Blind, Buried Via on Printed Circuits
Blind Via are defined as those vias that start on an outer layer but terminate on an inner layer. Buried Vias are defined as those vias that exist only between inner layers and do not begin or terminate on an outer layer.
Applications for Blind and Buried Via
Blind and buried vias help to save PCB real estate by allowing features and lines to be designed above or below them without making a connection. Many of today’s fine pitch BGA and flip-chip component footprints do not allow for running traces and through. Instead, the blind and buried vias will only connect those layers that are required to have a connection in that specific area, allowing for PCB real estate space savings.
(Laser Drilled) Blind / Buried Via
Voids—Desmear / DeAsh
To insure that blind vias are properly desmeared and deashed (if laser drilled), we utilize a two-step desmear process. This process first requires that the panels be submitted to a plasma conditioning process in our March Plasma System. We then process through a chemical desmear that has been optimized for micro- and blind vias. This line has been outfitted with long-stroke agitation and flight bar vibration to enhance fluid movement and prevent air bubble entrapment.
We have installed a Hollmuller Shadow hole preparation line that has been outfitted with advanced spray technologies. These spray technologies allow us to use this high-reliability hole preparation process for blind vias.
Further, our copper plating lines have been outfitted with long-stroke agitation and flight bar vibration to enhance fluid movement and prevent air bubble entrapment. By 2010, we expect to have installed Reverse Pulse Plating in our facility to plate even the most aggressive designs, and also to copper fill these so that your blind vias can also be used as via-in-pad technology.
For more information on this and other type of board technology, please contact us for a custom price quote.