Eagle SMD USB... confused

I’m kind of new to Eagle and hope someone can help. I tried asking on Eagle’s forums but after registering 3 days ago and STILL not having “permission” to post… I gave up and came here.

I’m designing a board that uses this mini USB receptacle: http://www.hirose.co.jp/cataloge_hp/e24000153.pdf

I’ve actually never done a USB part before.

On page 4 you’ll see the recommended PCB mounting pattern. Being just a simple b/w line drawing they don’t do a very good job of showing the landings but I think I figured it out. If I’m looking at it correctly, there are of course the 5 smd pads, 2 rectangular landings (sort of embedded in “No conductive traces” region) and then 2 large irregular shaped landings. The 5 smd’s are obvious I think. But I have no idea how to define the other landings in Eagle. I can do the two rectangles as two other SMDs I guess, but certainly not the irregular shaped ones.

Can someone dummy this right down for me? I’m a noob not only in Eagle but in PCB design in general so you really can’t be too elementary for me.

Thanks.

  • Steven

Check the SparkFun Eagle Library - I seem to recall a part that looks almost exactly like this being in there already (which would save you from having to make your own)

Thanks. Actually, I just spec’d a different part. Kobiconn has one with a far more straight-forward footprint and I was able to get it for 2c cheaper. @ 50,000 units it adds up.

I know I’m new to this, but I kind of find it odd that Molex and other co’s don’t have library files for ALL their parts read to download. I contacted Molex and they said they could send me a 3D file… what’s that going to do for me? I need assurance that their part will work on my PCB and really the only way they can be sure of that is to make certified library files for the major PCB CAD packages.

No matter… point to Kobiconn for keeping it simple.

  • Steven

If you view that page at 300% or larger, you can see that the connector outline has a dotted line and that the pads consist of two large and somewhat irregular shapes on the sides for the mechanical connection, two rectangles below them, a keepout area between them, and five electrical contacts above them. The dimensions on the sides and top give the position of every line for an actual pad.

Stupid to make the dots in the line invisible at normal size, but that’s life. I’ve attached a png of the drawing with the pads shaded.

Yeah, I saw that… that is exactly as I read the drawing too. Not that it matters any more (since I spec’d a different part), but how do you do that in Eagle? The large irregular shaped ones I mean… do you use a a few overlapping rectangles to achieve the shape? Or somehow use a poly?

s_mack:
Thanks. Actually, I just spec’d a different part. Kobiconn has one with a far more straight-forward footprint and I was able to get it for 2c cheaper. @ 50,000 units it adds up.

I know I’m new to this, but I kind of find it odd that Molex and other co’s don’t have library files for ALL their parts read to download. I contacted Molex and they said they could send me a 3D file… what’s that going to do for me? I need assurance that their part will work on my PCB and really the only way they can be sure of that is to make certified library files for the major PCB CAD packages.

No matter… point to Kobiconn for keeping it simple.

  • Steven
Do you have any idea how many PCB layout packages there are? And you expect Molex to provide a footprint for every part they make, for every single PCB layout package? Even obscure ones that are nearly unheard of in the professional world like Eagle?

I’m afraid you just aren’t going to find that. You’ll run in to companies providing schematic symbols in a couple different formats occasionally, and an occasional footprint. But it’s pretty rare. And for Eagle? Pretty much never.

Lol… that’s a funny attitude!

“you expect a company to provide customer service that will help you buy their product?”

Yes, of course I do. You don’t??

Molex has to go to the trouble of engineering, drawing, and providing 3d models of their products… you really think footprint libraries would be trouble for them?

Eagle is pretty darned well used, but it doesn’t really matter… they (the manufacturers) just need to decide on any format and the Eagle’s of the world will support the importation of it… or they won’t, at their own peril.

I find it amazing how there’s so many people that jump to the defense of these poor multinational conglomerates whenever a suggestion that something can be better comes up.

Hope that works out for you.

s_mack:
Lol… that’s a funny attitude!

“you expect a company to provide customer service that will help you buy their product?”

Yes, of course I do. You don’t??

Molex has to go to the trouble of engineering, drawing, and providing 3d models of their products… you really think footprint libraries would be trouble for them?

Eagle is pretty darned well used, but it doesn’t really matter… they (the manufacturers) just need to decide on any format and the Eagle’s of the world will support the importation of it… or they won’t, at their own peril.

I find it amazing how there’s so many people that jump to the defense of these poor multinational conglomerates whenever a suggestion that something can be better comes up.

Hope that works out for you.

Companies like Molex typically deal with high volume customers, and most of the high volume customers want a CAD model of the connector rather than a footprint for a PCB program. Industrial designers don’t use eagle to design enclosures and case hardware, they use CAD (most likely Autocad). From a DXF you can extract all the information you need to lay out a pad arrangement for anything that comes along, and it’s a format that has been in use for years. If they created footprint files for all their devices they’d run the risk that the formats would change, and that they’d suddenly have to re-create hundreds of board layouts. Also the CAD files are things they’re already producing anyway for fabrication purposes, and it costs them nothing to distribute them, whereas if they distribute footprints, they’d have to pay someone to create it for each of the popular layout programs.

Secondly, it’s trivial to convert a DXF to an eagle footprint. See [Cadsoft’s Page for details.

I see where you’re coming from, but to keep costs down the manufacturers will do whatever they can. Which would you rather pay - 1.20 for a connector that has a board layout in multiple software packages, or 1.10 for one that doesn’t. Now what if you’re buying 1000 units? 50,000? 100,000? As a hardware designer you have a lot more leeway in setting your price point. Component manufacturers don’t. In an OEM’s designs they need their cost per unit to be as low as possible, so more of their sales price can go towards overhead, and profit.](CADSoft Finanzportal - CADSoft Finanzportal)

s_mack:
Lol… that’s a funny attitude!

“you expect a company to provide customer service that will help you buy their product?”

Yes, of course I do. You don’t??

Molex has to go to the trouble of engineering, drawing, and providing 3d models of their products… you really think footprint libraries would be trouble for them?

Eagle is pretty darned well used, but it doesn’t really matter… they (the manufacturers) just need to decide on any format and the Eagle’s of the world will support the importation of it… or they won’t, at their own peril.

I find it amazing how there’s so many people that jump to the defense of these poor multinational conglomerates whenever a suggestion that something can be better comes up.

Hope that works out for you.

Go into the real (professional) world and see how many companies use Eagle. The only companies I've encountered using it are those that cater to hobbyists (ie SFE) or that started out as hobbyists. It is unheard of. Big companies generally don't care if hobbyists use their parts - to them they see it as a sale of 5 pieces when normally they're selling reels of their components. (there is the argument that a hobbyists might then design that part into an actual product - but most companies seem to ignore this)

However, I strongly agree that there needs to be a standardized format for this stuff. I suspect that if there was, you’d see a lot more companies providing footprints for their stuff. It’s incredible to me that there is no standard yet.

I believe its the lack of standards… and the lack of consumer pressure… and nothing to do with “it costs too much” or there’s too many parts or whatever. Say they hire a guy at a whopping $250k a year to make a foot print for ONE part number… they’re making at least 10,000,000 of that part so that’s only an extra $0.025 each. Now get real and figure that guy’s probably only getting paid $100k and covering 1000 part numbers… that’s now only $0.0001 each. Totally negligible. If there’s demand.

OK, you caught me… I’m not a big “professional” company. But its not a hobby either. Nor was it born from a hobby. Eagle honestly was chosen because we said to ourselves: “We have talented people in-house, can we start doing our own PCB designs?” and then looked at what suites there were. Eagle really kind of looked like a commonly used one by hobbyists and pros alike. When we contacted the place that was making our boards and asked them for recommendations, Eagle was not only their first… but only suggestion. So it seemed like a no brainer.

Someone above mentioned using “CAD”, as though that’s a software suite. Eagle is a CAD. “CAD” is a type of software package, not a brand. Do you mean AutoCAD? I’d expect only old big companies stuck in the stone-age would use a generic CAD like that for something specialized like this, but what do I know. I don’t get how 3D models have ANYTHING to do with PCB design, other than spacial assurance design. We use SolidWorks (3D cad) and make good use of Molex’s and others’ 3D models for spacial layout (make sure it fits the case, doesn’t touch anything, etc) but there’s nothing we can do with that which assists in the PCB circuit layout.

Aren’t footprints important? Don’t they have to be fairly exact? If the answer to that is “yes”, then absolutely Molex (et al.) should be providing footprint files for their customers. I still maintain that they’re missing a huge opportunity by not doing so. We ARE just a tiny company, but we’re still producing 50,000 of these at a time… that’s not trivial. its not millions, but I don’t think the Molex sales rep (if he knew) looks at this purchase going to a competitor and says, “good riddance”. And to answer the question above about whether I’d pay $1.30 instead of $1.20 if it had the library file… in this case, yes I would (well, considering they’re < $0.30 no I wouldn’t… but you know what I mean). I found the Molex part first and I wanted to use it. It wasn’t until the troublesome footprint thing happened that I looked elsewhere.

I actually made this suggestion to a local distributor. He got back to me saying it was a COMMON request from engineers. So while the “pros” can make their own footprints… I’m sure they’d appreciate doing more important things with their time as well.

  • Steven

Many companies designing PCBs use PCB Matrix software for creating their parts. It extracts the data for the pin names from PDF files and creates footprints with very little effort from the package data. The footprints conform to IPC standards, which sometimes isn’t the case for footprints supplied by manufacturers. All the professional PCB software packages are supported.

Hey, good to know… thanks!

Another reason companies like Molex may not bother providing library footprints is that the same footprint may not be ideal for all of their customers. Although for hand soldering all you really need is a footprint that the part will fit into, with automated reflow soldering the footprint shape is a factor that affects the reliability of the soldering process. Manufacturing process engineers will typically want to adjust the footprints to get the best results based on the equipment, temperature profiles, solder and flux chemistries, mechanical constraints, and so on that are used at their particular company.

And of course, they could still do that. It doesn’t change anything for the (majority of?) people that are sending their files off to a 3rd party manufacturer. How many co’s have in-house PCB production?

Interestingly, I just came to this forum via Google, typing “EAGLE irregular SMD pad”, and this was the first hit. But I realize that the thread is quite old. After reading the very interesting discussion, it occurs to me that the original question got so obfuscated that the thread never actually reached an acceptable answer.

Being an EAGLE non-pro myself, I recently came across this same question when I wanted to design my library part of the Aptina CMOS sensor chip MT9P031, which also has irregular landings for some of its leads. Unfortunately, I could not evade the challenge by going to another part, because there simply isn’t one. I hacked it such that I first did a smaller rectangular SMD, then added a “polygon” shape for the rest, also on the Top copper layer, overlapping the SMD. Of course the DRC was not too happy with my hack, so I had to shut it up by simply “Approving” the terrible things I did.

Surely, there must be a better way. [One drawback of my hack is that I have to keep approving in the laylout, because I cannot name the polygon with the same name as the SMD.] Hopefully, some pro(s) out there can give some guidance to s_mac and me.

Thanks for your help.

-bp-

PS

Perhaps the solution to the deeper question is not with the manufacturer, even though it is very much in their interest to do something about it. Big distributors such as Newark (Element14) who has acquired EAGLE, I believe, could weigh in by providing EAGLE libraries for the most popular parts, done by a pro they hire, preferably already named with the Newark part number. Guess where I would buy the parts?

Great idea… and you’re right, I’d do my shopping there and not worry about minor price differences if they did that.

You’re right that I never really got a solution. And in the end… I dropped Eagle because of it. I now use DipTrace, but I’d be lying if I said that didn’t have its share of frustrations. Still, I’ve done 3 projects with it and they all went to manufacturing and came back with zero issues. Custom footprints is something it does MUCH better (though still not ideal) and that’s why I went with it. It would be nice if they’d have an import feature where you could just draw the foot print in a cad program of your choice and import it. That way it would be a ton more precise.

Mostly though, I learned that its not as important as it first seemed. When I can’t get a footprint exactly as I need it… “close enough” tends to work just fine.

  • Steven