DFN COMPONENT PACKAGE
DFN Component Package
|Name||DFN (Dual Flat No-lead)|
|Variants||The SON package can have a varying number of pins. There are also VSON and WSON packages which are exactly the same as the SON package except for a different height. This package can also optionally include an exposed pad.|
|Pin Count||4-20+ (depends on variant)|
|Pitch||Depends on variant.|
|Solderability||Reflow soldering is recommended. Hard to solder with a soldering iron due to underside thermal pad (some don’t have a thermal pad, and in that case, your chances are better). The tiny pitch is not so much of an issue as unlike the TQFP package, solder bridges are really easy to remove. You can solder the exposed pad in some cases by drilling a hole in the centre of the pad and soldering from the underside.|
|Thermal Resistance||Depends on variant.|
|Package LxWxH||Depends on variant.|
|Typical PCB Land Area||Depends on variant.|
DFN (Dual Flat No-lead) component package is also commonly known as the
SON package. TI also calls this the Plastic Small Outline No-lead package.
DFN package is very closely related to the
QFN package. From what I can tell, the main difference between the DFN and QFN package is that the
DFN package generally only has pins running down two of it’s sides, while a
QFN package has pins on all four sides. However, this is not a hard-and-fast rule, for example the
V-DFN3020-13 (Type A) package by Diodes Inc. has pins on three of four sides3. The other big difference I have seen is that QFN packages seem to more standardized with consistent pin/package shapes and dimensions, whilst packages labelled “DFN” can have all sorts of “weird” pad/package geometries (see the below image).
JESD75-5 specifies how generic logic circuits will be connected to certain pins of the DFN package.
Below is an “odd shaped” SON package used by Numonyx flash chips that goes under the name VDFPN8. Notice the half-round appearance of the pins.
Texas Instruments AN-1187: Leadless Leadframe Package (LLP) is a great PCB designers reference document when using DFN or QFN packages (the document calls them LLP, but it is the same thing as DFN/QFN).
The SON package has a exposed thermal pad on the underside, similar to a QFN package.
For a comparable TQFP package with the same pin count, the SON package (with an exposed pad) can usually handle more than twice the power dissipation.
The DFN-6 3x3mm package is used for components such as MOSFETs.
The DFN-8 3x3mm package is used for components such as linear regulators4.
WSON And VSON Variants
The WSON and VSON variants of the SON package are identical to the SON package except for varying heights.
The WSON variant has a height of 0.80mm (max.)
The VSON variant has a height of 1.00mm (max.)
Texas Instruments (2011, Sep). DRC (S-PVSON-N9): Mechanical Data. Retrieved 2022-10-06, from https://www.ti.com/lit/ml/mpss035d/mpss035d.pdf. ↩︎
Texas Instruments. QFN/SON package FAQs. Retrieved 2020-07-30, from https://www.ti.com/support-quality/faqs/qfn-son-faqs.html. ↩︎
Diodes Incorporated. 3.8V to 32V input, 3.5A low Iq Synchronous Buck with Enhanced EMI Reduction. Retrieved 2021-12-14, from https://www.diodes.com/assets/Datasheets/AP63356-AP63357.pdf. ↩︎ ↩︎
STMicroelectronics (2020, Apr). LDK715 (datasheet). Retrieved 2021-12-14, from https://www.st.com/resource/en/datasheet/ldk715.pdf. ↩︎
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