JLCPCB SMT, weird issue with part placements - Page 1
Forum section: electronics / general

author: thinkfat
author_rank: Unknown
timestamp: January 30, 2022, 02:51:24 pm
content: Hi,I have an odd issue with JLCPCB SMT service. Uploaded Gerber files look OK in all previews, dimensions are correctly discovered. Uploaded BOM shows the correct parts and footprints.However, when I upload the CPL file and go to the "Review Parts Placement" page, the part locations are all completely off. It's not a constant offset, it seems like the coordinates are all "scaled down" by some factor. Parts closer to the origin are "less wrong" than parts further away.I've manually verified the CPL file against the plotted Gerber files, the center coordinates in the CPL files match the component center locations in the Gerber.I've ordered some boards assembled just a few days ago, everything worked perfectly then. No changes in my tooling that I'm aware of.Does anyone see a similar problem right now?

author: 48X24X48X
author_rank: Frequent Contributor
timestamp: January 30, 2022, 03:17:13 pm
content: Could it be measurement units?

author: up8051
author_rank: Frequent Contributor
timestamp: January 30, 2022, 03:21:46 pm
content: They have had a problem with the preview for a long time, especially when the elements are on the bottom layerI sent them simple examples .The answer as always: we will pass it on to the engineer.

author: thinkfat
author_rank: Unknown
timestamp: January 30, 2022, 08:34:44 pm
content: It seems that one particular part is responsible for the issue. I have an ESP32-C3-MINI-1-N4 module on the board. It might be the footprint on my side or the model on their side, maybe due to the fact that I chose to have the antenna outside of the PCB (as is recommended). Or something is off with the rotation, who knows. In any case, if I omit this module from the BOM, all other parts are placed perfectly.That it unfortunate. Might become another case of "the engineer will fix it".

author: SMTech
author_rank: Frequent Contributor
timestamp: January 31, 2022, 08:58:22 am
content: Quote from: thinkfat on January 30, 2022, 08:34:44 pmNot that unfortunate, the issue almost certainly lies with the preview and nothing else so I wouldn't be scared to order the assembly with that module fitted.

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: January 31, 2022, 11:16:03 am
content: On one order, the preview showed bad alignment on all components but no scale issue. The engineer said I should just send it, so ...Boards came back fine.

author: DIYGUY Chris
author_rank: Contributor
timestamp: February 01, 2022, 10:40:07 pm
content: I got several orders of PCBA and I got used to ignore the assembly viewer because sometimes it makes me junk for no reason, they say that the viewer is just for reference and their engineers will fix the mismatch of the components placement and orientation and honestly that's what they perfectly do because I had never faced an issue related to such topic when I receive my boards and everything look good.But I saw that they are sharing a post on GitHub about how to set the parts placement and orientation yourself (maybe this will make the life of their engineers easier) honestly I don't waste time on this so I just submit the BOM and P&P files and they deal with it their own way.Here is the GitHub post in case.. :https://github.com/JLCPCB/JLCPCB-SMT-Assembly-Components-orientation-fixIf you are looking for a feedback then I tell you to just submit your BOM and P&P and trust them

author: thinkfat
author_rank: Unknown
timestamp: February 02, 2022, 08:11:15 am
content: Well, that is likely what I will have to do, though I hate not being in full control and at the mercy of others making decisions on my behalf with less information than I have. For example, there's a BQ25015 on my PCB that has a symmetric package and pin 1 is at an unusual place. I will have to trust that they put it correctly.Here's when it pays off to have a good, informative silkscreen that clearly shows the orientation of a part.

author: pgo
author_rank: Regular Contributor
timestamp: February 03, 2022, 08:00:00 am
content: Hi,I had a similar issue with my last PCBA. I tried uploading a previous design that worked fine previously and it had the same issue - so something has changed. These were Altium designs.I was not comfortable proceeding without the preview so I tried using the the PCB tool provided by JLCPCB (Easy EDAhttps://easyeda.com/). It supported importing the Altium project and then I used it to produce the placement file.I then used that file with the gerbers directly from Altium and it worked fine.I couldn't locate the problem when comparing the Altium placement file compared to the one from Easy EDA.At least this way I could check the preview!bye

author: JLCPCB Official
author_rank: Regular Contributor
timestamp: February 04, 2022, 07:07:10 am
content: Quote from: 48X24X48X on January 30, 2022, 03:17:13 pmthanks for sharing such a topic, we admit that our assembly viewer shows some weaknesses but we are working on improving it and something really impressive is on the way.You still can deal with your orders situations through opened eyes because you can visualize the DFM results in just 4 hours after placing your assembly order, it means you just need to go to your order history and click on the "DFM results" and you will get the final assembly view prepared by our engineers then if you notice that any component is misplaced you can send them Email to fix it because the assembly comes after the PCB manufacturing so you will be having enough time to go over the process.We will bring a reliable assembly viewer as quickly as possible

author: thinkfat
author_rank: Unknown
timestamp: February 04, 2022, 02:31:45 pm
content: Thank you for taking care. I understand that automated tooling is most important for you. Tools that don't work and then require an engineer to step in and fix a problem are always unwanted cost.