Re: gEDA-user: How's my footprint?

["joe tarantino" <joeft@xxxxxxxxxxxxx>]

 

I've used this part and several others in the same package.  My $.02 worth...

 

- I would also recommend using the .01 mil resolution co-ordinate syntax.

 

- My experience is that most shops like the part co-ordinate origin to be the centroid, not on pin 1.  I've also had problems setting the "mark" or at least always seeing it, but you should place the origin at the centroid regardless.

 

- Regarding the copper clearance - you can probably default it - especially if there is no outside layer ground plane.  I would not default the solder mask opening however.  These leads are close together.   If your pin spacing would result in thin slivers of resist between pins you should explicitly set the solder mask openings to that they overlap.  Having no resist between pins is actually preferred over having a sliver of mask floating around and landing on some other pad where it doesn't belong.  (I've heard this from several fab shops.)

 

- Another hint.  Consider connecting Vin to a really large trace or piece of copper.  This will help in reducing the temperature rise of the part - this package has very high thermal resistance.

 

Joe T

 

On 6/2/07, Steve Meier <smeier@xxxxxxxxxxxxxxxxxxx> wrote:

Bert,

A high end (Diamond Quality) fab and assembly shop uses the "ascii" file
to program their flying probe tester. There is an existing standard
which I have an example off at the office which is based upon the pads
file format. If you are interested I can probably get you an example
early next week.

Steve Meier

L.J.H. Timmerman wrote:
> Hi Steve and all,
>
> So if I understand this correctly, you are asking for someone to write
> an exporter for pcb which outputs a file with XY-values of pads(pins)
> with an ID-reference to be able to check for copper conductivity etc.
> and maybe even frequency related impedance/capacitance (nelma ?).
>
> Something like (a csv file):
> <example>
> #Id  X  Y  top/bottom
> C1-1,100.50,50.20,top
> C1-2,100.50 ,50.25,top
> </example>
>
> or
>
> <example>
> #refdes  pad  X  Y  top/bottom
> C1,1,100.50,50.20,top
> C1,2,100.50,50.25,top
> </example>
>
> Or does a defacto standard format already exist ?
>
> Together with a netlist of connecting traces this would give enough
> information for testing conductity in an automated fashion.
>
> I think the BOM/XY exporter would be a good candidate to be extended for
> this functionality, as it already calculates all the XY values of
> pins/pads in some fashion.
>
> Hmm, I should probably X-post this one to geda-dev.
>
> Just my EUR 0.02
>
> Kind regards,
>
> bert Timmerman.
>
> On Fri, 2007-06-01 at 21:54 -0700, Steve Meier wrote:
>
>> [snip]
>> This is an issue that we need to address as board shops that have the
>> ability to do point to point probing are asking for files that define
>> the locations of each pad.
>>
>> Steve M.
>>
>
>
>
>
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>
>



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