What's Good About Updated Assembly Design Rules Checker? - Look to SPB16.2 and See!

21 Jan 2009 • 5 minute read

As packages continue to increase in complexity, particularly in the arrangement of multiple wirebond die components in stacked and side-by-side arrangements, there is a growing need for the ability to ensure that the final product meets manufacturing and assembly requirements.

These checks may range from something as simple as the percentage of a bond wire’s length that is over the extents of the die, or may be as complex as assessing the interaction between the bond wires and adjacent dies, spacers, and interposers above and below the wires in the same die stack.

Assembling a package can lead to a number of problems that are almost unique to this space, particularly when (stacked) wirebond dies are involved.

As a result of this, customers have asked Cadence to offer assembly/manufacturing specific design rule checking of several different rules in a package design product (SiP). These rules allow a user to gauge whether the package as designed will meet the physical and spacing requirements necessary for the part to be successfully manufactured and assembled. That is, most of the Design Rule Checks described below are checks on the size (length) of an object, the position or location of an object, or some measure of the distance between two objects. These Assembly Design Rule Checks are therefore different than the normal online DRC checks present in package design tools, which traditionally help the user find design flaws which will not meet the original system specifications or process technology limitations.

The user may wish to apply a certain check to similar items, but using different constraints depending on physical characteristics, or properties, of the items.

New Rules for 16.2

1.
Rule: “Any Metal To Any Metal Spacing”

Group: Package Substrate Rules Description: This rule will check all or top and bottom conductor layers.   The rule will check any metal to any metal (cline, via, shape) at two different clearance values for same net and different net.
2.
Rule: “Minimum Cline Segment”

Constraints: minLength (Minimum allowed length) Group: Miscellaneous Rules Description: This rule will check each cline in a design, and identify cline segments shorter than the length value entered by the user. This rule will help designers find small jogs in clines that flag as manufacturing issues, or small lines inside of pads not visible to the user.
3.
Rule: “Solder Mask Opening To Die Edge”

Constraints: clearance (Minimum Required Clearance) Group: Package Substrate Rules
Description: Checks the physical edge of single die, or the bottom die of any stack, against the boundary of Solder Mask openings, either defined as a pad or shape, to a clearance value. A check box for optional check under the die solder mask clearance to die edge will be available.
4.
Rule: “Bondable Area to Bondable Area”

Constraints: clearance (Minimum Required Clearance) Group: Miscellaneous Rules Description: For top and bottom, “AND” the top_cond metal layer with the same-side SM layer, which yields “bondable area” shapes. For top and bottom, check that BA to BA minimum clearance exceeds specified value.
5.
Rule: “Trace Minimum Angle To Trace” ( replacement for rule “Trace Minimum Angle To Conductor” )

Constraints: Min Legal Angle Group: Miscellaneous Rules
Description Checks that all trace to trace (Ts) angles are equal or greater than minimum legal angle. Trace width is not taken into consideration.
6.
Rule: “Trace Minimum Angle To Shape” ( replacement for rule “Trace Minimum Angle To Conductor”)

Constraints: Min Legal Angle Group: Miscellaneous Rules Description: Checks that all trace to shape angles are equal or greater than minimum legal angle. Trace width is taken into consideration, so each edge of the trace is checked rather than the center line.
7.
Rule: “Trace Minimum Angle To Pad” ( replacement for rule “Trace Minimum Angle To Conductor” )

Constraints: Min Legal Angle Group: Miscellaneous Rules Description Checks that all trace to via, bond finger, or pin angles are equal or greater than minimum legal angle. Trace width is taken into consideration, so each edge of the trace is checked rather then the center line. There is an option not to check bond fingers ( check box).
8.
Rule: “Acute Angle Merged Metal Check” Group: Miscellaneous Rules

Description: Checks that all cline segments to shape, via, bond finger, or pin angles are equal or greater than 90 degrees. In order to check that all metal per layer is combined into polygons and acute angle outside boundary check on each of the polygons is run.

As always, I welcome your feedback on these new features and how you're applying them in your Cadence environment.

Jerry GenPart