PCB Fabrication Enhancements

In aPriori Professional 2022 R1 SP1, these enhancements to the PCB Fabrication manufacturing process model improve aPriori's ability to recognize PCB features from the ECAD file exports and extends support to additional ECAD systems:

Improved Recognition of Internal and External Contours

Obtain more accurate cycle time and cost estimates for contours.

aPriori Professional can now read multiple ways of defining internal contours and better estimates the size of the PCB, resulting in more accurate cycle time and cost estimates.

Previously aPriori Professional extracted internal contours and holes only from the drill file within the Gerber Export. In this release aPriori also searches for internal contours and large holes defined in the Gerber layers. As a result of this enhancement, more internal contours may be recognized and if so, the cycle time and cost for routing of these contours now will be included in the manufacturing estimate.

Recognition of internal holes and cutouts from the Gerber layers is controlled by two site variables:

  • minInternalCutoutAreaMm2 – Minimum area for a contour that the algorithm will extract. This site variable does not affect contours extracted from the drill file. The default value is 2 mm2. To disable extraction of internal cutouts please set this site variable to a value larger than the largest PCB you design.

  • minInternalHoleDiameterMm – Minimum diameter for a hole that the algorithm will extract. This site variable does not affect holes extracted from the drill file. The default value is 4 mm. To disable extraction of internal large holes please set this site variable to value larger than the largest PCB you design.

When aPriori cannot find the outline of a PCB it defaults to using the bounding box of the extracted holes for the PCB outline. This release enhances the geometry extraction algorithm to improve the detection of the external perimeter and reduce the frequency of defaulting to the bounding box of the extracted holes.

These changes are accompanied by a new site variable, outlineToleranceRatio, which represents the maximum percentage difference between a possible external outline contour in a Gerber layer and the bounding rectangle of the extracted holes. By default, this value is set to 0.5.

The default value of the existing site variable contourSizeToleranceRatio was changed to 0.05 from 0.15.

Due to this enhancement, aPriori now estimates the board size more accurately in cases where it previously underestimated the size. This occurred in 7% of parts in a large test set. It did not result any negative changes to parts which previously had the external perimeter extracted correctly.

If you notice extraction differences and want to revert to previous behaviour, change contourSizeToleranceRatio back to 0.15 and set outlineToleranceRatio to 0.15.

PCB Extended Gerber Format and ECAD System Support

aPriori Professional can extract PCB information from additional ECAD systems and supports a greater range of format variations from previously-supported systems.

Minor extensions that have been added to the existing XSLT mapping file, allow aPriori Professional to successfully extract GCDs from more Allegro, PADs and Altium files. These updates do not affect files previously opened by aPriori Professional.

aPriori also has extended the XSLT mapping files to support Gerber files exported from the following ECAD systems.

  • Eagle

  • CADSTAR

  • Pentalogix

For more information on the XSLT mappings please see the 2022 R1 SP1 aPriori Cost Model Guide.

Important: You must manually import the latest PCB XLST mapping file to enable the enhanced support for additional ECAD systems and Gerber file variations. It is not applied automatically as part of the upgrade process. Please contact aPriori Support to obtain the updated XSLT mapping file.