How does removing pads on unused layers affect the reliability of these
small vias, if at all? Have there been any studies done?

David Ricketts

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Hodge
Sent: 01/17/2006 2:26 PM
To: [log in to unmask]
Subject: Re: [TN] <List>Re: [TN] <List>Re: [TN] Drill and plated hole
callouts

Specifying the drill size will not prevent fractured barrels or innerlayer
separation. People are designing on the edge of drill tool capability now.
Very small vias are hard to plate and get adequate copper to survive thermal
shock. Just ask for a thermally shocked cross section of the smallest via on
the panel if you need the peace of mind. JMO



At 03:11 PM 01/17/2006, you wrote:
>I do not have a problem with through-holes for component leads and
>press-fit pins be specified that way (lots of mechanical redundancy),
>but I sure have seen a lot of plated-through vias with fractured barrel
>walls and innerlayer-separation that were not properly spec'ed.
>
>
>
>Werner
>
>---------------------------------------------------

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