Re: gEDA-user: Blind & Buried Vias

[Steve Meier <smeier@xxxxxxxxxxxxxxxxxxx>]

having slept on this....

You can do this as a single project.

But you need to split the plated cnc file up into two files. One file
for your blind vias and a second for the vias that penetrate all layers.

My understanding is that if you do this as a four layer board, the fab
shop will build the first three layers then drill and plate them using
the first cnc file. The fab shop will then add the forth layer and use
the second cnc file to drill and plate the entire four layers. Check
with your fab shop to verify.

Steve M.


Steve Meier wrote:
> Neil,
>
> Another way to do this is to break your design up into two boards or two
> sets of gerber files and then combined the two sets of gerbers into one
> complete set.
>
> The first set would have your top layer and all routing layers on it.
> The second set would contain your bottom layers. You will have to hand
> edit the cnc's move the vias that you require to punch through from the
> top to the bottom to the second set.
>
> Steve Meier
>
> Neil Webster wrote:
>   
>> Hi Steve,
>>
>> Sorry I should have described things better. The non-component side of
>> the board has exposed pads that make deliberate contact with the body
>> for a couple of selected nets on the PCB. All other nets on the PCB (eg
>> power) can not be exposed on this side of the board. I had considered
>> using tented vias to selectively isolate certain vias but I am concerned
>> that this thin insulation layer could scrape off and expose the via.
>>
>> Regards, Neil
>>
>>   
>> On Sat, 2008-06-07 at 13:54 -0700, Steve Meier wrote: 
>>   
>>     
>>> Neil,
>>>
>>> If the requirement is not to have the board not make electrical contact
>>> with skin, why not put an insulator on the back of the board? There are
>>> various types of tapes and even sprayes that can be used to encapsolate
>>> one or both sides.
>>>
>>> Steve Meier
>>>
>>> Neil Webster wrote:
>>>     
>>>       
>>>> Hi all,
>>>>
>>>> I have an application where I am creating a small PCB as the basis of an
>>>> active electrode. The non-component side of the board is in contact with
>>>> skin and exposed vias on this side of the board therefore must be
>>>> avoided. In the previous generation of the design, the circuit was
>>>> simple enough to allow me to perform routing purely on the top surface.
>>>> However the new design is significantly more complex and I think I will
>>>> need to move to a multi-layer board. I therefore need blind vias.
>>>>
>>>> The official PCB documentation says that these are not supported.
>>>> Extract from section 2.2: "Each via exists on all copper layers. (i.e.
>>>> blind and buried vias are not supported)"
>>>>
>>>> However I did find a number of threads on this topic in the archive, one
>>>> of which is referenced below. However this was almost 1 year ago and
>>>> there may have been further developments.
>>>>
>>>> http://www.seul.org/pipermail/geda-dev/2006-July/000135.html
>>>>
>>>> Is there any way to achieve this with "pcb"?
>>>>
>>>> Regards, Neil
>>>>
>>>>
>>>>
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>>>       
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