Hehā¦ do you mean the user is stress-testing the application, or the application is stressing the user?
I think the fundamental issue here is that I am not at all familiar with the CAD part of the process. I do have FreeCAD but Iāve only used it for importing/exporting files really. I tried a fresh approach this morning to create a simple sketch and how to constain it - then FreeCAD crashed on me, twice. At that point I decided to leave it for a rainy dayā¦
As for my actual footprint - I decided to just use arcs a long time ago. But it annoys the hell out of me when I donāt understand something, especially something that looks as powerful & useful as this.
@maui - do you have any example Freecad file saved anywhere that I or anyone else could try?
Also, I have a small bug to report: I was exporting to a temporary footprint on my desktop and overwriting every time I tried something. When I use the KiCAD export button to save a footprint then select the existing file I get the āAre you sure?ā prompt then āFile saved toā¦ā. But it doesnāt actually overwrite the file! I was trying different things but loading the same old file into KiCAD
This is Win10 x64 and a fresh install of KiCAD 5.0.0 and FreeCAD 0.17.
Where were you trying to export the footprint to? Windows wonāt let you save to a system folder, for example anywhere in Program Files. I think in this case it might actually save it elsewhere and not let you know, but I forget where.
Also, if you were trying to save your export into the KiCad supplied libraries, DONāT for another reason. The next time you update KiCad the installer will happily overwrite your changes.
Doh! I didnāt notice the menu right in front of my eyes!
Anyways, thatās perfect, just what I needed. The example imported just fine and gave me a working baseline to start with. It looks like my sketch was broken - I used Sketcher to make a simple outline (basically one of the segments) and it worked OK.
Not sure what the naming conventions mean yet āPads_Polyxxxā etc, but thatās sure to be a case of RTFM which I can do at leisure. Right now itās a sunny day and my wife is reminding me I have a house to paintā¦
Thanks for your help & patience!
PS ref the save location - just my desktop which is definitely write-able. I think it may be the fact that something was wrong with the file causing the export to not happen.
I managed to implement also the recently added primitive geometry (only ācircleā and āpolylineā are supported atm).
Please update your KSU tools.
I updated also the FC demo modelā¦
Looks good! Actually I managed to create my footprint after a few days messing about with FreeCAD. I didnāt get on too well with the Sketcher UI which seemed [to me] to be doing strange things so I just used the macro facility then edited the macro with the values I needed to get the arcs / lines right. Then it was a pretty simple task to export it to a module.
The mic in question was a Knowles SPU0410LR5H, the footprint I made is attached.SPU0410LR5H.kicad_mod (3.4 KB)
Hi @nali
I would suggest you to remove BackCu (selecting Layers to F.Cu) and BackMask (unchecking B.Mask) from the PAD #6 of the footprintā¦ then you will have a full SMD fp as in the data sheet.
Thanks for the comment. I did ponder whether to make a B.Cu pad, and decided to include it after all. The footprint is SMD, but because it is a bottom-port type microphone a hole is needed anyway, so I thought I might as well include the bottom pad. Itās a GND connection, so I use it to connect to a B.Cu flood fill.
(In reality nothing will be mounted in this area on the underside of the PCB because it normally fits against whatever case the board is mounted in for sound entry.)
I can actually think of a good reason for not allowing that hole to be a PTH. You donāt have to worry about solder getting in the hole and blocking it during manufacture. The solder on the component side around the hole might have a tendency to wick down a plated hole, especially if there is slightly too much solder paste.
Iām not following that - the solder paste area is a long way from the hole ?
What may be an issue is solder mask ink getting into the hole - a NPTH hole avoids that, but if it is the only NPTH hole, that will cost more.
Careful tune of PADSTACK sizes to avoid both solder and mask-ink issues, should find a PTH solution ?
But it isnāt on the footprint that @nali posted. The 3D view up above is @mauiās example. Here is what @naliās design looks like (front and back) in the 3D viewer:
Though, I suppose a better question to @nali is why his design deviates so much from the originally posted image. Round pads where there should be square, two extra pads, size of the pad around the microphone hole (the OD of your pad is 1.224mm, but the drawing specifies 1.45), pin numbering doesnāt match, etc. Did you upload the right model?
Well, that depends on the manufacturer. More and more board houses now donāt charge extra for NPTH holes.
I donāt know why not having asked them, but I suspect that they expect everyone to have NPTH holes. Thus NPTH holes would already be built into the cost of the board, even if the board design doesnāt use them. For all I know may they have the routing bits and NPTH drill bits all on the same turret and do the routing and NPTH drilling all in one CNC job (probably in the other order, holes then routingā¦). Similarly, per via pricing seems to have also vanished from the industry.
Ah. He didnāt provide a link to the actual datasheet when he finally mentioned exactly what part he wants to use, and I didnāt bother to go find it.
Quite simply my OP was about how to generate the segmented ring, and the image was a Google Images search for such a pattern. I deliberately didnāt attach or link to the specific part because I wanted to find out how the process works rather than hope that somebody just comes up with my footprint (or give the impression thatās what I wanted).
I certainly wasnāt expecting @maui to add it to his demo!
I must admit I hadnāt considered solder migrating down the hole so Iāll probably tweak my footprint a bit. Knowlesā design guide isnāt much help in this respect, about all they offer is
The solder stencil pattern must be optimized for production, and for bottomport SiSonic models must use a broken solder ring such as that shown in the figure below
