How many PCB prototypes does your company allow in hardware design? - Page 1
Forum section: electronics / beginners

author: electronx
author_rank: Regular Contributor
timestamp: July 24, 2024, 08:16:30 am
content: How many PCB prototypes does your company allow in hardware design?Some prototype PCB's are expensive. I worked PCBs worth 1000 dollars (10 layers of blind via and impedance equalization, etc.).What is expected from me is that the PCB works in the first design, if there is any mistake I get a ton of mobbing. How is it at the company you work for?When I want a second prototype, and I get suggestions like "it should work on the first design". Is this normal?Especially when designing analog circuits, spice models can include simulation times of 7-8 hours (Cascade circuits).Divide and conquer spice simulations are partially faster. However, it can be difficult to predict what will happen in "cascade circuits". The simulation provides results to some extent.For example, in the data sheet of an opamp, everything such as chopper noise results etc. can be included and noise analysis can be done. However, sometimes there may be unexpected noise. (Meanwhile, I am reading technical books and making designs to broaden my perspective and learn more topology sub-topics.)Analog digital circuit topology design , power design, analog and power spice simulations , PCB place and route, high speed ddr electromagnetic simulations, power integrity ,syz parameters, signal integrity, decoupling cap optimiazation, impedance analyses), all of them I analyze it myself.But there are still points I miss.I also have to test pcb , time domain oscilloscope, vna for pdn impedance etc and SA analysis for active filter characteristics.What about your experience?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 24, 2024, 08:51:20 am
content: For a PCB of that complexity, expecting everything to be perfect first time is unrealistic, and that should be reflected in the development timeline and budget.It is common for a first prototype to add additional test points/signal breakouts, links to allow signals/power rails to be broken, and other functionality to make validation easier - that alone should cover the cost in time saved.It's also pretty common for revisions to be needed to address specs that have changed since the first prototype.

author: AndyC_772
author_rank: Super Contributor
timestamp: July 24, 2024, 09:07:09 am
content: Quote from: electronx on July 24, 2024, 08:16:30 amIt's normal if, and only if, the people you're working with are morons.Designing a new PCB for the first time is an incredibly complex undertaking, especially the type of board you're describing. Expecting it to work on the first revision is just a way for your colleagues to express the fact that they have no idea what the design process involves, or what the uncertainties are.As a concrete example... a while back I designed a board that used an RS485 transceiver. The data sheet explicitly stated that the output isguaranteedto be logic 1 when the bus isn't driven externally, which is a very common state in a multi master system."GUARANTEED"Turns out that's not the case; if the bus isn't driven it's instead highly sensitive to external noise. The amount of noise picked up depends on the enclosure, wiring, and other factors that aren't even part of the PCB.I humbly contest that there is no possible way that particular PCB could have been perfect, production ready on rev A. There isalwaysa process involving building a prototype, testing it, fixing the bugs, then issuing rev B.Rev B is usually production ready. Unless the goalposts have moved, in which case it might be rev C, or D, or E, but that's not the fault of the engineer either.

author: PGPG
author_rank: Frequent Contributor
timestamp: July 24, 2024, 11:29:19 am
content: Quote from: AndyC_772 on July 24, 2024, 09:07:09 amDo you remember the exact RS485 transceiver symbol?

author: electronx
author_rank: Regular Contributor
timestamp: July 24, 2024, 11:48:42 am
content: A similar situation occurred with the RS232 transceiver. It was claimed that pull up resistors (through the IC die) were connected when it was idle. However, when the serial numbers changed, it was understood that there was no pull up resistor inside. In this case, when the power came on, the RS232 was sending a noisy symbol to the output.

author: perieanuo
author_rank: Frequent Contributor
timestamp: July 24, 2024, 11:55:56 am
content: hi, in places i worked usually Rev D to F even H were clear winners. and it was micro/dsp usual automation boards at some low frequencies, not very high grade of complexity, smart step/brushless motor drivers, automations for machining (ie, pin insertion automated machine with display, up to 32 motors controlled on rs485 or wifi-enabled with incorporated trajectory control like speed, acceleration etc). so nothing top-notch... let's say Rev C was stable for production and later revs better and with other client new ideas (well, client have always new ideas after you do his stuff)br

author: Psi
author_rank: Super Contributor
timestamp: July 24, 2024, 12:03:15 pm
content: Obviously it varies a lot with pcb size and complexity.But 3 to 9 is normal for the stuff I work on, with most projects becoming mature around 4-6.Throw some high speed signals/FPGAs in the mix and watch your revision count go up.Sometimes you need many PCB changes that are totally unrelated to electronics. Mechanical changes affecting pcb outline for example.

author: coppercone2
author_rank: Super Contributor
timestamp: July 24, 2024, 12:47:50 pm
content: fuck those people that think its possible to get it right on the first time its like thinking your team is sure to win a basketball game, its ridiculousIt means they have a understanding through too many layers of abstraction and assumptions and they simulated a bogus ass representation of your work effort that has their desired outcome. i think the internet calls this an armchair tacticianMaybe a passive interconnect has a good chance of working on the first revision. more then likely there will be some issue related to manufacturing that means it always stand a 2nd version.I present to you, the interconnect industry. They have to make a object out of sheet metal, a simple conductor that is one part. How long does it take them to design a new crimp? The equivalent circuit is literally this " - ". And it takes years. Actually electrical engineers can't even see it in their dimension. Its something that manifests itself when a design comes into the real world.

author: CaptDon
author_rank: Super Contributor
timestamp: July 24, 2024, 01:31:59 pm
content: Management never has time to do it right, but spends years "Doing it over" and somehow they think they are winning? Management says "We have to be the first in the marketplace". A customer will remember what a worthless piece of shit your product was for a much longer time than they will remember something that was plug and play perfect. As for the software/human interface......So much software (client or operator interface) is written by and for software folks and is completely un-intuitive to the final user!! Operation should flow and be intuitive!! As for rev numbers, I worked with a power supply designer who's designs were so flawed he didn't even assign rev numbers or letters!!!! The final marketable product was always assigned Rev. A and rev 'A' was usually about his 5th try. It was impossible to know what version we were validating. Thank God he moved along!!! Our company usually goes to market with 'pile of shit Rev. B' and by the time we release Rev. D it is 'almost' on target. Or should that word be 'tarGEt?

author: AndyC_772
author_rank: Super Contributor
timestamp: July 24, 2024, 01:55:43 pm
content: Quote from: PGPG on July 24, 2024, 11:29:19 amSure do. From the data sheet:"The LTC2854/LTC2855 have a failsafe feature that guaranteesthe receiver output to be in a logic-high state whenthe inputs are either shorted, left open, or terminated(externally or internally), but not driven. This failsafe featureis guaranteed to work for inputs spanning the entirecommon mode range of –7V to +12V."I think the issue was a sensitivity to power supply noise when the bus was correctly terminated at both ends, but not actively driven.

author: tszaboo
author_rank: Super Contributor
timestamp: July 24, 2024, 02:15:53 pm
content: I usually go with 2 or 3, depending on how complex the project is.Often times we want a prototype which is good to start programming, and the certification part (which is 80% of the work in my case) is done later. It also went to 5 or 6 prototypes for other engineers, they still work here.

author: PGPG
author_rank: Frequent Contributor
timestamp: July 24, 2024, 02:36:09 pm
content: Quote from: AndyC_772 on July 24, 2024, 01:55:43 pmI asked because when used by us transceiver (SN65HVD72D) was absolutely unavailable I selected close replacements:- LTC2862IS8-2 (higher supply current what I don't like as I have linear regulator from up to 24V down to 3V3),- MAX3072EESA+ (internal protection working at -8/+13V while my protection is designed for -13/+16.5 from HVD72D).I wanted to know if it is not one of them.And regarding the thread question.Designed by me PCBs we order at once a production serie.But these are simple designs (not long ago it were only 2 layer PCBs) and our production series are rather small (around 100) so if it comes to making hand corrections it can be tolerated.

author: mawyatt
author_rank: Super Contributor
timestamp: July 24, 2024, 02:46:09 pm
content: Try chip design!!!Revisions here are extremely expensive and career limiting!!Best,

author: rich t
author_rank: Contributor
timestamp: July 24, 2024, 02:54:49 pm
content: > What about your experience?There can be no one-size-fits-all rule.IMO, the best approach is if you want to spin, have a full peer review and understand what went wrong the first time.And then assess whether it is reasonable or not -- and implement changes so unreasonable spins can't happen again!Some spins are totally unreasonable and should have been caught before PCB -- the typical one I think of is a component layout issue -- always print your PCB on paper and put all the parts on it!Other spins are less unavoidable -- things you have to measure in real-life -- I had power supply noise from the MCU VUSB3V3 show up in an analog circuit, and the only way to avoid it was a routing change.

author: electronx
author_rank: Regular Contributor
timestamp: July 24, 2024, 03:24:36 pm
content: I have approximately 1.5 years of experience. Before that, I did an embedded system internship for 2 years (while I was at university). I do not start PCB design without doing spice simulations in the analog and power parts. At the same time, if I have a high-speed signal on the PCB, I use pdn and si simulations.I think there is something causing flicker noise in my last design. It was a signal conditioner and they want that design it in 3 weeks.

author: electronx
author_rank: Regular Contributor
timestamp: July 24, 2024, 03:29:49 pm
content: Quote from: mawyatt on July 24, 2024, 02:46:09 pmI guess my heart can't stand it

author: Kleinstein
author_rank: Super Contributor
timestamp: July 24, 2024, 04:08:05 pm
content: With modern EDAs and afordable small scale production PCB redesigns are not that dramatic anymore. Even $1000 for an expensive multilayer PCB hardly pay for 1 week of the PCB designer. It still helps to not make too many iterations - how many depends a lot on the type. There can also be added costs to a design, like EMI testing if the design nearly works.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 24, 2024, 04:11:40 pm
content: On the flip side, if you know it is certain that there will be changes after the first proto, it doesn't make sense to spend too much time getting it as perfect as possible, as it will generally be quicker and easier to discover what needs changing once you have a board in front of you.Also often means the software can be progressed sooner.

author: coromonadalix
author_rank: Super Contributor
timestamp: July 24, 2024, 04:13:55 pm
content: normally under 2 or 3 pcb'sthe failure often come from pressure, thought processes, product evaluation needs, too many people buzzing around you lolland some failures come from the way you read and interpret schematics /symbols as mentioned earliertake you time to sit and evaluate, check re-check, and re-re check, and if all is done correctly you can get a 1st spin correct UNLESS the board maker mess things up (happened)One of our design was perfect 12 layers (mostly ground and supply lines), but the board maker mirrored a system on module (ZynQ based SOM 2x 100 pins headers) we had to create a sub board to invert their mistake ....a small pcb with 4 x 100 pins connectors, 10 layers a mere 200$ extrathe carrier cost 800$ loll

author: G0HZU
author_rank: Super Contributor
timestamp: July 24, 2024, 06:45:25 pm
content: It can be realistic to demand a 'right first time' design process. For those who don't agree, maybe look up what UOR means.I've had to work on projects like this in the past, where the first batch of boards 'is' the first production run for the customer.This applies to every PCB in the system so there might be a dozen different boards covering PSU, digital, RF Rx and RF Tx, and I/O. All are designed to be right first time and all have to be used in the first production run because there is no time allowed for a second attempt at the PCB design.This usually involves 8 to 12 layer boards with FR4 core and Rogers outer layers with expensive via options each costing more than the budget in the first post.To achieve success, this requires exotic CAD tools and a fairly large and experienced design team with lots of peer reviewing, and formal design reviewing. It is possible to get really close to a perfect design if you use the right CAD tools to model everything and produce a virtual system before you commit to real hardware. The downside is that it requires a lot of resources and lots of funding to do it.Nearly always a component value will change or a pullup resistor will have to be tacked on somewhere, but the original PCBs absolutely 'must' be good enough for the first production run.In all my years, I've only had to do this UOR thing twice and both times the original boards were used for the first production run of the first batch of systems. Any second ops mods were minor, such as component value changes or the odd pullup or shunt cap was added.

author: rfclown
author_rank: Frequent Contributor
timestamp: July 25, 2024, 12:58:34 am
content: My employer's business model ideally has the customer funding the development and making of the first items. The schedule is made with wishful thinking that the first board can be made to work. We will go through heroic efforts to make the first items work without a board re-spin, because it isn't in the budget or schedule. The time frame from product kick-off meeting to first item tested with customer and everything set in our system so that the customer can then order more is usually one year. One electrical and one mechanical engineer. It's pretty crazy. If a re-spin is needed, no one gets yelled at. This is small quantity stuff (<100 per year). Can be complex with high speed digital and RF. We usually farm out the simulation of high speed digital stuff like DDR and xx GHz ethernet.Interesting idea of printing out the board on paper and putting the parts on it. The problem I see with that is that if I sneeze the hundreds of 0201 components will fly everywhere. (to be honest, I can mostly use 0402, my preferred size for stuff <3 GHz).

author: Psi
author_rank: Super Contributor
timestamp: July 25, 2024, 11:47:02 am
content: You can spend an extra week or two thoroughly checking over the PCB for any issues before sending it out for fab. Or you can send it out 1-2 weeks early with only a casual check over. Then you can get started on the development 1-2 weeks early because your boards arrive 1-2 weeks early from the time you saved.If there's a PCB issue you can quickly make a change to fix it in an hour and send a new revision to the fab that day, while continuing to test on the current board and simply working around the issue it has.The net result, it's often cheaper overall to NOT try to get it right first time.The engineers time in $$ spent thoroughly checking the design is usually more than the cost of a respin or two.It's also often cheaper and faster to just order the raw PCBs plus do a digikey parts order so you can populate the PCBs yourself. It might take a full day or two to hand populate a few boards, but I guarantee it will take longer than that to organize PCBA, wait for the fab to get the parts and then populate and ship the boards to you. Just getting some black PCBs and a stencil is super fast.

author: CaptDon
author_rank: Super Contributor
timestamp: July 25, 2024, 01:26:44 pm
content: Saying it's 'kind of o.k.' so let's push out the first PCB design a couple weeks early is total B.S. What if the board simply refuses to boot up at all or power supply wiring is in error (SMPS with the MOSFET footprint inverted, we had that happen with a rush job and destroyed some VERY valuable parts) or you can't even get the JTAG to work correctly? Maybe some smaller stuff with a total landed cost of under $1000.00 per board but we were doing systems where the total landed cost per board was over $3000.00 and usually you will purchase 2 to 5 of those boards to distribute to the hardware and software test/verification/QA QC departments. You are looking at the potential of $6K to even $30K of useless junk if you skip the extra week of peer review steps. (Assuming your company even has any 'qualified peers' to do a review). We were extremely anal in our first spins and still had to do at least one re-spin. The second spin usually was marketable with one or two hand placed kludges added. In multi layer boards you can't probe the sub-terrainian signals so troubleshooting a dead or non-functional first spin with routing mistakes may be impossible!! Spend an extra week reviewing your routing. it's worth the labor cost!

author: tszaboo
author_rank: Super Contributor
timestamp: July 25, 2024, 01:47:51 pm
content: Quote from: CaptDon on July 25, 2024, 01:26:44 pmThen you desolder the power supply and connect a lab supply in it's place.If your JTAG doesn't work, you take a scalpel, cut the traces and wire it to a connector.If it doesn't fit into the enclosure, than you take a dremel to the enclosure or your PCB.These are issues that can be solved easily if you have experienced people working on a project. if you search this forum, you will find dead bug manually wired FGPAs upside down. It's just the question of determination.I even ordered PCBs that had zero components on them, just to be able to test fit it into an enclosure. it only had the connectors, place where the potting compound goes and nothing else.The only reason not to order early prototypes is money, and if a company cannot afford prototypes, I think it's time to look for a job somewhere else, because they will take this minimalist spending mentality to places that will affect your life in a bad way.

author: Psi
author_rank: Super Contributor
timestamp: July 26, 2024, 12:27:29 pm
content: Yep, i agree with tszaboo.You work around the issue any way you can. You only have to do so for a week or two until the new board revision arrives.There is usually a mountain of things that need to be checked/tested, often sub-circuits that don't even need the main MCU to be functional.Obviously there is some common sense to be applied here and some exceptions depending on the board complexity and if it has expensive parts that cannot easily be moved to a new PCB. You can reball and move most BGAs with some skill, but obviously if you're working with a $50,000 ASIC sample you are going to spend as much time as needed to fully check the PCB design.The first revision needs to have a good chance of working well enough to continue development taking into account the costs involved.No-one is suggesting wasting money, we are suggesting saving money by not wasting time aiming for perfection right out of the gate.There are definitely situations where thingsshouldbe made to work first time. They are just the exception and not the norm.

author: Just_another_Dave
author_rank: Regular Contributor
timestamp: July 27, 2024, 12:31:20 pm
content: Designing a PCB that works perfectly in a single iteration is pretty hard. When I designed PCBs in my previous employment, the project managers used to consider that it wasn’t going to happen and, therefore, they focused on mitigating the impact of the problems that could happen. Prototypes were normally designed to be as modular as possible, so even if something failed, other subcircuits could be tested. Additionally, breaking the system into several PCBs meant that you didn’t need to replace the entire prototype if something failed.Additionally, each module was reviewed by the entire team as well as by a second team that was not involved in the project before manufacturing it (sometimes someone that doesn’t know anything about the pcb can find routing mistakes that people involved have overseen)

author: Psi
author_rank: Super Contributor
timestamp: July 28, 2024, 12:12:30 pm
content: Quote from: Just_another_Dave on July 27, 2024, 12:31:20 pmExactly.If a manager/company isrelyingon the prototype to work first time then they're not doing their job.If a manager/company isexpectingthe prototype to work first time then they don't understand prototyping and are probably wasting resources that could be better spent iterating on the design.If a manager/company isplanningfor the prototype to have some issues and trying to mitigating those risks as much as practical then everyone is working correctly as a team and you're lucky to work there as opposed to the other 2 options.

author: dietert1
author_rank: Super Contributor
timestamp: July 28, 2024, 04:23:24 pm
content: I also think peer review is crucial in order to remove expensive errors and share responsibility. And avoid overly complex prototypes but rather make some test board for design confirmation. I often used test setups with evaluation boards and other modules before even thinking about PCB design.One needs to learn enough to be able and bodge the first prototype PCB into a working one, so its revision will be 99.9 % correct. Once a prototype is working, there shouldn't be a problem to order the revision.Regards, Dieter

author: coppercone2
author_rank: Super Contributor
timestamp: July 28, 2024, 05:45:15 pm
content: I mean I think its like a sport team, you wanna win, its not guaranteed, the better your team the more likely it is, but its chaos and you should not expect miracles. Their supposed to be like coaches. Only difference is that in most cases coaches played the game and know the game very well and are retired because of injuries or age... at least the best ones are like that.. and most of them are very interested in the game outside of work like a hobby/past time. With how corporate America works, you are likely to get one that never played the game and is not interested in it outside of work... so you need to set your bar a little lower.And the analogy falls apart more because its so much more chaotic and complicated then a sport game in terms of variables, plus the performance lasts for possibly years.I think it has to do with setting reasonable goals. I.e. that you expect the power rails should work for the first time and that the traces are sized not to fuse... there is a reasonable standard you can go by in terms of expected outcome.

author: free_electron
author_rank: Super Contributor
timestamp: July 28, 2024, 05:50:27 pm
content: Are we talking the pcb layout or the entire design ?Entire design : as many as needed. Build a number of prototypes. Possibly sections of the circuit. Simple rectangular board to get bench testing going and develop firmware. inject lots of testpoints and dummy parts or cuttable pathways.As the design nears completion start working on form and fit. Work within mechanical constraints: size, shape.After thermal , emi , vibration and other aspects have been tested respin the board. During this cycle component selection may change. Different connectors, transformers, capacitors. Different locations. Final enclosure shape may change.So the board needs to adapt.In telecoms i respun board because of components impeding proper airflow for cooling in the 24 inch telco racks. Or respin them because they had issues during assembly ( all heavy components on one side giving problems in the pick and place machine.In automotive I made modules that hade many late changes. The factory floor people complained it was difficult to plug in the wiring harness because of an odd bend they had to do on the conveyer. it was difficult to reach-in to plug in three connectors. Scrap the entire design, go to a different connector, position it differently. Later on we ditched it again because there was an additional cooling duct required above it for the power hungry computer module above it. ( between glove box and footwell ). Things change during design, especially when the board is part of a larger system. All these aspects were looked at. How difficult is it to assemble, how does the module fit, thermal, vibration, assembly time, installation time. Mosfets did not behave as intended. Global part shortages. Footprints were made so they could hold many different parts allowing for late-game changes. Optimize for mass production so it was faster to assembly with higher yield. It's a continuous process.Space was yet another can of worms. A launcher undergoes extreme vibration during take-off .J-bend stacked ceramic capacitors literally flew off the board. Ferrite core transformers would crack their core and bits and piece would go flying.Connectors had issues with foreign material ingress. Do we put the male or female on the board ? How many times will a connector be removed during assembly or launch operations. Where is the risk for damage. A bent pin on the wiring harness is a disaster as you can't easily swap the harness. But you can easily swap a module. A socket can get plugged by debris. Sometimes connectors need ability to be inspected visually. We're talking 38999 family onnectors that cost 500$ a piece... Someone has to reach into the interstage to plug in the GPS simulator while standing on a boom lift. Come launch day : remove simulator and plug in the stage computer.So these boards underwent extensive testing on vibration tables. The enclosures woudl flex and warp and needed reinforcement ribs. This would impede part placement and mounting hole placement. Boards would vibrate in spots and crack vias so additional mounting holes were required, or needed shifting of the holes to stop resonance points. Then all of a sudden the module was to be rotated or flipped in the nosecone or around the fuel tank and now the entire dynamics changed ... -> respin board. We need more sensors inputs -> respin. we need more actuators. we also want to monitor xyz -> respin respin respin.Same for aircraft. Rotate, consolidate, add stuff. The power controller got mechanically so complex that it became unreliable due to all the interconnects. Migrate to rigid flex. The board folds post-assembly and 90% of the interconnects are gone as they are now part of a single piece board instead of 4 boards plus associated wiring harnesses. Only two 38999 connectors and a power busbar remain. Electrically the system has not changed. But the pcb layout has shifted technology , form , assembly and installation to make the entire assembly more reliable and easier to manufacture. No more harness mistakes or bad connections between boards. It is one board and can be fully tested pin to pin before going into the mechanical assembly.it is unreasonable for a design to be frist time right, let alone the board to be first time right.The only place where i have known first time right is in silicon design, but that is a totally different world. There you have the tools and the timeline to do this. Simply becasue building the first run is so massively expensive. You can't prototype. PCB is cheap ( a few k$) and fast (3 to 4 days if needed) . Silicon not so much ( millions of $ for a maskset) and 6 to 8 week turnover in the factory.In silicon world you take your time and simulate the snot out of the design. You have the tools and data to do it ( which also cost a fortune)For PCB level this is not required. The respin is fast and cheap. The PCb level simulation tools are nowhere near the capabilities in the silicon world. They don't need to be different problem to tackle, different cost, different domain.

author: coppercone2
author_rank: Super Contributor
timestamp: July 28, 2024, 05:56:55 pm
content: Quote from: free_electron on July 28, 2024, 05:50:27 pmin this case my sports team analogy becomes "expectations on the performance of flash gordon" and/or vulcan baseball team management

author: djacobow
author_rank: Super Contributor
timestamp: July 28, 2024, 06:01:32 pm
content: Not only is "getting it right" on the first iteration unrealistic in most circumstances, it's not even a smart goal. It wastes a lot of time with extra reviews and stress that are unlikely to turn up the issues.The cost of pcba had moved so much that it's better to optimize for quick cycles. I do like to make sure that early spins are highly testable and as amenable to hand rework as possible. I generally like to try to get a board working via rework before spinning it and I get very cross with colleagues who find one issue and immediately start a new spin. I think it's important to take each board as far as your can get it, to uncover as many issues as possible before spinning.We usually get to an adequate board in three goes, but often management has moved to goalposts by then. Our product people are ... not good.

author: RoGeorge
author_rank: Super Contributor
timestamp: July 28, 2024, 06:11:51 pm
content: Listen to Rick Hartley, then design good PCBs from the first try:

author: wasedadoc
author_rank: Super Contributor
timestamp: July 28, 2024, 06:19:21 pm
content: Why should the hardware designers be expected to get it right first time when the software guys never do?

author: AndyC_772
author_rank: Super Contributor
timestamp: July 28, 2024, 06:25:34 pm
content: I can't email you a hardware update.

author: wasedadoc
author_rank: Super Contributor
timestamp: July 28, 2024, 06:43:39 pm
content: Quote from: AndyC_772 on July 28, 2024, 06:25:34 pmThe software guys didn't have that copout before the hardware engineers developed flash memory.

author: max_torque
author_rank: Super Contributor
timestamp: July 28, 2024, 08:31:41 pm
content: There is a modern effect called "integration hell" which unfortunately tends to often dominate fast paced "high tech" projects, and generally those that are poorely managed (and IME engineering managemen is most often either shockingly bad or effectively non-existant. Integration hell basically is that state where all the different teams of people working on the final solution have to put all their stuff together, and yup, i pretty much never works.So the answer to "how many goes should it take to get to a production spec solution really, really, really depends upon two critical facts:1) has the team desiging and developing this new pcb done this before?and2) how much "new" is there being implented?So how many iterations you should plan for should clealy simply be an inverse measure of the answer to those two questions multiplied together.So, you have a highly experienced team, doing something they have all done for years, well, honestly proddy spec should be board two imo (always a prototype for mostly physical reasons and typically because often the mech design is simply not progressed enough to allow a production representation, and why wait when you can get started!But if you have a green team, incorporating lots of new stuff, yup here, a Unit Testing approach (ie lots of small individual test boards to prove out and develop each new bit) is clearly and demonstrably (ime) going to provide, on average the best return for their effort!(PS ive done automotive electronics to the highest level (F1 and OE etc) for 30 odd years now)

author: djacobow
author_rank: Super Contributor
timestamp: July 28, 2024, 08:51:59 pm
content: There are a lot of reasons, like EE being a much older and more established discipline and being built on other engineering disciplines with standards of how to do things. Software has a ... different ... pedigree and continues to do so.But also, let's not kid ourselves; software is way more complex than board design, like many orders of magnitude so.

author: twospoons
author_rank: Frequent Contributor
timestamp: July 29, 2024, 03:04:21 am
content: Our standard project work flow allows for 3 planned revisions at minimum. Sometimes it takes more than this to iron out every last issue (we have an entire team dedicated to product validation). And thats for everything from simple 2 layer designs up to 12 layer HDI designs.Expecting a prototype to be perfect is stupidly unrealistic.

author: thermistor-guy
author_rank: Frequent Contributor
timestamp: July 29, 2024, 05:47:40 am
content: Quote from: electronx on July 24, 2024, 08:16:30 amIn my professional telecom days, three.First one was to prove the concept, and get some key features going.Second one was to correct the mistakes in the first, including layout issues. Production would look at thisand suggest changes to reduce factory costs (assembly, testing), Production would look over the first one too,but would focus on the second.Third one was very close to the production version. Production would look hard at this, and confirm theirjigs/tooling against it. This would undergo full compliance testing. Often it would go into production.Only once did I put a 2nd prototype into production. The layout lacked some load capacitors for a quartz crystal (doh!),but it was a low-volume board, and had no other issues. So, through-hole caps were added to the board duringassembly. The layout revision was deferred until it was justified - either by some other problem, or by a circuitchange that would give a notable cost reduction.More than three prototypes was taken as a sign that everyone involved weren't good at their jobs.

author: tszaboo
author_rank: Super Contributor
timestamp: July 29, 2024, 09:19:28 am
content: Quote from: max_torque on July 28, 2024, 08:31:41 pmThis happens 100% of the time, if you put software guys in charge. Or hardware guys who have to report to software guys. because they have this idea that they can manage it, because it's similar. It isn't. I would much rather have a mechanical engineer as manager than a software guy. At least they understand that time sheet is a waste of time, and why I need to wait 2 weeks with the project and do nothing when waiting for the boards to show up.

author: Psi
author_rank: Super Contributor
timestamp: July 29, 2024, 10:04:44 am
content: Yes, managers who don't understand what they are managing is a big problem. Especially when they "think" they understand it.To manage effectively you need to hold a degree or better in the same industry and have at least 8 years hands-on experience (in the trenches). And if you're managing both hardware and software you need that in both those areas.

author: free_electron
author_rank: Super Contributor
timestamp: July 29, 2024, 02:28:44 pm
content: Oh, forgot one thing : any manager that tries to implement "agile methodology" should be fired into the sun.

author: themadhippy
author_rank: Super Contributor
timestamp: July 29, 2024, 02:36:08 pm
content: QuoteWALOB

author: coppercone2
author_rank: Super Contributor
timestamp: July 30, 2024, 06:24:35 am
content: a guile

author: electronx
author_rank: Regular Contributor
timestamp: July 30, 2024, 11:23:27 am
content: The last PCB I made was tried for the first time in front of the customer and it worked successfully, I was literally sweating my ass off.There's a huge stress problem here. I think it's time for me to quit my job, I've made him thousands of dollars,

author: RoGeorge
author_rank: Super Contributor
timestamp: July 30, 2024, 11:42:17 am
content: Quote from: electronx on July 30, 2024, 11:23:27 amWhy doing that?

author: electronx
author_rank: Regular Contributor
timestamp: July 30, 2024, 11:45:07 am
content: I designed it in 3 weeks, I didn't even have the chance to try it. I explained this to him, he thought it was simple to design the circuit.Profit per pcb is more than 1000 dollars

author: Psi
author_rank: Super Contributor
timestamp: August 01, 2024, 09:07:25 am
content: Quote from: free_electron on July 29, 2024, 02:28:44 pmI assume you mean, "implement agile methodology in a situation where it has no place"Agile does work for some things but knowing when you should vs should not use it is key

author: tszaboo
author_rank: Super Contributor
timestamp: August 01, 2024, 09:34:41 am
content: Quote from: free_electron on July 29, 2024, 02:28:44 pmThey are not implementing agile. Only, standup meetings, weekly reviews, timesheets, an agile software management tool that's incapable to follow waterfall methodology, kanban boards, and they keep on changing the requirements even after we started shipping the product. But it's not agile, you are mistaken.

author: tooki
author_rank: Super Contributor
timestamp: August 01, 2024, 05:05:27 pm
content: A huge problem with agile is that managers oftensaythey’re using agile, when in fact they’re just allowing completely undisciplined development andcalling itagile, without doing any of the actual methods used in real Agile-with-a-capital-A development.So rather than reaping the benefits of Agile, you just gain undisciplined development and unpredictable, ill-prepared product releases.And yeah, there are areas where Agile should not even be attempted, IMHO, never mind fake agile.

author: Just_another_Dave
author_rank: Regular Contributor
timestamp: August 03, 2024, 01:21:28 pm
content: Quote from: tooki on August 01, 2024, 05:05:27 pmI hate when they use “agile” to justify constant specification changes. Suddenly you need to rush because a manager has decided that a feature that wasn’t considered before is incredibly important, just to forget about it next week due to a new feature that they want

author: tooki
author_rank: Super Contributor
timestamp: August 04, 2024, 02:53:21 pm
content: Exactly. Or, if the boss also happens to be the lead developer, then chooses to pull an all-nighter implementing it, and rolls it into the next day’s production update without telling anyone, like us testers… 😂“Fun” ensues as customers report serious bugs that literally 5 minutes of informal testing would have caught…

author: Sagar
author_rank: Contributor
timestamp: August 06, 2024, 07:20:52 pm
content: I am also a hardware designer, I know sometimes prototypes may fail completely. Even if they tested when not fully assembled. Some of my PCB fails and I have a lot of them lane around. But good thing is that, chinese manufacturers are good in PCB design and they are always have a cheaper alternative, may be due to high production quantity.