Stefan,
I think this is a good idea. We used to use test patterns for eval of
copiers that I repaired, and after awhile, one gets VERY good at
seeing errors in the test pattern. Nearly anything with a wide range
of size, line width, text, and claearances will work well.
I would think you will want "typical" traces, with each pair (or
three) getting thinner and closer together. Be sure to include some
45 degree turns, and perhaps "target" circles, one inside the other.
Also crosshatching, as is done on some ground planes.
Pads of different sizes of course, from through hole to SMD.
Text also will show up errors, so it would be good to have a series
of words, each one the same but smaller and smaller. If you choose a
font with serifs, fewer sizes will give you more information. Times
Roman is a good font for this.
Basically you want what would be considered the PCB from hell, as far
as traces and clearances go. At least at one end of the scale that's
what it would be. At the other end, it will be BIG solid lines with
lots of room between. By doing it this way, you will be able to see
in ONE sample, exactly WHERE the problems lie...
Hope this helps,
Ballendo
P.S. Although I think it's a good idea, I'm not sure how much people
will be willing to use it. Seems most will not want to "waste" the
time to make a non-essential board... If you agree, then try to make
the design a REAL board. Something that WOULD be useful... Not sure
right now what that would be, but I'll give it some thought.
Maybe some sort of "prototyping area", since you'll be putting pads
down of various sizes and types. Maybe a "conversion from SMD to TH
parts. These are Ridiculously expensive to buy, and if we were using
something like that to test our systems and setups, we'd have
a "sellable" item each time it "worked"... (I cant believe it when I
read the ad copy in mouser or digikey for these. They actually act as
if using this 16 buck "converters" will save money! "Use PLCC chips
in through hole designs!" they say...
Anybody got an idea for a "universal" pcb that we wouldn't mind
having after the test is over?
--- In
Homebrew_PCBs@yahoogroups.com, Stefan Trethan
<stefan_trethan@g...> wrote:
>
> Hi all...
>
> I wonder why there wasn't said more about a standardized test
pattern
> to compare results..
>
> I'm still interested in one, and i will make one but
> i have hoped there is some input on what is a good pattern....
>
>
> I've bought some inkjet paper yesterday, brand is "Rex".
> It is the kind with the glossy surface, the package says "ceramic
coated"
> but
> i really doubt that a bit.
>
> I will try this one and compare to the matt paper.
>
> For a test pattern i thought about making such a "star" where you
start
> with
> stripes/wedges which meet at one point. i have see this on printer
test
> patterns.
> I guess you can make marks on the side, writing which width you are
at
> this radius.
> another thing will be a relatively big black area.
>
> Any ideas very welcome!
>
> ST