mislabelled reel ! A zero-Ohm resistor that's accidentally slipped into the board could kill every thing.
I think it's a worthwhile nice piece for hardware engineers/designers. It's very good to have an alternative or perhaps better testing for passive components.
Could a ” bed of nails” kind of test point out such wrong passive parts?
May be yes . But building such bed of nail test rigs for each board to be tested itself is a task which takes a lot of human effort.
So a system where each reel is checked manually for correct value , is the safest way to avoid wrong passive components getting inserted .
They test a few from the reel, not every single passive component, right? If the problem is mislabelling, then its not that bad.
If the problem is organizing them and that you can get a mix of values, that's harder and more expensive to solve.
What a true life story! I have spent days to find these little guys in most urgent schedule. It takes a lots of effort and rework is very painful. Sometime you have 25 or more parts with same value and all wrong by one decimal point.
My advise for CM is to perform incoming inspection for these little fellows. Just measure value for two to five samples in 5000 pc reel.
If it is not really expensive all the pick and place machines would come with the feature to measure the value of the resistors and polarity of the parts. I believe the reason for not having the feature is both the economical and technical constraints.
It may be that this source of error in passive first may be attributed to select few manufacturers. Also, if detail analysis is done, it may turn out that only some kind of machines or operators are involved for this source of errors.
Is it possible to investigate and analyze how the this error occurs? It may not be that difficult to prevent. And it is very essential to prevent it. We do not want to change 0201 and 0402 resistors in 10s or sometime 100 per PCB assembly.
It is not the major issue but I was wondering if the supplier has any liability for a mislabeling error or is the onus on the consumer of the goods to check suitability?
FLYINGSCOT, this is a good point. Pehaps supplier should have some sort of guarantee and compensation should their reels are mislabelled.
@Michael, do you have any sort of stats about how common mislabing is? Is it more common in certain types of parts? (I am assuming, smaller parts more mislabeling)
The human element is always the most common way that mistakes get introduced into systems. Ironically, it's probably a human element, in this case, that is also teh best panacea.
@_HM, sorry for your pain! Do you think these kinds of problems would make you look to source products elsewhere? Or is it just something that happens and you have to remain alert to it?
@Hailey: Good question. My advice would be to be on your toes and try to figure out at the beginning itself so you can mitigate the issue then and there itself before it gets out of hand.
Hailey,
We mostly see it in the passives like resistors and capacitors. Seldom are IC's miss marked. We have seen them missed marked from the manufactures as well as by the distrubutors. It sort of reminds me of the old days when non ROHS parts came in marked ROHS but our XRF equipment clearly indicated lead on the end caps. So it all comes down to trust but verify.
@Michael, “trust but verity” is a great motto in many instances. And passives are something like flour in the baking world–no one thinks about it but you can't bake without it.
I have to squint a little to get a picture of this in my head (thanks for the videos, they help a lot!) i'd be interested in knowing more about how the materials that can be printed will evolve. Are these 4D products mainly plastic now? What about metals?
3D printing makes supply chain show new characteristics , such as becoming faster, smaller, cheaper and local.
But to implement large-scale 3D or 4D printing, there are still a lot of obstables, because 3D printing largely cut employees.
@Lily, can you say more about why you think this technology will cut employees? I find that we are often afraid of that. However, many times it makes the job obsolete but frees up people to do other, and more strategic things.
3D printing is a technology producing products with less human resources in the production line. In fact, there is another factor-intelligent robot contributing to the simpler supply chain. This change largely reduce the number of general workers.
Susan, very interesting. Actually 3D printing is not still common and before it get popularized another version 4D technology is evolving. What I understood from the video is 'transformation capacity' is the significance in 4D, when compare with 3D. But am not getting what's it's significance in supply chain
“3D printing is a technology producing products with less human resources in the production line. In fact, there is another factor-intelligent robot contributing to the simpler supply chain. This change largely reduce the number of general workers.”
Lily, so again unemployment is the issue. So how the sector is going to deal this is the big question
Hailey, I had those very same issues in my head! Having experimented with 3D printing myself I can tell u the technology is not yet ready for mass use today-the plastic breaks too easily. But we r definitely getting there.just need more time and experimentation.
Jacob, The issues of transformative capacity are definitely some way away today-as more amd more people experimenting with this , u will discover more and more exciting stuff happening in the future-sort of like crowdsourcing revolution! !!
@Ashish I'd love to hear more about your experience with 3D printing. It's not jsut a matter of figurines and playthings any more. Industries are using it in various ways. GE even uses 3D printing techniques for titanium parts of jet engines.
Lily,
Your concerns when it comes to Employment(Especially Youth ) are very-very real here.
Unfortunately as long as Capital stays as cheap as it is today;I don't see any real way for this Trend of Increasing Robotics to change.
On the plus side,what with Rapidly Ageing populations in most of the Developed world today very soon you will see lots of Jobs for the Youngsters as the Baby Boomers start to die off.
An Interesting perspective on Welfare and Jobs here
http://globaleconomicanalysis.blogspot.ae/2013/08/why-work-for-725-when-welfare-pays-1500.html
@Ariella, “GE even uses 3D printing techniques for titanium parts of jet engines” That sounds interesting, but I always wonder if there is a large market for 3D printing besides “figurines and playthings”, as you said.
Ariella,
As I Said earlier the Big Problem I had was that Parts are too Brittle and break easy.
Not usable for Heavy-Duty /Rough Use today.
I am sure as a lot of Crowd sourcing takes off on this issue,we will see more Improvements(and better materials developed) here.
But it takes time.
Sure was exciting to play with these Printers!
@Ashish I'm sure it was.
@HH Here's GE's video on it. http://www.youtube.com/watch?v=l0SXlkrmzyw
Todd Rockstroh, the GE consulting engineer in charge of the printing project, told MIT Technology Review that his company would save about $25,000 for each engine from the reduced time and waste of materials in production. He also anticipated using 3D printing to redesign parts more efficiently. For example, a redesign of a fuel injector stem took only a week. “Before, we would have had to redesign 20 different parts, with all the associated tooling,” and the company still may not have been able to pull it off.
The only thing holding GE back from fully integrating 3D printing was insufficient data to assure uniform results, and they solved that with a big data solution that I wrote about for another site.
3D printing (and i'm sure 4D printing) really is making a splash. There has been a rush on the patent office to try to own some of these capabilities. According to this article in NBC:
Goldman Sachs recently cited 3-D printing as one of eight trends poised to disrupt industries. In the last decade, the Patent and Trademark Office has received more than 6,800 patent applications related to 3-D printing, also known as additive manufacturing. By one estimate, the global market reached $2.2 billion last year—up 28.6 percent from 2011.
Thanks for this link, Ariella. This is a fascinating real-world example of how this kind of technology can enhance speed to design.
Yes, the aging population in developed countries provides jobs to young people; but for the populous developing countries, the intelligent robot still has a long way.
While looking at the new breakthrough technologies , we should not always fear about the jobs lost. These technologies actually help to eliminate the mundane repetitive jobs , and create an environment for more creative jobs . So instead of doing dumb repetitive work , a person is free to put his energies where he can also apply his mind.
“The issues of transformative capacity are definitely some way away today-as more amd more people experimenting with this , u will discover more and more exciting stuff happening in the future-sort of like crowdsourcing revolution! !!”
Tech4people, you are right. when the technology get popularized there is no doubt that it can make many changes.
“While looking at the new breakthrough technologies , we should not always fear about the jobs lost.”
Prabhakar, but always happening in reverse, I mean negative thoughts are popping up. When computer came peoples feared about losing job, but actually it created more job opportunities. Similarly for 4D printing also the same thing is going to happen.
“These technologies actually help to eliminate the mundane repetitive jobs , and create an environment for more creative jobs”
@prabhakar: That's exactly what my point is too. New technologies help in creating new jobs which are much greater in number than the jobs they eliminate. Take the example of 3D and 4D printing. Every company that owns a printer will require a technician to operate it and that's a new job. Similarly, companies will need other vendors to sell these and maintain these which leads to the creation of new businesses and hence new jobs.
“Goldman Sachs recently cited 3-D printing as one of eight trends poised to disrupt industries”
@Hailey: I think 3D printing will continue to dominate but the usage will mostly be restricted to designing and prototyping. I don't think we will see it being used commercially for large scale manufacturing as yet. It will be a long way before the technology becomes more advanced and the price drops down.
This sound fascinating. Do you know what kind of specific applications there are in electronics?
Jacob,
There are many things that you can visualize happening here(not all of that positive/Beneficial to the Global economy going ahead).
Still that does'nt mean one should'nt try and experiment with this very exciting Technology today.
Crowd-sourcing can create many-many great inventions today!
FlyingScot,
Right now I am looking at Basic Analog and Digital Circuits.
To do something complex (especially Motherboards,etc) will take more time and expertise.
Its probably 3 years away from full functionality today.
As we are still talking about the intelligent 3D printing, 4D priniting is alredy here. Is it really going to be game changer in terms of the technology that provide more benefits to humans or it is going to be just another fancy piece of technology without many added benefits.
This should be hepful to design prototypes. But perhaps, it may not be able to help much in mass production. To realize this potential, it will need many other resources and will add higher cost to it.
Electric,
Your sceptism is wholly justified.
As I had said so earlier here,Its very much a matter of time before anything serious (impactful for Society at large)happens here.
Right now its mainly Hard-core Technology Enthusiasts who are playing with this Technology today.
That does'nt mean that it will never take off;Its just that crowd-sourcing still has to figure out where all can it be used effectively today.
“Still that does'nt mean one should'nt try and experiment with this very exciting Technology today.”
Tech4people, if you are not able to visualize and use cases, there is no invension.
Jacob,
Just because I can't visualize something currently does'nt mean the Whole World Wide Web can't.
There are so many super-smart people on the Web today,its beyond Astounding.
That's the magic of Crowdsourcing.
@Jacob, Invention is first about idea, the conceptual design before the implementation. But in many cases, the finished product is what the end user wants to see.
At least that's what you would hope for…
“ust because I can't visualize something currently does'nt mean the Whole World Wide Web can't. There are so many super-smart people on the Web today,its beyond Astounding. That's the magic of Crowdsourcing.”
Tech4people, finally its also by visualization capability of somebody else.
“Invention is first about idea, the conceptual design before the implementation. But in many cases, the finished product is what the end user wants to see.”
HH, Its all the differential imaginary stages passing through the mind of a developer or R&D engineers. End user is bother only about the various use cases and their conveniences.
Hailey,
Stratasys 3D printer can produce multi-layered materials, usually a regular rigid plastic layer, along with an outer layer made of “smart” materials. When submerged in water, as you can see in the first video, the “smart” material absorbs and expands, causing the parts to move, and form a pre-specified object like the cube you see in the video.
-Susan
Lily,
So you mean progress, innovation, and evolution in technology has to immediately stop because people are not able to learn new skills to cover the new positions that will be emerge as a consequence of changes in manufacturing, and the supply chain?
-Susan
Hailey,
As Skylar Tibbits explained, as I wrote, and as it is obvious, jobs will not be cut, but they will changed. As manufacturing, technology, the supply chain evolve it is simply logical that jobs will evolve as well.
Old jobs that become redundant will disappear to give space for new jobs where humans will have more interaction with machines.
Thinking otherwise is not having a view into the future. There is a need for people to start being more open-minded, and less afraid of change.
-Susan
Lily,
“This change largely reduce the number of general workers.”
Why it's so difficult for you to understand that jobs will change, and employees will be doing other new jobs that will be required?
-Susan
Jacob,
As I wrote, the fourth dimension opens doors to new possibilities that can be applied to different manufacturing sectors, including aerospace, automotive, building, and water-piping. The possibilities are endless. 4D printing is in its beginnings. Tibbits it's looking for a a visionary manufacturer to start giving 4D printing a space in the industry.
You will be able to see change in the assembly-line, which will become a self-assembly line. I wrote especifically about this, and you will see the article soon here. Maybe that clarifies more your question. The fourth dimension which adds tranformation capabilities is a game changer. Think of water piping, and how 4D printing can help.
-Susan
Jacob,
“so again unemployment is the issue. So how the sector is going to deal this is the big question”
No, that's wrong. As I said, jobs will evolve in the same way the new technologies are evolving. People's jobs will change to do apply their best skills. This has happened in the history of humanity, if you come to think about. People are just slow to accept changes. Without changes there is no evolution.
-Susan
Ashish,
Well, if they have even 3D printed a kidney using human stem cells don't you think the technology is more advanced than what people think?
Now, think of Ikea furniture. Wouldn't you like to to just sit on your new chair after it has assembled itself while you were sipping your coffee? 😀
Everything depends on the materials used in the 3D printing process. If you had an experience where the materials broke easily most likely they were not of a good quality. Tell me more about your experience with 3D printing.
-Susan
Ashish,
There is a new industrial revolution happening. Soon I will be writing about this. It's fascinating. A crowdsourcing, open-source revolution will also be playing a role.
-Susan
HH,
The fact that we don't know something doesn't mean it doesn't exist. As I always say, remember? This applies to the 3D, and 4D printing in industrial scale.
If there are researchers working on this, is there is something like Tibbits' Assembly-Lab in existence it's probably because there is, or will be soon a market for it. Would you work real hard on something that goes nowhere? Most likely not.
There is a 3D printer on its way to ISS, for example. Do you think NASA is going to invest in sending such a thing if it wouldn't be useful up there? No.
-Susan
Prabhakar,
“These technologies actually help to eliminate the mundane repetitive jobs , and create an environment for more creative jobs . So instead of doing dumb repetitive work , a person is free to put his energies where he can also apply his mind.”
Exactly! That's the smart way to think about this.
-Susan
Jacob,
“When computer came peoples feared about losing job, but actually it created more job opportunities. Similarly for 4D printing also the same thing is going to happen.”
That's right. People should start having so much fear about evolution, and change. Or, go and and live in a cave if they can't adapt to evolution.
-Susan
Taimoor,
“I don't think we will see it being used commercially for large scale manufacturing as yet”
Why not?
-Susan
Flyingscot,
The possibilities are plenty, and that's the point, to start thinking, and developing applications for the new technologies. Did you watch the video?
-Susan
Susan,
My sentiments precisely.
Lot of people have no clue about the extent and capability of this Technology and especially the Crowd sourcing Aspect.
Lot of sceptics present today(you can find many on your blog as well).
I ain't one of them!
Regards
Ashish.
Susan,
My experience was enjoyable(I felt like I was in the Lab/workshop after so so long!!!).
Just feel like the Materials are too brittle today and if we try to use harder stuff the Printer gets messed up.
So lot of work still remains to be done here!
Jacob,
Clearly you are not convinced/Have no experience about how the Crowdsourcing Phenomenon works today.
I recommend you give it some time and let it warm upto You!
Jacob,
Clearly you are not convinced/Have no experience about how the Crowdsourcing Phenomenon works today.
I recommend you give it some time and let it warm upto You!
Ashish,
Yes, I have already seen many sceptics. I think there are two main reasons why people remain sceptic regarding new technologies: one is repeating what someone has said, just like a parrot.
The other one is lacking of vision, and understanding of the technology in question. It has happened with other new technologies, like the cloud, for example. How many people still talk about the security, and privacy “concerns”. Honestly, I am quite fed up with those “concerns”.
Both 3D, and 4D printing are fascinating technolgies with great potential to improve manufacturing, making the supply chain faster, better, and more efficient while humans watch that everything is going smoothly. Then there are the ones with “concerns” (I hate the word) about people losing their jobs. Adaptation is required here, and those who will not adapt will disappear.
You have mentioned crowdsourcing here several times. Why are you linking this to crowdsourcing? This is not a crowdsourced project. :/
-Susan
Susan,
To get an idea about where all this Technology can be used most effectively we need to Tap into Many different brains globally-That's where Crowdsourcing aspect comes in.
As for the Cloud not having Security/Privacy issues,I recommend you read up on NSAs PRISM,Keyscore Programs.
Heck I can see Governments Globally engage in all kinds of Covert Surveillance of their Own Citizens because they have frankly speaking lost control over the Economy.
Its beyond Disgusting and the coolest part is that the World's Biggest Democracies[US,UK and India] are at the forefront of this move.
Ashish,
So nice to hear you have an enjoyable 3D printing experience. 😀 I would attribute the problem you experienced with materials to low quality. What I know is that there are some very good quality materials for 3D printing out there.
Well, I think you maybe saw the GE video Ariella posted somewhere below. That's no 3D printing joke, or any toy.
However, I agree with you that still more work needs to be done. But hey! This is just the beginning, and we should be appreciative of the work of all these researchers who spend hours, and hours experimenting to bring great things like 4D printing to our daily life.
Yes, I know, not so yet. But yet, I find it fascinating, I believe in it's potential, in the many applications that this will have, and I wish everyone would be more supporting, and encouraging.
-Susan
Ashish,
Yes, I know you always recommend me good readings. I appreciate it. And I see your point. But what I was saying is more about the same people repeating the same thing over, and over, and over during years. Pay attention, and you will see what I mean.
-Susan
Hailey,
This GE turbine is 3D, not 4D printed but it gives you an idea of the potential, and uses of these technologies. When you add tranformation capabilities to the materials you can create amazing things. Have you ever seen Transformers? Think of something like that when you think 4D printing, and you will get a better picture of what it could be done.
The link didn't work as I wanted (GE turbine), it goes to my Twitter profile. Just click on the picture of the turbine that you see on the left.
-Susan
Susan,
Please Don't start on the Transformers!!!
They are part of My Favorite Movies of all time(Alongwith The Avengers as well as Pacific Rim) but putting aside the Sci-Fi capabilities ;one has to agree.
The Transformation capabilities are endless today.
Susan,
I always pay attention to every single thing that you say(LOL!!!).
But yes your sentiments are very accurate here as well.
Too many Sceptics who don't really understand/Appreciate the Change Agents today.
And they cause a lot of problems for everyone involved!!!
Ashish,
Yay! I almost add a video of the Transformers to this piece as example of what you can expect in the future of 4D printing. I don't remember why I didn't. :/
All what was sci-fi yesterday is reality today.
-Susan
Ashish,
Adding transformation capabilities:
{youtubenew|/embed/7pd9uUEZCnE?rel=0|315|560}
“I always pay attention to every single thing that you say(LOL!!!).”
Thanks, Ashish! 😀
Yes, it's quite problematic in many ways.
-Susan
@Ariella, that $25,000 is probably just a drop in the bucket compared with teh cost of teh end product, or even the cost of the engine, but certainly these are numbers that will catch the attention of people who are struggling wth a tough budget. I wonder if it will end up making people more people willing to do redesign because it isn't so costly…
@Susan, to your point: “Old jobs that become redundant will disappear to give space for new jobs where humans will have more interaction with machines.
Thinking otherwise is not having a view into the future. There is a need for people to start being more open-minded, and less afraid of change.”
Very well said and i agree… fear of change is a huge stumbling block to transformation and movement forward. an excellent reminder.
@Susan, thanks for posting the video…it was a bit of weekend fun for me!
The supply chain has been facing these problems for a while. The parts that come on board need to be tested and retested. Human errors prove to be costly and often a company has to provide support that costs even more money.
The supply chain needs better testing equipment. As the article explains that a ten ohm resistor looks the same as a high output variant. However this is easily said than done. The process of testing when done through human hands is tedious, and when done through high tech testing equipment proves costly.
Hailey
“. . . fear of change is a huge stumbling block to transformation and movement forward. an excellent reminder.”
Exactly. That's why I never understand when some people can't see forward, beyond their nose, can't adapt to changes, and most importantly they can't see the work and effort of these researchers working on bringing new technologies like 4D printing to the industrial level, working to make them available to everybody.
I simply can't justify someone who is more worried about things than can be fixed, like workers learning new skills to access the new jobs that will emerge when these technologies reach the supply chain in so many fields. Plenty of new jobs that don't exist today will be available. I think people who think otherwise are lazy thinkers, who won't go far if they don't change their attitude, because for them complaining is a daily habit.
As I was saying below, I have seen the same people repeating the same things about their “concerns” for years now. They use the same old argument every time there is a discussion about new technologies, and their incorporation to manufacturing, for example. So, after many times of reading the same it becomes boring, unthoughtful, and way too narrow-minded.
If there is no change there is no evolution. If everyone would have been so unwilling to adapt in the past, and to embrace change humanity would be still living in the Stone Age.
-Susan
Hailey,
Glad you liked it. I tried to find a Transformers video for the article, but none of the ones I found showing what I wanted to show was short enough. But if you think of Transformers you get a pretty clear picture of what 4D printing might bring in the future.
-Susan
@Susan, let's hope not! that clip was a little high impact for me. 🙂 Indeed, though, it gets you to thinking that this technology will take us in directions that we can't imagine.
“That's right. People should start having so much fear about evolution, and change. Or, go and and live in a cave if they can't adapt to evolution. “
Susan, its always better to educate peoples for keeping out such fears.
“As I said, jobs will evolve in the same way the new technologies are evolving. People's jobs will change to do apply their best skills. This has happened in the history of humanity, if you come to think about. People are just slow to accept changes. Without changes there is no evolution.”
Susan, infact it will create more job opportunities, but may be in some other rolls.
“You will be able to see change in the assembly-line, which will become a self-assembly line. I wrote especifically about this, and you will see the article soon here. Maybe that clarifies more your question. The fourth dimension which adds tranformation capabilities is a game changer. Think of water piping, and how 4D printing can help. ”
Susan, thanks and hope to read more about it.
“Clearly you are not convinced/Have no experience about how the Crowdsourcing Phenomenon works today. I recommend you give it some time and let it warm upto You!”
Tech4people, I don't know what made you to think like that. I hope almost everybody in this community may be well known about crowd sourcing and how it will help in need.
The videos did help a lot. I dont think it can handle metal although maybe some alloy. I'm assuming the advantage would be making thousands of them because the individual speed is very low.
Mr.R,
Making thousands of what? :/
-Susan
Michael,
Thanks for a good overview of the potential problems of incorrect passive components. Sometimes it can even come down to a device with the correct value, but incorrect tolernce in a particular circuit application, producing borderline circuit behavior.