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

Date: Thu Nov 04 1999 - 10:12:51 PST

Sorry, Laurence, 1 inch is 1000 mils.

----->Chris

At 12:12 PM, you wrote:
>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
>>(deleted )
>Ermm... No...
>1 inch = 100 mils 1 sq inch = 10000 sq mils
>1 meter = 1000 millimeter 1 sq meter = 1000000 sq millimeter.
>
>Contrary to SI prefixes, 1 mil isn't 1/1000 inch.
>It's 1/100 of an inch. That's one of the places I made a mistake.
>
>Using my trusty \$X000 computer as a simple calculator:
>
>gitm\$ units
>you have: inch
>you want: mil
> * 1.000000e+02
> / 1.000000e-02
>you have: m
>you want: mm
> * 1.000000e+03
> / 1.000000e-03
>you have: inch2
>you want: mil2
> * 1.000000e+04
> / 1.000000e-04
>you have: 25 mil2
>you want: mm2
> * 1.612900e+00
> / 6.200012e-01
>you have: 0.0025 in2
>you want: mm2
> * 1.612900e+00
> / 6.200012e-01
>
>Strange, but true.
>
>Anyone else care to share their mistakes with the rest of the world?
>
>> 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)
>> >
>> > Thanks,
>> > --
>> > Laurence Michaels
>> >
>>
>> --
>> Regards
>>
>> Mike
>> ________________________________________________________________
>> | Mike Ventham - Vice-President Engineering, |
>> | Quantic EMC Inc Headquarters |
>> | Croft House, Chilcompton, 191 Lombard Ave, Winnipeg, |
>> | Somerset, UK, BA3 4JA Manitoba, Canada R3B 0X1 |
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>> | Email: [email protected] http://www.quantic-emc.com |
>
>--
>Laurence Michaels
>Fiat GDC
>
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