PCB: Hole and pad size

For a regular through hole PCB, how big should the holes be and how big for the pads around the hole (diameter & line thickness?

Remember, holes reduce in diameter when plated through.

Manufacturers have a list of available drill bit sizes they offer, check their web site.

I like to have the pads/traces as large as possible to allow for future rework.

For somebody making their first PCB in CorelDraw what sizes would you suggest.
The holes need to fit 1/4 watt resistors, LEDs, TIP120s, chip sockets.

I know CorelDraw is not ideal but it is something I know well and the circuit is fairly basic.
If this works out I may invest the time to learn a PCB design system.

It depends on the device you want to mount. You can always find it in the datasheet. But 0,8mm should be fine for stuff like resistors and LED's ans 1mm for lager transistors etc.

MartynC:
. . . I know CorelDraw is not ideal but it is something I know well and the circuit is fairly basic.
If this works out I may invest the time to learn a PCB design system.

I too have used Corel Draw for many years, even for creating DXF files for use with CNC, but for that had to switch to CAD for certain things since it segments things like arcs and some other weird stuff. Anyhow, if the PCB won't be very large, I'd highly recommend getting the free version of Eagle. There's lots of "how-to" vids online, and it's relatively easy to use. One of the least expensive small-order places to have your PCB made, oshPark also works with the output files created by Eagle.

Especially after Eagle was sold I would go with KiCad. Since version 4 is very good. No size limits and no surprises in the future if Eagle decides to skip the free version.

But 0,8mm should be fine

I agree. 0.8mm is my "generic component hole size", and the only thing I've found that needs a larger hole is the 0.025inch square header pins (1 to 1.1mm) and th power rectifiers (1n400x, for example) (1.3mm? I used EAGLE's library.)
It's a bit ambiguous, when you specify a hole size of 0.8mm to a PCB fabricator, whether they're increase the drill size slightly to allow for plating on the inside of the hole. Some apparently think that 0.8mm should be the FINISHED hold size, and some think that should be the exact drill size. So far, I haven't had boards come back (from several different vendors) with too-tight holes... If it's going to be really important, ask ahead of time...

Yeah, for soldering components it's not to critical. Just don't make them to tight, little oversize is filled with solder. It's only critical with press fit connections.

I recommend a small digital caliper guage - very handy for measuring parts. I guess for a hole
add 0.2mm to the measured part should do, a bit more would be fine, especially for anything with
lots of pins as a close fit makes insertion more fiddly.

I use a 75mil pad for 1/4 watt resistors.
A #64 drill bit is more than enough for the hole (non plated single sided PCB).

.

MartynC:
For somebody making their first PCB in CorelDraw what sizes would you suggest.
The holes need to fit 1/4 watt resistors, LEDs, TIP120s, chip sockets.

I know CorelDraw is not ideal but it is something I know well and the circuit is fairly basic.
If this works out I may invest the time to learn a PCB design system.

Have a look at DesignSpark PCB - it's free from RS components:
https://www.rs-online.com/designspark/pcb-software

You can draw your schematic and then make a PCB from it and just print it out. It also lets you just put down pads and tracks for a PCB if you don't want to do the schematic bit.

For hole sizes on a simple PCB I'd go with 0.8mm which will fit most things. You may need to go down to 0.7mm for IC's. If you are hand drilling the board, anything smaller is a real pain to do without snapping bits.

Yours,
TonyWilk

I only use three sizes depending on the component. 0.8, 1mm and 1.2mm - makes creating the PCB easier for the cnc mill with minimal tool changes

I use DesignSpark which is fairly easy to use once you get over the learning curve. To create the symbols and pads etc look up the parts specs which will give you the sizing, pad sizes and spacings

Thanks everyone.

I've gone with 1mm holes for all. See what happens.