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What's Good About Allegro Measure, Grids and Formulas? See For Yourself in SPB16.3!

Comments(0)Filed under: PCB Layout and routing, PCB design, SPB, Allegro PCB Editor, High-Density Interconnect, HDI, Allegro, via, microvia, PCB Editor, Cline change, PCB, SPB 16.3, Allegro 16.3, layout, design, formulas, grids

This week, I’m tossing together a mix of a few new SPB16.3 Allegro PCB Editor features.

Show Measure any Layer

In the SPB16.3 release, the show measure (Display — Measure) command now measures the separation between any two objects regardless of the layer. For padstacks, the active layer as shown in the Options panel is used to determine the layer of interest. If the padstack doesn't exist on that layer then the closest regular pad to that layer is used.

When measuring between two padstacks that don't share a common layer, for example High-Density Interconnect (HDI) designs, the bottom of one padstack is compared against the top of another padstack.

Unfilled shapes are treated as solid and objects measured to these shapes are considered "no air gap" if the element is inside the shape. Text is measured to its bounding box extent.

Logic Retention on Vias

Often power and ground planes are connected together with "stitching" vias. These vias, at times, can become disconnected and re-assigned to other nets as a result of ECO (Engineering Change Order) processing or workarounds used to improve productivity with shapes. When shapes are moved off of a design and then back in place you may find the logical names of some vias have changed because the vias, like clines, take on the association of the net which is the first object touched by the moved element.

To maintain the logic associated with vias a new property "RETAIN_NET_ON_VIAS" is available and can be assigned to nets that have shapes used to flood planes -- typically power and ground nets. To add stitching vias to your design, add your first via with the add connect command and ensure that the via is associated with the correct net. You can then use the copy via command with the "preserve net" option to stitch in the remaining vias.

A side effect of this property is that nets with the property attached will keep the net name association regardless of a net name change by logic import.

If your subsection needs to be broken into smaller subsections, use the "blacktitle3" style.

Grid Setup with Formulas

With the SPB16.3 release, the grid form now supports the use of formulas to determine etch and non-etch grid settings. When entering a formula expression begin with an equal sign then enter the formula. Allegro will calculate the number and populate the grid values with the result.


Please share your experinces using these new SPB16.3 capabilities.

Jerry "GenPart" Grzenia


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