How's schematic / layout done in your company? - Page 1
Forum section: electronics / general

author: capt bullshot
author_rank: Super Contributor
timestamp: July 26, 2017, 10:11:50 am
content: While waiting for some script in the background to finish, I'm thinking of the efficiency of the schematic entry and layout process here.IMO it's quite inefficient:- We start the paperwork for introducing new components- They build the libraries for new components if our paperwork passes all stages- We (the HW guys) make our HW design, either from scratch or modifying some existing stuff, often copy and paste from existing stuff together. Bring it all to paper (by various methods - paper & pencil, editing in our locally installed SW, whatever you imagine)- They (the CAD guys and girls) capture our schematic from our paper printouts using their big badass CAD system- We get paper (or PDF) printouts from them, check for errors etc.- We supply them with our findings on paper printouts- Repeat last two steps until no more errors found- Do the last three steps for net classes, design rules, ...- Mechanical guys supply outline, height restrictions etc. to layout guys, we are responsible to check- They start to layout on their big badass CAD system- We get occassionally asked about details- Mechanical guys need changes for whatever reason, components won't fit anymore, ...- We get layout data - either printout or in big badass CAD system viewer format (yes, we've a suitable layout viewer)- We review the layouts and find errors / bad design and report in any imaginable format to them. Range is from making printouts and painting by hand to sitting next to them and explain what is to be done- Repeat last 5 steps until layout looks OK- We sign off the design and ordering of boards and manufacturing of prototypes is done buy other guys and girls- Wait, do something else, e.g. EEVblog forum- Prototypes arrive, everyone expects them to work the next day (SW guys already finished everything)

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: July 26, 2017, 10:39:36 am
content: Just wait and see how inefficient it can be WITHOUT a process.The only thing surprising about your process is the paper.

author: Rerouter
author_rank: Super Contributor
timestamp: July 26, 2017, 11:04:25 am
content: Much Smaller company here, but way less paper in the mix, we prefer flinging PDF's instead because of the whole "think green" thing,Equally Its rarely as fancy as a mechanical department here, we select a suitable enclosure, pull the 3D model, then the layout pass has it loaded and works to make sure it will fit. generally having forward and back annotation between layout and schematic for small things, like missing specifications for current handling, or a footprint change due to costing.Then have 3 sets of eyes pass over the 3d, the schematic, and the gerbers before the final order, looking for stupid things like missing junctions on schematics, a collision in 3D, etc.

author: tszaboo
author_rank: Super Contributor
timestamp: July 26, 2017, 11:55:36 am
content: IMHO the hardware team should be the CAD team. I work with that principle. Otherwise the entire process is inefficient, as you noted. Help is of course welcomed, like making footprints, sch symbols, or entering it to the ERP system. Parts of the circuit can be done by other people. This method scales to a team of about 5-6 people (on a single project). I just cant think, that larger teams would be that more effective. Electronics PCB design does not scale well. I just think that BIG companies just throw 10-20 times the resources at the same problem, to maybe solve it 2x the time.That being said, lab assistants (to do those long and boring measurements) or secretaries (documentation) would be very welcomed addition to any team.

author: dave_k
author_rank: Frequent Contributor
timestamp: July 27, 2017, 12:06:00 am
content: Quote from: capt bullshot on July 26, 2017, 10:11:50 amGoodness .... where do you work?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 27, 2017, 06:28:06 am
content: You actuallyfinishproducts that way? And more to the point, you have customers that pay for that?Surely it must be aerospace or military or something along those lines?Typical commercial development is more free-form, on small teams. A large team might be half a dozen people working on various aspects (PM, ME, EE, SE) of a complete product, to push to a working prototype in a quarter or two. There is absolutely no need or desire for careful isolation between departments, paper trails, and a dozen error-ridden handoffs.(Medical development proceeds similarly, but with the quality department involved, and a paper trail added. Mostly the PMs and QAs take care of that, letting the engineers work pretty much as normal. Paper trail, ECOs and all that are handled in the electronic QMS.)I would imagine larger tasks (say, designing all the systems of an aircraft) take many more people, and more time to design all the interfaces (top-down design stage), but I find it hard to imagine that such a dysfunctional, error-ridden process, as described, could evolve, as a beneficial process, in a competitive market -- unless, of course it's not competitive for some reason.Tim

author: komet
author_rank: Unknown
timestamp: July 27, 2017, 06:53:24 am
content: Quote from: T3sl4co1l on July 27, 2017, 06:28:06 amDid you notice that OP has a German flag? In my experience it is a good country for extraneous but also superfluous processes.

author: capt bullshot
author_rank: Super Contributor
timestamp: July 27, 2017, 07:11:54 am
content: Quote from: T3sl4co1l on July 27, 2017, 06:28:06 amNo, just plain industrial. And yes, we finish products that way and customers pay for that.Quote from: T3sl4co1l on July 27, 2017, 06:28:06 amWe do about 2...3 redesigns until the product works as desired, depends on the complexity. At some products we've got product / project managers making technical decisions on a bereft of any knowledge basis, but forcing us to do it. Add 2 more redesings for that.The market is competitive, product managers force us to build to a deadline and a price. Deadlines usually are missed. Lucky enough, the market is way slower than the product stakeholders think, so eventually things get into market.

author: halexa
author_rank: Regular Contributor
timestamp: July 27, 2017, 08:31:19 am
content: Hi,As a HW engineer at my company a normal project looks like this:Read all HW related requirment from costumer.Write my own HW requirments.Review.Sit down with SW team and do system design.Review.Start with schematic.Review.Do layout.ReviewGenerate Gerbers and BOM.ReviewSend design to FAB.Itterate.During fabrication time I write HW test cases and EMC test specifications.Were usally 1-2 persons doing HW in one project. Usally one person is lead and the other supports.

author: tszaboo
author_rank: Super Contributor
timestamp: July 27, 2017, 08:44:41 am
content: Quote from: T3sl4co1l on July 27, 2017, 06:28:06 amI'm guessing automotive or automation. Bosch, siemens, something along those lines.Once I was on an interview for Bosch. Just for the kick of it. There was this row of cubicles, filled with engineers, Dilbert style. So I progressed on the interview, and then they introduced what the team is actually working on. It was a CAN bus intelligent 12V battery monitor, monitoring current and voltage, estimating charge, etc... OK, so how long is the project? Well, a team of 12 enginers is working on it, we are estimated to make the next prototype in 4-5 months, shipping in like 3-4 years. WTF?I could draw probably a compatible one in 2-3 hours in one sitting. I mean it is really not rocket science.A (distant) friend of mine is working there, and he mentioned, that someone's 3 month task was to determine, if they can leave out a resistor, or is it necessary.So if you ever wonder, why a car costs as much...

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 27, 2017, 03:59:29 pm
content: I believe these will be the last labors of humanity. Jobs that are so superfluous and counterproductive, but in businesses that are so huge and flush with cash that they feel no need to optimize out their already expensive humans, let alone spend the huge NRE of an AI replacement. Maybe that too will come, by the next century perhaps, but it will surely be the last holdout of technical human employment. Not a very glamorous position, of course...Sorry to go futurist all of a sudden...Tim

author: vodka
author_rank: Frequent Contributor
timestamp: July 27, 2017, 06:06:45 pm
content: QuoteThey don't feel confident on themselves or thier prototypes have more faults than a shotgun of fairground.http://www.telegraph.co.uk/travel/news/the-crazy-saga-of-berlins-long-delayed-airport/Quote"paper & pencil" Do you still use drawing pens and parallexs?

author: floobydust
author_rank: Super Contributor
timestamp: July 27, 2017, 06:58:58 pm
content: Surely we've all experienced hardware development fail.I've been through several companies that bungle it and a train wreck occurs, every time.The product is taking forever to develop, late on milestones/deadlines, costs too much, failing approvals, overheats, is buggy, over budget, missing features etc.I've tried to explain the best order things are done in, what steps to get a design done but Mr. PhD Manager says "let's speed that up!" and "optimizes" the process. Butr he has no experience or skills building anything. A fabulous train wreck results.I didn't know that what we all do in our head, the EE design process, is something few modern corporations can organize and do well.

author: ebastler
author_rank: Super Contributor
timestamp: July 27, 2017, 07:10:04 pm
content: Quote from: capt bullshot on July 26, 2017, 10:11:50 amAny chance this description has been sitting in your outbox for the past 30 years or so? Or is this actually how the company works today?I had not realized that this division of labor was still in use. I had firmly assumed that designers would at least enter their schematics into CAD themselves; and often do the layout (or at least fine-tune it) too.It seems that you do get to type your own forum posts though -- or do you send a dictation tape off to the typing pool?

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: July 27, 2017, 07:59:30 pm
content: Quote from: ebastler on July 27, 2017, 07:10:04 pmYes, it is, and for good reason. And it is not limited to overstaffed companies.I do not consider myself a tool operator. And that also seems to be the notion of the powers above me.I did a lot of project-specific work (rent-an-expert via Hays and others) in companies using various CAD systems. Most of the time, this tasks were delegated. And I did not do a layout since they were done Brady-style, but I do produce layout guidelines and review the results. Same reasoning behind this.Now, I am the principal HW design engineer in a company with few resources, but even they follow this path because the have me at 200+% with tasks that I really have to do. Even if project teams can be very large (I'm doing mostly Aerospace&Defence), what do you think how many experts for EMC, SMPS, FPGA and so on there are? Barely enough to take care of the stuff that matters!

author: tszaboo
author_rank: Super Contributor
timestamp: July 27, 2017, 08:00:18 pm
content: Quote from: floobydust on July 27, 2017, 06:58:58 pmI had to explain this to some MBA recently. He asked, how much time does the first prototype take. It was a very simple project, so he expected it to take much less time. Told him, two weeks design for sch..., this much time to get for the PCB, this much for the components, subcontractor for the assembly, testing, programming. He punched it into the project planning software, 4 months.Oh, no that is impossible. We need it earlier. OK. Smart design (I do everything as I please, no meetings), 2 day PCB service, components from farnell, hand assembly, fuck documentation. Well, look at that, isnt it ready much faster. You know, just bend the rules a little bit, and suddenly everything is possible.

author: b_force
author_rank: Super Contributor
timestamp: July 27, 2017, 08:01:39 pm
content: The part what I always find amusing, is that even when people have "years of experience", they still expect that the whole thing works the first time.I have worked for so many companies/customers who make that mistake over and over again.Same goes for that certain people think schematic and board are two separate things.Once you finally get most of your requirements done, I always say that that's where the romantic dance starts.Going back and forth between schematic, boards design and reevaluating the requirements

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 27, 2017, 08:09:27 pm
content: Quote from: b_force on July 27, 2017, 08:01:39 pmI try my best to do one prototype and one revision.It's worked out pretty well so far.The major reasons for additional revisions are incomplete specifications (the customer "can't make up their minds" kind of thing, but not to be unfair, changes do happen), or, to be honest, if I've not put enough thought into it and made oversights, or forgot some specs. Which is more common on very small projects (so few specs, so little time required to build it, what could possibly go wrong?) and very large projects (where getting it right the first time is very difficult anyway, and reviews don't help much because there's just so much to look at).Tim

author: ebastler
author_rank: Super Contributor
timestamp: July 27, 2017, 08:17:40 pm
content: Quote from: Neomys Sapiens on July 27, 2017, 07:59:30 pmMany thanks for the additional perspective. I see your point that there are menial, time-consuming tasks which are best delegated. But do you really draw out your designs using pen and paper, for others to make sense of them and manually redraw them into a schematic entry CAD tool? (Don't you want/need the CAD tool's support when entering the schematic, to remind you of pending connections, perform an ERC etc.?) And do you use printouts to check schematics and layouts, and provide corrections?Pushing it that far might actually still save you a bit of time at first -- scribbling a correction onto a printout may indeed be faster than fixing it in the schematic. But I would assume that information loss, misunderstandings and oversights would result in a larger number of correction cycles, which end up taking more of your time (and the other guys' time too)?

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: July 27, 2017, 08:48:36 pm
content: Quote from: ebastler on July 27, 2017, 08:17:40 pmYou are partially right there. If I am familiar with the tool in use, I use it. But if, for example, the corrections have to be applied to every ocurrence of the circuit, I won't. And, even if this contradicts both your and my idea of reason, a lot of things get drawn where the person in charge has not yet proceeded beyond the 'roughly about like that' point. So what will really be pressing is that I take it to the lab. I often said that I would have preferred to spend the allocated man-years alone on a object, doing it from start to end and through the various subdisciplines. But development work does unfortunately have certain interfaces to the world of managers, project clerks, saleswonks and so on. So a lot of our life is coping with that, and if somebody said the milestone X consists of drawing y, what could one do?And, on the other side, I did not say that those other guys are dumb. Only limited, and most like it to stay that way. It has the benefit of not dreaming circuit-level FMECA or measurements you are looking for for days! So I mostly don't scribble notes on printouts, bit talk to them and/or show them the right 'typicals'.

author: tszaboo
author_rank: Super Contributor
timestamp: July 27, 2017, 10:18:54 pm
content: Quote from: b_force on July 27, 2017, 08:01:39 pmI happen to "sabotage" prototypes, so they cannot be used as a final product. You dont need to make huge things, just little ones. Like make it, so the mechanical dimensions of PCB are not good. Or the other thing had 4 channels of something, while the final design called for a 8 channel design. It was to reduce the cost of prototype of course. Or move an LED 2mm so it does not align. Or leave out a function or two, to be implemented later.Every single time I did this, there was something on the PCB which should be corrected. Some minor thing, which calls for proto 2 or even just a pre-production board. Every single time. And I know for sure, if it wasnt for these deliberate "mistakes" they would have gone into production. Because management does not listen to the engineer.I tell you all, be very careful with the design, because if management see a blinking LED on the board, they will for sure think that we are ready for production.

author: b_force
author_rank: Super Contributor
timestamp: July 28, 2017, 12:51:16 pm
content: Quote from: NANDBlog on July 27, 2017, 10:18:54 pmLol, that's actually a very good and simple trick.Never thought about it!

author: Tomorokoshi
author_rank: Super Contributor
timestamp: July 28, 2017, 02:07:03 pm
content: While from a software perspective, but perfectly valid here, Fred Brooks recommends to design one to throw away. It's the first prototype, not the first revision, to which Marketing will typically say, "Ship it!"Ideally I would like to make prototype boards to test sub-circuits, much less the entire design. But that never flies.Some designs require strict adherence to very specific standards and methods. Of course these are the ones that are more likely to be farmed out to someone who isn't in tune with them unless a lot of reputation-damaging effort is used to intervene (for it labels one as being "slow", "inefficient", "not-a-team-player", etc.).There's also the "black art" of EMC design, which is really just saying that there was a lack of design, testing, and instrumentation to get it more correct earlier in the process. This is where the problem of sending schematic design and/or PCB layout to someone who is not going to do the EMC testing really becomes penny wise, pound foolish.

author: senso
author_rank: Frequent Contributor
timestamp: July 28, 2017, 02:37:47 pm
content: Receive idea in a more or less half explained half baked form.Start research.Make schematic.Make pcb.Order everything.Solder, bring up, bodge what is repairable(if necessary).If MCU present, start programming.(This is about 1 month).New idea comes in, drop everything, this must be done ASAP express delivery.Repeat from the start, collect dozens of projects in various states of "finished".One man band

author: VK3DRB
author_rank: Super Contributor
timestamp: July 28, 2017, 03:45:36 pm
content: Companies that do not embrace embedded C coding standards or, Altium design standards if they use Altium, are destined to succumb to cost and deadline blowouts.Those professional companies who use documented PCB development processes and design standards end up more successful than two-bit companies that do things in a rushed and uncontrolled manner. I have seen companies go bankrupt to poor development practices.I instil this philospohy in my team where we design complicated boards with RF, SMPS, BGA, high speed digital, 8 layers:Design a PCB and it works first time, then that is abonus. One re-spin, then that isexpected. Two or more re-spins, then that isfailure.We have a very strong review process, good processes and highly skilled engineers and technicians. Incidentally, you pay peanuts you get monkeys. It is worth paying good money for good people else it is false economy.We do not design a damn thing until the requirements and architecture have been clearly defined, agreed to and documented. We do proof-of-concept and model the risk items with electrical and thermal characteristics using SPICE, eval boards, or other tools before the schematics have even been started.Therefore the actual design work is started after all the risks have been mitigated, all the features have been included, and the applicable regulatory standard have been understood and adhered to.

author: free_electron
author_rank: Super Contributor
timestamp: July 28, 2017, 04:44:49 pm
content: paper? what millenium do you live in ?Design engineer creates schematic using parts from master library. ( under revision control and tied in with procurement and PLM database )Placing such a part is end of the line for everybody. All data for everybody involved is known for a library part.1) When a new part is needed : engineer goes to a dedicated internal portal where he is logged in. click the 'new part request' button and provides manufacturer and manufacturer part number for the part and optionally a link to a datasheet ( from manufacturer website / distributor website) or attached the datasheet if it is confidential. 3 pieces of info are needed . manufacturer, fully qualified part number and a datasheet or link to datasheet. If the engineer has already made a symbol , knows about a usable symbol , he attaches it. footprints are not allowed to be made by designers.2) The portal triggers various people: supply chain checks if this part is critical and crosschecks alternates / substitutes potentially already existing. if a problem is encountered it goes back to the requester for more info. if it passes it is routed to the PLM team3) PLM team creates an entry in the master PLM database and attached all data ( where to buy , substitutes , datasheet. the whole nine yards ). An internal part number is now available that has all product, procurement and lifecycle information. the portal now triggers the CAD librarians.4) CAD librarians pull the datasheet and potentially the provided symbol form the designer . crosscheck, bring symbols up to internal drafting standards. Find or create IPC compliant footprint and push the part int he master CAD database with correct link to the PLM system.5) the system now sends out an approval request to the designer which checks the symbol and attached data and approves or rejects it ( in which case the CAD group corrects it ).the database now has a new correctly defined part for which all data (manufacturer, part number,datasheet, where to buy, alternates, symbol, footprint ,3d model ) is available to all.multiple people can wear multiple hats of course , depending on size of company and skillset.but in generalDesign engineer requests parts and makes schematic symbolProcurement creates internal order codeLayout engineer creates footprint and applies drafting standard to symbolLibrarian compiles all data into CAD library.You do really want a second pair of eyes on anything you do. so a single person wearing all hats is a big no-no.if the systems and support software is properly set up creating a new part can be as fast as 30 seconds.new resistor needed ? clone an existing one, attach new data and commit. if someone needs a new value, and it is available from an approved vendor it is 4 mouseclicks away. clone part, click on part number , ctrl-a,ctrl-c, click in target field , ctrl-v , click 'route for release'.since footprint and symbol already existed there is no needed signoff.new connector in pin mix neeeded ? find something similar, clone symbol edit and submit for approval , meanwhile pull the step fiel from the manufacturer, run a script that extracts coordinates and pinsizes and pops down pads , draws courtyard and silkscreen. , cleanup and commit to library. when approval for symbol is gotten . compile and release. i can do a fairly complex connecotr in a few minutes. ona good day i release 40 to 50 new parts. the library is so large i rarely need to build footprints anymore. ( i had an intern make all possible permutations of dfn, sop ,so , tqfp ) same for capacitors. i made solidworks model for an aluminum electrolyitic cap. send control command to solidworks and it spits out a new model for any height , diameter, pinwidth i want. i built a whoel bunch of 'programmable parts in solidworks. (pinheaders vertical , horizontal , shrouded not shrouded , smt thru hole different pitches. need a new boxheader ? takes 5 seconds to get the footprint. one command calls solidworks the other runs an altium script that populates the pins.tools are your friend. Get good tools. don;t muck about redoing the same thing over and over if you can automate it. tools don't always have to cost money.inkscape : opens any known vector format including pdf's .... strip what you need ->send out as dxf converted to polylines only -> can be read in any pcb package worth its salt.. cost : freeDraftsight : . cost : free. made by Dassault Systems. runs circles around autocrap.Notepad++ : nice text editorOctopart / Ciiva / findchips / digikey and mouser websites. : drill for information3dcontentcentral and many many manufacturers websites : grab step and or 3d cad models for almost anything out thereZofZ : gerber viewer / explorer. cost : free

author: Berni
author_rank: Super Contributor
timestamp: July 28, 2017, 05:03:52 pm
content: Wow that is a lot of back and forth before a project is out the door.I work in a smaller and younger company and the hardware part is pretty much on one guy. There is no paper involved, its all PDFs stored on a server that are generated out of Altium projects using automated scripts to keep things consistant.Process is more like this:-Boss comes to the meeting with a new project-We figure out who is the best guy to give it to and explain what the project needs to do-A list of requirements and goals is written down-The guy goes back to his office to research the things needed by the project-Go tell the boss why some of the requirements are impossible and figure out what is possible instead-Start drawing a schematic (Often lots of copypasting parts off existing products)-Get all the PCB libraries sorted with 3D components-Pull over the mechanical engineer to discuss basic layout of stuff-Start layout with the big components first-Give the 3d model to the mechanical engineer so he can start work-Move stuff when he comes back saying it wont fit-Finish the PCB layout-Show it to one coworker for a checking over-Send the gerbers to the guy that orders PCBs-Order all the components so that they get here when the PCB comes back from china-Solder together the prototype boards-Curse all the things you fucked up-Bodge wire stuff until it works-Build one or two more copies of the prototype with the same bodges and throw it at the software department-Fix the PCB layout so that it doesn't need bodges and make it production ready-Occasionally explain to the software guy why that bug he is having is not a hardware problem-Shoehorn in 3 extra features on the PCB with no room left, because the boss just found out that the competitors product will have them.-In the following months/years update the PCB when components become obsolete or hard to order on short notice.-Go back to the meeting to get the next project assigned to youAll this is done by one hardware engineer. If its a larger project then you might have multiple people each working on one PCB for that project.

author: floobydust
author_rank: Super Contributor
timestamp: July 28, 2017, 08:36:36 pm
content: There's another layer (loop) everyone is missing- regulatory approvals, like safety, HazLoc, EMC.Even after a pre-production sample is submitted to a certification agency, any "findings" mean changes to the schematic/bom/PCB/manuals and another board spin.It's just an additional iteration but management can't handle it. Wasn't in the stupid Gantt chart

author: SimonR
author_rank: Regular Contributor
timestamp: July 28, 2017, 10:06:36 pm
content: Wow this took me back to my first job. There was a lot of paperwork but not nearly as much as capt bullshot has to contend with.In my company the design was also mainly controlled by the Drawing Office but with more engineer input.So the procedure was like this.- The D.O. creates a login for the project. The CAD system ran on networked workstations, this was 1988.- Engineer supplies the data for any new parts that are not in the library.- The D.O. assigns a part number and adds the parts to the library- The engineer checks each part, On screen, not on paper and if all is OK signs an approval sheet which is on paper.- The D.O. also creates a manufacturing record card for the part number. The engineer may approve substitute components and add them to this card.Purchasing may not buy anything not on the card without the engineers approval.And yes we did have failures because purchasing didn't follow the rules.- The engineer logs in to the CAD and draws the schematic. It has to follow company style guide but it was still the engineer that did the schematic entry.Schematic entry does not have to wait for the new components before starting, but obviously cannot finish without them.- The engineer releases the finished schematic to the D.O. by signing the job form. two other people also check and sign the release.- The engineer provides layout guidance notes to the D.O., But mostly they ignored them until EMC became a thing.- The D.O. at this point prints off a netlist and single term net list which must be checked and also signed off on the job form.- The D.O. does the PCB layout. Finally!- The engineer checks the layout. This is the only time an engineer is allowed near the PCB layout tool.- The engineer approves the layout by signing the job form if there are no changes.- The D.O. renumbers the components according to placement, if this is issue 1, and back annotates the schematic including any pin or gate swaps that may have occurred.- The D.O. plots all schematics sheets onto A1 or A2 draughting film. The engineer signs them and the two other people approve and sign them as well.- The drawings are then stored in a drawing cabinet. Once this point is reached any changes mean a new version number.- The job was then sent off to another company to photo-plot the Gerber files. Later this step became redundant once the PCB manufacturers started accepting Gerber files on floppy disk, or possibly mag tape.- The engineer checks and signs the Gerber plots. which may then be passed to production for manufacture.- The D.O. prints off the bill of materials which is also signed off by the engineer and passed to manufacture.- Pick and place placement files may also be issued by the D.O. if it was a surface mount design. The only step that was entirely electronic at the time.Wow that take me back. There was no internet then, no PDFs, no 3D models, only data books and data sheets. And there certainly weren't any ready made libraries available, but maybe that was actually a good thing.that list took a bit of thinking about, there is less paperwork than capt bullshot has to contend with but it still seems long winded.On the other hand I have since worked for companies with much less stringent procedures in place and they had lots of screw ups as a result, so maybe it wasn't such a bad system.I remember that at the time for every library part you wanted to add to your schematic you had to enter the part number by hand. Although you could obviously copy components already in the job.I was disappointed by that at the time, I was hoping for some sort of selection list to choose components from, but this was leading edge tech at the time. The schematic itself was brilliant.Checking of the netlist annoyed me also but I always did check before signing until I realised that there was no point and just signed it without checking.The job of the CAD after all is to keep track of the connections and maintain their integrity always. This was something that CAD system was incredibly good at. If it was connected on screen it was connected in the netlist, something quite a few modern PCB CAD systems can't seem to do.If you've got 5000 connections to check its easier to check the schematic than a great big list of text. That's the point of CAD to make life easier.Single term nets on the other hand have to be checked because the CAD can't tell if you meant them or not. At our company single term nets were not allowed anyway.Bernie your list reflects my more recent experience. The last bit made me laugh but you forgot the bit where the boss looks at the case design after its finished and the board is routed. Then decides to move a connector from the left side to the right side and you have to rip up the entire board because you can't meet EMC.

author: Berni
author_rank: Super Contributor
timestamp: July 28, 2017, 10:30:50 pm
content: Quote from: SimonR on July 28, 2017, 10:06:36 pmActually that did almost happen. The prototype was assembled in a 3d printed case and i get the question "So when did we decide to put the microUSB connector on the top? Wouldn't it make more sense for it to be on the bottom?" Luckily everyone agreed that its a bit late to change that.As for EMC, that's another set of adventures. Turns out aircraft radios and GPS are very sensitive little buggers.