JLCPCB having an "interesting" attitude to reading text on layers - Page 1
Forum section: electronics / general

author: peter-h
author_rank: Super Contributor
timestamp: October 18, 2019, 08:35:17 am
content: For about 30 years I have been submitting gerbers with Mechanical Layer 1 being the PCB outline, and with this written on the layerNobody ever had a problem with it.I just used JLCPCB for the first time to get some prototypes made. They arrived (after quite some time; the job initially got "stuck" somewhere) and they didn't fit into the plastic moulded box we have.I thought oh damn I made a mistake. Then I checked and they made them 0.025" too big all around. Obviously they used themiddleof the outline track (which is 0.050" thick).Initially the guy saidYour order Y5 was audit by the system automatically.We can not read the words in the Gerber file. And in all the factory if the outline is thick, they will make it according to the middle line.Since this is your first order, we will try to find a solution for you, so do you need to reproduce it again?But pls note that make sure the outlie is thin enough to almost 0mm, otherwise we will make it accould to the middle line.Sorry for the trouble!.but later saidI contacted with the factory and they refused to remake it. Since as the PCB industry rules, they will make it in the middle of the line.So I will go back to ITEAD who I have used many times and who never created any problems. Presumably they (along with every other PCB company, including many in China I have used; most Chinese ones go bust after a few years) actually read what is on the layer!There are just two issues with ITEAD: they cost several times more, and your email address gets onto loads of PCB manufacturer mailing lists (presumably their employees leave frequently, as is normal in China, and take their customer database to their next employer).

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: October 18, 2019, 09:16:58 am
content: Like you said, the price is low. At that price, you can't expect a skilled engineer is going to look through your Gerber files.Their instructions for orderingspecifically address this:Quote(emphasis added)They also mention that if you leave such a remark, your order will take longer, because an English-speaking engineer will need to read it.

author: OwO
author_rank: Super Contributor
timestamp: October 18, 2019, 09:20:56 am
content: What's the reason to deviate from industry standard in this case? Why not just make the outline really thin as suggested, then you won't have to worry which edge is used?

author: peter-h
author_rank: Super Contributor
timestamp: October 18, 2019, 09:58:00 am
content: I didn't know that not reading English notes on a layer (actually, not readinganynotes on a layer) was industry standard. I am sure it isn't.The more strange thing is that on the earlier job (the one which got "stuck" in their system) I got contacted by a person there who was processing the gerbers, and she knew exactly what it was, what the outline was, etc.When the job was restarted, after some weeks, it was evidently picked up by somebody who cannot read.Sure, if anybody wants to use JLCPCB they need to use a 0.001" track on the Mechanical Layer. However, which layer is going to be standard for the PCB outline? Ever since PCB CAD started, over 30 years ago, it was always the 1st Mech layer.

author: OwO
author_rank: Super Contributor
timestamp: October 18, 2019, 12:52:47 pm
content: I'm pretty sure humans reading text embedded in normally machine parsed files is not industry standard. Even more so expecting your language of choice to be understood by everyone in the industry. What's wrong with just denoting the board outline by the center of the line like everybody else does? Or actually reading specifications before ordering that clearly state such things must be in specified in the remarks field on the order page?

author: voltsandjolts
author_rank: Unknown
timestamp: October 18, 2019, 01:16:14 pm
content: The advantage of using the centre of the board outline to define the board edge is that it's expected.You then don't have to write a note about using the inside edge and someone else doesn't have to read it.Life is easier when you go with the flow.

author: asmi
author_rank: Super Contributor
timestamp: October 18, 2019, 01:25:37 pm
content: I always assumed that the board is cut at the middle of the outline... Will check some of my boards when I get home just out of curiosity.

author: peter-h
author_rank: Super Contributor
timestamp: October 18, 2019, 01:29:02 pm
content: Hmmm ... some human interaction with the plots is often required with PCBs other than trivial ones.And if I sell a product which I advertise on an English speaking website (this one)andI have my own website in English, then saying I reserve the right to not read English job instructions doesn't wash.Jobs often have instructions especially when it comes to things like routing breakout tabs.Certainly all proper production outfits do read the text. I've been buying production from China for about 20 years and never had one that did not / could not read. I can see a cheap prototyping service like JLCPCB might choose not to but it is dumb business for the reasons given above. I've seen all kinds of junk behaviour in China, with small print saying customer tooling will be destroyed 12 months after last order getting the prize (when they phoned why we stopped buying, I explained that you cannot treat western customers in such a manner, but they didn't get it at all).I think the "outline = middle of the track" assumption is one from fairly recent years. I've been doing PCBs since c. 1975 so have a fairly good overview.Probably the reason for the tradition was that you automatically get the inevitable routing radius depicted (if the outline is not a simple rectangle). If you use e.g. a 0.001" track then you have to draw arcs in all the corners. It's no big deal but most people will probably not bother and they the PCB company doesn't know how tightly he wants it routed.

author: ataradov
author_rank: Super Contributor
timestamp: October 18, 2019, 04:46:04 pm
content: When discussing "industry standards", you need to make some assumptions. For a typical board I make, ordering prototypes in the US would cost me $50-100. Ordering prototypes from China will cost me $5. For this price difference I have very different expectations. For $5 I expect to adapt my design to the manufacturer's requirement. For $50 I expect manufacturer to accommodate reasonable requests.In the future I would not be surprised if humans won't even look at your boards. So you will have to follow the rules set by the machines.I see no reason to blame JLC PCB in this case. If you don't like the results - do not use them next time.

author: james_s
author_rank: Super Contributor
timestamp: October 18, 2019, 05:00:03 pm
content: I've always assumed that the edge cut would be down the center of the PCB outline, with that line treated as essentially zero-thickness, it never even occurred to me that it might be possible to specify one side or the other of that line and I'm not sure what reason one could possibly have for adding that potential ambiguity. I'm actually kind of surprised someone would expect human oversight with a company that specializes in producing absurdly low cost PCBs for hobbyists, the process is as automated as possible, it has to be, and most of the people doing the processing are not engineers, they are by necessity low wage employees and probably are not going to speak English. I've personally been very satisfied with their service, it's extremely cheap so I don't expect any frills or assistance with my design, I simply send them gerbers tailored to the requirements they list and my boards turn out exactly as I expect.

author: peter-h
author_rank: Super Contributor
timestamp: October 18, 2019, 08:23:52 pm
content: Let me ask a question. Not meant to be personal, or suggesting anything.How long have you guys been doing PCB design?If 5-10 years then I can believe procedures have changed within that time.

author: oPossum
author_rank: Super Contributor
timestamp: October 18, 2019, 08:27:38 pm
content: About 30 years. I always use zero width lines for board outline and slots. JLCPCB allows you to attach notes during the ordering process. They do read that.

author: Yansi
author_rank: Super Contributor
timestamp: October 18, 2019, 09:06:11 pm
content: About 12 years. I have always used zero width outline. Specifying outline like you did is certainly nonstandard, you should probably blame yourself in this case.

author: wraper
author_rank: Unknown
timestamp: October 18, 2019, 09:24:20 pm
content: Quote from: peter-h on October 18, 2019, 08:23:52 pmDon't you suspect that in the past fabs just charged you more for dealing with your nonsense manually? Or orders were expensive enough they just fixed it for free.

author: james_s
author_rank: Super Contributor
timestamp: October 18, 2019, 09:25:17 pm
content: I've been doing it for about 10 years, ever since it became cost effective to have boards made in China. Always used a near zero width edge cut.

author: ataradov
author_rank: Super Contributor
timestamp: October 18, 2019, 09:41:53 pm
content: I was ordering boards since OSHPark became known and popular, probably close to 5 years. It never even occurred to me that the with of the board outline would be significant. I just automatically assumed that the board will be defined by the center line.

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 18, 2019, 10:03:09 pm
content: What we see here is an expensive process with lots of manual steps becoming a commodity with the associated automation and streamline. This means that less usual configurations caught by humans before now are simply produced. There will companies who are more than happy to charge you extra for the additional effort of dealing with human readable instructions stuck in layers or you can update your design process to match the production process of your manufacturer. The process is known so by correctly controlling the input you have control over the output.

author: thm_w
author_rank: Super Contributor
timestamp: October 18, 2019, 10:53:35 pm
content: Quote from: wraper on October 18, 2019, 09:24:20 pmThis is why I love JLC (and other newer online PCB companies) for basic designs, they make or try to make exactly what you put in the gerbers.In the past I'd pay $300 for NRE fees, the PCB engineer calls you up and asks "did you mean to put this trace going to nowhere?", "Did you want to carbon plate this area? It looks like a button".If I screw the design up its on me, I will always accept that.JLC doesn't specifically say where they will cut the board, but they do say they will do what the PCB tool shows, which in this case for all modern PCB tools I know of would be true (route in middle). I think it will even show up in their gerber preview too (although its not flawless).

author: asmi
author_rank: Super Contributor
timestamp: October 19, 2019, 05:00:50 am
content: Quote from: ataradov on October 18, 2019, 09:41:53 pmSame here. Moreover, in Orcad/Allegro default behavior of outline is using zero-width lines (as they are shown in the editor), which you can set to be whatever default width when you generate gerbers. And this software is probably older than me

author: peter-h
author_rank: Super Contributor
timestamp: October 19, 2019, 06:28:25 am
content: I think the biggest lesson for me is that this firm doesn't read any text on a layer.I've never seen that before.Sure one pays tooling etc for production boards (usually).JLC do examine the boards, actually. It isn't a totally automated process. I did the last one with 0.004 tracks and 0.004 clearances (it's a tight board) and they trimmed some pads to increase this. So somebody must be looking at it. They just can't read any English.

author: ataradov
author_rank: Super Contributor
timestamp: October 19, 2019, 06:32:29 am
content: That trimming is automated. CAM software just brings everything to meet their requirements.AllPcb instead sends you the screenshots of the CAM with problem places and asks what you want to do.So there are humans involved when CAM says there is a problem. Otherwise it can be totally automated.

author: BravoV
author_rank: Super Contributor
timestamp: October 19, 2019, 06:53:44 am
content: Quote from: peter-h on October 19, 2019, 06:28:25 amWhat cheap & reasonable ? Consider learning Chinese.

author: thinkfat
author_rank: Unknown
timestamp: October 19, 2019, 07:40:28 am
content: Quote from: peter-h on October 19, 2019, 06:28:25 amYes, they do examine the boards. But it's tough to find a Chinese who's really good at English and able to converse with customers AND have engineering skills at the same time. These are expensive to hire, which goes against their business model for quick and cheap prototypes.Additionally, your requirement to use the inner edge of the board outline means the audit will have to take details of the production process into account, especially the router bit diameter. This creates an unnecessary dependency between the ordering process and the production. Result: more complaints and rejects. Again, goes against their bottom line.This whole prototype business is hardly sustainable for them, it only works if they can automate the process as much as possible and use humans only if it cannot be avoided. If you want to use their services, you stick to their requirements meticulously. If you cannot do that for whatever reason, by all means, go elsewhere.

author: wraper
author_rank: Unknown
timestamp: October 19, 2019, 12:41:37 pm
content: Quote from: peter-h on October 19, 2019, 06:28:25 amNo, the biggest lesson for you should be that if you are doing something for 30 years, does not mean you are doing it right.

author: nctnico
author_rank: Super Contributor
timestamp: October 20, 2019, 05:01:39 pm
content: Quote from: OwO on October 18, 2019, 09:20:56 amI agree. Every board house I have used so far uses the middle line as the cut out except if it is one thick line which marks a slit in the board; then they'll use the outer edges. This may seem contradicting but from the PCB designer's point of view it is very easy.You have to expect the person sitting behind the CAD station can't read / speak English. Even Eurocircuits seems to have people in India or so doing the file preparation.And usually people do look at the layout to see if it meets production standards. If necessary changes are made automatically to suit the production process.

author: Fire Doger
author_rank: Regular Contributor
timestamp: October 21, 2019, 10:55:56 am
content: I am relative new to pcb manufacturing but never thought that they will consider the thickness of a line for outline, every 3D viewer uses the middleOn the other hand for slot cutouts it's a little blur to me.For ex. square cutouts with all sides bigger than 0.8mm (pretty standard mill tool diameter and cheap afaik) I define cutout by making a square (with 0.8 arcs in corners) and use the center of the line as the edge for consistency.I guess the same way they offset their path for complex outline shapes will apply and at this cuts but will offset inside (Am I wrong?)But in case I want a 0.8 width cutout for panelization I use a single line because I imagine that for cnc it's a single pass.I guess it will require more modification if I design a square with thickness same as the toolhead or the mill head will make 2 passes in same path. (And it's so more time consuming designing squares for every cut)But this deviates from above method so I am not sure if I am doing it according to standard...

author: james_s
author_rank: Super Contributor
timestamp: October 21, 2019, 05:16:26 pm
content: I think that only matters for the manufacturing process. When it comes to designing the board you should assume a zero width line for cuts.

author: cgroen
author_rank: Unknown
timestamp: October 22, 2019, 07:27:15 am
content: Quote from: peter-h on October 18, 2019, 08:23:52 pmSince 1990, and have never been doing anything else than middle of line for outline (since using CAD, after approx 1992). In the "tape days" I used the inside of the tape as you suggest, but that was due to the implications involved...)

author: rrinker
author_rank: Super Contributor
timestamp: October 23, 2019, 06:30:08 pm
content: I haven't been designing PCBs for long at all, in fact most would probably laugh at the noobishness of my designs. However, I do have machine shop experience with CNC machine tools and it's normally assumed that a toolpath shown on the drawing or on the machine (very few of the machine we had back when I did this work had graphical displays, not like modern ones) meant that the cut point was the center line and the rest was the tool diameter. SO if you wanted to cut off 100mm length of material, using a cutter with a 2mm diameter, the line had to be at 101mm to result in the finished product having a 100mm length.Probably not explaining my thought process correctly, but this is also something I learned as a child, learning how to saw wood. Always mark which side is the scrap piece, so you place the saw blade on the proper side of the line so the finished piece will be the size you want, not the size you want less the width or partial width of the saw blade.It sounds like I am actually agreeing with the OP, however, it is not the job of the Gerber to specify the tool path, but to specify the desired dimension. The CAM software provides the tool compensation to the finished product ends up with the specified dimension regardless of the size of the tool bit being used.

author: mac.6
author_rank: Regular Contributor
timestamp: October 24, 2019, 08:58:36 am
content: Using middle of lines for dimension is pretty much the norm in the CAD industry. And when I say norm, is it probably written explicitly in some ISO/ANSI norm.

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 24, 2019, 01:21:04 pm
content: I think so too.Some people seem to assume that the line thickness would somehow represent the milling bit diameter to be used - hence the reasoning of the inner edge being the final result - but I haven't seen this in use for ages.The "middle" is just the line position. The thickness conveys no useful information AFAIK, except of course for PCB traces.

author: peter-h
author_rank: Super Contributor
timestamp: October 25, 2019, 03:50:12 pm
content: Clearly the reason I have got away with doing it "wrong" is because I used companies (including Chinese ones) where somebody visually examines the layers and reads the text on themIt was only when I used a super cheap company that this happened.If nobody looks at the layers, how do they e.g. know which is the top layer and which is the bottom layer?And how would you do a board which has a lot of tracks within a plane? Normally that's done by dropping a polygon into the plane, to clear out the required area within it, and then creating another layer (on a 4L board with 2 planes, this would be Layer 3) with the tracks on it, and on that layer you put a text note to merge that layer with the plane. So, somebody has to read this, to do it.

author: cgroen
author_rank: Unknown
timestamp: October 25, 2019, 03:53:32 pm
content: Quote from: peter-h on October 25, 2019, 03:50:12 pmBecause of the names of the files. Has so far worked for me for more than 100 projects submitted to JLCPCB (and also for PCBWay and ALLPCB)I use:

author: wraper
author_rank: Unknown
timestamp: October 25, 2019, 03:58:31 pm
content: Quote from: peter-h on October 25, 2019, 03:50:12 pmIt could also be that in some cases you just did not notice that PCB was larger than intended. Simply because there was no tight mechanical constraint around the board.

author: nctnico
author_rank: Super Contributor
timestamp: October 25, 2019, 05:08:18 pm
content: Quote from: peter-h on October 25, 2019, 03:50:12 pmSimple: Put a number on each layer. 1=top, the last one is bottom.QuoteThat is the wrong way to do it. Just make sure the artwork for 1 layer is in 1 gerber. Having the PCB house doing post processing like this is asking for trouble. A plane with traces isn't a plane. I never use pure plane layers but always put polygons on layers; I find having to use inverse drawing on one or more layers confusing and thus prone to errors.Using two artworks for one layer is also likely to get you in trouble when an assembler prefers an ODB+ container.

author: grbk
author_rank: Contributor
timestamp: October 25, 2019, 05:22:24 pm
content: Quote from: peter-h on October 25, 2019, 03:50:12 pmPerhaps I'm misunderstanding you. Are you saying that for a copper layer that has both a plane and traces, you would submit two separate gerber files, one with the traces and one with the plane, and then write in text that they should be merged into one copper layer?You say "Normally that's done" but normally done by whom?? And why? What tool are you using? I have never in my life heard of anything remotely similar to that.

author: james_s
author_rank: Super Contributor
timestamp: October 25, 2019, 05:46:02 pm
content: I've never seen anything other than one single copper layer per layer of the board. If you have a combination of traces and a pour, they would all just be drawn on the gerber file for that layer, regardless of the process by which you created it.

author: bpiphany
author_rank: Regular Contributor
timestamp: October 27, 2019, 03:47:32 pm
content: There actually is a gerber tag for drawing in "negative", no need to do multiple files and "merge" them by hand.Doing planes this way (a big plane with negatives, and later tracks on top) would however be prone to creating copper island, and I believe most CAD packages will do it in different ways.

author: peter-h
author_rank: Super Contributor
timestamp: October 27, 2019, 06:03:36 pm
content: I would be interested to know how you do tracks within a plane, and end up with a single gerber layer.Obviously one way is to not have a "plane" and instead construct the desired areas of the plane with filled polygons / pours / etc.

author: james_s
author_rank: Super Contributor
timestamp: October 27, 2019, 06:11:31 pm
content: Easy, I draw my tracks then outline a copper pour, then I outline any keepout areas, then I tell it to fill the copper pour(s) and the software (KiCad in my case) does its thing. The copper on that side is all one layer before I even think about exporting gerbers, I do not do any manipulation of the gerbers themselves at all, they are the final output I have the software generate when the board is finished.Modern board design is not like laying everything out manually with tape, you don't have to think about the intermediate steps, you let the software figure all that out.

author: ataradov
author_rank: Super Contributor
timestamp: October 27, 2019, 06:17:30 pm
content: Yes, I don't see why would you even think about gertbers. It is just a garbage, but standard interchange format at this point.EDAs will do whatever they need to do to make your chopped planes appear fine.

author: james_s
author_rank: Super Contributor
timestamp: October 27, 2019, 06:20:32 pm
content: Just as an example, here's the top copper layer of a board I did some time back, this is a single layer. I laid out the traces, then put a pour boundary around the edge of the entire PCB, then placed several keepout zones on top of that. The software knows what net the pour is connected to and will automatically avoid pouring copper within a set distance of traces in any other net. When I was finished with the layout one of the last steps was to tell it to fill the pours.

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 28, 2019, 05:25:26 pm
content: Quote from: peter-h on October 25, 2019, 03:50:12 pmIt seems you've gotten so wrapped up in a badly formatted design process you can't quite imagine what a well defined process looks like. It's important to understand that what you see at JLPCB is tight process control and tolerances and not a lack thereof. A better defined input leads to a better output. The fact that someone has corrected for sloppy tolerances all those years doesn't mean the input was good.

author: Pseudobyte
author_rank: Frequent Contributor
timestamp: November 01, 2019, 01:19:41 pm
content: If you define your own panel then it is never a question how big your boards are or what line to use.The only way I see that a thick line could define a board edge is if it was interpreted to be routing. That being said, I never rely on gerber extensions to define what my layers are. The FAB houses that I interact with are very capable. We require checkplots from all of our suppliers. When we get a checkplot back, we verify in a gerber viewer that the layers match and the step and repeats are accurate. Set one set of gerbers to blue, and the other to red. The differences become obvious.