Tag Archives: Gerber

Electronics Manufacturing Files: What We Need

Posted on by

Manufacturing is all about taking data from you and delivering some good working circuit boards. Well, it can be just data — as in full turnkey — or data plus some parts and or PCBs, as in a partial turnkey or a kitted job. Regardless of whether you’re sending parts and boards, or having the us as the EMS buy everything, we need good data, and a lot of it.

That data are the difference between the working boards you want and need and a random jumble of expensive paperweights.

We need a bill of materials (BoM), the job specifications (which you give us by ordering and describing any special instructions on our website), and the CAD design files. Fab and assembly drawings are always a good idea too. A little extra time spent on the files sent reduces risk, and that’s a very good thing.

The CAD design files include Gerbers, a centroid (aka pick-and-place or XYRLS file), and intelligent CAD files, such as ODB++ or IPC-2581. In some cases, such as Eagle CAD, we can use the native CAD board file.

The ODB++ and IPC-2581 file formats are the future of electronics manufacturing. They come with more data, and more accurate data, than do Gerbers. If you can send either of these two, please do so. Even if you have those, still send us the Gerber files. Gerbers are the lowest common denominator, and provide a base that we and PCB fabricators can work from.


The Gerbers are a set of files used to create the various layers of the board. Each layer requires an individual file, so a six-layer board (six copper layers) will typically require at least 13 distinct files: one for each copper layer, top solder mask, bottom solder mask, top silkscreen, bottom silkscreen, the drills holes, and solder paste for the top, and bottom if the board has SMT parts on both sides.

The drill file is combined with the Gerber files to line up the via and through-hole component holes with the appropriate spots in the PCB. Then the pick-and-place file will tell the assembler where to put each component, what angle to place it at, and which side of the board it goes in.

Fab drawings hold a human-readable, often in PDF format, description of the board and any special instructions needed by the fabricator. The assembly drawing would be the same, but for the assembler.

Sometimes the parts are too densely packed for the reference designators and polarity marks to show up on the actual board, or for aesthetic reasons, the designer doesn’t want them on the board. In such cases, all that information would be put into a set of assembly drawings; PDF files showing all of the necessary reference information.

As of this writing, the ODB++ and IPC-2581 file formats aren’t universally accepted, but are getting more so all the time. Use of these new intelligent CAD output file formats helps to reduce the number of manual steps and human interpretation, and will eventually lead to better quality and faster manufacturing times.

Duane Benson
What do we need?
What does it really matter?
Matter converts to energy
E=(what we need)C2

Gerber: The Format that Just Won’t Die

Posted on by

I’m a big believer in standards but I’m not so sure why IPC is pushing a Gerber Coupon Generator when it has spent so many years developing IPC-2581, a much more comprehensive electronic data format.

Now in its B revision, IPC-2581 has been implemented in trial and production, and represents the most comprehensive set of industry requirements for printed circuit board fabrication, assembly, and test in a data-centric, open, license-free, industry driven standard format. Moreover, the consortium supporting its adoption boasts more than 90 members, including all the major PCB software vendors, plus a host of major OEMs, equipment suppliers, manufacturers, and service suppliers.

It’s time the emphasis be placed on moving the industry out of the buggy era. (Pun intended.)

Full disclosure: I’ve been a member of the IPC-2581 task group since its inception, and spent several years at IPC working on the predecessors to IPC-2581.

ODB++ Plus, Plus, Plus

Posted on by

I wrote a bit about ODB++ back in October. Nothing has really changed much since then. I’m just clarifying a few things.

First, I want to put more emphasis on the use of ODB++. In addition to being beneficial to the manufacturing process, it can make your job a little easier. If you send ODB++, you do not need to send either the centroid or Gerber files. The ODB++ replaces both.

Eagle CAD does not have an ODB++ export. However, the Eagle .brd file will work too. You can send the .brd instead of the centroid and Gerber files.

If you can’t send either of those formats, we as an EMS still need the centroid and Gerbers (top copper, bottom copper, solder paste stencil, silkscreen and solder mask layers).

Duane Benson

Number Six
I am not a number, I am a free man!

http://blog.screamingcircuits.com/

More Fun File Facts: ODB++

Posted on by

In my last post, I wrote about the up and coming IPC-2581 PCB manufacturing file format. While IPC-2581 may be looked at by PCB fabricators and assemblers as a holy grail of sorts, it’s not yet widely adopted by CAD software. But, that doesn’t mean that Gerbers are the only option.

ODB++ was developed by Valor in the waning years of the last century as an improved method for getting manufacturing data into their CAM systems. Valor and, hence, ODB++ was purchased by Mentor Graphics in 2010. ODB++ is still widely available, however there’s concern in some circles that it’s not truly open. That concern is where IPC-2581 came from. In fact, IPC-2581 is somewhat derivative of ODB++.

I can see how a CAD software developer might fear the use of something owned by a rival. However, my understanding is that Mentor does it’s best to treat it like an open standard and has made it available more or less as though it is open.

The history isn’t really important. What is important is that ODB++ is a more complete format than the Gerber and is widely supported. Pretty much everything good that I said about IPC-2581 in my prior post also applies to ODB++.

The bottom line is that, regardless of whether Screaming Circuits is your fab (through our partner Sunstone) and assembly (through our factory right here) provider, ODB++ is a good thing. It makes the job easier and more accurate than does use of Gerber files. Both “easier” and “more accurate” help keep costs down and keep ambiguities to a minimum. As you know, ambiguity is the bitter enemy of both accuracy and quality.

Unfortunately, for all of you Eagle users, Eagle does not yet support ODB++. If anyone out there is really good with Eagle ULP scripting, you might want to create a on ODB++ and/or IPC-2581 creation ULP.

Duane Benson
I was ionized, but I’m better now. 

http://blog.screamingcircuits.com/

Fun Facts about Manufacturing Files

Posted on by

Circuit boards live and die by their manufacturing files. Without complete and accurate information, the board fab house can’t fab the boards, the assembly house can’t assemble your boards and nobody can buy the parts.

Our old standard, the Gerber file, has been around since about the time King Arthur pulled the inductor out of the solder pot. It’s old. We all use it because it’s familiar, but it’s day is done. It’s time to pass the torch.

IPC-2581 is the new standard in manufacturing files. It hasn’t been fully adopted, but it’s showing up in more and more CAD packages. The IPC-2581 format is much more advanced and has the complete data set in one file. While we still work with Gerbers every day, we can also accept IPC-2581 manufacturing files.

I’ve been called the champion of bad analogies, but I’ll try one out anyway.

Imagine, if you will, a map of the city. All of the streets are there. All of the houses are there. What’s missing are all of the street names. No street names, no numbers and no landmarks of any sort are labeled.

Given that information, find John Smith, at 1620 SW 14th Avenue. There is a house at 1620 SW 14th Avenue. There are a dozen or so houses at 1620 something. You just don’t know where 14th is, or which direction 14th runs, or where the street numbering starts.

You can physically walk each and every street until you find John’s name on his mailbox, but it’s not an easy nor error-safe process. And, hopefully, the town only has one John Smith. That’s a Gerber file.

IPC-2581, on the other hand, is an electronic map, with everything clearly labeled, and a GPS guiding you. Which would give you more confidence?

Duane Benson
IPC-2581 is like shatter-proof glasses for Henry Bemis

http://blog.screamingcircuits.com/

 

CAD Data Files

Posted on by

I’ve spent a fair amount of time researching and writing about the centroid file and about CAD library footprints. One of the challenges in this industry is that somethings that are “standard” really aren’t all that standard. That’s why we emphasize following IPC guidelines when creating library components.

Well, a few things have changed since we started doing this a decade ago. For one, some of the enhanced manufacturing file formats (as opposed to the 1970’s vintage Gerber format) have become more prevelent. Those new formats are a very good thing.

Most CAD packages can now output either ASCII formatted CAD data or ODB++ format data. Those file formats have all of the data that would otherwise be found in the centroid and Gerber files. They also have more accurate data. If you can get one of those formats out, go ahead and send it to us. We can also take plain old Eagle CAD .brd files. If in doubt send one of these newer files along with the centroid and Gerbers. We’ll use the file with the best data and, we may be able to simplify the file preparation you have to do with future jobs.

And speaking of the Centroid, don’t worry so much about the rotation column in the Centroid file. You can consider rotation to be optional now. You don’t need to check the rotation, nor do you need to remove it.

Duane Benson
Who will win? Godzilla or Centroid? Maybe the Smog Monster?

BOMS Away

Posted on by

Yes, I’m talking about BoMs (bills of materials), not bombs. That would be silly and irrelevant. At least mostly irrelevant. If you make bombs, it wouldn’t be, but it would probably be all secret so we couldn’t talk about it.

The question of the day is: “What makes a good BoM?” There are a lot of BoM formats in use. It’s one area that the standards train more or less left behind. Well, there are standards. For example, IPC-2581 covers not only BoM standards, but a replacement for Gerbers and the whole manufacturing data package. One of these days, we’ll all be using the IPC-2581 formats for our data and life will be beautiful all of the time.

However, those standards aren’t really in common use today. And, they are complex enough that they can’t really be used in spreadsheet form. There’s a lot of nesting and hierarchy that makes it more difficult to deal with without a BoM management software package. Still there is good data in there. A lot of good data. So much good data that my head is still swimming.

But until that day, there is a set of data and data labels that will help ensure accuracy. The headers are important too. If this seems quite rudimentary, that’s because it is. But it’s important.

BOM snippet

  • “BomItem” or “Item #”: This is just the line number. Each type of part gets an item line, not each part. If the pat number is the same, you just put it down once and give the quantity.
  • “quantity” or “Qty”: How many of this specific part you need per board
  • “RefDes”: The reference designators used by the parts on the PCB silk screen. All of the same part number should be in the same excel spreadsheet cell: i.e., “R3, R4, R5, R6”. You can also indicate a contiguous range with a dash: “R3-R6” or “R3-R6, R10, R15”
  • “Manufacturer” or “Manf”: The name of the component manufacturer. It’s best to spell out the full name, e.g., “Texas Instruments”, but common abbreviations such as “TI” generally work too. The less ambiguity, the better.
  • “Mfg Part #” or “Manufacturer Part #”: The part number that you would use if you were buying this exact part from the manufacturer or a distributor. All of the suffixes are important too. For example, “PIC16F88” is not enough when you really need a “PIC16F88-I/P”.
  • “Dist. Part #” or “Distributor Part #”:Not strictly necessary, but can help in cases with a bit of ambiguity. Again, this would need to be the exact part numer as you would order it from that distributor.
  • “Description”or “Desc”: This is the component description as given by the manufacturer. Again, this isn’t strictly required, just a good idea.
  • “Package”: This is the standard package type, e.g., “SOT-23”, “TO-92”, “0201”. Again, not strictly necessary but can be a good redundant check.
  • “Type”: Optional indicator of the generic type. e.g., “fine pitch”, “smt”, “thru-hole”, “Leadless”. Not required but can help with assembly quoting.

That’s not IPC-2581, but it is a good set of usual requirements. It’s also best to put your final BoM on the first tab in your excel spreadsheet. That will make it easier for buyers to know exactly what you want.

Duane Benson
So long mom, I’m off to drop the bill of materials
So, don’t wait up for me

http://blog.screamingcircuits.com/

Major Major and Standard Standard

Posted on by

We ask for your bill of materials, Gerber and centroid files to assemble your PCBs. All those pieces of information are necessary to properly program our machines to place your parts. That’s pretty standard stuff, but did you know that when the Gerber format reference book was first published, Jimmy Carter was President of the United States, Russia was the “Soviet Union” and Voyager 1 was well inside the Solar System?

Use of the format has been going on even longer. Yeah. It’s been around a while. For some reason, it has been very difficult to get everyone to agree to and use a standard file format. Gerbers really don’t have enough information in them to do the job properly, but it is the standard. Hopefully not for too much longer. How many of you reading this were even born when Gerber was new?

There are a number of formats around that are better than gerber and Screaming Circuits will accept many of them. First, your CAD software probably will export an “ASCII CAD file”. This is a good format. Some export ODB++, which is one of the newer formats, again a good choice. One of the newest standards is the IPC-2581. It’s been around a few years and is now getting a lot of attention. If you happen to use Eagle CAD, you can also send us the Eagle “.brd” file.

IPC-2581 includes the best of ODB++ and GenCAM. It has all of the fab data, assembly data, netlist and BOM. Everything needed in one convenient file. My understanding of the format is that you can exclude portions of the data set that you consider proprietary. You can learn more about the format here. There’s more background information on the subject at PCD&F magazine.

Duane Benson
Where’s Henry?
I need an inductor.

http://blog.screamingcircuits.com/

Intelligent Design

Posted on by
In my monthly column for PCD&F last month, I was ostensibly discussing standards and how they come to be. The first standard I worked on was IPC-D-350, one of the first of the would-be slayers of Gerber, the so-called unintelligent data format. Indeed, I’ve spent a good part of my life watching electronic data transfer formats come and go, and at the end of the day, Gerber, warts and all, has remained the one to beat. So I’m not prepared to rise up and shout to the heavens that IPC-2581, the latest iteration in 40 years’ worth of attempts at an “industry” standard, is at long last the answer.

But as we noted in “Around the World,” there are enough notable differences in the process this time around to make it newsworthy. First and foremost, there are real live CAD tool vendors not just showing up at the meetings, but actively participating (!).

To understand why this is significant, we must go back to my IPC-D-350 days. Digital Equipment and the late, great Harry Parkinson were instrumental in trying to revive interest, and we at IPC also had support from several smaller software folks like Dino Ditta at Router Solutions and Steve Klare at Intercept Technology. But we never managed to break through, and a big part of the problem was the major CAD vendors’ collective refusal to offer IPC-D-350 as an output (or input). The response always was, “We’ll do it if our customers ask us.” But what they were really saying was, “We don’t want to make it easy for our customers to migrate their designs to a competitor’s tools.”

In the meantime, AT&T offered up RS-274X (aka extended Gerber), which UCamco continues to support, and Valor developed ODB++, and (like Gerber) while it was originally conceived as much a machine language as a format for electronic design data, it was accepted by fabricators desperate for something, anything, more intelligent than Gerber.

Under the leadership of Dieter Bergman, IPC also continued the fight, enlisting the help of the National Institute of Standard and Technology (NIST) through not one but two (GenCAM, Offspring) successors to IPC-D-350. (For a short history of the standards, click here.) Yet even now, after decades of trying, no group has been able to dismount Gerber from its perch, and it’s long past time we did. Data transfer formats are not something anyone ever will make money from, but every day we go without a better one, everyone will lose some.

Curiously, just a few weeks ago, I was contacted by David Gerber, son of H. Joseph Gerber, who invented the photoplotter and the eponymously named de facto standard that ran it. Gerber’s genius cut across many industries, from electronics to apparel, and he was awarded the 1994 National Medal of Technology for his life’s work.

For such an esteemed inventor, Gerber’s backstory is even more interesting than his career. As a teenager in 1940, he fled Nazi Germany for America. As an aeronautical engineering student at Rensselaer Polytechnic Institute, he discovered a way to reduce the time-consuming nature of graphing calculus problems using (seriously) an “expandable ruler” created from the elastic waistband of his pajamas. And of course, he formed The Gerber Scientific Instrument Co. in 1948, which is still going strong today.

The younger Gerber is writing a book about his father’s exploits. I look forward to learning more about the life of one of our industry’s true unsung heroes. But at the same time, I’m going to do everything I can to help retire one of his legacies.

In our cover story this month, Hemant Shah and Keith Felton of Cadence explain a new consortium taking root. The consortium is backed by a Who’s Who of OEMs and EDA vendors, including Harris, Ericsson, Fujitsu, nVidia, Sanmina-SCI, Cadence, Zuken, Adiva and Downstream Technologies. Its goal is to accelerate the adoption of IPC-2581 as an open, neutrally maintained global standard to encourage innovation, improve efficiency and reduce costs. The members are committed to adopting IPC-2581, which as I noted gives this latest effort a big leg up on all previous attempts.

Where does UP Media Group stand on this? For 20 years, we have supported the development of an intelligent, robust format for electronics data transfer. As such, we fully support the consortium’s effort to ensure a viable, supported and independent data transfer format that is driven by user needs.

That new task group attempting to update IPC-2581 recognizes that design needs will at some point “break” Gerber. Many of the players are new to the game, and a lot of the old rivalries appear to have died off due to retirements and, well, death. That’s good, because the industry needs a better standard than Gerber. Thanks in part to his son, Joseph Gerber’s name and many contributions will hopefully never be forgotten. But it’s time his namesake data format is.

Trading Places

Posted on by
I’ve spent a good part of my life watching electronic data transfer formats come and go and at the end of the day, Gerber, warts and all, has remained the one to beat. So I’m not prepared to rise up and shout to the heavens that IPC-2581, the latest iteration in 40 years’ worth of attempts at an “industry” standard, is at long last the answer.

But there are enough notable differences in the process this time around to make it newsworthy. First and foremost, there are real, live CAD tool vendors not just showing up at the meetings, but actively participating (!).

Going back to my IPC-D-350 days, Digital Equipment and the late, great Harry Parkinson were instrumental in trying to revive interest, and they had support from several smaller software folks like Dino Ditta at Router Solutions and Steve Klare at Intercept. But they never managed to break through, and a big part of the problem was the CAD vendors’ collective refusal to offer IPC-D-350 as an output (or input). The response always was, “We’ll do it if our customers ask us.” But what they were really saying was, “We don’t want to make it easy for our customers to migrate their designs to a competitor’s tools.”

In the meantime, AT&T offered up RS-274X (aka extended Gerber), which UCamco continues to support, and Valor developed ODB++, and while it is more of a machine language than a format for electronic design data, it was accepted by fabricators desperate for something, anything more intelligent than Gerber.

A new task group is attempting to update IPC-2581, recognizing that design needs will at some point “break” Gerber. Many of the players are new to the game, and a lot of the old rivalries appear to have died off due to retirements and, well, death. That’s good, because the industry needs a better standard than Gerber. It’s not something anyone ever will make any money off of, but every day we go without it, everyone will lose some.