COMMENT All about integrated circuit enclosures:
Transfer Multisort Elektronik (TME) This article provides an overview of the most widely used package types encountered by engineers, technicians and hobbyists, starting from simple transistor outlines and moving toward advanced packages designed for modern microcontrollers and processors.
The simplest semiconductors The “TO” designation (Transistor Outline) refers to packages originally designed for transistors. For example, TO-92 is a small, through-hole (THT) package commonly used for signal transistors, small voltage regulators, or digital sensors. Larger metal packages such as TO-3 and TO-220 were historically used for power semiconductors and remain relevant today due to their effective heat dissipation and mounting options. Motorola’s DPAK format, standardised as TO-252, was introduced as a surface-mount alternative for power devices. DPAK adheres directly to the PCB, using the copper plane for passive cooling, enabling compact, mechanically robust designs without external heatsinks.
DIP/DIL, SIL and ZIP Packages DIP (Dual In-Line Package) is one of the earliest and most recognisable formats, used since the 1960s. Available in widths of 0.3” and 0.6”, DIPs feature two parallel rows of pins and remain popular due to their ease of manual assembly. SIL/SIP and ZIP packages use a single row of pins and are often found in power modules.
Surface mount
The transition from THT (Through-Hole Technology) to SMT ( Surface Mount Technology) was driven by miniaturisation, automation and cost efficiency. SMT packages are smaller, lighter and more resistant to mechanical stress, and allow components on both PCB sides. For amateurs and enthusiasts, this might pose some problems, but is a huge convenience for electronics designers and manufacturers.
SOIC and related enclosures SOIC (Small Outline Integrated Circuit) and SOP (Small Outline Package) represent early SMT versions of DIP-style ICs. SSOP (Shrink Small-Outline Package) further decreases pitch and size. Lead shape is crucial here: gull-wing leads extend outward for easy
inspection, while J-leads curl underneath the package.
TSOP and TSSOP
TSOP (Thin Small Outline Package) and TSSOP (extra S for “Shrink”) provide extremely low profiles and fine pitches, suitable for memory devices and applications requiring many pins.
PLCC and QFP
PLCC (Plastic Leaded Chip Carrier) uses J-leads and supports 20 to 84 pins. QFP (Quad Flat Package) and its variants provide four-sided lead placement and can accommodate hundreds of pins, commonly used in microcontrollers and logic ICs.
QFN
QFN packages eliminate external pins. Instead of wire leads, the component has solder fields located on the bottom edge of its square body. This improves inductance and thermals but requires precise reflow soldering. On the other hand, the probability of short-circuiting pins during soldering or due to contamination is minimal.
BGA and PGA
BGA (Ball Grid Array) packages place solder balls on the underside, enabling high pin counts and excellent electrical characteristics. BGA circuits are characterised by high durability and negligible defectiveness during machine assembly. Unfortunately, when a failure occurs, inspection and replacement of the component pose many difficulties, especially in service. PGA (Pin Grid Array), its predecessor, used through-hole pins and was very popular at the beginning of the century, but is now largely obsolete.
SiP and CAN
SiP (System in a Package) integrates multiple chips within one enclosure, intended to be assembled entirely as a module. CAN refers to metal can packages. Nowadays such format is rarely seen, but it’s still used for transistors and sensitive analog circuits due to the shielding of the interior and good heat dissipation.
DECEMBER/JANUARY 2026 | ELECTRONICS FOR ENGINEERS
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