When you are new to PCB design and assembly, it is surprisingly easy to get tripped up by things that seem like they should “just work.”
We recently went through this with a small illuminated through-hole button in EasyEDA Pro and JLCPCB, and along the way learned a bunch of useful beginner lessons that would have saved a lot of confusion if we had known them earlier.
This guide is written from a noob perspective for other noobs.
The situation
We had a button in the design:
- TPB01-107L1S-RF
Then stock got awkward, and we ended up switching to:
- TPB01-103L1S-RF
At first that sounded scary. Different part number, different stock status, different library mapping. It felt like we might break the footprint, the BOM, or the assembly order.
In the end, it was much more manageable than it first seemed.
Lesson 1: LCSC stock is not the same thing as JLCPCB assembly stock
This is one of the biggest beginner traps.
A part can show:
- available on LCSC
- but unavailable in JLCPCB’s normal assembly stock
That does not necessarily mean the part is impossible to use. It just means JLC may not have it in the exact stock pool they use for turnkey assembly.
So the practical beginner rule is:
- LCSC stock means the part exists and can likely be sourced
- JLCPCB stock / My Parts / assembly availability means JLC can actually place it on your board order
Do not assume those are the same thing.
Lesson 2: “My Parts Lib” is gold
This was a big aha moment.
If the part is already in your My Parts Lib in JLCPCB, that is much better than having to manually consign it or source it again.
That usually means JLC already has it associated with your account inventory, and you may be able to use it directly in the order flow.
So if you are in doubt:
- check whether the part is in My Parts Lib
- if it is, use that path first
- do not jump straight to Consign Parts unless you are physically mailing parts to JLC yourself
Lesson 3: EasyEDA Pro makes part swapping easier than expected
One of the best discoveries was this:
In EasyEDA Pro, you can click the placed component, then click the device/part name in Properties, and swap it to another part.
That is much cleaner than:
- deleting parts manually
- re-placing everything from scratch
- breaking schematic links
- causing BOM headaches
For us, this made it easy to go from the 107 button to the 103 button.
That is a really useful feature for beginners to know.
Lesson 4: Use the schematic/device workflow, not just raw footprints
Another huge lesson:
If you want your BOM and assembly files to work properly, do not just throw a footprint onto the PCB and call it a day.
Use the proper device in the schematic, with:
- symbol
- footprint
- supplier metadata
- LCSC/JLC part code
That helps with:
- BOM export
- CPL / pick-and-place flow
- part matching on the assembly order page
- future replacements
This is one of those things that seems boring until it saves you.
Lesson 5: Different part numbers do not always mean different footprints
We uploaded datasheets for both parts and compared them.
The 103 and 107 versions looked extremely close:
- same style of right-angle illuminated switch
- same 4-pin layout
- same general body size
- same kind of PCB hole pattern
- same electrical function
That does not mean every suffix change is safe. But it taught us that sometimes two nearby part numbers are just family variants, not total redesigns.
The lesson:
- do not panic immediately when a part number changes
- check the datasheet
- compare the footprint
- compare pin names
- compare dimensions
- then decide
Lesson 6: The 3D model is not the same thing as assembly rotation
This caused a lot of confusion.
EasyEDA has a 3D Model Manager where you can rotate the visual model.
That is useful for:
- making the part look right in 3D view
- enclosure checks
- confirming how the body sits on the board
But it is not what controls how JLCPCB places the component during assembly.
That was a major lesson.
So if your part:
- looks fine in the PCB/silkscreen
- but appears rotated in JLCPCB’s assembly preview
then the problem is usually not the 3D model.
Lesson 7: If the part is rotated in the assembly preview, fix it there
This was the most practical takeaway of all.
We found that the part looked right in the board design, but appeared rotated 180 degrees in the JLCPCB order preview.
The fix was simple:
- rotate the part in the JLCPCB pick-and-place / assembly preview
Once that was done, it looked right.
This is the sort of thing that feels like a disaster the first time you see it, but it is actually a very normal part of assembly prep.
And this applies more broadly too. Whether you are using:
- JLCPCB
- PCBWay
- or other assembly services
the assembly preview / centroid / pick-and-place review stage is where you sanity-check orientation.
So if a part looks wrong there, do not assume your whole PCB is ruined. Check whether the preview allows rotation or adjustment first.
Lesson 8: Silkscreen being correct is an important clue
One helpful clue was this:
- in EasyEDA, the part looked correct on the silkscreen
- on JLCPCB, it looked wrong in assembly preview
That strongly suggested the board footprint itself was probably okay, and the issue was more about assembly rotation metadata.
That is a useful beginner debugging trick:
If the silkscreen, pad layout, and footprint look right in the PCB editor, but the assembly preview looks wrong, suspect:
- rotation metadata
- CPL conventions
- library mapping differences
before assuming the footprint is broken.
Lesson 9: The actual code matters a lot
This is easy to mess up.
We learned to pay close attention to:
- manufacturer part number
- LCSC/JLC part code
Because these are not interchangeable.
For example:
- TPB01-107L1S-RF matched one code
- TPB01-103L1S-RF matched a different code
If you swap the physical part but leave the old supplier code, you can end up with a BOM mismatch even if the footprint looks right.
So always make sure the metadata follows the new part.
Lesson 10: A weird preview does not always mean a ruined order
This is probably the emotional takeaway.
As a beginner, when you see:
- wrong rotation
- different stock pools
- part number changes
- assembly preview quirks
it feels like you are one click away from wasting money.
But often the path is:
- confirm the part family
- confirm footprint and pins
- confirm BOM part code
- check My Parts
- fix any preview rotation
- order with confidence
There are more safety nets in the workflow than you think.
Practical beginner checklist
If you are replacing a part in EasyEDA Pro and sending it to JLCPCB:
- confirm the new part is really the one you want
- compare datasheet dimensions and pinout
- update the device in the schematic, not just the PCB
- make sure the LCSC/JLC code matches the new part
- sync or update the PCB
- inspect the silkscreen and pads
- export BOM/CPL properly
- check whether the part is in My Parts Lib
- review the JLCPCB assembly preview carefully
- rotate the part in preview if needed
- only use Consign Parts if you are physically sending parts to JLC
Final thoughts
The biggest thing we learned is that beginner PCB work is less about never making mistakes and more about knowing where to fix things.
A part looking wrong in one view does not mean the whole project is wrong.
Sometimes:
- the footprint is right
- the 3D model is irrelevant
- the BOM just needs the right code
- and the final rotation is best fixed in the assembly preview
That is normal.
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