Publishing Venue
The IP.com Prior Art Database
Abstract
Disclosed is a method for cap lamination for tighter impedance control. Benefits include improved performance and improved design flexibility.
Method for cap lamination for tighter impedance control
Disclosed is a method for cap lamination for tighter impedance
control. Benefits include improved performance and improved design flexibility.
Background
� � � � � Variations in dielectric constant (Dk) and impedance
(Zo) are caused by glass/resin variations in the woven glass fabric used as
material reinforcement, limiting the range of impedance control that a board
can maintain.
� � � � � Conventional methods
of reducing Dk variation in glass woven reinforced printed circuit board (PCB)
laminate materials are to use multiple layers of woven glass fabric in the
dielectric and wider traces for the bus design.
� � � � � The conventional method of building a PCB uses layers of woven
glass fibers embedded in an epoxy resin to provide a dielectric separation
between circuit layers (see Figure 1).
� � � � � A double thickness of glass fibers at the cross over points in
a material weave results in variations of the epoxy/glass ratio between points
along an external circuit and the internal reference plane below it.
Description
� � � � � The disclosed method
is PCB fabrication that reduces the range of impedance and dielectric constant
variation. The
key elements of the method include:
• � � � � Cap lamination, which
is typically used for laser-drilled microvias, can be applied to conventional
PCBs for tighter impedance control.
• � � � � Eliminating the
irregular thickness of glass fibers results in a more homogenous diel...