[gta02-core] Board parameters update

[Rene Harder]

Werner Almesberger wrote:
> Rene Harder wrote:
>   
>> The chemical deposition of organometallic compounds (OSP) is becoming
>> more and more popular, and you'll find it in prototype spec quite often
>> these days. However I have no idea about long time stability (have never
>> used it myself)
>>     
>
> All I know about OSP I learned on the Web ;-) How do unsoldered pads
> perform (NC, test pads) ? Can you leave them "clean" or do you apply
> solder paste as a protection ?
>
> Also, with stability, I'm less concerned about whether the board will
> still work in ten years, but how long we can store it between PCB and
> SMT. If that time is very short, that may be a problem. There are
> always surprises ...
>
>   

I agree, these are interesting questions, unfortunately I cannot give
you an proper answer. My Electronic Materials and Processes Handbook
doesn't really handle OSP. There is a small section about organic
compound (e.g. conductive epoxies) as solder finish though, but this
seems to be an outdated technology (although the book is not too old,
it's from 2004). I guess it'll be time for a new one.

>> Indeed, that makes things more complicated However, there are companies
>> who have boards with an overall thickness of 0.31" or 0.40" for 6
>> layer[1] or 0.48" for 8 layer[2] in their standard specs.
>>     
>
> This board is begging for six layers ;-)
>   

Yes it really does. :-D