More Fun File Facts: ODB++

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.

Fun Facts about Manufacturing Files

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



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

ODB ‘Partners’ Up

After the IPC-2581 Consortium was founded to support the move from Gerber, it was only a matter of time before Mentor responded with a similar group to push its own format, ODB++.

Today, that measure was officially announced, with some 18 companies among the initial partners in what is being called the ODB++ Solutions Alliance.

Astute readers will notice many of the same companies are publicly supporting both formats. It will be interesting to see how that unfolds, given concerns by some of Mentor’s competitors about the advantage it gains with its hold on the ODB++ format.

IPC-2581 ‘Chat’ Recap

We had nearly 1,000 visitors to today’s PCB Chat on IPC-2581. The moderators, led including Gary Carter of Fujitsu, answered more than 20 questions in a chat that lasted almost twice as long as planned. (The moderators plan to respond to some of the other questions they received that they couldn’t get to during the chat, so be sure to check back in a few days and see the updated transcript.) You may also contact them directly with questions at

The results show that data transfer is an area of high interest to the industry. The committee will be presenting a poster next week at IPC Apex Expo and will also have a booth there, where members can answer your questions about the new standard.

Speaking of Apex, on March 2 I will moderate a chat on the show. As always, we’ll open the chat to questions a few days early.

Chatting It Up

Fresh off the success of our premiere PCB Chat, we have quite a few more planned.

Tomorrow (Feb. 7), SMT process consultant Phil Zarrow will take your questions. Designers may remember Phil from some of the past PCB West and PCB East conferences, where he spoke on DfM/DfA.

Next week we will host the IPC-2581 Consortium, taking questions on the new data transfer standard.

On March 2, yours truly will discuss the IPC Apex Expo trade show.

We begin accepting questions for the chats a few days early, so don’t worry if you can’t make the live event. Transcripts are available in real-time and after, too.

IPC-2581 Update

It’s been a while since I updated readers on the IPC-2581 Consortium. Here’s a few tidbits:

  • The group of supporters continues to grow, and a couple large IT and test equipment OEMs are now considering joining. At least one announcement could be coming shortly.
  • The verification team, led by Ed Acheson at Cadence, is making progress. They are looking at some designs to use for test runs. At least 10 designs are expected to be validated using the members’ CAD and CAM tools.
  • Wise Solutions expects to have an IPC-2581 viewer by January. It will likely be made available through multiple websites.
  • The Consortium will have a booth at the IPC Apex show in late February and PCB West in September. Members will also have a poster at Apex and will make a presentation at PCB West.

Here’s a question: Should Mentor or Frontline (which Mentor owns a 50% stake in) join the IPC-2581 Consortium? Feel free to reply here or directly to me if you wish.

Talking Data Transfer at ZDAC

I had the great pleasure of attending Zuken’s ZDAC users group meeting earlier this month in San Antonio at the invitation of Steve Chidester, head of product marketing, and Amy Clements, marketing/sales manager.

Steve and Amy had asked me to present on electronics data transfer, a subject many readers know has long held my interest.

There were about 100 people who attended the event this year, slightly up over last year. All the usual Zuken folks were there: Gerhard Lipski, GM of Zuken Europe; Dave Gullickson, GM of Zuken USA; apps engineer Griff Derryberry; Humair Mandavia; Sandy Jones; and so on. I also was fortunate to meet with Zuken COO Jinya Katsube and CTO Kazuhiro Kariya.

As we’ve reported over at, just before ZDAC, Zuken rolled out two new tools: DesignForce, which accelerates prototyping by enabling chip-package-interconnect substrate optimization in a single, native 3D format. The CAD company also released CR-8000, its primary CAD flow. (DesignForce is embedded in CR-8000.) They spent a considerable amount of time discussing those two new tools and their ongoing product roadmap, including CR-5000 Lighting v. 14 next March, which will include a netless router. Zuken says it sees a need to move more information to upstream design, such as system and architecture. The main takeaway was that design makes up 4% of the cost of the process, but it determines 60% of the product cost.

I had about 45 people in my session. There was great interest in the topic, in part because some of the people there have been pushing their companies (RIM, Rockwell Collins, Northrop Grumman, to name but a few) to standardize on IPC-2581. All in all, it was well worth the time.

Also, Zuken is doing a lot in wiring harness design. This is a big market for many EMS companies (especially for military and aerospace work), and there are probably 12 to 15 companies that supply design software for wiring harness. (Some big ones are Mentor, Zuken, Eplan, Autodesk, and IGE-XAO). I didn’t attend the wiring harness design sessions, but it seems the audience was fairly split between the two.

Next year’s event will be held in Newport, CA, around the same time frame (early November).

Major Major and Standard Standard

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.

Data Transfer in the News

A couple new articles are out on the IPC-2581 and ODB++ data transfer formats.

On Oct. 2, longtime EDA journalist Richard Goering provided a well-written writeup on the “lively panel discussion” (“Data Transfer in the 21st Century”) we held during PCB West on Sept. 29. Richard does a nice job capturing the frustration of the designers present and historical give-and-take that has led us to the current situation.

And yesterday, EDN weighed in with interviews of participants from the data transfer panel held at PCB West and other key spokespersons.

Given the new support for IPC-2581 by Cadence and Zuken, among others, this issue isn’t going away.