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If you use cross-hatched shapes in your package design, you are doubtless aware of some considerations. Namely, if your shape outline is anything but a rectangular outline at a multiple of the hatch line width pattern, and unless it has no objects to be voided or connecting to it, then some of the negative space in the shape fill is likely to be partial holes.
Looking below, this is a simple shape outline. The size, outline angles, and hatch pattern result in a collection of smaller than desired holes:
The small, barely-visible triangles along the diagonal edge and the long, skinny hole along the right-hand side will both be issues come manufacturing time. Most designers opt, instead, to have these areas filled instead of left as small unfilled areas.
How, then, do you accomplish this within the Cadence® SiP Layout tool?
For years, the design community has made use of the beta command Cross-Hatch Void Fill. Enabled with the icp_crosshatch_void_fill_beta user preference, this command was in the Shapes menu near the Create Bounding Shape feature.
When run, it provided a simple interface, below, which permitted you to select one or more cross-hatched shapes in your design and add small, solid-filled shapes to cover the partial openings.
While you can control the minimum hole size before the hole gets filled, and while the tool would also consider voids, clines, pins, and other objects on the same net which connected to the shape, this command has some significant downsides:
It is not dynamic, meaning that if you make any changes to the shape, you must re-run the command again to remove unnecessary fill areas and refill any new areas not meeting the parameters.
Small fill shapes could be left behind in the design if you didn’t notice to remove them when removing/modifying the master shape. As these objects are typically very small, they are easy to miss visually in the canvas.
Because these fill elements are themselves shapes, you must configure the minimum shape area in the global shape parameters to be small enough to enable them to be filled, otherwise, they do not perform their intended role.
Using our original example, the shape, after running this command, would look like the below. There are some advantages to this fill style, though. You can select any of those fill items and, if desired, manually remove them. This gives you total control over the shape fill.
With the 17.2 release, however, the command above is slowly being phased out (we understand there is always a migration period with your designs!), replaced with a much simpler, more intuitive interface…
If you run 17.2 today, bring up the global shape parameters form (or the instance parameters form for one of your hatched shapes). On the void controls tab, seen below for our example shape instance, you’ll notice the Fill XHatch Cells entry near the bottom. Or, maybe you did not – it’s just one item on a complex form. You may have overlooked it!
This option provides much of the same functionality as the old, standalone command did. But in a far superior manner. Using this, the partial holes will be filled with fill lines that are part of the parent shape itself.
As fill lines, the holes will never fail to fill because they violate the minimum area parameter, meaning you needn’t edit that value. Whenever you modify the design and impact this shape, the partial void covers are updated as part of the hatching fill line update. This means you never have to worry about small shapes being orphaned you didn’t see, or that there may be unfilled holes which could result in manufacturing complications.
The parameter on the form has four values – Off, Low, Medium, and High. Off, being the default, provides the fill style you’re used to for a standard cross-hatched shape. The other three options provide increasing levels of coverage for what size of hole is considered too small and must be filled. High, for instance, says that any hole not 100% complete, should be filled in.
Because the system manages the filled cells, you cannot delete specific elements to re-expose that partial hole. If you find you have a requirement to do this, please contact us so we can understand your manufacturing concerns and use model.
The new options provide you with much better performance and improved integration within your design flow, eliminating manual steps you must remember to follow and replacing them with automation that ensures your design is as ready for manufacturing today as you are!