# Re: [SI-LIST] : Recommendations for High Density PCB to PCB Connection

From: Laurence Michaels ([email protected])
Date: Thu Nov 04 1999 - 10:13:55 PST

Mike Ventham wrote:
>
> Laurence,
>
> I still think you are having calculation problems.
>
> 1 sq inch = 1000 mils * 1000 mils = 1000000 sq mil. NOT 10000 sq mil
>
> >From this
> 1 sq inch = 25.4 mm * 25.4mm = 645.16 sq mm
> 0.0025 sq inch = 1.61 sq mm. which matches your answer.
>
> Laurence Michaels wrote:
> >
> ( deleted)
> > Argh... I was asleep when I did that calculation. Time to check
> > everything else I did yesterday :-)
> >
> > 0.2*0.5=0.1 square inch.
> > 0.1/40=0.0025 square inches per connection
> >
> > (calculation error was probably here... 0.0025 square inches does
> > NOT equal 2.5 square mils... that's what I get for using non-metric
> > units, and only turning on half of my conversion algorithms.
> > 1 sq in = 10000 sq mil 1 sq meter = 1000000 sq mm)
> >
> > 0.0025 square inches gives 1.6 sq mm per connection
> > 25 square mils gives 1.6 sq mm per connection
> >
> > I'm not usually that stupid. (I hope)

OK, I'm that stupid. I give up.

Apparently the units program on the unix machine may be broken.
Or, maybe it's trying to convert inches into milliliters ;-)

I'm going to be researching this. It may confuse other people
who might try to use that "units" program.

I'm trying to fix the thing that seems to have caused my
mistake. It may be between my ears, but I'm not sure, yet.

1 mil = one thousand headaches per inch.

Thanks,

```--
Laurence Michaels
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