I try to make circuit board with SMD IC with Snapmaker 2.0.
However, I think the positional accuracy of the Z axis is insufficient.
Since the XY table is fixed at the two central points, the table swings in the direction of the arrow.
The width of the copper foil to be machined has a strong influence on the positional accuracy of the Z axis, so please refer to it if you are developing the next version.
As you identify correctly, the Z-axis in itself is not the real issue, but the movement of the bed is.
Some tips in general when trying to make pcbs personal experience):
- when doing cnc there is no auto bed leveling like with 3d printing, so you must ensure that your cnc sheet is level with the machine and that your stock is flat.
- a lot of people (myself included have milled the cnc waste board flat
- these pcb sheets aren’t really known to be flat and do have significant variances in thickness
- The results you’re seeing are even more prevalent if you’re using a v-bit (as tracks get wider as you go lower. Personally I always use a flat end mill that doesn’t show this behavior. And then just going a bit deeper isn’t an issue.
- the copper layer actually is quite hard, so enough depth is needed to pierce through it the first time (and preferably sharp bits). This is where a v-bit is actually more suited, but that doesn’t give reliable results because of the depth/platform stability issues.
If you go through the forum you can find a number of “solutions” of people adding additional support rails to the platform to reduce the wobble of the platform. That will definitely help too.
or check this thread:
it shows it is possible!
Thank you for your reply.
After all, as with 3D printing, some kind of Z-axis correction function needs to be added.
Such a function should never be the default. If want to mill a piece of stock flat, there is no use for such a function. And in most cases, that’s exactly what you would do. Even if your stock isn’t flat, for most use cases, you’ll first make it flat.
There are very specific scenario’s where it’s not necessarily the case, unless you deliberately want to engrave a curved surface.
And even this case isn’t a good one imho, it’s a workaround for another root cause (your pcb not being flat, wobble in the bed etc). Sure it might help in some cases, but it might just as well introduce other issues.
From a practical point of view, there aren’t any sensors in the cnc module that would allow you to probe the bed or your stock. And as you don’t know what material you would be working on, that would be a challenge.
Welcome to the forum! 
Can you visually see your bed “rock” when you move in the Y direction?
As in this video? April 19, 2020 - YouTube
I send @brvdboss’s recommendation to mill the wasteboard flat, after tramming to a repeatable reference (not the surface of the wasteboard, although it could work).
I’m not a fan of using the endstops at the top of the z modules because they are not engineered to precisely be level with the surface of the wasteboard, but if you are getting good side-to-side level that would work.
As someone who hates a poor work surface this seems like a grand idea. I would be willing to mill the wasteboard flat, but my eye would be twitching the whole time.