Homebrew PCBs

Paul,
I will disagree with your statement of 2 to 4 mils above lead diameter. For the past 40 years, the standard play for through hole has been a minimum of 7 mils in order to have tin/lead solder flow easily and make a good solder joint. Lead-free solder flow less easily than tin-lead, so I would use at least 8 mils over the lead diameter.

But that is just what the industry is saying (check IPC recomendations), you might know better.

Jean-Paul
AC9GH


On Sep 13, 2014, at 11:30 PM, Paul Alciatore palciatore@... [Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:

> Generally you go by the size of the leads on the components. You want 
> a drill that is about 5 to 10 percent larger. But at least a minimum 
> of 0.002" to 0.004" larger in any case.
> 
> Specific sizes: Many components, including DIP packages, will be OK 
> with a #65 - #72, or a 1/32" or a 0.8mm. Half Watt and larger 
> resistors will need larger sizes. Capacitors are all over the map so 
> a 3/64", #55 - #60, or a 1.2mm would be a good second size. Beyond 
> that, you just have to measure your component leads. And do it BEFORE 
> making the board unless you want to make it twice.
> 
> Carbide may not be the best choice for your first efforts. Carbide 
> will break very easily so if you are using a hand drill or a drill 
> press with any amount of play, you may snap the small diameter ones 
> quickly. I would start with HSS (High Speed Steel) bits and work my 
> way into carbide after some experience. A good HSS bit can last for 
> many dozens, even hundreds of holes, even in fiberglass epoxy. And 
> you can buy several HSS bits for the price of one carbide one. 
> 
> 
>