Working with electrical/PCB engineers 2

[JH2015]

Hi all

I wondered how you guys deal with passing information to and from any electrical engineers that you work with?

In my experience, there are always problems with them understanding the mechanical restrictions we have for the PCB size and shape, and locations of mounting holes etc. Do you generally send them DXFs to import into the electrical design software?

What about importing their PCB designs into your mechanical CAD software? Do they generally export STEP models for you?

Or are there any combinations of electrical and mechanical packages that integrate nicely together in this way?

Thoughts much appreciated.

 

[3DDave]

All of those methods. Why do you ask? Are you intending to replace all your CAD/CAE with an integrated package? AFAIK no one has one that is suitable for both general mechanical design and detailed electrical PCB design, though maybe Siemens have bought enough pieces you could license them from the same company.

 

[TheTick]

The three biggest problems, in order of magnitude, are communication, communication, and communication.

Use your words. Use pictures. Learn their side. Teach your side.

 

[drawoh]

JH2015,

Which one of you is first to define the outline of the PCBs?

I have designed lots of assemblies where I prepared an arrangement drawing of the PCB for the designer. I asked ahead of time what area was needed on the board, and what interesting parts were required to stick out. I dimensioned the drawings to show the external mounting, and the important components. If the PCB guy has a problem, we chat.

I have much less often, but recently, used STL files generated by the PCB software. Updates to the PCB design are a pain in the butt, but inevitable. I try to suppress the detail that I don't need. The STL[ ]file should be a precise image of your PCB. If it is available, why would you try to work with anything else?

--
JHG

 

[CWB1]

It depends on the company. I've worked for a few with amazing EEs that did everything including FEA/thermal/modal analysis themselves and others that relied heavily on ME for support. In the later cases, the EEs gave me an approximate size of the board, connectors, and harness bundle they needed so that I could create a couple dummy solids to review the rough space-claim and identify any issues. Once we've reviewed and agreed on that, I shared either a STEP or IGES file of the dummy parts, they put that into Altium or other PCB tool, and eventually they returned a detailed STEP or IGES assembly of the board + components to run FEA before adding to the larger product assembly. I'd usually then have to detail the harness, connectors/fasteners, and any other EE garbage they couldn't/wouldn't.

 

[JohnRBaker]

To a lot of ECAD guys, the world is flat. Even the more traditional Electrical Engineer don't always appreciate that the real world is 3D. Granted, most of my experience working with Electrical types was when I was a machine designer and I did feel for them somewhat since often they were the last people involved in designing a new piece of equipment (we manufactured commercial machinery for the food and chemical processing industries). Now, we worked with them to define all of the electrical components that were included in the machine, such as electric motors, limit switches, electric eyes and other sensors, as well as where the operators controls needed to be located as well as how these items controlled what the machine did. However, most often, the first time that they would have any idea where these items were physically located, you know, in that 3D world, was when the machine was fully assembled, or nearly so, and they were now expected to run their conduit, install their control panels, locate their junctions boxes, etc. And I have to admit that we machine designers didn't always take into consideration the impact of having to leave space for said conduit runs, junction boxes and such. Now we weren't looking for a pretty result and often the electrical parts of the machine did look like afterthoughts, which in reality they were, at least in terms of how they were connected together and so on.

Anyway, we always managed to get the job done, but it wasn't without its confrontations and forced compromises, which both side had to make, but I still think they had the harder task as it was often very hard or even totally impractical to have to change some part of the mechanical or structural aspect of a machine to accommodate an electrical issue. Most of the time, the Electrical guys just had to work with what we gave them.

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[JH2015]

Thanks guys, for all the replies.

I have never liked the reliance on sending files backwards and forwards - the hassle of constantly exporting/importing, and the risk of my updates not being incorporated by my EE colleagues (missed the email, imported a previous version etc).

Since my original post I have come across Altium's "CoDesigner" (

https://www.altium.com/documentatio...t-ecad-mcad-design-with-altium-codesigner-ad)

which looks like a nice way for Solidworks (and other MCAD packages it seems) to work with PCB assemblies from Altium Designer, with a live link allowing changes to be made by either ME or EE and then synchronised with the other.

Does anyone have any experience of this, or any similar tools?

Thanks

 

[drawoh]

JH2015,

I have worked with STEP files of PCBs generated by Altium. It works. Updates are a pain, but everything else probably is worse.

--
JHG

 

[JH2015]

@drawhoh - thanks - if you work with Altium, have you tried their "CoDesigner"?

 

[3DDave]

If you are considering CoDesigner consider this - it needs to be compatible with both Altium and the 3rd party CAD software, which means that you might end up one or more revisions behind in one or both packages waiting for Altium to release an update.

Having used software bridges before - specifically the case of non-native document management electronic document vault software, they would release a new version of the Doc Management software, but we could not use it until they also released the new version of the bridge. By that time the CAD people had released one and sometimes two significantly better versions of their software, leaving us up to a year behind while still paying maintenance on software we could not benefit from bug-fixes on.

Since they made Doc Management software that 3rd party support was way, way, way down on their list.

So, it would be wise to evaluate if Altium has side-by-side developers for the 3rd party M-CAD software you are using that will keep in lock-step release or if they are a development partner that has to wait for official releases to start their integration process.

 

[drawoh]

JH2015,

I am the SolidWorks guy. Somehow, Altium users send me files.

--
JHG

 

[itsmoked]

Unless your products are Mobius strip connected Klein bottles you generally don't need to have integration between the mechanical and the board layout engineers. As soon as you do that you are forcing someone to use a tool they probably don't like or don't want to waste exorbitant dollars on. This can EASILY cut out the very person you should be using because of his/her skilz and technical panache.

The normal way you do this so everyone can do their jobs in a friendly professional manner void of extra stress not a single soul needs is to sit down with the EE and (1) go over what the machine is and how exactly it operates.

After the basic needs operation is understood by the EE go (2) next over any potential additions that could be needed if system issues present themselves. "We could need heat tracing on these 3 pipes but we don't think so." "We might need to control an additional valve for the hydrazine."

(3) Ask the EE if there are any features or additions that might make sense. This could provide some serious product benefits for amazingly little expense. Improvements that could easily be completely out of reach logically or cost-wise if they needed to be implemented later. Give these ideas serious thought. Avoid tossing them in this meeting. Discuss them with others, especially the sales/field people. Numerous times I've shocked the MEs with possibilities they had no idea could be added without much or any expense.

(4) At this point go over what's needed for a user interface in general terms. "Buttons for flush, regurgitate, swill dump, etc." "A knob to control churning and two temperatures."
If you have a specific interface look that is needed for a proper product line feng shui then provide examples to the EE. This will be the guide. If not let the EE ponder it for a day and get back. The EE will be the most UP on the latest way to do Human Machine Interfaces (HMIs) and can give you some examples and pros and cons.

More than a couple of switches and buttons will quickly lead to maintenance and needless wiring expense. Head for a graphical touch HMI if the product exceeds a very few buttons and knobs (steam controls). Avoid steam controls immediately if different product models would result in a single change to them OR if the product is poorly defined at the moment and may need addition controls.

But I digress.

(5) Ask what kind of space the EE needs for the controller or show a proposed area with general dimensional limitations and talk about it. If it's immediately tight the EE will need to ruminate on the situation. Could be a multi board design will be needed. Perhaps the system requirements speak to a distributed control system so the controller can use a couple of interstitial spaces effectively. Perhaps he can educate you on reliable controller needs like not roasting it. Or, putting it somewhere dollar connectors can used instead of $25 dollar connectors.

On a different plane if a product needs to be really crammed it may make more sense for the EE to do the packaging with much communication and approval and mods coming from the ME side. An example might be a hearing aide or a cell phone.

In the current, completely insane semiconductor supply chain situation, I can only recommend you don't bother thinking "real small" unless you're okay with year long production blocks. Things like processors are often single sourced and I've seen ones that were $6 now being over $100. You can comb the planet for a common commodity part of two years ago, end up at a grey market vendor that demands 3X what the part was priced at paid up-front. A week later they inform you the price has gone up 25%, pay another 25% or they'll refund you. Now you're a week later, you have to pay. Requiring smaller parts can add to this dilemma.

Communicate. Wait as long as possible before locking the controller-space. Communicate.


Keith Cress
kcress -

http://www.flaminsystems.com

 

[ctopher]

The most common problem I have always come across is communication. PCB designers/engineers go off in their own world, design a PCB, release the dwgs/gerbers, then done. Before I know the final mechanical design, PCBs have been ordered, then issues with fit.
They send me original files, or sometimes STEP. I either can't import them into SolidWorks, or they are bare PCBs and sometimes not drawn correctly.
I now have CAM installed in our SW add-ins, but can't get the OK for any of us to have training.
It's always been a grey area at every company I have worked at.
Either know both mech and elect, or battle with poor communication.

ctopher, CSWP
SolidWorks '19
ctophers home
SolidWorks Legion

 

[3DDave]

I like it when they leave zero room around the mounting holes for screws and washers or cram components right up against the mounting holes or along the edges of the board so there is literally no place to mount the board without shorting something to the chassis or crushing some tiny capacitor or microscopic resistor.

I applaud the PC-104 connector designers - given the way the EEs stacked them like a Jenga tower and those connectors were the only thing taking the shear loads in a test box that was likely to be tossed to the pavement from the top of a troop transport vehicle.

 

[btrueblood]

Star for a very good post, 'smoked. LOL for this: "Mobius strip connected Klein bottles". Haven't designed one of those recently...

 

[itsmoked]

THanks btrue; And stay away from "nested" Klein Bottles.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[3DDave]

Don't disturb them when they are nesting. They are a protected species.

 

[itsmoked]

They have trouble getting oriented.. (mathematical term)

Keith Cress
kcress -

http://www.flaminsystems.com

 

[btrueblood]

At least they don't take up much space, since they have zero volume. FWIW, I have one of Mr. Stoll's products on my shelf -

http://www.kleinbottles.com,

and the calibration certificates (0.00 ml volume +/-.001 ml) to go with it, verified by an undergraduate math student.