I’m really enjoying creating some simple PCB’s for some different projects - amazing what.people such as PCBWay can do!
I’m creating a PCB shield for a Arduino Mega, and want to mount a LM2596 DC-DC power module vertically on it - simply putting pins on the ground connections which then attach to the PCB, then use flying leads for the Vin & Vout back to the PCB shield.
I can’t see how to create a footprint of the LM2596 module that allows me to do this.
I can’t find anything like this anywhere so - help please
Create a footprint with two rows of pads. One row sized and spaced for the pins and the other row sized for wire. (Honestly, pads sized for 0.25mm square pins are probably large enough for most hookup wire though.)
Thank you very much for your reply
Still not sure how to create the connection between the floating Vin & Vout which are not directly connected to the shield - as they are flying leads to come back to the shield.
The part I don’t understand is where to put the pads on the footprint, and then connect the flying leads to the shield itself to complete the circuit in Pcbnew
Mechanical stability is always an issue with this kind of tinkering, especially because solder is not very strong.
Most LM2596 modules have relatively big square pads, and I would make use of that.
I would make 2 short loops from folded wire to strenghthen the solder connection of the 2 boards together.
The flying lead can be regular through hole pads, but again use thick wire for mechanical stability, and fold the wire over the LM2596 module for mechanical stability.
A picture for inspiration:
Also:
It’s always hard to think of things when sitting behind a keyboard.
If you take a piece of vero board and start experimenting you will get ideas along the way.
And if you found a nice solution you can simply count holes on the veroboard and copy the Footprit into KiCad.
If you want to use SMD pad’s then put 2 via’s through each SMD pad for mechanical strength. Copper does not adhere too good to the epoxy (especially while hot) and the copper in the via’s make SMD pads a lot stronger.
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Thank you very much Paul - I really appreciate your help
I’m still not sure about how to make the connection to the PC for the positive connections, but am “just doing” it. Certainly encountering a lot of unexpected issues on the way through but learning heaps. There’s certainly a big change from version 4 to version 5 as well.
Very interesting about how you have mounted the module. A concern relates to your statement that copper does not adhere that well to the epoxy - yet this seems to be the only mechanical strength for the lower connections. In my prototype shield I used a right angle male header which has the advantage of going right through the holes on both the PCB and module
Curious, does your LM2596 module have holes in the large pads? If so you can use some stiff wire from the board to the LM2596 module in each corner. While solder is not supposed to be used for a “structural” feature, I’ve never had issues with such construction.
One caveat, If you try this, make the length of the wires long enough that you can snip them if you later decide to remove the module.
If you want to try this you can simply place 4 mounting holes with pads and vias on the schematic. Then in PCBnew you can place them to correspond with the corners of the module.
In my opinion, this is the best way to start out the design. Create a Footprint that matches the bottom half of the module to the shield board, to get the GND pin headers lined up on both of them.
If you need more mechanical strength later on, it is then a secondary concern that one need not waste time on now.
Since you are using flying-leads, create a second, or third, symbol, on the schematic. Assign Footprint/s as required by your design.
In your case, you need to think a little bit bassakwards. The module is already defined physically. What you need to figure out is where the output of the module ends up on your shield. If the outputs end up close to each other, you may well get away with a single Symbol and Footprint. However, since you started using flying leads, and they may fly nearly anywhere, you might need to create two(2) more Symbols with individual Footprints such that you can locate them separately anywhere on the PCB that your design requires.
Huge thanks Sprig. Your idea worked a treat, and I just had to tweak where the flying leads are positioned on the PCB and put them there in the footprint
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