3Di Geometry

Geometries form the core of the 3Di file. They should be grouped together following the keyword GEOMETRIES.

At this time, four types of 3D geometries are supported -- useful for describing an IC package. These are:

extrusion [EXTR] - modelling the metal and dielectric layers.

wire [WIRE] modelling bond wires.

sphere [SPHERE] - modelling ball pads.

barrel [BARL] - modeling a "squashed" ball pad or bump

All geometries are identified using the GEOM keyword, followed by one or more attribute [table index] or [attribute value] combinations which are used to assign properties to the GEOM: LAYER, COLOR, NET and so on. There is no limit to the number of properties that can be assigned to a geometry.

  GEOMETRIES
     GEOM
     NAME AA2
     WIRE_MODEL 1
     OBJECT 1
     COLOR 13
     NET    4
     LAYER  5

Associating properties with each geometry is what gives the 3Di database intelligence. The initial release of 3Di required that each property have a table associated with it and index numbers pointed to the values in the table.

Direct vs. Indirect Attributes

After some usage it was determined that tables were not always the most efficient way to store attributes. For example, net names are best placed in tables since the same net will be used to describe many different geometries. However pin numbers or bond finger labels are best associated directly with a geometry since these are generally never re-used -- i.e. the pin name is unique to one geometry.

We found this could be implemented without major changes to the 3Di database by placing the TABLEs before the GEOMETRIES section. By reading the TABLES section first, the 3Di interpreter knows which attributes are stored in tables and that the following string must be an index number into the table. If a attribute doesn't match one of the TABLEs then the following string is a value.

Some of our customers have requested that Artwork support the concept of padstacks. However this concept does not work with 3Di since we don't "place" nested objects in 3Di and a pad stack is essentially a collection of nested pads. However we have recently added a PADSTACK attribute so that a 3Di parser could identify all objects associated with a particular padstack and then process them as a group.