The very first step in designing a BGA is preparing the die netlist in a format that FA3ST can read. This is a simple ASCII format and can easily be produced by a program or using a spreadsheet such as Microsoft Excel or Lotus 123.

By adhering to this format the BGA designer will not need to spend valuable time reformatting or reviewing it and can immediately import it correctly into his design software.

Header Info

The first few lines of the file tell the program about the name of the die, the physical size of the die outline and the pad size. If the die has pads of different sizes use the smallest side. Any line starting with a semicolon (;) is a comment.

;Die Released 07/28/98 Super Transistor Corp...
DIE_NAME=2N5907A
DIE_UNITS=um
DIE_X=8500
DIE_Y=8100
DIE_PAD_SIZE=80

After the header information comes the data. Data items are separated by either tabs or spaces.

Column 1         Column 2   Column 3     Column 4     Column 5
;die_pad_num      x coord    y coord      net_name     ball_num

    1             5750       5655        clock_fast     A23
    2             5750       5645        pwr             -
    3             5750       5635        gnd             -
    4             5750       5535        nc              -

1. Die Pad Number
   This is the first column of data. It must be a number between 1 and 9999. No letters or non numerical characters are allowed. The same die pad number may not appear twice. It is not neccessary that these pad numbers be in any particular order as the program will re-order them automatically.

2. X Coordinate
   This is the X coordinate of the pad center. Units should match what appears in the header. Decimal points are allowed.

3. Y coordinate
   Y coordinate of the pad center. Units should match what appears in the header.

4. Net Name
   This is the signal name for the die pad. Each signal should have a unique name (unless of course one or more die pads are electrically connected.)
   
   
   Naming Rules

   16 Characters Maximum
   No spaces or punctuation marks i.e. no , . " : ;
   Underscore and dash and brackets are allowed: _ - [ ] ( )
   Every die pad must have a net name (i.e. no blank assignments)
   If possible only one name for all power nets and one name for all ground nets
   

5. Ball Assignments
   Unless this is a "free" route design, BGA balls will be associated with each netlist. The appropriate ball (or list of balls should begin in column 5. The standard JEDEC labels should be used such as A1, CC5, D25. If more than one ball is assigned to this net they can be listed sequentially using only a comma as a delimited. (No spaces).

   If no predefined netlist exists you can leave column 5 completely blank. If some die pads are not connected to a ball (such as power, ground or no_connect) then put a dash in column 5 - do not leave it blank.

;DEVICE NAME: TM3588A
;Package:PBGA 31mm
;Header
DIE_NAME=DIE2
DIE_X=8500
DIE_Y=8100
Die_pad_size=80


;diepad#     x           y          signal       Ball      
  1       -4090.1         3776.9     vss_ring      - 
  2       -4090.1         3676.9     vss_ring      - 
  3       -4090.1         3557       d_addr[6]     B1
  4       -4090.1         3470.2     d_addr[5]     B2
  5       -4090.1         3383.5     d_addr[4]     D4
  6       -4090.1         3296.7     d_addr[3]     C1
  7       -4090.1         3209.9     d_addr[2]     C2
  8       -4090.1         3123.2     d_addr[1]     D3
  9       -4090.1         3036.4     d_addr[0]     E4
  10      -4090.1         2949.7     vss2          vss_ring
  11      -4090.1         2862.9     grxd[0]       vss_ring