Alpha and Beta  Circuit Boards  Cover Note
    --------------------------------------------

                                              26-Sept-2022
                                              
We would like 6 each of the Alpha and the Beta circuit
boards manufactured.  Except for their center section,
these two boards are very similar.  I believe that 6 of
these cards will fit onto a  9" x 12"  panel.

Both of these pcb designs need to be built on the same type
of RF microwave high Dk laminate such as  Rogers  3010  or
AD1000.  The laminate needs to have a Dk of about 10.

We do not want the individual cards cut out from the panel.
The final milling of these cards will be done at the
customer's site.  The full panel as processed by the pcb
vendor will be the delivered product.

The intent is that 6 of the Alpha cards will be on one
panel and 6 of the Beta cards on another  9" x 12"  panel
of the specialized laminate.

The Gerber files and Excellon drill files and a
manufacturing readme file for each board are in the:
alpha_board.zip  and  beta_board.zip  files.

The drill tables for the Alpha and Beta designs are
exactly the same to facilitate manufacturing of these
two boards.

You are welcome to treat this as either one overall job
or as two separate jobs - which every is easier for your
system.

These are rather unusual circuit board designs.  In case
there is difficulty interpreting the design data the
following is a description of the Gerber files for either
design.

 - artwork_1
   Top Side Copper,  it is almost 100% solid Ground Plane
   copper, with 16 embedded traces, there is a square area
   in the center with no Ground Plane,  there are 16
   circular areas around the perimeter with no Ground
   Plane,  within the Ground Plane area itself, which is
   defined by a "Fill Shape", all of the plated through
   ground vias have a circular Flash, so that both the
   Fill Shape and these circular Flashes say that there
   is copper in the area of these vias,  there are about
   468 of these vias in 3 different sizes on the Alpha card.

 - artwork_2
   Bottom Side Copper,  it is almost 100% solid Ground Plane
   copper, with 16 circular holes around the perimeter and
   4 much smaller circular holes near the center,  this
   Ground Plane is defined by a Fill Shape and within this
   Fill Shape you will see about 468 Flashes where the
   ground vias come through from the top side for the Alpha
   card.

 - artwork_3
   Dimensioned plot of the outline of the square board
   showing that the  0,0  of the coordinate system used
   for all of the data files is in the center of the square
   board,  after you manufacture these square boards
   (leaving them in the panel)  we will in house route
   them into circular shaped boards and do other
   specialized milling in the central area.

 - artwork_4
   Top Side Solder Mask,  the solder mask is Relieved on
   most of the Top side of this card,  the solder mask is
   present basically only in a ring near the perimeter of
   the final circular shaped card and in spokes running
   out to its perimeter,  all of the area in a big circle
   around the center of the card will be exposed ENIG
   plated copper,  there are circular Flashes so that
   none of the ground vias are tented with solder mask.

 - artwork_5
   Bottom Side Solder Mask,  much of the Bottom side of
   the final circular card is covered with solder mask,
   it is relieved by circular Flashes around all holes
   and vias.

 - artwork_6
   Bottom Side Silkscreen,  a thin ring around the 61 mm
   diameter of the finished circular card, and just labels
   for the 16 connectors around the perimeter and "Alpha"
   or "Beta" and "MSU Physics".

 - There is no Top Side Silkscreen