Dbl sided board w/all solder on bottom

I’ve gone through a ton of research and testing and finally have a process for creating boards by spray painting, drawing traces with my laser, chemical etching, masking with photo film, etc. It’s taken a ton of trial and error but I was able to assemble my first real board this morning when I realized I made a massive error - some of the component connections on top I can’t access to solder. I knew some connections would be on top for my arduino, and had planned for that knowing the pins were long enough that I can access them top and bottom to solder. But I guess I totally spaced out on other connections like headers and my power. So many details to keep track of! Anyhow, I got those other components out of the box and the pins are just long enough to solder on the bottom side if on the top side they are against the board and cover the solder area.

My question is how in fritzing to use a double-sided board, but force all soldering connections to be on the bottom? In other words - allow autorouting to use both sides for traces and utilize all the vias it wants - but don’t put trace end-points anywhere on the top?

I’ve searched and found a couple mentions of these general terms, but nothing specific to this problem - which is surprising since surely it’s a common issue. In fritzing I’ve tried disabling traces from autorouting and going back and forth from single-sided to double-sided boards, but since a trace and its end/solder connections can’t be independently forced to top or bottom layers nothing has worked.
Is there something I’m missing or is this just one of those things that totally has to be manually worked around overall?



I expect you would need to do it manual. Fritzing is expecting double sided boards to have plated through holes (which you can’t do at home.) If you want to run traces on the top you need a double sided board. So you choices would be a single sided board and do crossovers with jumpers or manually reroute anything you can’t solder on the top using vias.


When working with traces in PCB view, you can specify (and move) individual traces between top and bottom of the board. If you make “sure” that all of the traces that connect to pins that need to be soldered (those that connect to solder pads) are on the bottom of the board, everything should work. Something like a single pin header can be used connect to a trace on the top. Since a standard via will not work, if it is not plated through.

The real answer is you can’t tell autorouting to do what you want for regular THT parts. You need to do it yourself. If you use SMD parts, autorouting would keep all of the connection on the side that parts are on. You can toggle that. What it looks like is needed, is parts that are THT (so the hole is shown to be drilled), but that only have a solder connection on one side. I think that breaks all sorts of ‘rules’ for making Fritzing parts, but it MIGHT be possible. I don’t want to go there to find out. Especially since every part used would have to be modified the same way.

If all of the parts you are using have SMD versions (with the same spacing), you could try placing those, then manually adding a pcb hole part in the middle of the solder pad.

Thank you for the replies. Glad it wasn’t just a setting I couldn’t find, but wouldn’t it be nice?
I’m etching the new boards at this moment. I finally just did a double-sided autoroute, then started to get the hang of how to go to each top route, move it to the bottom, adding 2 vias and then moving the connector between the vias to the top. Fortunately it’s not a crazy complex board.

I haven’t tried it yet, but I’m curious if a potential way to do this with autoroute would be to add a via right next to each solder connector - a proxy ‘either side’ option - then do an autoroute. If resulting routes are already on the bottom, then the via can be removed and routed straight to the connector. Otherwise, just leave it via-ed. It wouldn’t be ideal, but for homebrew boards it might actually solve this problem while still allowing autoroute to work fully.

Just to save someone some time -
I did try the proxy-via method and it didn’t work. (You have to set each proxy trace to not autoroute of course.)
Fritzing basically ignored them and generally routed around them instead of using them as the closest connection point to the actual connection point.
A shame. If the autorouter had a ‘closest connection’ mode this could work.

That is because they aren’t in the net that defines the connections (that is also the same problem that makes a solution to this difficult.) You could maybe do what you want by using a single row 1 pin 0.1 header and adding a connection between it and the actual connection in breadboard or schematic. That will add the connector to the appropriate net and allow autorouter to connect to it in pcb (because the pcb pad will be in the correct net) after moving the pad in pcb to the appropriate place.