Incorrect print & Gerber

I have two identically sized, single sided, PCBs (only 1" x 0.8") and both PCBs generate the Gerber files correctly. I wanted to use both sides of the board to reduce stock levels so following advice, I used “append board” to add the second PCB to the rear of the first one. Everything looks fine on screen but when I try to generate the Gerber files I get the tracks from side two on side one pads and the tracks from side one on side two pads. Totally confused as to why, I tried printing the PCB with seperate pages for each copper layer and had the same result. The boards are very simple with NO drill holes, NO silk screens and NO solder resist. Has anyone any ideas as to what I am doing wrong - I don’t want to have to redraw everything as a single board.

If there are no drill holes (or only mechanical holes), you can try to have board 1 designed all on the top layer, and then have board 2 designed all on the bottom layer. Generate your gerbers for each board, then collect by hand the top gerbers (copper, silk, mask) from board 1, the bottom gerbers (copper, silk, mask) from board 2, and the common layers (drill, board outline) from either.

Make sure you NEVER move the board outline differently one board vs the other. The outline (and drills) MUST have the identical coordinates in both boards or you will have registration errors.

Just my thoughts. I’ve never done this, but this would be my initial approach. Make sure you use a board house that will provide images of what the board will look like for you to check to make sure nothing gets messed up.

You can try to experiment with temporarily transforming your board to a 4 layer design:

Pcbnew / Setup / Layers Setup / Copper Layers:
And then copy all the copper to the inner layer and back with:
Pcbnew / Edit / Move and Swap Layers…

How are you handling the schematics and netlists?
GND and Vcc nets can get automatically merged when combining boards.

Another thing, is that you have to mirror one of the layers, or your components won’t fit.

If your boards are the same size, then you can simply combine the Gerber files of the 2 designes. Gerbers (at least the old version) have separate files for each layer.

As a last resort:
How much work is it to re-create the traces of one of those small single sided boards?

Are you willing to post your project here? I’m curious if I can separate heads from tails here.

I have already designed the top PCB copper and the bottom PCB copper as two seperate boards (and by pure chance one design was copper on top and the other was copper below) which is why I wanted to make a single PCB that could be used “either way up” but only populated on one side depending on requirements. It is when I tried to “append board” that I got any problems.

Hi paulvdh, the boards were hand drawn without schematics and netlists. I have only recently moved to kicad from an old program “WinPCB” which allowed me to design PCBs without having to input schematics first - I find that I can design a simple PCB quicker than I can input the schematics (which is the way I have been doing it for many, many years so it is a difficult habit to break). The second layer was drawn “mirrored” so it wasn’t going to be a problem (I thought). I don’t have a problem sending you the gerber files or the saved kicad file either but how do I attach them ?

When you are editing a post there is an “upload” button. (See mouse pointer in screenshot).
As an anti-spam measure new members have to accumulate some “trust” on the forum by some computer algorithm (for example hovering around for some time, or making some posts and getting responses from posts).

Not having a schematic and netlists may make things more complicated in Pcbnew.

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Hi paulvdh, I’ve tried attaching the “append board” kicad file (RFcomboV2-01a), the two seperate kicad files (includes front & rear in filename) and the two gerber files generated for the “combo” PCB by kicad. Unfortunately “new users cannot upload files” message appears so I am now stuck. I don’t have ANY of my schematics saved on the PC - I’m old enough to remember “pencil & paper” ! Seriously though, I just don’t usually bother with schematics for my PCBs. These two boards are so simple, one has an 8-pin chip and a dozen small components and the other has two transistors and a similar number of passives.

I’ve hand solderd quite some PCB prototypes on vero-board and the mirror image of soldering stuff from the bottom has caused me lots of frustrations.
If you start with a schematic, then KiCad will beep at you if you make such silly mistakes.

And it works both ways. The schematic for a board with 2 transistors and a hand full of passives can be drawn in 10 minutes, and with the ever improving KiCad you will then also already have selected the Footprints for the PCB, which saves time when drawing the PCB.

If you’ve drawn everything by hand, could it be that you put the components on top, but drew the traces on the bottom in your original design and it got “flattened” in the Gerbers?

Hi paulvdh - I always print a board on to paper to make sure I can actually fit the components onto the finished board. Both of the individual boards work OK from that point of view. Just wondering if it may be an old version of kicad - the “Help, about” returns : Build: (2013-07-07 BZR 4022)-stable

That KiCad version looks ancient.
Halfway 2018 there has been a tremendous update from KiCad V4 to KiCad V5. and the difference between those versions alone is … significant.

Because do not use KiCad very much I’m still getting to grips with the changes, and I like everything I see, but it does take some time getting used to the changes.

KiCad V4 has been active for a long time, and over it’s life many bugs have been fixed and small things added. Especially the library management of the earlier V4 versions was … pretty awful & buggy.
It seems like a good Idea if you upgrade to a more modern version of KiCad.
Unfortunately this is not a trivial expedition. There are some potential problems of the libraries of V4 and V5 getting mixed. There are some recent threads on this forum about upgrading and porting projects from KiCad V4 to KiCad V5.

In the newer KiCad versions there is also:

Help / About KiCad / [Copy Version Info]

which can then be pasted.
This is a handy feature for identifying sub versions of components. The complete info looks like:

Application: kicad
Version: 5.0.2+dfsg1-1, release build
wxWidgets 3.0.4
libcurl/7.63.0 OpenSSL/1.1.1a zlib/1.2.11 libidn2/2.0.5 libpsl/0.20.2 (+libidn2/2.0.5) libssh2/1.8.0 nghttp2/1.36.0 librtmp/2.3
Platform: Linux 4.19.0-2-amd64 x86_64, 64 bit, Little endian, wxGTK
Build Info:
wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 2.24
Boost: 1.67.0
OpenCASCADE Community Edition: 6.9.1
Curl: 7.62.0
Compiler: GCC 8.2.0 with C++ ABI 1013

Build settings:

Thanks for the info - I think I will upgrade to the newest version, you never know, it may solve my problem. At worst I can supply both sets of Gerber files to my PCB company and ask them to put them either side of the board. I’ll let you know how I get on with the upgrade. Many thanks for your help so far.

You can make a single set of Gerber files by combining the right layers yourself, and checking what’s on it in KiCad Gerber viewer.

Also: with the "f"lip shortcut you can flip traces, components, or selections to the other side of the board. Have you found the 3D viewer yet?

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Hi (paulvdh) or anyone - I tried downloading the latest version of kicad but after installation, when I tried to run anything I get an error message “not a valid Win32 application”. I assume it could be not compatable with Windows XP Pro and I can’t change that (it is a business machine with custom software that won’t run on later versions of Windows). I have further examined what I am doing and have managed to suss that the tracks were on the oposite side of the board to the pads, which I have now corrected (I think - the pads are red and the tracks are green on one PCB and the reverse on the second PCB). I also find that the two sides of the PCB are the wrong way, resulting in a mirrored PCB for one of them. The other board, although mirrored, won’t cause any assembly problems. Any ideas ?

I don’t use windows, can’t help you there.

THT pads are yellow by default, but SMD pads have the same default colors as the layers: Red for Top and Green for bottom. But Traces and pads should have the same color if they’re on the same layer.

Even in your old KiCad version there should be a panel on the right named “Layers Manager”. If you turn off all layers but one, you can see what’s on that layer.
By double clicking on the colored box in front of the layer name you can change it’s color. In the “Items” tab on the “Layers Manager” you can turn on/off the visibility of items such as Pads, Ratsnest & texts. (and/or change their colors).

I just (re?) discovered a nice function. By Right clicking on the “Layers” tab in the “Layers Manager” you get a popup menu with nice pre-selectrions such as “turn off all non-copper layers”, wich is a lot more comfortable than clicking on 16 check boxes for those individual layers.

A faster method (and might help you from getting lost) is use the “High contrast” mode. In this mode all items in the currently active layer (the layer with the indicator triangle in the Layers Manager) show with default coloring. All items visible on all other layers is dark gray. You can make out that they are there (helpful for seeing where highlighted items are relative to everything else), but they are literally faded into the background.

Hi - I have turned off ALL the layers using layer manager and it still displays the SMD pads (but has removed the tracks). On double sided boards, both sets of pads are visible, although different colours. The tracks and the pads are still different colours, even though I expected them to be the same (as you comment). When I look at the print preview of my single sided board it shows three pages - page one has only the board edge, page two has the board edge plus all the pads (red) and the tracks (green) and page 3 is the same as page one (I assume because there is nothing on the other side of the board). The same checks on a double sided board show page one as the copper I require on the BACK of the board (but the view is as I require it looking through the board) page two is as I require the front face of the board (although I am assuming because it is page 2, that should be the rear). Any ideas about swapping them around ?

On my older version of kicad, nothing happens when “right clicking” on the layer tab. A (very) quick check about the “high contrast” mode looks as though it is only really of any use on multi-layer boards and I have two single layer boards that I am trying to combine.

Further to the last comment - I have discovered I can now turn off the pads using the “render” tab in the layer manager and change their colours so the tracks match the pads - that resolves one problem. Can anyone help with swapping the two sides without flipping them ?

Pcbnew / Edit / Move and Swap Layers

But I’m not sure if this works in your old KiCad.
If you keep holding on to your old KiCad version it will become ever more difficult to communicate over a forum. Your “Layer Manager / Render” tab is now called “Layer Manager / Items” and the functionality of the High contrast mode may have been improved in the meantime, etc.

There is also still some legacy stuff in KiCad which influences how stuff is drawn on the monitor and menu functions by pressing [F9], [F11] or [F12].

Hi paulvdh, I found “edit / swap layers” and tried it but for some strange reason it only swaps the tracks and not the SMD pads. A friend has suggested I “dual boot” this PC with Linux and that will enable me to use the latest version of kicad. I am going to ask the PCB manufacturer to add the two seperate files to either side of the board because I have wasted a considerable amount of time on what appears to be an outdated piece of software. Many thanks for your help so far.

You are my kind of people.
Do you append your second board to an empty area of the destination pcb then drag into place?

All but one of my projects start running a file with two GND through hole pads, then add footprints and traces with DRC auto checker switched off. The one project that I drew a complete schematic created a maze in a small area. I needed the ratsnest to keep destination in sight (and memory) when half way to destination pad. Thinking back, I could have circled the destination or followed two graphic lines starting from both pads.

I had trouble once after placing top and bottom surface mount pads on the same module. The footprint was created as part of a board to insert into a card edge connector. All went well except solder mask covered the bottom pads of the footprint placed on the top copper layer. I have not tried mixing through hole and SM pads on the same module.

Kicad 5.0.2 is slick. 5.0.2 will run from a two GND pad file as well, but I miss the append feature to place multiple SMALL completed projects (without edge cuts) on a single pcb, then wrap in one outline before submitting to the fabricator. My versions BZR2017 and 19 for Ubuntu Linux and Windows (7 and 10.1) install to a single folder extracted from the .zip, and not by using an installer. V2.7 and V5.0.2 can run at the same time on Linux - have not tried that on Windows. NOTE. clicking on my Kicad 2.7 .pro or .kicad_pcb files will start Kicad in V5.0.2 . Use a ‘shortcut’ or ‘open with’ icon - linked to early version .exe program files - to start the early versions.