Modern Printed Circuit Boards (PCBs) deal more with the use of the right type of packages that help improve the board’s performance, as well as reducing heat dissipation. The Small Outline No-Lead package (SON) is increasingly popular because of the improvements to those ends.
What is SON?
First of all, we want to mention that it is not so popularly-known by that acronym again as it were some years ago. It is now commonly referred to as Flat No-Leads package.
With that being said, the Small Outline No-Lead package (SON) is a type of miniaturized IC package that uses both compact sizing and increased thermal capabilities to drive the performance of the target applications.
Excellent IC Connection
Connecting the Integrated Circuit (IC) to the Printed Circuit Board (PCB) is SON’s primary function. To do that, it passes the IC through the through holes from where it would be connected or attached to the Printed Circuit Board (PCB).
As a near-chip scale IC encapsulated package, the SON ensures that none of the leads or pins extend beyond the body of the package.
The contact pads of the package are also exposed, and are often flushed with the package’s bottom. The bottom of the SON package helps to provide the much-needed electrical connection from the package to the Printed Circuit Board (PCB).
Features of the Small Outline No-Lead Package (SON)
Here are some of the attributes to expect from the SON IC package:
1. Compact Size
As one of the miniaturized IC packages, the SON ensures that the minimal space on the package is enough to contain the semiconductor components.
2. Moderate Heat Dissipation
Excellent heat dissipation is also a bonus for the SON. For emphasis, the package has an exposed thermal pad from where the heat on the Integrated Circuit (IC) is passed out and transported to the Printed Circuit Board (PCB).
3. SON has Several Variants
Choosing the Small Outline No-Lead package (SON) is a matter of understanding that it doesn’t use leads – and there are several options to pick from.
The following are some of the package’s variants:
Dual-Sided SONs
As the name implies, these are the SON IC packages with thermal pads on both sides.
Quad SONs
These are the SON IC packages with thermal pads located on all the four (4) sides of the package.
The QFN Connection
The Small Outline No-Lead package (SON) is also called the Quad Flat No-Lead package (QFN).
As a compact, lead-less and low-profile IC package, the QFN also helps to improve the thermal capabilities via the copper alloy and lead frames.
Advantages of the SON IC Package
Small Outline No-Lead IC packages gained popularity not only because of the compactness, but also because of the following additional benefits:
1. Improved Heat Dissipation
The package is best for applications that require a higher heat dissipation. The process of connecting the exposed thermal pads to the PCB is an excellent pathway for moving heat from the IC to the circuit board in real-time.
2. Small Footprint
We are not leaving out the smaller footprint of the SON, which helps in saving more real estate on the Printed Circuit Board (PCB).
3. Availability
You can check up the SON IC package across different suppliers and find it stocked, despite the high-demand.
The availability of the package is possible because of the affordability.
4. Standard Configurations
The process of optimizing the SON for performance are not fraught with challenges, thanks to the simplicity.
The Surface Mount Technology (SMT) is the underlying technology used when configuring it, thereby, ensuring a free flow for the PCB design.
5. Low Lead Inductance
The lead inductance levels of the SON package are considerably low because of the negligibility.
6. Strategic Component Placement
Placing the parts or components of a Printed Circuit Board (PCB) can sometimes be challenging, especially when you are working with a compact package.
Nevertheless, the SON IC package doesn’t compromise on that because it uses a strategic component placement format.
For example, the package has a proximity in the thermal pads, which allow for the placement of the components or parts closer to the circuit board.
7. Improved Thermal Performance
Overall, the thermal performance of the SON IC package is one of the features that bolster the circuit board’s performance. It comes in handy in the areas of transferring heat from the die/thermal pads to the board and soldering the exposed thermal pads with ease.
8. Support for Multiple Applications
The Small Outline No-Lead IC package (SON) supports the optimization of different kinds of applications.
These are the examples of the supported applications priorities:
- Weight
- Electrical performance
- Size
- Thermal performance
SON Design Challenges
As much as using the SON IC package guarantees improved thermal performance, it does have some reliability challenges.
Here are some of the bottlenecks:
Reduced Solder Bridging
The process of bridging the solder pads may be affected, especially by the Surface Mount Technology (SMT) pads.
When that happens, the overall reliability of the joints may be put at risk.
Poor Reworking
Small Outline No-Lead (SON) comes in handy when making a Printed Circuit Board (PCB), but the process of reworking or reoptimizing the design isn’t easy to come by.
Moisture Absorption Issues
Moisture absorption tends to take place during the solder reflow process, but it can lead to some issues if not properly managed.
An instance is when there is an excessive moisture absorption, possibly caused by the unmanaged inflow. In that instance, the heating of the circuit board during the reflow process can often lead to component warpage.
That means some of the components inside the SON IC package will start warping or overlapping one another.
Floating Components
In addition to warping, the parts or components used in the SON package may also float. The floating happens when there has been an excessive presence of solder paste under the thermal pad located at the center of the package.
Conclusion
The Small Outline No-Lead (SON) IC package is lead-less and increases the performance of the circuit boards. It also has its fair share of design downsides ranging from component warping to excessive moisture absorption.
If you are looking to get the best SON package configurations, contact an expert – RayPCB is one!
