"Avoid Re-Spins! Designing PCBs in the Age of Prototyping ..." - Mihir Shah (KiCon 2019)

the disadvantage of having parallel sessions is you can't be in two places at once right all right all right our next speaker is me here Shaw talk is avoid Reese pins designing PCBs in the age of prototyping from the manufacturers perspective he's the founder and CEO of PCB layout comm and director of special projects at Royal circuits formerly an electrical engineer at Tesla and taser he now developed or helps Royal circuits constantly push the limits of manufacturability building more complex boards faster and more cost-effectively in addition he works with different programs and partnerships that allow Royal circuits to continue bringing value to its customers in the larger hardware community please welcome thank you thank you for the great a very formal introduction I never get those that's awesome so so yeah like Dan said today's talk is about the main purpose of today's talk is to really bring you guys in to the funding from the manufacturers perspective of what really goes on in a board shop and why boards cost money at all because I know you guys love to get everything real cheap for free you guys use a free CAD tool and then you got to pay for the board's so we'll kind of go over why that is what things cost more and how you can then factor these notes back into your design to design more cost-effectively for manufacturability for scaling etc so how many guys have actually ordered a PCB or yourself okay that's pretty amazing whoo just like a show kind of sample the room like who do you who do you use for boards PCB way China okay Josh Park jails AP circuits okay we build almost all their boards in in Canada they're really really great customers Royall okay yeah so it's a good sample of the room but the trend I'm seeing is price-sensitive correct so as you guys design more complex electronics this becomes even more of a concern so now that you guys have kind of told me where you're getting your boards the first thing I want to show you is me shutting up and I'm going to show you a view of just our fab shop because I can take a video of it it's a high-speed walkthrough but just kind of take a note of what you're gonna see so that's that's our shop in the Bay Area but I want you all to look for is just the number of people and the number of hands that even a two-layer board has to touch save our cam team more inside sales quoting support and then you go across the street to the actual fab and this is where you see the complexity and what's actually involved in building a fabrication facility material test Aoi you know wet process after wet process all these different bats and chemicals that even a two layer board that you want to pay a dollar for has to go through you have seven drills stack up lay up lamination route second drill route via fill etc but you see just like the complexity in building a company in a factory around making boards of whatever complexity and what you find is no matter the complexity ninety percent of the steps are the same all these boards still need to be imaged and etched and go through tests and Aoi and drill and solder mask and legend and the list goes on and on and all those things have generally a person associated with it all the things have a machine associated with it and does they all have a cost associated with it correct so just at a high level but obviously you Hagrid Systems wash Park Eisler have done an incredible job being able to aggregate and bring the cost down per user but as you start developing more complex electronics just understanding why so in any design you generally can break it up into four main you'd like you designed to be manufacturable you'd like it to be cost effective you want to get it as fast as possible and be able to iterate as fast as possible and you'd like it to ultimately be somewhat scalable or at least manufacturable across different manufacturers whether you go here or in China you want to send the yields like Patrick Patrick talked about in the Eisler talk and things like that so these are the four main goals so thinking about these what can you do when you're working with your manufacturer for the first or second time to make sure these are playing into effect and as you design so how many of you guys are at the Eisler talk with Patrick okay so you guys remember that nice note on confab France correct so for most simple boards yeah avoid the fat print bake it into the data as much as possible be very clear but this is the reality of what a fat print that we get every single day and we're doing literary hundreds of coats a day for all these different companies all over everybody has a different fab and like 98% of Engineers will not necessarily go through everything that was on their company standard sheet so it's a two layer board we're reviewing it just puts the ezpz no big deal you know bare metal price we're just gonna throw it through shop on a one day turn no problem but then we get to the end of it and it says class three more like I was that even possible but we can't assume so now we got to pause it I gotta reach out to the engineer and say hey is this thing really a class three board he's like what no just get it through the shop like simple I mean care if you put solder mask on it but how can you know that right prior so avoid the fab sheet and if you're gonna have one be like extra meticulous in the pre process and that's something you're probably here whether you're a professional engineer or not is just like in your design double and then triple check before you send it to the fab because we don't know so a good fab will pause and reach out to you thus still wasting time and a bad fab will either miss it or ignore it so you're just gonna come out losing no matter what you anyways so in general provide the correct information upfront and then choose your manufacturer wisely so at least you're going to be told and being to know with the transparency so at the highest level this is these are the general inputs that you will want to have ready to send to your manufacturer if you're going direct to a manufacturer for all the different three processes so if it's four fab have either your native cad files not every fab shop accepts those we do all the aggregate guys like I saw a notch mark they do as well but some people need Gerber's some people are ok today excepting ODB Plus+ just have those and then it's good to do this even if you want standard just say I'd like your standard stack up with one ounce copper and we're gonna use that far four and it's hassle finish green solder mask etc but if you're not sure just feet meticulous just put it in there in a fab note be okay with the stack up because they can look like this like this is our standard four layer stack up so for assembly same deal either you can put your native like ODB plus-plus that has everything baked in or you could send like the design files and then the bill of materials and XY r s XY RS is just location on the board per part and it's the pic in place file so centroid file XY rotation and then side top or bottom of board so generally you can get it from the CAD tool yourself like all team and all these guys have pretty standard ways on how to find them I couldn't tell you about my hand out together for each one but that's a good thing to put in a ref to of this presentation and then for a layout because we do layout as well and a lot of other people do too it's your schematic file in the parts libraries if they're not baked into one and then of course any notes component placement mechanical I'll into the board etc so DFM and this is something you guys have probably heard throughout this day and conference try to bake in the DFM into your design rules ideally work with the manufacturer to get those design rules and to what they're checking for and what their tolerances are especially for more constrained boards but in general the main things the issue is all these cat tools are so powerful and they lets you do kind of anything right you have this really tight pitch package and you could run one mill traces and put stack vias and you know this is great everything routed this is perfect and then you go to a guy like me and I charge you one hundred thousand dollars and you're like what's going on oh oh or it's not manufacturable so just try to understand like what are the limitations not every fab shop can handle laser microchip microvias under five mils not every fab shop can do - and - and no fab shop can do two mill traces if your copper weight is like four ounces so understanding the trade-offs and these are things that are not baked into the CAD tools like your stack up in your copper way and how that affects design understanding the limitation of what can the actual fabricator I'm going to use handle and if they can't handle it what's it going to cost me all right what are the adders in the design tight vias anything that requires us to use a special machine or outside the norm is certainly gonna cost because that's a special skill with labor and machine time and things like that associated but basically if you are aware of the DFM tools copper traces you have a very strong and clear fat print and your stack of information is aligned with the manufacturers or you have something that you know they can build and the material is available when it's it's not price sensitive or whatever then you're in good shape so this is what I was talking about earlier this is a good sheet to just have on reference and this is our minimum trace in space per copper weight so that changes as you increase your copper weight the smallest and the thinnest you can make or trace changes and it increases with increasing copper weight and the reason for that is because when you h the etching process is not perfectly linear you don't run traces through an etch or the plain copper and they H it out it doesn't work like a nice vertical wall it actually etches like a trapezoid so what happens is if you have really thick copper you have a long way to etch down to the bottom and your traces are too close it's gonna edge like this and they're gonna touch before you can get to the bottom so you're gonna get an internal short if your traces are too close together yeah fetching gets better and better but it's not perfect so you're still limited so in general I mean to mill trace on four ounce copper you're crazy if you did that but it's trying not to so if you have a really really high power board you wouldn't want to use thin traces anyways but understanding what your manufacturer is capable of and just general understanding of how boards are constructed will help you guys make good design decisions what you plan to do and also that affects the yield and so again I'm bringing up great points from Patrick czeisler talk because he took so many points that I wanted to be the first to introduce but yield is a really really good point and you should ask your manufacturer if you ask me and I don't know you I'll just tell you got 100 percent yield but really I mean depending on the board if it's a really complex board and we only get a 50 percent yield and the manufacturer doesn't tell you when you go to your next manufacturer they might charge you differently and then when you scale up you could be in serious trouble if you get a 50 percent yield on ten boards and then you went to ten thousand boards as ten thousand boards or five thousand boards that are scrapped and no manufacturers gonna handle that so Thank You Patrick for that the catalyst for that kind of discussion so yeah same kind of these are just some examples so a member of trace in space for a BGA generally three and three if you get tighter you're gonna have to use a blind via does everyone know what a blind via is so just a via inside the board a blind via is a via inside the board that you can't see all the way through so it starts on one of the outer layers but it ends on an inner layer so it's you have a BGA package on the outside you route from outside and stops on layer two or three of a four layer board so you can't see all the way through it it's blind and a buried it starts all the way buried so it's only in between the board you can't see the opening or anything it's an internal connection on the board but the reason that costs so much money like it's doable but we're saying it's gonna require blind via but the reason that's even worth noting is because that's gonna cost you more money and the reason they cost you more money and maybe take more time because it might need via fill or phase V and pad etcetera is because we have to run full additional drill cycle just to handle that one particular point via normally a board is constructed you do your imaging you get all your layers together then you do drill at the end once everything's together and you have full through holes but if you have a blind via I have to do an internal construction an internal lamination ply a cycle so that's four hours in the press which is expensive and time-consuming because other boards can't get in it and then I have to run it into the drill and then you have to do your deeper ring you have to do all your different sort of cleanup and parts associated with the drilling itself and then I have to go get my other layers and make sure the lineup and the lamination is good on there so now I've run the risk that I have multiple lamination cycles and I could have skewing or other issues on my board if they don't stack up properly and I've run the drill twice and I've taken more time with that drill operator that has a labor cost associated with it and the Machine time and the set of time etc so even a small blind via can significantly increase the cost of your board factors they mean it just depends on the full board construction but it can add up pretty pretty quickly if you start doing that especially if they're small holes though we'd use a laser drill for etc this is just another example solder mask dams minimum of four mil space that's pretty standard across the industry so between your SMTP pads you have like a small little clearance like maybe two mil to mil and then in between that you have a four mil space and that's just you need to have some sorry I'm asking between and generally for it to actually handle and like stay there the formulas accurate and then also the reason you need is so they don't bridge when you do your ear reflow or your assembly and this is via fill this is a pretty expensive process you can add like a thousand dollars to your board like instantly if you do via fill depending on who you use but it gets pretty expensive and again for the same reason because you're running it through a bunch of different processes and so if you use via and pad VN pad is where if you have a BGA or some other part and you want to put a via underneath that pad so the connection goes right away to another layer you don't have traces expanding out it almost always requires via fill there's just a cost associated with it so it's not as easy as just dropping it in and making your design really nice and constrained so the pad doesn't rip off so you don't have voids in the board you almost have to have via fill and there's other benefits of doing it too especially if it's under a pad like via fill can be really good for conductive just just heat transfer through the board and kind of out to the other side so a lot of people use it for that as well this is probably the most important one so royal circuits is a board shop we also own a company called advanced assembly so they're actually all sort of tied together same ownership between the businesses advanced assembly the latest stat and I called right before 15 years in the business we have 15,000 active customers 98% of jobs have an issue with them I don't care if you are the top engineer at SpaceX I don't care where you work 90 percent of jobs have some sort of issue with them no matter how clean the data is and the pre-processing etc but the issue isn't always that they're not manufacturable in fact the issue isn't at all that there's an issue with the board if you ultimately built it the way that they came in the issue is almost 95% or 98% of that statistic is related to the Bill of Materials this is the bane of every assembly shops existence because they're all different even if you try to modernize them and there's like we have a software on advanced Assemblies tool you go on you can pick your columns it works out it's still there are still issues one the information generally it's a lack of information it's not there they don't put the manufacturing part number your reference designators don't match up etc but there's also issues with you picked one part and everything looks great you have a manufacturer part number everything's but when we go to order it it's an O six of it's an O two O one but you want on a 402 and we don't know and the other issue is maybe you wanted that and you've made the pad bigger so for future proofing but there's no note there and even if it would fit if it's not an exact match between the Gerber or the the board data and the bill materials we have to ask and that ask process is going to slow you down because we're in the QuickTrim business and you guys are trying to get your boards faster and faster so if you want a one-day turn which we do all the time you want to make sure the input is as clean as possible so we can get it straight on to the floor kit all your parts put them on the pick in place etc so that's kind of the idea just be really really like go over the top on your bomb and make sure it's as clean as possible I'm sure Chris can probably attest to that that's the bane of every sin we saw its existence is issues coming in on the bomb and having questions and all it's based on that so I went through a lot of this stuff earlier but I'll just at a very high level with the limited time that I have left go over how a fab shop prices their boards so no fab shop and this may be obvious to you but you'd be surprised is not common knowledge no fab shop builds boards individually right like if you have a even if you have a square-shaped board I don't run that through the shop we have to run a shop panel and most shops have a standard panel size 18 24 21 24 etcetera so you could put a bunch of different designs on your panel which is what Eisler does you can try to use it part of it but no matter what we still have a cost which is the entire panel so the more you fill up on that panel the cheaper the unit cost per board is going to be for you no matter what because we have to charge you a minimum to run that big sheet of metal and its associated layers through the whole factory we have to test that whole board we have to handle it and it has to go through and that's real estate it's going through no matter what whether you use one square inch or all 362 available square inches of it whatever so understanding that and trying to optimize four-panel ization is a huge step the thing that you can do in your in your design but the the weight in the formula is pretty much a factor of the size how fast you want your turn time which is probably the biggest factor and then the number of layers so what's the size of your board how many can we fit on a panel how many layers is it and how fast do you want it based on those three factors your price is gonna come out pretty similar and then you have adders blind and buried vias via fill do you have a random material that we don't stock or like a 20 ounce copper which we have seen and it's crazy yeah so things like that will add cost and then on the assembly side choosing easy to source easy to assemble parts makes it easier for everybody and obviously SMT is a lot cheaper than through all because through all has a human element to it labor cost and the time goes through the roof so SMT is the way to go with that and then the last one I'm running out of time I didn't realize it went in so much brief industry overview because I think people like hearing about how the industry is progressed in 2008 there's about 2000 quick-turn PCB shops in the United States today there's like less than 135 so 95% reduction in this in the in the actual supply people that can do this stuff yet demand has more than tripled in that time so the number of boards that people are ordering has gone up significantly and the number of people number of people individually that are consigning to build these boards has gone down considerably a lot of that is due to equity firms buying them they're merging with big guys etc but the big thing is it costs more to keep up with today's technology and a lot of people in business especially in the 80s and 90s doing two four layer boards and making a killing it's very difficult to continue doing that because now you need four or five laser drills now you need AC plating pulse plating now you need vision drill vision route for depth drilling and back trilling and all these are the things that technology just requires and so to operate a business like that it changes the game and we then have to pass on that cost incrementally to the customer is getting more and more used to $2.00 boards 3/4 so kind of understanding where you stay in that consumer model and who the manufacturer is can help you also save some cost to make good decisions but the other big thing is understanding who builds your board's aggregate systems I serve our spiced other guys that can save you a ton of money because you're just paying for your piece on the panel you're not paying for the whole panel but if you have a 12 layer board with blind and buried and high-speed trace controlled impedance etc you better go with the board shop that's actually building it see their factory talk to the guys the engineers at the shop because that'll affect your cost for sure and it'll certainly affect your turn time and the likelihood that you'll get it built and the other thing is assembly and fab try to choose a shop that owns an assembly shop and owns a fab shop at the highest level most assembly shops it's a pretty low margin business you make your money off the markup on the bare board and on the overage on parts if you own the board shop if that company owns a board shop that cost has gone down significantly because you're not brokering it out to a board shop that's not always possible and in the hacker hobbyist wash park space that's not necessarily true because like for the new things able to offer incredible prices but owning a board shop when you have more complex bills and you need them on like a one-day turn can save you a ton of time because there's no brokering of communication and there's no brokering of the money or the or the material in the process and that's often hard because everybody disguises everybody is as everybody but sometimes more complex bills where you really want to get down and try to save like a couple thousand bucks that could be a smart move so I got what a minute not even okay so last thing is this is something that we've built internally as priority PCB it's an API for PCB fab assembly in parts so if anyone was interested and has a niche customer base and wants to sell boards and have an added Previn you stream to their business or if you're an assembly shop or if you're a fab shop and you want to make it easier to order boards but you don't necessarily have a software team we've built an API that you can use and integrate on your site to immediately that ties to our factory floor so boards come in they go straight to the floor so you've cut out a huge human in that process last one is just I mean slight promotion PCB layout comm we do layout we do parts library management and things like that so if you want more ongoing management or you have a dirty tar ball of a set of libraries from 10 years of switching engineers we can take care of that for you and usually it only takes a couple weeks to go through all your parts homogenized the whole system for you and then again Royal circuits we have two fab shops in California one in the Bay Area and one in Los Angeles we do flex rigid flex and rigid boards we stock a ton of material been in the business 20 years we own advanced assembly so we do quick-turn assembly as well like super low volume one board and one day fab and assemble done in 24 hours and so that's kind of the the state that we play at and we can handle a lot of the HDI builds on a quick turn as well so that's where I'll leave it at that thanks a lot for listening questions on the bomb yes what's in your opinion the most proper way to designate parts that aren't populated because I see in there you have like red I don't know no that's I think to be be as explicit as you can but be consistent so don't put DNP and then DNI and this just be really clear most of the time it's pretty obvious and again with our ordering system and with most ordering systems for most assembly shops today they're kind of up to speed so they're gonna catch it if it's a DNI or a 10 P or something like that for sure alright two quick ones the base you know most of your business do you find that you get one individual board design at a time or do you does the customer prep analyze it themselves it just depends okay you know it it depends a lot of time customers will say I got three four designs from my team coming in at once we will penalize it for you and it's generally cheaper and easier for us to do that so you don't need to worry about in it's not an added cost okay that was my second question yeah we're just being you guys yeah boil circuits or whoever and anything most pork chops can attest to that they're happy to kind of auto penalize for you depending on the order but that'll save you a lot of money because again we run the whole panel so if you fit four designs of the image I don't care what it looks like we just it's just an image so to us it doesn't matter you still got to put it in your guys labored it actually panel eyes the thing though yeah yeah but again that's a service that we offer it's just part of our business yeah good point so there's I'm just gonna stand over here there's all these DFM and DFA tricks that we as engineers pick up over time just like from here and they're like on your page for with solder mask dams yeah between the pads one thing that I learned recently is if you have traces escaping from all different directions that you're a oh I has a really hard time figuring out the solder Philips are good yeah so you want to like escape all your traces in the same direction that's like how would someone know that if they didn't see it on a random reddit post for example so like why don't or do board houses publish like a good checklist of like these are DFM things that like will solve 90% of the questions that we would have to ask you or we'd have to email you about and then that would slow down your turn time so the a oh I think I I can't even say that that's made it harder for us to catch errors again it depends on the board and the quality in the yield but generally that's not an issue but if it's like a BGA and you know I mean you're naturally gonna have traces going everywhere it's still just not an issue you do an electrical test you store on the UI but most porkchop's us included do have some score DFM checklist but I think the industry is still so old-school people are like I mean I told you there's ninety five percent reduction in the number of individually owned corporate board shops that exist in the country in the last ten years so if you think about that I mean who was in business before was in business today the way they're viewing and trying to run it is also different so that's that's coming and a lot of the newer companies also included are like trying to figure what can we do to make it easier on the engineer to design stuff that works because oh it turns out that easier for us to build and my yield goes up and we make more profit on the job so yeah that's a great point I think it's something to look forward to so all right we're gonna have to cut off the questions to keep going here I'm sure you'd be available thanks for listening all right thank you [Applause]

Channel: Contextual Electronics

Views: 6,177

Keywords: Electronics, Mihir Shah, KiCad, KiCon, KiCon 2019, PCB Fabrication, Board House

Id: CoD8IdCWn5s

Length: 29min 1sec (1741 seconds)

Published: Fri May 17 2019