QFP vs. QFN

Introduction

If you’re someone who’s currently dealing with surface-mount packages that deal with integrated circuits (IC) in their circuit boards, then the QFN and QFP are familiar to you.

However, you might be here because you’re confused about their capabilities and differences. Hence, we’ve created a thorough differentiation between the QFN against QFP.

All of your questions concerning the Quad Flat Package (QFP) and Quad Flat No-Lead Package (QFN) will be addressed in this article, including their definition, working principle, advantages, various classifications, and their critical distinctions from each other.

Thus, we recommend finishing the article by the end to choose between these two packages carefully; we’ll help you decide the highly suitable one for your applications!

Introduction to QFP vs. QFN

What is QFN?

Another term for QFN would be Quad Flat No-Lead Package. As its term indicates, this package doesn’t contain any presence of lead on them. It is considered to be compact in design and provides average performance for heat dissipation.

Further, its process of integration requires a Surface Mount Technology (SMT) to apply in a device successfully. In terms of its functionality, it is similar to other IC packages; it acts as a bridge to link the silicon die through the circuit board IC.

As for its properties, the QFN features a halogen-free and lead-free material. Additionally, its seated height could range from 0.35 mm up to 2.10 mm as its maximum value. However, it is suggested to go for the traditional value of 0.85 mm to achieve optimum results.

In addition, the QFN fully complies with RoHS, ELV, and REACH; thus, they are safe for any environmental purposes. As for its terminal plating, it is primarily comprised of Nickel, Palladium, Gold, and Tin (Ni-Pd-A and Sn).

In-depth Understanding of QFN Package

Advantages of QFN Packages

In order to narrow down one’s choices between the QFN and QFP, we’ve listed the benefits one could get from the QFN package. Further, having the knowledge of its abilities will make you understand the package way better and assess whether they are suitable for your desired purposes and applications.

• Since QFNs are compactly designed, they are lightweight and straightforward to handle.
• The QFN comes with both small footprint factors and slender profiles.
• Its adhesive strands that link the die and structure are only a few inches long.
• The QFN has low lead inductance.
• If the application requires efficient heat dissipation, then the QFN is the perfect option.
• As for its cost, it is inexpensive and highly accessible to everyone.

Different Types of QFN Packages

The QFN Packages are available in a range of configurations, as indicated. All of them will be discussed underneath.

Plastic-Molded

The Plastic-Molded version of QFN Packages is the least costly of the various varieties. However, it doesn’t include any lids on it, and it is only comprised of a plastic composite and a copper-lead structure. As for its operation capability, it can perform well in frequency that ranges from two (2) to three (3) GHz. If the project exceeds the limit, it might not function flawlessly.

The Air Cavity QFN

The Air Cavity QFN, as its name suggests, includes a contained air within its packaging. As a result, it may be costlier than other QFN variants. Yet, given that it operates between 20 and 25 GHz, its value is justified. Apart from that, it comprises a copper-lead structure, ceramic lead, and a plastic molded foundation that is plastic molded that comes with or without an enclosure.

Wettable Flanks QFN

Each platform of these flanks is raised to display the sticky wetness. In order to determine whether the pads are correctly seated on the circuit board, one can scrutinize them.

The Punch-Type QFN

The formed module is contained in one casting process in such QFNs, and the chamber is divided by a punch tool, hence the term. Conversely, this technique can also be used to shape the QFN into a standalone product.

The Sawn Type QFN

This package mainly employs the MAP or also known as Mold Array Process, wherein one big package is divided into countless little pieces and then sorted afterward.

Flip Chip QFN

The silicon die and copper-lead frame are joined together using flip-chip QFN technology, as its name indicates. This technique is appropriate for electronic applications since it makes the current link between them quicker.

Wire Bond QFN

As the term indicates, the Wire Bond QFN utilizes the presence of cables to link the terminal chip to other components externally; it can directly attach to an IC, PCB track, and even a semiconductor.

What is QFP?

Another type of surface-mount IC package, the QFP, also referred to as the Quad Flat Package, is identical to the QFN. However, with a specific purpose, they are widely preferred in applications that deal with large-scale integrated circuits (IC).

In terms of dimensions, the QFP is small in size, making them ideal for high-frequency applications. As for the materials used in its production, it is composed of ceramic, metal, and plastic. However, they aren’t leadless, unlike the QFN.

Nevertheless, it still ranks first concerning quantity since it is a plastic package; hence, many industries prefer this package to the QFN. Further, it can come in two shape variations, square, and rectangle. They only differ in terms of pin placements on each side; the square has an equal count of pins on every side, while the rectangular has a varying count of pins on every side due to its varying lengths.

In-depth Understanding of QFP Package

Advantages and Disadvantages of QFP Packages

Since we already know the QFN Package advantages, it is the perfect time to discuss the QFP Package benefits and limitations to narrow down further the choices one must take. We’ve compiled its pros and cons in this section to comprehend QFP fully.

Advantages

• It employs cutting-edge engineering.
• It is able to use ports.
• In contrast to rectangular QFP packages, square QFP packages may hold more pins.

Disadvantages

• It only has 500MHz input-output capacity.
• Its chips have insufficiently sophisticated input/output.
• Since there are more pins on square packaging, they are flimsier.

Different Types of QFP Packages

As noted previously, there are loads of different QFP Packages. A discussion of each will follow.

Bumper QFP

This package has guard appendages on all four edges to prevent surface defects to the leads prior to assembling. Due to their fine pitch, nearly none of these lead connectors can be twisted to mend them after being deformed or destroyed.

Bumper Quad Flat Pack with Heat Spreaders

It is regarded that this variation is an enhanced version of the BQFP; however, with an additional heat spreader on them that allows quick dissipation even when exposed to high power levels.

Ceramic QFP

As its term states, the Ceramic QFP utilizes a ceramic material as its foundation that increases the device’s quality, efficiency, and performance.

Fine-Pitched QFP

Similar to the Ceramic QFP, the Fine-Pitched QFP features materials on them that are finely pitched.

Heat-Sink QFP

Integrated circuits (ICs) with increased pin values can dissipate much heat. Consequently, this temperature must be effectively dispersed for an IC to perform to its full potential. One can add a heat sink in such packages by switching out some connections for sturdier ones, usually in the middle of the opposition side. Then, attach these leads to a larger PCB chip with a larger copper surface. This system ought to regulate temperature considerably more efficiently.

Low Profile QFP

In this particular package, they are well-known for their thickness, which is commonly at 1.4 mm. Further, it has a 2 mm lead-frame dimension, 32 to 256 as its lead count value, several body size options ranging from 5 mm by 5 mm to 28 mm by 28 mm, and varying pitches options.

Metric QFP

This version employs metric measurements instead of the English ones used by standard QFPs to specify their dimensions.

Plastic QFP

As its term suggests, this package is constructed with the use of plastic.

Thin QFP

Despite its slim profile shape and a 1 mm height, it is plastic-built. Additionally, they use a standard 2 mm lead frame structure.

Difference Between the QFN Packages and QFP Packages

In order to fully distinguish the QFN Package from the QFP Package, we’ve created a table to grasp their concepts quickly.

Factors	QFP	QFN
Lead	It spreads like an L-shape.	It extends on all four sides.
Assembly	Even throughout the process of assembling the PCB, the QFP-Lead configuration provides an excellent foundation for the QFP package.	The median cabling for QFN packages happens in the PCB assembly process.
Pin Count	It can accommodate countless pins, as many as a total of 280.	It only has a total of eight (8) pins with an additional thermal pad.

QFN Assembly

Since we value transparency in PCBTok, we’d like to discuss the fundamental phases we take in assembling a QFN Package.

Solder-Paste Printing

In this stage, we conduct even solder paste application across the entire board before submitting it to the next phase of the assembly, the integration of components.

Component Placement

After being subjected to a thorough solder printing and verifying if they are suitable for component placement, we strictly and precisely select the tools needed for the incorporation to prevent issues since the components possess high interconnection density.

Pre-Reflow Inspection

We conduct this stage to guarantee that the board is suitable to enter the oven for the reflow soldering. In that way, unnecessary elements on the board’s surface will be eradicated, ensuring a smooth soldering process.

Reflow Soldering

In this phase, the components are soldered through the board.

Post-Reflow Inspection

Ultimately, we conduct this stage to assess the quality of the byproduct.

QFN Soldering

As we all know, soldering is a crucial stage of the board assembly, and some cases of failures during this phase cannot be undone. Hence, it is essential to have knowledge of the soldering process performed in a QFN Package.

After filtering the solder paste, the elements are put together in the production system. In addition, when the QFN components have been inserted using a pick and spot tool, they are connected using reflow soldering. Additionally, the temperature of the soldering furnace will cause some PCB components to warm up more rapidly than others. While heavier parts and areas with a lot of copper will take longer to respond.

Further, the degree of the QFN package’s upper surface is monitored using thermocouples during the process. In order to ensure that the maximal bundle core temperature does not go above the established limits.

QFP Assembly

In assembling the QFP, it doesn’t differ that much from the QFN Package. Its process will be dissected underneath.

Stencil Printing

In this stage, the solder paste will be applied through the use of a stencil. It must be conducted thoroughly since overly attached solder paste can lead to bridging, whereas bad solder can lead to minimal spreading. Hence, we carefully select the appropriate thickness during this stage. Further, it is necessary to consider the solder paste as well. It is recommended to utilize a lead-free paste.

Component Placement

After the stencil printing, we can now install its necessary components. Given the surface pressure of the liquid solder, QFP pieces self-align, leading to robust solder junctions. However, one still needs to arrange the piece correctly, and a P&P machine can help to do this.

Reflow Soldering

Since reflow soldering is performed in a nitrogen-filled environment, force convection ovens are the optimal option. Nevertheless, this is not required; consideration of the package recommendations is essential.

Conclusion

To wrap things up, there are countless factors that differentiate the QFN from QFP. However, both of these packages are helpful in various applications. On the other hand, they also have a lot of similarities with each other. We hope that we’ve helped you in deciding through this article.

PCBTok genuinely cares for its readers and potential customers; hence, we’ve extensively researched these two packages. However, if there is still some confusion left, we suggest reaching out directly to us so that we can address all of them.

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