For better use of the SMT service, make sure you sue the EASYEDA platform to make the design. Because they are in cooperation with JLCPCB so the search bar will tell you which component is available for SMT solder and which not. JLCPCB has more than 30.000 components ready for the pick and place machine, but you have to make sure you will use components they have available. For that. in EASYEDA, when you search for components, make sure you select the LCSC Assembled library and therem make sure the component has the SMT icon on the side. That means it is available for SMT solder.
So, search the component name, click LCSC Assembled and then select the component. In this way you make sure they will be able to solder it for you. If you don't do this before you make the design, changing the components after you make the PCB is a pain in the Axx.
Usually, when I desing PCBs, I select just the package of the component and not the value. That's because I will be the one who will buy the component separatelly, so the value on the Schematic doesn't matter. I can only change the name from 1K to 10K if I want. But, when you want the PCB to be sent to SMT service, you must select not just the correct package but also the value.
So, for example, if you need a 0805 resistor of 10K, search for that package and value. Because that value will be placed in the BOM file and the will solder the wrong value if you don't specify that in the BOM file.
To order the SMT service we need 3 things. The GERBER files for the PCB, the BOM file wiht the components details and the Pick and Place file with all the coordinates for each component so the Pick and Place machine will know exactly where to place each component.
So, you have your design ready in EASYEda and the PCB layout is made and with no errors. To downlaod the GERBERs, just go to PCB design window and select file, then Generate Fabriocation File (GERBER). That will downlaod a zip file with the GERBER files. Don't extract it, we need it like that.
Now, with these 3 files, go to JLCPCB. First make sure you read all the details here in order to know everything is there to know about this servie. Then on the main page select QUOTE STM Service. On the first order page uplaod the GERBER file. Once is uploaded, select how many PCBs you want. The only available color for the solder mask with SMT service is green so leave taht by default.
Ok, now on the bottom of the page enable the STM serice button. Then select the side where you whant the SMT service because this service is available for now only for one side of the PCB. It could be top or bottom but not both. So, in my case I select the top part of the PCB and click next.
On the next page uplaod the BOM and PaP files. Select each one and click upload and then next.
Finally, you get the list with all the components you will have on the PCB and you must confirm each one so make sure is the correct component. So, confirm that and click next.
On the final page you get a review of the order and see the component placement. If everything is ok click order and that's it. make the payment and wait a week or so and get the PCB.