Guidance notes for Structure Copy and Paste

Structure Copy and Paste allows single or multiple structures to be copied between layers.

Note: when copying and pasting structures between layers it will be necessary to ensure that the structures are pasted to appropriate signal and plane layers. When specifying these signal and plane layers it is important to consider the influence of any intermediate electrical layers and how they might impact the pasted structures from a signal integrity viewpoint.

Consider the stackup below.

Select the Controlled Impedance tab to display the controlled impedance structures – the stackup contains has eight structures, four coated microstrips on layer 1, four offset striplines on layer 4. Note that this 14-layer stackup has very similar foil, prepreg and core materials throughout.

Stepping through the eight structures displays the structures on each layer along with all the associated controlled impedance parameters for each structure.

Example 1 Copying and pasting microstrip structures

In this first example, microstrip structures will be copied from Layer 1 to Layer 14

Layer one structures

Specifying the source and target layers

The dialog comprises the structure graphic and two columns:

• the Copy column, detailing the originating structure’s signal and plane layers (layers 1 and 3 in the example below) and the total number of structures on the source layers (4 in this example.)
• the Paste column, with the new structure’s target signal and plane layers (layers 14 and 12 in the example.)

Choose the appropriate layers via the Paste dropdowns.

Click Apply – the selected structure will be reproduced on the specified destination layers. Rebuild the structures.

Example 2 Copying and pasting stripline structures

In this second example, stripline structures will be copied from Layer 4 to Layer 6

Switch to 2D view and select the Offset Stripline in Layer4

Layer 4 structures

With the first structure on layer 4 selected click on the Copy / Paste Structures button – the Structure Copy and Paste dialog is displayed.

Note that for this stripline structure, both Upper and Lower plane layers are specified in the Copy and Paste columns.

In the Paste Column:

• Choose layer 6 in the Upper Signal layer dropdown
• Choose Layer 5 as the Upper Plane Layer
• Choose layer 7 as the Lower Plane Layer
• Click Apply
• Rebuild and Calculate Structures

The new structure appears on the selected layers and Speedstack increments the total number of structures in the stackup.

Copying all of a layer’s structures

Click the Copy All check box to copy all the structures on the originating layers to the specified destination layers.
Note: it may be necessary to Goal Seek the trace widths copied from the original structure to meet the target impedance.

Many stackup designs have similar impedance structure requirements across multiple electrical layers. Once the initial set of structures has been added,
Structure Copy and Paste speeds the duplication of those structures considerably. Using Structure Copy and Paste in conjunction with the existing Mirror Structures feature provides a powerful way of quickly adding structures to the stackup.