--- In
Homebrew_PCBs@yahoogroups.com, Bruce Parham <obparham@...> wrote:
>
> A quick look at the spec's shows 16 mil (0.4mm) minimum hole size and
> 2.5:1 aspect ratio. Not so hot... A good board house can do 8 mil (0.2
> mm) holes with 10:1 aspect ratios all day long.
>
> Just my $0.02.
>
> Bruce
>
Well, I'm not trying to compete with a board-house, I'm trying to save myself some time. I tend to use an 18mil drill for vias at home anyway, giving me 0.4572mm diameter vias. Typically you add 0.1mm to any CNC-drilled via to get the real diameter, so really I'm using 0.55mm...
To get to a 2.5:1 aspect ratio, I'd have to migrate up from 18-mil drills to 22-mil drills for vias (when you include the 0.1mm drill variance factor). Not so bad, at least for me :) Or, of course, I could move to using 0.039" thick FR4 instead, which would actually allow me to shrink my vias down to 16mil...
Actually, using Bing (rather than Google) to find information on the HW-K1000 gives slightly different specs - in
http://www.microsofttranslator.com/bv.aspx?from=zh-CHS&to=en&a=http%3A%2F%2Fwww.merke.com.cn%2Fproduct.asp%3Flt%3D24 they specify 0.3mm as the smallest drill-size...
[aside: I just checked, the board-house I tend to use (PCB-Pool) has a standard (as opposed to high-spec) DRU requirement of 0.3mm vias... They'll do 0.2mm at extra cost...]
Simon