David Hoover wrote:
> 
> But Roger,
> 
>     Once you have the e-less copper <or DM> coverage and panel
> strike plate I have seen the <pattern> plate rob from the bottom
> and plate the knees of the hole producing a week connection when
> we go higher than 1:1. (Like a little isolated plating cell).
> It also appears that once the hole hits a certain size, these
> limitations
> are not so much an issue <?????????>. Also, if the hole bottom is
> not conductive, like accidently covered with photoresist, sometimes
> the plating covers all the way down <????????>. Sounds like a chemistry
> supplier DOE to me. Please include ASF in the matrix too!
> 
> Groovy
> 
> [log in to unmask] wrote:
> >
> > A 1:1 aspect ratio for blind vias should not be considered the limit.
> >
> > There are some DM processes that can "coat" blind vias to make them
> > conductive rather than rely on the electroless copper process to get
> into the
> > bottom of the hole.  Since the gassing of electroless copper precludes
> going
> > much higher than a 1:1 aspect ratio, i.e.the gassing limits deposition
> in the
> > bottom of a blind via, the next limitation becomes that of
> electrodeposition
> > itself.  Providing the entire hole is conductive, I've seen aspect
> ratios of
> > closer to 2:1 for blind vias.  And that's only with conventional
> > electroplating technology.
> >
> > Imagine the possibilities when the industry gets to working more on
> the
> > electroplating aspects of blind via board construction.
> >
> > Roger Mouton
> > INSULECTRO
> > Lake Forest, CA
> >
> >
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> 
>     ---------------------------------------------------------------
> But Roger,
> 
>     Once you have the e-less copper <or DM> coverage and panel
> strike plate I have seen the <pattern> plate rob from the bottom
> and plate the knees of the hole producing a week connection when
> we go higher than 1:1. (Like a little isolated plating cell).
> It also appears that once the hole hits a certain size, these
> limitations
> are not so much an issue <?????????>. Also, if the hole bottom is
> not conductive, like accidently covered with photoresist, sometimes
> the plating covers all the way down <????????>. Sounds like a
> chemistry
> supplier DOE to me. Please include ASF in the matrix too!
> 
> Groovy
> 
> [log in to unmask] wrote:
> >
> > A 1:1 aspect ratio for blind vias should not be considered the
> limit.
> >
> > There are some DM processes that can "coat" blind vias to make them
> > conductive rather than rely on the electroless copper process to get
> into the
> > bottom of the hole.  Since the gassing of electroless copper
> precludes going
> > much higher than a 1:1 aspect ratio, i.e.the gassing limits
> deposition in the
> > bottom of a blind via, the next limitation becomes that of
> electrodeposition
> > itself.  Providing the entire hole is conductive, I've seen aspect
> ratios of
> > closer to 2:1 for blind vias.  And that's only with conventional
> > electroplating technology.
> >
> > Imagine the possibilities when the industry gets to working more on
> the
> > electroplating aspects of blind via board construction.
> >
> > Roger Mouton
> > INSULECTRO
> > Lake Forest, CA
> >
> >
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> [log in to unmask]>   *
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> contact   *
> > * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at
> [log in to unmask]      *
> >
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> Groovy,I agree with Roger's comments.
There are a number of companies successfully fabricating blind vias with 
ratios greater than 1:1. They have not seen any of the problems you 
describe. alternatives to electroless copper is the preferred 
metalization technique. Leveling and the overall quality of the 
electrodeposited is also excellent.

Best regards

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