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QFN
Flat no-leads packages such as quad-flat no-leads (QFN) and dual-flat no-leads (DFN) physically and electrically connect integrated circuits to printed circuit boards. Flat no-leads, also known as micro leadframe (MLF) and SON (small-outline no leads), is a surface-mount technology, one of several package technologies that connect ICs to the ''surfaces'' of PCBs without through-holes. Flat no-lead is a near chip scale plastic encapsulated package made with a planar copper lead frame substrate. Perimeter lands on the package bottom provide electrical connections to the PCB. Flat no-lead packages include an exposed thermally conductive pad to improve heat transfer out of the IC (into the PCB). Heat transfer can be further facilitated by metal vias in the thermal pad. The QFN package is similar to the quad-flat package (QFP), and a ball grid array (BGA). Flat no-lead cross-section The figure shows the cross section of a flat no-lead package with a lead frame and wire bonding. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
QFN Sideview
Flat no-leads packages such as quad-flat no-leads (QFN) and dual-flat no-leads (DFN) physically and electrically connect integrated circuits to printed circuit boards. Flat no-leads, also known as micro leadframe (MLF) and SON (small-outline no leads), is a surface-mount technology, one of several package technologies that connect ICs to the ''surfaces'' of PCBs without through-holes. Flat no-lead is a near chip scale plastic encapsulated package made with a planar copper lead frame substrate. Perimeter lands on the package bottom provide electrical connections to the PCB. Flat no-lead packages include an exposed thermally conductive pad to improve heat transfer out of the IC (into the PCB). Heat transfer can be further facilitated by metal vias in the thermal pad. The QFN package is similar to the quad-flat package (QFP), and a ball grid array (BGA). Flat no-lead cross-section The figure shows the cross section of a flat no-lead package with a lead frame and wire bonding. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Integrated Circuit Packaging Types
Integrated circuits are put into protective packages to allow easy handling and assembly onto printed circuit boards and to protect the devices from damage. A very large number of different types of package exist. Some package types have standardized dimensions and tolerances, and are registered with trade industry associations such as JEDEC and Pro Electron. Other types are proprietary designations that may be made by only one or two manufacturers. Integrated circuit packaging is the last assembly process before testing and shipping devices to customers. Occasionally specially-processed integrated circuit dies are prepared for direct connections to a substrate without an intermediate header or carrier. In flip chip systems the IC is connected by solder bumps to a substrate. In beam-lead technology, the metallized pads that would be used for wire bonding connections in a conventional chip are thickened and extended to allow external connections to the circuit. Assemblies using " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quad-flat Package
A quad flat package (QFP) is a surface-mounted integrated circuit package with "gull wing" leads extending from each of the four sides. Socketing such packages is rare and through-hole mounting is not possible. Versions ranging from 32 to 304 pins with a pitch ranging from 0.4 to 1.0 mm are common. Other special variants include low-profile QFP (LQFP) and thin QFP (TQFP). The QFP component package type became common in Europe and United States during the early nineties, even though it has been used in Japanese consumer electronics since the seventies. It is often mixed with hole mounted, and sometimes socketed, components on the same printed circuit board (PCB). A package related to QFP is plastic leaded chip carrier (PLCC) which is similar but has pins with larger pitch, 1.27 mm (or 1/20 inch), curved up underneath a thicker body to simplify socketing (soldering is also possible). It is commonly used for NOR flash memories and other programmable components. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quad Flat Package
A quad flat package (QFP) is a surface-mounted integrated circuit package with "gull wing" leads extending from each of the four sides. Socketing such packages is rare and through-hole mounting is not possible. Versions ranging from 32 to 304 pins with a pitch ranging from 0.4 to 1.0 mm are common. Other special variants include low-profile QFP (LQFP) and thin QFP (TQFP). The QFP component package type became common in Europe and United States during the early nineties, even though it has been used in Japanese consumer electronics since the seventies. It is often mixed with hole mounted, and sometimes socketed, components on the same printed circuit board (PCB). A package related to QFP is plastic leaded chip carrier (PLCC) which is similar but has pins with larger pitch, 1.27 mm (or 1/20 inch), curved up underneath a thicker body to simplify socketing (soldering is also possible). It is commonly used for NOR flash memories and other programmable components. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead Frame
A lead frame (pronounced ) is the metal structure inside a chip package that carries signals from the die to the outside. The lead frame consists of a central die pad, where the die is placed, surrounded by leads, metal conductors leading away from the die to the outside world. The end of each lead closest to the die ends in a bond pad. Small bond wires connect the die to each bond pad. Mechanical connections fix all these parts into a rigid structure, which makes the whole lead frame easy to handle automatically. Manufacturing Lead frames are manufactured by removing material from a flat plate of copper, copper-alloy, or iron-nickel alloy like alloy 42. Two processes used for this are etching (suitable for high density of leads), or stamping (suitable for low density of leads). The mechanical bending process can be applied after both techniques. The die is glued or soldered to the die pad inside the lead frame, and then bond wires are attached between the die and the bond p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solder Fatigue
Solder fatigue is the mechanical degradation of solder due to deformation under cyclic loading. This can often occur at stress levels below the yield stress of solder as a result of repeated temperature fluctuations, mechanical vibrations, or mechanical loads. Techniques to evaluate solder fatigue behavior include finite element analysis and semi-analytical closed-form equations. Overview Solder is a metal alloy used to form electrical, thermal, and mechanical interconnections between the component and printed circuit board (PCB) substrate in an electronic assembly. Although other forms of cyclic loading are known to cause solder fatigue, it has been estimated that the largest portion of electronic failures are thermomechanically driven due to temperature cycling. Under thermal cycling, stresses are generated in the solder due to coefficient of thermal expansion (CTE) mismatches. This causes the solder joints to experience non-recoverable deformation via creep and plasticity tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflow Soldering
Reflow soldering is a process in which a solder paste (a sticky mixture of powdered solder and flux) is used to temporarily attach one or thousands of tiny electrical components to their contact pads, after which the entire assembly is subjected to controlled heat. The solder paste reflows in a molten state, creating permanent solder joints. Heating may be accomplished by passing the assembly through a reflow oven, under an infrared lamp, or (unconventionally) by soldering individual joints with a desoldering hot air pencil. Reflow soldering with long industrial convection ovens is the preferred method of soldering surface mount technology components or SMT to a printed circuit board or PCB. Each segment of the oven has a regulated temperature, according to the specific thermal requirements of each assembly. Reflow ovens meant specifically for the soldering of surface mount components may also be used for through-hole components by filling the holes with solder paste and inse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moisture Sensitivity Level
Moisture sensitivity level (MSL) relates to the packaging and handling precautions for some semiconductors. The MSL is an electronic standard for the time period in which a moisture sensitive device can be exposed to ambient room conditions (30 °C/85%RH at Level 1; 30 °C/60%RH at all other levels). Increasingly, semiconductors have been manufactured in smaller sizes. Components such as thin fine-pitch devices and ball grid arrays could be damaged during SMT reflow when moisture trapped inside the component expands. The expansion of trapped moisture can result in internal separation (delamination) of the plastic from the die or lead-frame, wire bond damage, die damage, and internal cracks. Most of this damage is not visible on the component surface. In extreme cases, cracks will extend to the component surface. In the most severe cases, the component will bulge and pop. This is known as the "popcorn" effect. This occurs when part temperature rises rapidly to a high ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coefficient Of Thermal Expansion
Thermal expansion is the tendency of matter to change its shape A shape or figure is a graphics, graphical representation of an object or its external boundary, outline, or external Surface (mathematics), surface, as opposed to other properties such as color, Surface texture, texture, or material type. A pl ..., area, volume, and density in response to a change in temperature, usually not including phase transitions. Temperature is a monotonic function of the average molecular kinetic energy of a substance. When a substance is heated, molecules begin to vibrate and move more, usually creating more distance between themselves. Substances which contract with increasing temperature are unusual, and only occur within limited temperature ranges (see examples below). The relative expansion (also called strain (mechanics), strain) divided by the change in temperature is called the material's coefficient of linear thermal expansion and generally varies with temperature. As energy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Temperature Cycling
Temperature cycling (or temperature cycle) is the process of cycling through two temperature extremes, typically at relatively high rates of change. It is an environmental stress test used in evaluating product reliability as well as in manufacturing to catch early-term, latent defects by inducing failure through thermal fatigue Fatigue describes a state of tiredness that does not resolve with rest or sleep. In general usage, fatigue is synonymous with extreme tiredness or exhaustion that normally follows prolonged physical or mental activity. When it does not resolve .... External links Temperature Cycling (JEDEC Standard No. 22-A104D) Environmental testing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solder
Solder (; NA: ) is a fusible metal alloy used to create a permanent bond between metal workpieces. Solder is melted in order to wet the parts of the joint, where it adheres to and connects the pieces after cooling. Metals or alloys suitable for use as solder should have a lower melting point than the pieces to be joined. The solder should also be resistant to oxidative and corrosive effects that would degrade the joint over time. Solder used in making electrical connections also needs to have favorable electrical characteristics. Soft solder typically has a melting point range of , and is commonly used in electronics, plumbing, and sheet metal work. Alloys that melt between are the most commonly used. Soldering performed using alloys with a melting point above is called "hard soldering", "silver soldering", or brazing. In specific proportions, some alloys are eutectic — that is, the alloy's melting point is the lowest possible for a mixture of those components, and co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JEDEC
The JEDEC Solid State Technology Association is an independent semiconductor engineering trade organization and standardization body headquartered in Arlington County, Virginia, United States. JEDEC has over 300 members, including some of the world's largest computer companies. Its scope and past activities includes standardization of part numbers, defining an electrostatic discharge (ESD) standard, and leadership in the lead-free manufacturing transition. The origin of JEDEC traces back to 1944, when RMA (subsequently renamed EIA) and NEMA established the Joint Electron Tube Engineering Council (JETEC) to coordinate vacuum tube type numberings. In 1958, with the advent of semiconductor technology, the joint JETEC-activity of EIA and NEMA was renamed into Joint Electron Device Engineering Council. NEMA discontinued its involvement in 1979. In the fall of 1999, JEDEC became a separate trade association under the current name, but maintained an EIA alliance, until EIA ceased o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
