Issues with BOM / pick & place file when ordering from JLCPCB

[second-string]

Hello,

Thanks for trying to make it so easy to order PCBAs from JLC, but for some reason I'm still having trouble with lots of parts not included in the pick and place CSV.

When I upload theBOM_v2.1.csv and POS_v2.1.csv files from production_v2.1 directly with no modifications, I get the following list of components that won't be placed from the BOM because they aren't found in the placement file:

I was expecting a few designators here because I noticed some parts marked DNP in the BOM (like the first part, C49). I was surprised by a couple other things in the list that were also marked DNP in the BOM like U6 (SSM2603, audio codec IC) and U7 (wifi module). Some other designators like C92/C99/X1 have valid BOM part numbers and aren't marked DNP in the BOM, so I would expect them to have data in the pick and place file (especially, X1, a 26MH oscillator seems like it would be necessary?).

I haven't seen any other issues posted about this, so am I just missing something really obvious and this is totally fine, or has something changed and there needs to be a repo/design update?

[second-string]

A followup question(s) is regarding the parts that apparently JLC doesn't source and so they must be purchased beforehand.

1. Most of them have LCSC part numbers - I though JLC would order directly from LCSC so any part available on the site was available on JLC? They have a full on partnership
2. Is the expectation that the user (me) would purchase these parts, then ship them to JLC to use as consignment parts for the assembly? I can theoretically assemble everything on this board by hand either by reflowing or with hot air except for the main BGA, but that's the one thing that's difficult to source and must be bought from AliExpress. So how does one coordinate that part shipment and assembly?

[Jana-Marie]

Hey, sorry for that! The BOM is a bit out of date. I will update it asap. The missing parts have new JLC part numbers

Most of them have LCSC part numbers - I though JLC would order directly from LCSC so any part available on the site was available on JLC? They have a full on partnership

One would guess that, but sadly this is not true. Those are different warehouses

Is the expectation that the user (me) would purchase these parts, then ship them to JLC to use as consignment parts for the assembly

We have had most parts assembled by JLC, all leftovers were hand-soldered, including the BGA. It is not beginner friendly :/ Maybe you can ask JLC if they can add the Sochip s3 to their warehouse or if they accept consigned parts via AliExpress. They do the latter via Mouser.

[second-string]

No problem - I'm happy to create a PR to update things if you give me the newer BOM info needed, although I'm guessing it's going to be faster/easier for you to just do it since you know the design.

We have had most parts assembled by JLC, all leftovers were hand-soldered, including the BGA

Ah okay so I didn't misunderstand. Wow I'm surprised so many people have been reflowing BGAs by themselves, that's impressive! I'll see what steps are needed to get JLC to assemble the BGA (and ideally the rest of the parts as well). I'll also look into some of the other inexpensive manufacturers that have a bit more flexible of a quote process than JLC (aka they allow you to give them a BOM instead of forcing you through an online upload form).

[second-string]

AliExpress does not ship to China, so it's not possible to dropship the AllWinner BGA straight to JLC. I confirmed with them that they do accept consigned parts and no cost, so theoretically one could order the S3 to their home location, then ship it to JLC.

@Jana-Marie do you have some upcoming time to update the BOM with the correct LCSC part numbers? I would be able to quote a full assembly from PCBCart/PCBWay, who do support ordering parts from multiple locations (although maybe not aliexpress still).

[Jana-Marie]

Updated the BOM and POS file, please note that most of the components in your screenshot are actually placed on the bottom side and hence are no errors here. Still JLC added a few more components so the board will come more fully populated :)

Sadly, even though they did have the S3 they don't anymore. So as you noted already, you probably will head to PCBway there. You can also add it after the fact, it might be a bit complicated though

[second-string]

Thanks for the update! It looks like there are still a handful of parts missing from the POS that seem like they should be placed. Here's a list of everything, separated into what I think should be in the POS versus what makes sense to not include:

What isn't included, but I think should be:

• C79: a 10uF cap on the 3v3 input to the HPVCCBP pin of the S3. This component isn't in the design at all, and when I forward changes from the schematic to PCB there is an error that the footprint otter:C_0603 isn't found (there looks like there might be room to stick it in the little grouping of caps C38/C92/C32 on the bottom layer, but then I guess it doesn't need to be in pick and place file)
• U6: SSM2603, audio codec IC. Seems pretty important and has an LCSC number in the BOM. Also in layout on top
• U7: WiFi + BT IC, seems very important, in the layout, and has an LCSC number in the BOM
• C99: same issue as C79 - bypass cap on VCC_PLL in the schematic but not in layout because otter:C_0402 not found (not much room to dive to the bottom with a via here, but it would be do-able probably)
• X1: 26Mhz oscillator for the wifi/bt IC, seems very important, has LCSC number in the BOM, also in layout on top

What isn't included, and it makes sense:

• C49: bypass cap marked DNP, should not be placed
  MK1: microphone - I don't know what mic capabilities this project has but I wouldn't use it anyway
• AE1: KH-5220-A56_U.FL, looks like both an SMD antenna with a u.FL attachment (I don't see that in the LCSC part
  though), on the bottom so should not be in POS file
• C92: 10uF bypass cap on the 1V1 EPHY_VDD net on the S3, on bottom so should not be in POS file
• J1: UART header, not needed, should not be in POS file
• J2: SIM card header, on bottom so should not be in POS file
• J4: USB OTG breakout header, not needed, should not be in POS file
• J5: line in, important but through hole so we don't want assembled, should not be in POS file
• J6: amp out, important but through hole so we don't want assembled, should not be in POS file
• J7: line out, important but through hole so we don't want assembled, should not be in POS file
• J8: SMD RJ45 eth jack, important but on bottom, should not be in POS file
• C32: bypass cap on the S3 DRAM, important but on bottom, should not be in POS file
• C38: bypass cap on the S3 VCC_IO net, important but on bottom, should not be in POS file