Screaming Circuits: October 2013


Boo

Nosferatu-le-vampire-05-gGooood evening (said with my best vampire accent)

Turn out the lights. Hide your Mosfets. Keep your phase-locked loops locked. Calm your Verilog.

Your simulation is useless against the terrors of the infinite state machine. Your impedance is no longer matched and your bypass caps have stopped bypassing. Your RF signals will not stop reflecting.

Beware

Beware

But, do not fear the evil lectroids

  

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

The Dangers of ESD

Question:

EsdWhat do a conductive floor, foot grounding straps, conductive work smocks, wrist ground straps, foot grounding testers, ESD training, bench-top grounding monitors, anti-static bags, anti-static boxes, grounded carts, anti-static attitudes, conductive desk mats and grounded tools have in common?

Answer:

They are some of the things that Screaming Circuits uses to protect components and circuit boards from the dangers of electrostatic discharge.

Ideally, those are things that everyone handling electronic components and circuit boards would use. This is the real world, though, so there are likely companies that don't use such tools or follow good ESD control procedures. Some companies might even charge extra for what is essentially a basic right. Bad news.

Just the act of getting up from a chair can cause an in body potential of 10 kV. The human threshold for feeling a shock is around 25 kV. Silicon chips can sometimes be damaged at significantly less than that. One of the worst things about ESD damage is that sometimes the failure mode doesn't show up until the device is out in the field.

One of our many missions here at Screaming Circuits is to keep the dreaded ESD monster away from your boards. Your PCBs and your trust are very important to us.

 

Duane Benson
"Zero potential" is bad when when coming from
your parents talking about career prospects.
But it's good when evading ESD.

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