Question: How does the silkscreen spacing option considerpads are too close?

Example of a trimming rule: the Calculator trims padsizes for you when they fail to meet the specifications in Rules.  Thedefault values we use are all considered best industry practice.

Note: pad clearances are not guaranteed for FP Designer footprintsand there are no warnings.

The clearance of the silkscreen to the body and any pads isset in the Drafting > Silkscreen options. The silkscreen isautomatically trimmed, if required, to meet these values.

There is a hard-coded minimum silkscreen line length of 3silkscreen line widths.  Any silkscreen line segment lessthan this length is removed to avoid the appearance of ‘specks’ on a PCB.

Here is a 0603 chip capacitor that has enough pad-to-padspacing to allow a silkscreen line. This silkscreen outline length exceeds 3line widths.

Here is a 0603 chip capacitor that violates the pad-to-padspacing to allow a silkscreen line. The silkscreen outline wraps around thepads and the courtyard outline is pushed out to include the expanded silkscreenoutline.

You have options to turn off the silkscreen outline if thepattern is too small to create one.

You can also turn off the courtyard excess for including thesilkscreen outline.

The Local Options are in the Footprint Expert standard component package calculators. These Options are used to test option features to experience the settings in real time. The user makes notes of the features they want to use in Global Options. Once all the Global Options are defined, the Local Options are only used for one of a kind footprint.

One of the most popular FAQs regarding using Local Options is "I set the Local Options to create a custom footprint and save the data to a FPX file library and when I reopen the footprint from the FPX library into the Viewer, all the Local Option Settings that were selected are reset to default Options".

The Local Option Settings are not saved to the FPX file library, except 3D STEP Colors, Footprint Rotation and Mfr. Recommended Footprint as noted by Bold Italic Characters.

Here are the Local Options in every standard package Calculator:

Options

 

• Set the Pin 1 Orientation. Changes to this setting are saved to the FPX file library.
• Lower Left - default setting
• Lower Right
• Upper Right
• Upper Left
• Origin - This is set locally and not saved to the FPX file library.
• Center Of Extents - default setting
• Pin 1
• Pads On Assembly - This is set locally and not saved to the FPX file library.
• None - default setting
• Outline
• Filled
• Tabs On Assembly - This is set locally and not saved to the FPX file library.
• None - default setting
• Outline
• Filled
• Default Pad Shape - This is set locally and not saved to the FPX file library.
• D-Shape
• Oblong
• Rectangle
• Rounded Rectangle - default setting
• Pin 1 Pad Shape - This is set locally and not saved to the FPX file library.
• D-Shape
• Oblong
• Rectangle
• Rounded Rectangle - default setting

3D Colors - Any changes are saved to the FPX file library.

• Set the Primary Body
• Secondary Body
• Default Leads
• Pin 1
• Primary Polarity

Design Options

Units and Decimal Place Accuracy - These settings are not saved to FPX file library

• Units - units are not saved to the FPX library
• Millimeters - default setting
• Micrometers
• Mils
• Inches
• Specifications and Calculations
• Minimum settings appear in the Calculators
• 1 = 0.1
• 2 = 0.01- default setting
• 3 = 0.001
• 4 = 0.0001
• 5 = 0.00001
• 6 = 0.000001
• Maximum setting is the character limit in the Calculators
• A setting of 3 will limit the calculator input values to 3 places to the right of the decimal point
• Calculated Footprint
• Pad Size roundoff
• 1 = 0.1
• 2 = 0.01- default setting
• 3 = 0.001
• 4 = 0.0001
• 5 = 0.00001
• 6 = 0.000001
• Pad Place roundoff
• 1 = 0.1
• 2 = 0.01- default setting
• 3 = 0.001
• 4 = 0.0001
• 5 = 0.00001
• 6 = 0.000001

Footprint and Pad Stack Naming - These settings are not saved to FPX file library

• Footprint Naming Convention
• PCB Libraries (formally IPC-7351C and approved by the IPC Land Pattern Committee)
• IPC-7351B
• IPC-7352
• Create Footprint Name Using (Units)
• Millimeters - default setting
• Micrometers
• Mils
• Inches
• Replace Density Level Suffix With… - users can create their own Density Level
• Pad Stack Naming Convention
• IPC-7352 - default setting
• IPC-7351B
• Create Pad Stack Name Using (Units)
• Millimeters - default setting
• Micrometers
• Mils
• Inches

Footprint Inclusions

• Ignore Manufacturer's Footprint Dimensions (for Batch Builds) - Default Off
• Include Suffix in Footprint Name - Default On
• Generate Solder Mask - Default On
• Generate Surface Mount Paste Mask - Default On
• Generate Through-hole Paste Mask - Default Off (Pin-in-Paste Technology 

Terminal Density Level - These settings are not saved to FPX file library

• Density Level (Suffix)
• Least (L)
• Nominal (N) - Default Setting
• Most (M)
• Courtyard to Body Excess
• 0.20 - Default Setting
• Courtyard to Pad Excess
• 0.20 - Default Setting
• Toe
• Heel
• Side

Terminal Lead image pop-out

SMD Pad Stack Rules - These settings are not saved to FPX file library

• Solder and Paste Masks - None of these settings are saved to FPX file library
• Minimum Allowable Solder mask Web - 0.075 (default)
• Solder Mask Annular Expansion (+/-) - 0.00 (default)
• Paste Mask Annular Expansion (+/-) - unchecked default setting
• Paste Mask (% of Pad Size) - 100% (default)
• Set SM Grid Array Options in Terminal Density Settings
• Corner Rounding
• Corner Radius Size (% of Pad Width) - 25% (default)
• Corner Radius Size Limit - 0.10 (default)
• Manufacturing Tolerances
• Fabrication Tol. (+/-) - 0.00 (default setting per IPC-7352)
• Placement Tol. (+/-) - 0.00 (default setting per IPC-7352)
• Minimum Trim and Spacing
• Minimum Pad to Pad - 0.15 (default)
• Minimum Pad to Thermal - 0.20 (default)
• Minimum Trim Standoff Height - 0.03 (default)
• This is used on Gullwing Terminal Leads to trim pads under packages with the PCB standoff of less than 0.03
• Thermal Tabs
• Thermal Tab Solder Mask Expansion (+/-) - 0.00 (default)
• Thermal Tab Pattern Defined Solder Mask - Off (default)
• Thermal Tab Paste Mask (%) - 60% (default)
• Thermal Tab Minimum Pattern Space - 0.20 (default)
• SMD and TH Miscellaneous
• Cathode/Anode Pin Names 
• Alphanumeric (default)
• Numeric

Drafting Options > Silkscreen - These settings are not saved to FPX file library

• Outline Width 0.15 (default)
• Clearance to Pads - 0.15 (default)
• Map Outline to Body 
• None
• Minimum
• Nominal 
• Maximum (default)
• Margin
• Outline to Body Margin - 0.15 (default)
• This is used when Map Outline to Body Margin is selected
• Offset Outline Away From SM Body - On (default)
• This converts the line origin from the center to the edge of the line
• Minimize Silkscreen Ink - Off (default)
• This converts Full Silkscreen Outline to Hatched Outline
• Allow Expanded Outline - On (default)
• This wraps the silkscreen outline around the footprint if the silkscreen outline clearance to pads rule is violated
• Pin 1 Marker Size Not Larger Than - 0.50 (default)
• The polarity dot diameter is determined by the pad width. This setting limits the diameter.
• Pin 1 Marker Size Not Smaller Than - 0.50 (default)
• The minimum polarity dot size for visual inspection without magnification is 0.40
• Add Pin 1 Marker to Footprint - On (default)
• Autogenerate Pin 1 Indicator Line - Off (default)
• This feature only works for pads outside the component body and not BTC components
• Reference Designator Height - 1.20 (default)
• Ref. Des. Width (% of Height) - 10% (default)
• Add Ref. Des. to Footprint - On (default)
• Add Text Value to Footprint - Off (default)

Drafting Options > Assembly - These settings are not saved to FPX file library

• Outline Width - 0.12 (default)
• Add Outline to Footprint - On (default)
• Add Polarity Indication to Footprint - On (default)
• This adds a 45-degree chamfer in the assembly outline near pin 1
• Map Outline to Body
• Minimum
• Nominal
• Maximum (default)
• Ref. Des. Height Min. - 0.50 (default)
• The Ref Des is scaled to fit inside the assembly outline
• Ref. Des. Height Max. - 2.00 (default) 
• This is the maximum assembly ref des height
• Ref. Des. Width (% of Height) - 10% (default)
• Add Ref. Des. to Footprint - On (default) 
• Add Text Value to Footprint - Off (default)

Drafting Options > Courtyard - These settings are not saved to FPX file library

• Outline Width - 0.05 (default)
• Add Outline to Footprint - On (default)
• Expand Courtyard to Include Silkscreen - On (default)
• Apply Courtyard Excess Option to Body - Yes (default)
• Selecting No will turn off the courtyard excess
• Apply Courtyard Excess Option to Pads - Yes (default)
• Selecting No will turn off the courtyard excess
• Selecting Ignore will turn off the pads
• Contoured Outline - On (default)
• Off = a rectangular courtyard
• Minimum Courtyard Cut-in Gap - 5.00 (default)
• This feature controls the courtyard cut-in between the pads

Drafting Options > Origin - These settings are not saved to FPX file library

• Outline Width - 0.05 (default)
• Crosshair Size - 0.70 (default)
• Add Crosshair to Footprint - On (default)
• Target Diameter - 0.50 (default)
• Add Target to Footprint - On (default)

Drafting Options > Component and Terminal Outlines - These settings are not saved to FPX file library

• Component Outline Width - 0.025 (default)
• Add Component Outline to Footprint - On (default)
• Terminal Outline Width - 0.025 (default)
• Add Terminal Outlines to Footprint - On (default)

Footprint > Manufacturer's Dimensions - These dimensions are saved to the FPX file library

• Use manufacturer's recommended dimensions - Off (default)
• Selecting On turns on the manufacturer's dimension cells
• G = pad to pad gap
• X = pad length
• Y = pad width

Footprint > Calculation Details - These settings are not saved to FPX file library

• Component 
• These are package dimensions
• L = E
• S = G
• T = L

 

• True Footprint
• Zmax = G + X times 2
• Gmin = G
• Yref = Y

• Terminal Protrusion Goals
• Outer - Goal, Min, Max
• Inner - Goal, Min, Max
• Side - Goal, Min, Max

 

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LEAP - Libraries Enhanced by Automated Preferences

• Minimum pad to pad spacing
• Minimum pad to thermal pad spacing
• Minimum trim stand-off height for gullwing terminals

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To get a fully functional Footprint Expert license, complete the Evaluation License request on the Downloads page. Make sure to provide all the requested information, such as your company details and CAD outputs needed.

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Call:  847-557-2300

These Drafting Outlines are Auto Generated in Footprint Expert and 100% user controlled:

1. Silkscreen Outline, Reference Designator and Pin 1 Polarity Dot
2. Assembly Outline, Reference Designator and Polarity Chamfer
3. Courtyard Excess (Contoured or Rectangle)
4. Origin Marker (Crosshair and Target)
5. Component and Terminals
6. Assembly Pads

1. Silkscreen Outlines and Reference Designators for 3 Density Levels Most, Nominal and Least
Silkscreen outlines and reference designators are included in the PCB fabrication output files. The following rules can be applied separately to each Density Level. It is important to note that in most fabrication shops the minimum legend line width is 0.10.

a. Outline Width Default Settings (user definable)

• Most Density default width is set to 0.20
• Nominal Density default width is set to 0.15
• Least Density default width is set to 0.12

b. Clearance to Pads

• This rule must consider the solder mask expansion annular ring and add 0.10 to that value. If your solder mask annular ring is 0.05 + 0.10 = 0.15 pad to silkscreen gap. Appling the silkscreen to the PCB has a 0.05 misalignment tolerance and the minimum silkscreen to solder mask rule is 0.05.

c. Map Outline Body

• Maximum (default setting)
• Nominal
• Minimum

d. Reference Designator Height

• Most Density default height is set to 1.50
• Nominal Density default height is set to 1.20
• Least Density default height is set to 1.00

e. Pin 1 Marker Size Not Larger Than... (defaults)

• 0.60 - Density Level Most (M)
• 0.50 - Density Level Nominal (N)
• 0.40 - Density Level Least (L)

f. Pin 1 Marker Size Not Smaller Than... (defaults)

• 0.60 - Density Level Most (M)
• 0.50 - Density Level Nominal (N)
• 0.40 - Density Level Least (L)

The CAD librarian can enter different values for the "Not Larger Than" and "Not Smaller Than" the program will auto-size the dot per the pad width. The smallest polarity dot visible on the PCB without magnification is 0.40. The silkscreen polarity dot is placed to the left of Pin 1 because the end of pin 1 could be a via location. Avoid placing silkscreen in potential via locations.

Here is an example of a 0.65 mm pitch SOP with a 0.50 Pin 1 Dot. 

2. Silkscreen Settings All Density Levels

 

a. Ref. Des. Width (% of Height)

• This feature is used for "Stroke" font.
• The default setting is 10% of the ref des height. Larger percentages can cause character bleeding, making the letters illegible on the PCB.  

b. Add Outline to Footprint (on-off)

• The default is On, but some companies do not put silkscreen legend on final PCBs
• You can build an entire PCB library with legend and one without

c. Autogenerate Pin 1 Indicator Line

d. Add Polarity Marker to Footprint (on/off)

e. Add Ref. Des. to Footprint (on/off)

f. Add Value to Footprint (on/off)

• The default is Off

g. Offset Outline Away from SM Body

• The default is On. Places silkscreen outline outside the component body.
  
  

h. Minimize Silkscreen Ink (crop rectangle Outlines)

• Unchecked equals a Full Silkscreen outline
• Checked equals a Hatched Silkscreen outline

i. Allow Alternate Outline (when geometry is too small for default outline)

• Unchecked equals no silkscreen outline if the footprint is too small
• Checked equals a wraparound silkscreen outline if the footprint is too small

3. Assembly Outlines and Text

 

a. Outline Width

• Default value is set to 0.12, but users change this value for their own custom library

b. Add Outline to Footprint (on/off)

• The default setting is On

c. Add Polarity Indicators to Footprint (on/off)

• This feature adds a polarity chamfer in the outline to the corner where Pin 1 is located. The default setting is On

d. Map Outline Body

• Maximum (default setting)
  This means that the legend outline will map to the maximum package dimensions
• Nominal
• Minimum

e. Ref. Des. Height Minimum

• Footprint Expert auto-sizes the ref. des. height to fit in the middle of the assembly outline. The default minimum value is 0.50.

f. Ref. Des. Height Maximum

• The default maximum value is 2.00

g. Ref. Des. Width (% of Height)

• This feature is only used for the CAD tool "Stroke" font. It is not used for Windows text fonts. The default value is 10%.

h. Add Ref. Des. to Footprint (on/off)

• The default setting is On

4. Courtyard Outlines

a. Outline Width

• The default value is 0.05

b. Add Outline to Footprint (on/off)

• This feature turns the courtyard outline on or off. The default setting in On.

c. Expand Courtyard to Include Legend (on/off)

• The default setting is On

d. Apply Courtyard Excess Option to Body (Yes/No)

• This feature applies the Courtyard Excess to Body or turns it off.

e. Expand Courtyard Excess Option to Pads (Yes/No/Ignore)

• This feature applies the Courtyard Excess to Pads or turns it off or Ignores pads.

f. Contoured Courtyard (on/off)

• This feature selection is contoured outlines (on) or rectangular outlines (off):
• Contoured On
  
  
• Contoured Off
  
  

g. Minimum Courtyard Cut-in Gap

• The default value is 5.00. This feature allows the courtyard outline to cut in-between pads of whatever value you set. If the cut-in gap is 1.00 then the courtyard will contour between pads that have greater than 1.00 separation. Cut-in Gap 5.00 
  
  
  Cut-in Gap 0.50. The courtyard cut-in between pins 1 & 2
   
  

a. Outline Width 

• The default line width setting is 0.05

b. Crosshair Size

• The default value is 0.70

c. Add Crosshair to Footprint (on/off)

• The default setting in On

d. Target Diameter

• The default value is 0.50

e. Add Origin Target to Footprint (on/off)

• The default setting in On

6. Component and Terminal Outlines

 

a. Component Outline Width

• The default value is 0.025

b. Include Comp. Outline in CAD Output (on/off)

• The default setting is On

c. Terminal Outline Width

• The default value is 0.025

d. Include Terminals in CAD Output (on/off)

• The default setting is On

Terminal Outlines