Example of Creating a Flatpack Package Footprint With a Thermal Pad

PartQuest Portal Subscription: Essential or Professional

This example steps you through the process of using the Footprint Creator wizard to create a custom footprint for a Quad Flatpack No-Lead (QFN) package with a thermal pad of a PartQuest Portal part. A flatpack is a surface mount package with terminals parallel to the seating plane. A thermal pad is exposed on the bottom of the IC. Terminals can be on 3 or 4 sides.

Procedure

  1. Use the PartQuest Portal search to find “TSV524IQ”, and then from any of the search results, click , and examine the part’s package information.

    The following shows package information for the TSV524IQ part.

    Figure 1. TSV524IQ Package Information



  2. From the Search page, start the Footprint Creator wizard.
  3. Use the Package Outline page to specify the package outline style and dimensions using the selections and values from the table below. When you are finished, click Continue to Terminals.

    Datasheet

    Wizard Option

    Wizard Selection/Value

    -

    Package Outline



    Dimensions (mm)

    General, Unit-of-Measure (UOM)

    mm (millimeters)

    -

    General, Mounting Preparation

    Straight Mounted

    -

    General, Body Direction

    Horizontal

    -

    Package Shape



    D (Min.)=2.90D (Nom.)=3.00D (Max.)=3.10

    Dimensions, Dimension1

    • Minimum(mm)=2.9

    • Nominal(mm)=3

    • Maximum(mm)=3.1

    E (Min.)=2.90E (Nom.)=3.00E (Max.)=3.10

    Dimensions, Dimension2

    • Minimum(mm)=2.9

    • Nominal(mm)=3

    • Maximum(mm)=3.1

    A1 (MIN)=0.00A1 (MAX)=0.05

    Dimensions, Vertical Dimension, Standoff

    • Minimum(mm)=0

    • Maximum(mm)=0.05

    A (MIN)=0.80A (NOM)=0.90A (MAX)=1.00

    Dimensions, Vertical Dimension, Body Height

    • Minimum(mm)=0.8

    • Nominal(mm)=0.9

    • Maximum(mm)=1

    The following shows the 2D package view, which results from the package outline options.



  4. Use the Terminals page to specify three terminal groups as follows:

    You can refer to the following diagram to see how the example’s terminal groups are organized.



    1. Use the Terminals page, Terminal Group 1 tab to specify the package terminal type and dimensions using the selections and values from the table below. When you are finished, click the + icon to add Terminal Group 2.
      Table 1. Terminal Group 1: Left/Right Edges

      Datasheet

      Wizard Option

      Wizard Selection/Value

      -

      Terminal



      -

      Terminal Position



      -

      Additional Terminal Position Information

      Edge-In, Left-to-Right



      -

      Additional Terminal Position Information, Rows/Columns

      NY=4

      -

      Additional Terminal Position Information, Terminal Function

      Electrical

      -

      Terminal Shape



      e=0.5

      Terminal Contact Positions, Pitch (Y)

      Nominal(mm)=0.5

      L (MIN)=0.30L (MAX=0.50

      Terminal Dimension (T.Dim), Dimension1

      • Minimum(mm)=0.3

      • Maximum(mm)=0.5

      b (MIN)=0.18b (MAX=0.30

      Terminal Dimension (T.Dim), Dimension2

      • Minimum(mm)=0.18

      • Maximum(mm)=0.3

      A3=0.20

      Terminal Dimension (T.Dim), Terminal Height

      Nominal(mm)=0.2

      A1 (MIN)=0.00A1 (MAX)=0.05

      Terminal Dimension (T.Dim), Exposed Terminal Thickness

      • Minimum(mm)=0

      • Nominal(mm)=0

      • Maximum(mm)=0.05

      The following shows the 2D package view, which results from the Terminal Group 1 options.



    2. Use the Terminals page, Terminal Group 2 tab to specify the package terminal type and dimensions from the table below. When you are finished, click the + icon to add Terminal Group 3.
      Table 2. Terminal Group 2: Back/Front Edges

      Datasheet

      Wizard Option

      Wizard Selection/Value

      -

      Terminal



      -

      Terminal Position



      -

      Additional Terminal Position Information

      Edge-In, Back-to-Front



      -

      Additional Terminal Position Information, Rows/Columns

      NX=4

      -

      Additional Terminal Position Information, Terminal Function

      Electrical

      -

      Terminal Shape



      e=0.50

      Terminal Contact Positions, Pitch (x)

      Nominal(mm)=0.5

      L (MIN)=0.18L(MAX=0.30

      Terminal Dimension (T.Dim), Dimension1

      • Minimum(mm)=0.18

      • Maximum(mm)=0.3

      b (MIN)=0.30b (MAX=0.50

      Terminal Dimension (T.Dim), Dimension2

      • Minimum(mm)=0.3

      • Maximum(mm)=0.5

      A3=0.20

      Terminal Dimension (T.Dim), Terminal Height

      Nominal(mm)=0.2

      A1 (MIN)=0.00A1 (MAX)=0.05

      Terminal Dimension (T.Dim), Exposed Terminal Thickness

      • Minimum(mm)=0

      • Nominal(mm)=0

      • Maximum(mm)=0.05

      The following shows the 2D package view, which results from the Terminal Group 2 options.



    3. Use the Terminals page, Terminal Group 3 tab to specify the package terminal type and dimensions using the selections and values from the table below.
      Table 3. Terminal Group 3: Thermal Pad In the Center

      Datasheet

      Wizard Option

      Wizard Selection/Value

      -

      Terminal



      -

      Terminal Position



      -

      Terminal Position, Rows/Columns

      NX=1NY=1

      -

      Terminal Position, Terminal Function

      Electrical

      -

      Terminal Shape



      D2 (MIN)=1.50D2 (MAX=1.80

      Terminal Dimension (T.Dim), Dimension1

      • Minimum(mm)=1.5

      • Maximum(mm)=1.8

      E2 (MIN)=1.50E2 (MAX=1.80

      Terminal Dimension (T.Dim), Dimension2

      • Minimum(mm)=1.5

      • Maximum(mm)=1.8

      A1 (MIN)=0.00A1 (MAX)=0.05

      Terminal Dimension (T.Dim), Exposed Terminal Thickness

      • Minimum(mm)=0

      • Nominal(mm)=0

      • Maximum(mm)=0.05

      The following shows the 2D package view, which results from the Terminal Group 3 options.



    4. When you are finished, click Continue to Details.
  5. Use the Details page to specify the package terminal numbering pattern as follow:
    1. From the 2D package preview, select the terminals on the left edge of the package by clicking the lower-left terminal, and then shift-clicking the upper-left terminal.

      The tool highlights the terminals.

    2. Click , choose Numerical from the dropdown list, and then type 1 in the text entry field.

      The tool numbers the pads from back to front.

      The following shows the 2D package view, which results from the terminal numbering options.



    3. From the 2D package preview, select the terminals on the top edge of the package by clicking the top-left terminal, and then shift-clicking the top-right terminal.

      The tool highlights the terminals.

    4. Click , choose Numerical from the dropdown list, and then type 5 in the text entry field.

      The following shows the 2D package view, which results from the terminal numbering options.



    5. From the 2D package preview, select the terminals on the right edge of the package by clicking the upper-right terminal, and then shift-clicking the lower-right terminal.

      The tool highlights the terminals.

    6. Click , choose Numerical from the dropdown list, and then type 9 in the text entry field.

      The following shows the 2D package view, which results from the terminal numbering options.



    7. From the 2D package preview, select the terminals on the bottom edge of the package by clicking the bottom-right terminal, and then shift-clicking the bottom-left terminal.

      The tool highlights the terminals.

    8. Click , choose Numerical from the dropdown list, and then type 13 in the text entry field.

      The following shows the 2D package view, which results from the terminal numbering options.



    9. From the 2D package preview, select the terminal at the center of the package.

      The tool highlights the center terminal.

    10. Click , choose Custom Pattern from the dropdown list, and then type NC into the text entry field.

      The following shows the 2D package view, which results from the terminal numbering options.



    11. Choose Plastic from the Package-body Material list, and then click Continue to Validate.
  6. Close the Solder Mask Gang Relief Alert popup message box.
  7. Use the Validate page to view the footprint for various target design densities.

    The following 2D package view shows the footprint summary generated by the Footprint Creator wizard for the TSV524IQ part package and a target design density setting of most material condition (low density).



    The Footprint Creator wizard displays the footprint summary as follows:

    Manufacturing Process Part is Compatible with:

    • SMT (May require special attention)

    • Manual Placement

    Solder Mask Clearance — 60.0 µm

    Stencil Thickness Allowable:

    • 75 µm (3mil)

    • 100 µm (4mil)

    • 125 µm (5mil)

    • 150 µm (6mil) (May require special attention)

    Solder Paste Size — Solder Paste Aperture is set to 1:1 with the Pad.

Results

The flatpack package footprint is complete.