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What's Good About Dynamic Fillets in Allegro PCB Editor? Check out the SPB16.2 Release!

Comments(2)Filed under: PCB design, SPB 16.2, t-juntions, Dynamic Fillets, PCB Editor, Allegroro

The existing Fillet application, a function of the Gloss routine, has been enhanced to support the dynamic updating of fillets on pins, vias or T-junctions. The application continues to support the interactive or Batch mode options as well as the parameters in place. The new dynamic option offers the convenience of filleting during interactive etch editing with no additional procedural steps.

Shape based fill

The fill associated with Fillets has transitioned from line to shape based. For DRCs purposes, the fillet is considered an extension of the pad or via. Prior to the SPB16.2 release, line base fillets contributed to unwanted DRCs.

Shape-based fillets -

Line-based fillets -


Parameter form update

New parameters, located in the Pad and T Connection Fillet form, associated with the Fillet application include

  • Allow DRCs
  • Dynamic Fillets
  • Curved Lines



Fillet Algorithm

The algorithm first tries to create the fillet at the desired angle, tangent to the pad. If the fillet cannot be created, the angle is incremented up to the Max Angle. If the fillet length, pad tip to vertex of fillet, is greater than the Max Offset, the vertex is adjusted by an amount to satisfy the Max Offset requirement. The end points of the fillet are adjusted by the same amount to maintain the angle.



A new report called Missing Fillets Report lists junctions with missing or partial fillets. This report can be found in Tools> Reports or Tools> Quick Reports.


Boards with fillets will uprev with no conversion to shape based fillets. The SPB16.2 release will support the combination of line and shape based fillets, however new fillets added will be shape based.


Shape based fillets will be removed on downrev to the SPB16.01 release.


As always, I look forward to your comments about this new Allegro PCB Editor capability.

Jerry GenPart


By lukman on April 5, 2011
what's the benefit of a 'curved' fillet?

By Jerry GenPart on April 6, 2011
Flex designs use arcs for traces and thus curved fillets are useful in these designs.

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