How to create custom pad / package?

[understress]

I have the need to create a custom package (or maybe I should call it a pad) for a PCB I'm laying out. The PCB will mount to some heat sinks via 1/4-20 bolts. At these mounting locations, I need a hole of 0.312" diameter and an exposed copper area of 0.750" x 1.000".

The closest I can come is by creating a very large DIL pad, but that has the corners cut off which I don't want. A square pad won't work because of the spacing of the heat sinks, I need rectangular. I can create a large surface mount pad, but I can't figure out how to create a stack of two of these pads with a circular 'pad' in the middle for the hole. I need the hole to be through plated for electrical connectivity.

I'm a newer user of Proteus and just not sure how to do this. Any help anyone can provide will be greatly appreciated.

Thanks,

Scott

[understress]

All, as of right now, my original post was read 78 times with zero reply's.

I was really hoping that someone with considerably more knowledge than I would know how to do what I need.

Does anyone even know if what I want is possible? Any help is greatly appreciated.

Thanks,

Scott

[rberek]

The best I was able to do with a few minutes work was to create a top copper zone .75 inches by 1 inch. Then I created a circular thru hole pad with an inner diameter of .312 in and an outer one of .32 in or so. I then placed the pad in the zone. It worked almost perfectly, except that there was a bit of copper relief around the hole. Perhaps with some experimenting it could be made better, but it looked like it might work well.

r. b.

[Richard_Reeves]

The best I was able to do with a few minutes work was to create a top copper zone .75 inches by 1 inch. Then I created a circular thru hole pad with an inner diameter of .312 in and an outer one of .32 in or so. I then placed the pad in the zone. It worked almost perfectly, except that there was a bit of copper relief around the hole. Perhaps with some experimenting it could be made better, but it looked like it might work well.

r. b.

And the hole's relief can be set to 'solid', which will get rid of the gap.



Richard

[understress]

rberek & Richard_Reeves, thanks for the discussion. This is what I wanted to get started!

rberek, Your suggestion is what I initially tried. But, it seems that the copper zones will have resist on them. This is what I'm trying to get around. I need the 0.75" x 1.0" pads to NOT have resist on them, just exposed copper.

I have attached a small example layout file of how I've tried doing this. In my real board layout, the pads and zones are connected to nets of course. The example doesn't have nets in it.

Maybe someone has a suggestion for a better way?

[Dennis Welbourn]

Hi

I don't know if the attached is a better way but it works for me.

Basically start with mounting hole / holes required then surround as required with SMT pads to achieve
required overall size for heatsink.
Name all pads as NC which later can be connected to any net if required, but also ensures Groundplanes
will avoid them if so wished.
The whole area for heatsink will be solder resist free.

Regards

Den