Wrong resistor size :(

[Waldo32]

Hi folks. I just finished a layout, got the pcb, and realized I used a resistor footprint for about 60 resistors that’s a just a bit too small. Aside from several choice curse words (measure twice, cut once, I know)…is there any “easy” way to fix the board layout?

Like, just swap the new footprints in for the old ones in their exact location, then I can go fix up the ends of each of the traces? Or do I need to essentially re layout the whole thing?

Speaking of, what is the proper way to read the footprint names for resistors in KiCad (e.g. what are L.D.P?) – for example, I’m using the CF14 resistor from this datasheet: https://www.seielect.com/catalog/sei-cf_cfm.pdf.

[Rene_Poschl]

Both the assign footprints tool and the edit symbol fields tool can change the footprint assignment of multiple symbols at once. After you have done so simply update the pcb from schematic with exchange footprints selected.

• How can i assign a footprint to a symbol?

[eelik]

@Waldo32

Speaking of, what is the proper way to read the footprint names for resistors in KiCad (e.g. what are L.D.P?)

Resistor body Length, Diameter, distance of two Pin holes

[Sprig]

@Waldo32

Or do I need to essentially re layout the whole thing?

No.

KiCad allows for trace segments to be individually deleted. This may mean 120 (or only 60 if the other side is a Fill-Zone) for the affected components.

[Rene_Poschl]

Footprint naming is documented in the KLC: https://kicad.org/libraries/klc
Responsible sections (for tht resistors):

• https://kicad.org/libraries/klc/F2.1/ (General naming rules)
• https://kicad.org/libraries/klc/F2.2/ (Field prefixes -> Defines what L, D, P mean)
• https://kicad.org/libraries/klc/F3.2/ (Resistor convention)

[Waldo32]

Thanks everyone. Much appreciated.

[dchisholm]

@Waldo32

…is there any “easy” way to fix the board layout? . . .

Have you considered a rush order, overnight shipping, etc, for 60 resistors that fit? Then fix the footprints on the next board cycle. (It sounds like this is the first implementation of a fresh design. I’ll wager that there will be a couple other changes to the board layout in the near future. If I was the administrator for your project, the schedule would have time allocated for at least two prototype builds before committing to production.)

Dale

[John_Pateman]

No room to mount them vertically I suppose?

http://www.pcb-3d.com/wordpress/wp-content/uploads/600/RESADV-600.jpg

[Sprig]

@John_Pateman

…mount them vertically…

And if this is done in tight spacing, the Symbol Pin Number matters; as it most likely also specifies the polarity of a non-polarized part.

Also, consider that the leads can be insulated with heat shrink if the design requires it as a Last Resort.

[mr_bandit]

It is also possible, if you are careful, to edit the .kicad_pcb file.
I do this to change hole sizes to reduce the number of hole types.
Have a backup file!!!
I just use vim - use your favorite text editor

[Just_Me]

I am no expert, but have spent enough time to see several potential powerful tools that I have not really used. When you change a footprint association, there are several options. Working from memory, one is to change a range of, for example resistor numbers. If yours are sequential - or if you want ALL resistors to be, say 0.4" pin spacing rather than 0.3", you may be able to change them all at once. I suspect you will still have to “trim” the traces - but maybe not so long as they don’t touch. I am slowly building my own library of standard footprints with holes MY size and spacing as I want them. Best Grant