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Imagine you're printing 10 PCBs and you want each PCB to have its own serial number, but you want to add the serial numbers automatically from Kicad. Is this possible or not? Does it depend on the manufacturer? Does it depend on the software I am using to generate the Gerber files?

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    \$\begingroup\$ Due to the process at a PCB manufacturer, this is normally done at the next step in the process at your EMS. Have you talked to yours? \$\endgroup\$
    – winny
    Dec 11, 2023 at 9:01
  • \$\begingroup\$ Where would the serial number be? On silk screen, copper, solder mask, how would the serial numbering work? \$\endgroup\$
    – Justme
    Dec 11, 2023 at 9:05
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    \$\begingroup\$ @Justme see this example youtu.be/xbzX3eUD4_I?si=4f4iwX-ywGGUmppv&t=850 \$\endgroup\$
    – Vincent
    Dec 11, 2023 at 9:14
  • \$\begingroup\$ A problem with this could be that a Fab house may build 20 boards to yield 10 so your numbers may not be sequential \$\endgroup\$ Dec 11, 2023 at 21:32
  • \$\begingroup\$ Don't know enough for a full answer, so this. Yes, see atomic14.com/2022/10/24/…. Kicad is scrip-table, and just adding silkscreen text like a UUID seems simpleish... \$\endgroup\$
    – Paul Uszak
    Dec 12, 2023 at 0:34

7 Answers 7

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It depends on what you ask the manufacturer to do!

  1. You might just submit your single board with the info "10 pieces of this" to your manufacturer. The manufacturer takes your design, and places it on a larger panel (probably with other designs). Some manufacturers print a serial number on each board, others don't. Some let you specify a placeholder silkscreen text, which gets replaced by the serial number.
  2. You might be submitting the ten boards, panelized, meaning that you made 10 copies of the board design, put them in a larger design, where you connected them with "mousebites", or with V-grooves, or just with solid connections, depending on how you plan to assemble, test, and separate the boards. Then, of course, you would be the one putting the serial number on the panel elements (because to the manufacturer, you're not doing 10 identical boards – you're doing one large board).
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    \$\begingroup\$ You might find for 10 off that a set of sequentially numbered stickers is much cheaper. And the option of using a Sharpie pen is cheaper still. \$\endgroup\$
    – D Duck
    Dec 11, 2023 at 9:02
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    \$\begingroup\$ and note that even large international manufacturers choose that sharpie route for smaller series, especially if there's manual quality control, anyways. just put a sufficiently large white rectangle in silkscreen somewhere, and you've got your serial number field for easy filling in. \$\endgroup\$ Dec 11, 2023 at 9:10
  • \$\begingroup\$ Or use an engraver on copper or fibre portions of your board. \$\endgroup\$
    – jonathanjo
    Dec 11, 2023 at 9:17
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    \$\begingroup\$ @DDuck If going the sharpie route, it's a good idea to provide a large silkscreen fill to write the number on. Makes it easier to see, and it sticks better. \$\endgroup\$
    – Hearth
    Dec 11, 2023 at 15:11
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If you're making low-volume boards, the PCB house may be able to do this with minimal additional work.

There's multiple ways of printing the silkscreen on PCB boards. The traditional way is via a plastic screen and squeegee process. This is used for the cheapest, high volume boards. The next is a photolithography process, called liquid photoimaging; the UV-cure ink is exposed through a photomask. This has higher resolution at higher cost. Both of these require tooling to be made.

However, low-volume PCBs, particularly one-offs, may use inkjet printing, also called direct legend printing. This avoids the cost of a mask and actually is the highest resolution. Inkjet legend printing is indeed regularly used to serialize boards in one step. You'd have to talk to the PCB house to have them program the printer to appropriately place the serial number.

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PCB's manufacturers or PCBA's assemblers usually laser mark a unique QR code on the PCB.

The laser marking is made in the production line by a QR printer.

See the picture in this blog and read the article:

https://cycjetinkjet.com/what-are-the-advantages-and-disadvantages-of-pcb-qr-code-printer/

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  • \$\begingroup\$ Enrico Migliore - Hi, Is that photo you just added, copied or adapted from elsewhere or taken by you? In the first case, please add its source reference name & link. If it's your photo, then although not required by the site rules, it will avoid people repeatedly asking about its source, if you add a short note in the answer just saying "My photo" or similar :) Thanks. \$\endgroup\$
    – SamGibson
    Dec 13, 2023 at 9:51
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    \$\begingroup\$ Enrico Migliore - Hi, I see you updated the image. However, that seems to be adapted from the same source image (which I found online) as before. Therefore it does not seem to be your photo, as you did not take the photo. Instead it was adapted from elsewhere and therefore still needs to be correctly referenced. || Instead of trying to obscure its origins, I recommend using the original photo and linking to its source. OK? \$\endgroup\$
    – SamGibson
    Dec 13, 2023 at 13:31
  • \$\begingroup\$ Hi Sam, I removed the image and added a link. \$\endgroup\$ Dec 13, 2023 at 15:04
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tl; dr: KiCAD is the wrong tool for this job.

Not saying what you're asking for is impossible. But it's not typical. There's a few reasons for this.

First, KiCAD is a design tool. Its outputs are a schematic, BOM and artwork. Managing serial numbers is outside of its scope. Part numbers? Yes. PCB artwork revisions? Of course. But not singulated serial numbers. This would imply a unique schematic and artwork database for each serialized board, which would be unwieldy to manage even for a handful of boards.

Second, PCB bare-board manufacturing flow uses a single 'tool' (that is, artwork) to 'print' boards. Because board-making is essentially a printing process, it's just not economically practical to have unique artwork for each singlated board, even if KiCAD or some other process could do this.

Could a serial number be scribbled onto a board at some step in the PCB fab process? Say, by laser etch, injet or some other means? Sure, it's possible. It may even be possible to use a photo-print process on the etch resist. That's something you'd need to discuss with your PCB manufacturer. It would certainly add cost.

But there's some other things to consider. Typical practice is that serial numbers are usually managed as part of an MRP / product life cycle tracking system. It's this MRP system that generates the database record for individual board, including its serial number and other information.

Also, note that bare boards could be scrapped if they fail test, or a revision makes them obsolete, so if you were to assign serial numbers to scrap you'd be wasting serial numbers. That has some cost, too.

With this in mind, typical board assembly flows don't give the board its 'personality', including its unique serial number, until later steps in the build process. One practical reason is that stickers and reflow process don't get along well (heat tends to damage the adhesive), so the sticker is applied after reflow, but before testing.

Also, there are often additional unique identifiers for a board besides its serial number, including things like MAC addresses and private keying material for security functions like secure boot and encryption, that are part of the board's 'personality'. Keying material in particular can require special IT provisioning to meet its security requirements to ensure keys aren't compromised in the field.

Again, managing all this is well-established practice within the domain of an MRP system. Board CAD? Not so much.

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Do not add a serial number to the PCB design file, just request a serial number in the manufacturing process, it will cost less.

When you add the serial number into the PCB files, it means you need more films for manufacturing. These days, a serial number or QR code on board can easily be added by laser or silkscreen during manufacturing.

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  • \$\begingroup\$ RAYMING PCB - You seem to be representing raypcb.com so please see this site rule on promotions. You must include a clear disclosure of that association anywhere that you link, mention, or even hint at anything related to them or associated companies, products, websites etc. e.g. by adding: "Disclosure: I work for RayMing PCB" or whatever. You need to be accurate in the disclosure statement, so please consider what you say. Please quickly edit all your posts to add that. \$\endgroup\$
    – SamGibson
    Dec 13, 2023 at 9:05
  • \$\begingroup\$ (continued) There needs to be sufficient added value at that link for it to be allowed, or it might be voted by site members as spam, if it is seen as pure advertising. Also, not too many of your posts can include links, or that will be considered as spam. (In case you were going to ask, mentioning the company in your username is not enough, since usernames can be changed. The disclosure of being affiliated with something related to a post, needs to be a statement within the text of the post itself.) \$\endgroup\$
    – SamGibson
    Dec 13, 2023 at 9:05
  • \$\begingroup\$ RAYMING PCB - (Update) The answer has been edited after my comments above, so parts of those comments no longer apply. However I'm leaving them there, at least for a while, because you need to see the explanations e.g. about the site rule on promotions, the requirement for you to include a disclosure in posts which mention, link to or even hint at something related to your company, and the fact that you are taking a risk of your posts being treated as spam if they look like spam including too many of them linking back to your company website, or a linked page not being relevant enough. \$\endgroup\$
    – SamGibson
    Dec 13, 2023 at 13:38
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    \$\begingroup\$ ok, noted ,thanks \$\endgroup\$ Dec 14, 2023 at 3:02
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You may consider DS2401 from Dallas semiconductor, it's an electronic serial number in a to92 package

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  • \$\begingroup\$ Maria vR - Hi, Thanks for trying to help. However considering the tags (e.g. "pcb-design" and "kicad") and context in the text "e.g. "kicad" and "gerber files") I think that, although it could be clearer that the question is referring to printed serial numbers, there is no other interpretation. Your answer to add a new IC to the board would mean changing the design, not just a process step when manufacturing the PCB. Therefore personally, I think this answer is misinterpreting this specific question. That IC (or other similar ones) might be a solution to a different serialisation question. \$\endgroup\$
    – SamGibson
    Dec 12, 2023 at 19:25
  • \$\begingroup\$ (P.S. As you're new here, please see the site rules in the tour & help center as the differ from typical forums.) \$\endgroup\$
    – SamGibson
    Dec 12, 2023 at 19:25
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First, call your board house and ask.

If you can't or won't, consider writing "serial no. _______" on the silkscreen layer and then penning the numbers in afterward. Replace the blank line with a white box and use a dark marker if you'd like.

There are also serialization ICs that are machine-readable (RFID for example) and polyamide stickers that you can order and apply during final assembly or QA.

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