A QFN package is a small, lead-free package that physically connects an integrated circuit to a printed circuit board. It is available in various sizes and shapes, including square and multi-row. These packages are used in many electronic components, including consumer electronics. They are ideal for high-volume production and are also suitable for small-sized circuits.
Lead-free
The Lead-free QFN package is a semiconductor package with solder joints that are free of lead. This type of package is suitable for use in consumer and portable communications products such as digital cameras, PDAs, laptops, and wireless transmitters. Its use is anticipated to increase in the coming years.
Square-shaped
In contrast to conventional QFN packages, which are circular, they can be made square or rectangular. A square-shaped QFN package has an aperture that is similar in size to that of a BGA package. This arrangement will improve yield and reliability of the solder bonding process. In addition, the geometry of the QFN package allows for solder balls to be placed on the package. In this way, the QFN package can be mounted on the substrate in the same manner as the BGA package.
Multi-row
The multi-row QFN package is a semiconductor package with multiple rows of leads. It utilizes an interstitial lead design that results in a staggered lead arrangement. The inner lead row is offset by 0.5mm from the outer row, maximizing die size while not exceeding the pitch requirements of surface mount technology.
Mold array
The mold array process is a preferred method for manufacturing semiconductor packages. This process uses a substrate strip having a plurality of substrate units, which are arranged in an array within the molding area. Chips are disposed on these substrate units. The encapsulant is continuously applied over the substrate strip. FIGS. 2A to 2D illustrate the mold array process.
Thermal conductivity
Thermal conductivity of QFN package is a vital factor to be considered during the manufacturing process. The design of the QFN package is very similar to that of a quad flat package, but this new package has several differences that require special considerations. To begin, it is difficult to hand-solder this type of package. Also, it is difficult to probe lead holes and inspect solder joints.
Assembly
The QFN package consists of a copper lead frame that surrounds a chip. This copper lead frame connects the chip terminals to the PCB tracks. To make the QFN package, solder paste needs to be printed with a precise pattern and spread evenly. In addition, precision tools are necessary to produce a quality chip.