JLCPCB - inner layers done as a positive not negative

[peter-h]

No inner planes



What I don't get is why they have made an almost identical board correctly a few weeks back, as well as all the other 4-layer boards, and their BBT test passes connectivity which obviously does not exist.

because orders be divided to different engineers each time, the engineer may did not notice it somtimes. to avoid misunderstanding, we recommend leaving remarks about the negative layers when ordering..

I had a bit of fun getting these boards to run

we recommend exporting files in positibe layers, if there has negative copper layers, better to leave remarks to remind our engineers in the future

but I have never seen PCB software which does layers as positive e.g. filled polygons or some such.

I have been using PCBWAY for 3D printing. Their PCB quote is a lot more than JLCPCB, and while they do have a gerber viewer, it doesn't show planes.

ALLPCB is same price as JLCPCB and no gerber viewer.  They refer me to their domestic website https://www.jiepei.com/ but that one doesn't translate well enough (in Chrome) to use.

It is many years since I had a screwup like this. These used to happen in the UK from time to time, with e.g. all holes plated through on every via, so the whole board was totally shorted.

[AndyC_772]

but I have never seen PCB software which does layers as positive e.g. filled polygons or some such.

Seriously?

I've not even seen a negative plane in years. I use OrCAD, filled polygons are exactly what you get in the Gerber output by default.

[langwadt]

but I have never seen PCB software which does layers as positive e.g. filled polygons or some such.

Seriously?

I've not even seen a negative plane in years. I use OrCAD, filled polygons are exactly what you get in the Gerber output by default.

yeh, negative planes is just a legacy from the times of using tape, easier to put a circle and invert than  to tape the whole plane

see no reason to use it anymore

[peter-h]

Let's take an example. In Protel PCB a pad can have a "relief" and you can choose Plane 1, Plane 2, etc.

If you choose 1 and 2 then every PCB company I have ever used (probably dozens) will realise there are two inner layers.

And sure enough when you upload the design to any of these firms (just done 3 tonight) they correctly state "4 layer".

The other interpretation of the relief shape is meaningless because it (the 2 or 4 "fingers") goes nowhere, and has no electrical connectivity to anywhere. I can see the BBT test will pass because it references the meaningless gerber so of course it will pass

I've been using PCB CAD since 1991 and have not seen this issue before.

[jc101]

I've just ordered a 6 layer board from PCBWay. Recent batches of the same board from JLCPCB have had odd traces that have a break along the path somewhere internal. Despite them all apparently passing a full electrical test. Managed to bridge with a tiny wire between vias. Naturally, I find the problem once the PCB is assembled. It a very busy double sided load, so saving the board is worth while.

Despite PCBWay cost more, I don't mind if I don't end up chasing a PCB issue.

[Whales]

I do not believe JLCPCB does "100%" electrical testing, despite their claims.  I once received boards where a couple had clear gashes through them that cut some top traces.  The cut copper surfaces looked like they were done before the end of the pcb fab process, because of a mix of them being plated & unplated, I'll have to dig and see if I can find the photos, my memory is rough.

EDIT: Retract that, looks like the gash was through a GND plane and didn't cut any traces, so it would still pass flying probe electrical testing.  Note that the left edge of the gash in the soldermask has plating showing through it, suggesting the damage/contamination was done prior to HASL but after copper.

[Smokey]

I feel like the soldermask layer is often drawn as a negative layer in CAD.