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64-423: PGAs are often mounted on printed circuit boards using the through hole method or inserted into a socket . PGAs allow for more pins per integrated circuit than older packages, such as dual in-line package (DIP). The chip can be mounted either on the top or the bottom (the pinned side). Connections can be made either by wire bonding or through flip chip mounting. Typically, PGA packages use wire bonding when

128-512: A ceramic substrate with pins arranged in an array. An organic pin grid array (OPGA) is a type of connection for integrated circuits , and especially CPUs , where the silicon die is attached to a plate made out of an organic plastic which is pierced by an array of pins which make the requisite connections to the socket . Plastic pin grid array (PPGA) packaging was used by Intel for late-model Mendocino core Celeron processors based on Socket 370 . Some pre-Socket 8 processors also used

192-602: A PCB had holes drilled for each wire of each component. The component leads were then inserted through the holes and soldered to the copper PCB traces. This method of assembly is called through-hole construction . In 1949, Moe Abramson and Stanislaus F. Danko of the United States Army Signal Corps developed the Auto-Sembly process in which component leads were inserted into a copper foil interconnection pattern and dip soldered . The patent they obtained in 1956

256-426: A PCB may have a coating that protects the copper from corrosion and reduces the chances of solder shorts between traces or undesired electrical contact with stray bare wires. For its function in helping to prevent solder shorts, the coating is called solder resist or solder mask . The pattern to be etched into each copper layer of a PCB is called the "artwork". The etching is usually done using photoresist which

320-692: A flat surface) etched from one or more sheet layers of copper laminated onto or between sheet layers of a non-conductive substrate. Electrical components may be fixed to conductive pads on the outer layers, generally by means of soldering , which both electrically connects and mechanically fastens the components to the board. Another manufacturing process adds vias , drilled holes that allow electrical interconnections between conductive layers. Printed circuit boards are used in nearly all electronic products. Alternatives to PCBs include wire wrap and point-to-point construction , both once popular but now rarely used. PCBs require additional design effort to lay out

384-460: A flat, narrow part of the copper foil that remains after etching. Its resistance , determined by its width, thickness, and length, must be sufficiently low for the current the conductor will carry. Power and ground traces may need to be wider than signal traces . In a multi-layer board one entire layer may be mostly solid copper to act as a ground plane for shielding and power return. For microwave circuits, transmission lines can be laid out in

448-418: A general estimate of the board complexity. Using more layers allow for more routing options and better control of signal integrity, but are also time-consuming and costly to manufacture. Likewise, selection of the vias for the board also allow fine tuning of the board size, escaping of signals off complex ICs, routing, and long term reliability, but are tightly coupled with production complexity and cost. One of

512-783: A liquid ink that contains electronic functionalities. HDI (High Density Interconnect) technology allows for a denser design on the PCB and thus potentially smaller PCBs with more traces and components in a given area. As a result, the paths between components can be shorter. HDIs use blind/buried vias, or a combination that includes microvias. With multi-layer HDI PCBs the interconnection of several vias stacked on top of each other (stacked vías, instead of one deep buried via) can be made stronger, thus enhancing reliability in all conditions. The most common applications for HDI technology are computer and mobile phone components as well as medical equipment and military communication equipment. A 4-layer HDI microvia PCB

576-399: A more direct contact with the heatsink or other cooling mechanism. FC-PGA CPUs were introduced by Intel in 1999, for Coppermine core Pentium III and Celeron processors based on Socket 370 , and were produced until Socket G3 in 2013. FC-PGA processors fit into zero insertion force (ZIF) motherboard sockets ; similar packages were also used by AMD. A ceramic pin grid array (CPGA)

640-446: A planar form such as stripline or microstrip with carefully controlled dimensions to assure a consistent impedance . In radio-frequency and fast switching circuits the inductance and capacitance of the printed circuit board conductors become significant circuit elements, usually undesired; conversely, they can be used as a deliberate part of the circuit design, as in distributed-element filters , antennae , and fuses , obviating

704-636: A print-and- etch method in the UK, and in the United States Max Schoop obtained a patent to flame-spray metal onto a board through a patterned mask. Charles Ducas in 1925 patented a method of electroplating circuit patterns. Predating the printed circuit invention, and similar in spirit, was John Sargrove 's 1936–1947 Electronic Circuit Making Equipment (ECME) that sprayed metal onto a Bakelite plastic board. The ECME could produce three radio boards per minute. The Austrian engineer Paul Eisler invented

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768-595: A proposal which met the requirements: a ceramic plate would be screenprinted with metallic paint for conductors and carbon material for resistors , with ceramic disc capacitors and subminiature vacuum tubes soldered in place. The technique proved viable, and the resulting patent on the process, which was classified by the U.S. Army, was assigned to Globe Union. It was not until 1984 that the Institute of Electrical and Electronics Engineers (IEEE) awarded Harry W. Rubinstein its Cledo Brunetti Award for early key contributions to

832-399: A similar form factor, although they were not officially referred to as PPGA. The staggered pin grid array (SPGA) is used by Intel processors based on Socket 5 and Socket 7 . Socket 8 used a partial SPGA layout on half the processor. It consists of two square arrays of pins, offset in both directions by half the minimum distance between pins in one of the arrays. Put differently: within

896-440: A square boundary the pins form a diagonal square lattice . There is generally a section in the center of the package without any pins. SPGA packages are usually used by devices that require a higher pin density than what a PGA can provide, such as microprocessors . A stud grid array (SGA) is a short-pinned pin grid array chip scale package for use in surface-mount technology . The polymer stud grid array or plastic stud grid array

960-440: Is cotton paper impregnated with phenolic resin , often tan or brown. When a PCB has no components installed, it is less ambiguously called a printed wiring board ( PWB ) or etched wiring board . However, the term "printed wiring board" has fallen into disuse. A PCB populated with electronic components is called a printed circuit assembly ( PCA ), printed circuit board assembly or PCB assembly ( PCBA ). In informal usage,

1024-451: Is fire retardant , the dielectric constant (e r ), the loss tangent (tan δ), the tensile strength , the shear strength , the glass transition temperature (T g ), and the Z-axis expansion coefficient (how much the thickness changes with temperature). There are quite a few different dielectrics that can be chosen to provide different insulating values depending on the requirements of

1088-543: Is a CPU socket introduced by Intel in 2009 for the mobile variants of the first-generation Intel Core processors. It is the successor to Socket P , and the mobile counterpart to LGA 1156 and LGA 1366 . The first CPUs for the Socket G1 platform were released on September 23, 2009, in the form of the i7-720QM, 820QM, and 920XM. These CPUs use the Clarksfield core, which maintained the same 45 nm manufacturing process as

1152-437: Is a common engineering error in high-frequency digital design; it increases the cost of the boards without a corresponding benefit. Signal degradation by loss tangent and dielectric constant can be easily assessed by an eye pattern . Moisture absorption occurs when the material is exposed to high humidity or water. Both the resin and the reinforcement may absorb water; water also may be soaked by capillary forces through voids in

1216-615: Is a type of packaging used by integrated circuits . This type of packaging uses a ceramic substrate with pins arranged in a pin grid array. Some CPUs that use CPGA packaging are the AMD Socket A Athlons and the Duron . A CPGA was used by AMD for Athlon and Duron processors based on Socket A, as well as some AMD processors based on Socket AM2 and Socket AM2+ . While similar form factors have been used by other manufacturers, they are not officially referred to as CPGA. This type of packaging uses

1280-477: Is about 73, compared to about 4 for common circuit board materials. Absorbed moisture can also vaporize on heating, as during soldering , and cause cracking and delamination , the same effect responsible for "popcorning" damage on wet packaging of electronic parts. Careful baking of the substrates may be required to dry them prior to soldering. Often encountered materials: Less-often encountered materials: Copper thickness of PCBs can be specified directly or as

1344-468: Is an important consideration especially with ball grid array (BGA) and naked die technologies, and glass fiber offers the best dimensional stability. FR-4 is by far the most common material used today. The board stock with unetched copper on it is called "copper-clad laminate". With decreasing size of board features and increasing frequencies, small nonhomogeneities like uneven distribution of fiberglass or other filler, thickness variations, and bubbles in

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1408-451: Is coated onto the PCB, then exposed to light projected in the pattern of the artwork. The resist material protects the copper from dissolution into the etching solution. The etched board is then cleaned. A PCB design can be mass-reproduced in a way similar to the way photographs can be mass-duplicated from film negatives using a photographic printer . FR-4 glass epoxy is the most common insulating substrate. Another substrate material

1472-418: Is equivalent in quality to an 8-layer through-hole PCB, so HDI technology can reduce costs. HDI PCBs are often made using build-up film such as ajinomoto build-up film, which is also used in the production of flip chip packages. Some PCBs have optical waveguides, similar to optical fibers built on the PCB. A basic PCB consists of a flat sheet of insulating material and a layer of copper foil , laminated to

1536-632: Is estimated to reach $ 79 billion by 2024. Before the development of printed circuit boards, electrical and electronic circuits were wired point-to-point on a chassis. Typically, the chassis was a sheet metal frame or pan, sometimes with a wooden bottom. Components were attached to the chassis, usually by insulators when the connecting point on the chassis was metal, and then their leads were connected directly or with jumper wires by soldering , or sometimes using crimp connectors, wire connector lugs on screw terminals, or other methods. Circuits were large, bulky, heavy, and relatively fragile (even discounting

1600-474: Is specified in units of ounces per square foot (oz/ft ), commonly referred to simply as ounce . Common thicknesses are 1/2 oz/ft (150 g/m ), 1 oz/ft (300 g/m ), 2 oz/ft (600 g/m ), and 3 oz/ft (900 g/m ). These work out to thicknesses of 17.05 μm (0.67 thou ), 34.1 μm (1.34 thou ), 68.2 μm (2.68 thou), and 102.3 μm (4.02 thou), respectively. Socket G1 Socket G1 , also known as rPGA 988A ,

1664-468: Is the most common thickness; 2 oz (70 μm) and 0.5 oz (17.5 μm) thickness is often an option. Less common are 12 and 105 μm, 9 μm is sometimes available on some substrates. Flexible substrates typically have thinner metalization. Metal-core boards for high power devices commonly use thicker copper; 35 μm is usual but also 140 and 400 μm can be encountered. In the US, copper foil thickness

1728-491: The G1 , G2 , and G3 sockets. Printed circuit board A printed circuit board ( PCB ), also called printed wiring board ( PWB ), is a medium used to connect or "wire" components to one another in a circuit . It takes the form of a laminated sandwich structure of conductive and insulating layers: each of the conductive layers is designed with a pattern of traces, planes and other features (similar to wires on

1792-449: The glass transition temperature the resin in the composite softens and significantly increases thermal expansion; exceeding T g then exerts mechanical overload on the board components - e.g. the joints and the vias. Below T g the thermal expansion of the resin roughly matches copper and glass, above it gets significantly higher. As the reinforcement and copper confine the board along the plane, virtually all volume expansion projects to

1856-399: The signal propagation speed , frequency dependence introduces phase distortion in wideband applications; as flat a dielectric constant vs frequency characteristics as is achievable is important here. The impedance of transmission lines decreases with frequency, therefore faster edges of signals reflect more than slower ones. Dielectric breakdown voltage determines the maximum voltage gradient

1920-558: The PCB surface, instead of wire leads to pass through holes. Components became much smaller and component placement on both sides of the board became more common than with through-hole mounting, allowing much smaller PCB assemblies with much higher circuit densities. Surface mounting lends itself well to a high degree of automation, reducing labor costs and greatly increasing production rates compared with through-hole circuit boards. Components can be supplied mounted on carrier tapes. Surface mount components can be about one-quarter to one-tenth of

1984-453: The back of the board in opposite directions to improve the part's mechanical strength), soldering the leads, and trimming off the ends. Leads may be soldered either manually or by a wave soldering machine. Surface-mount technology emerged in the 1960s, gained momentum in the early 1980s, and became widely used by the mid-1990s. Components were mechanically redesigned to have small metal tabs or end caps that could be soldered directly onto

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2048-437: The board and soldered onto copper traces on the other side. Boards may be single-sided, with an unplated component side, or more compact double-sided boards, with components soldered on both sides. Horizontal installation of through-hole parts with two axial leads (such as resistors, capacitors, and diodes) is done by bending the leads 90 degrees in the same direction, inserting the part in the board (often bending leads located on

2112-519: The breakable glass envelopes of the vacuum tubes that were often included in the circuits), and production was labor-intensive, so the products were expensive. Development of the methods used in modern printed circuit boards started early in the 20th century. In 1903, a German inventor, Albert Hanson, described flat foil conductors laminated to an insulating board, in multiple layers. Thomas Edison experimented with chemical methods of plating conductors onto linen paper in 1904. Arthur Berry in 1913 patented

2176-512: The ceramic substrate. In 1948, the US released the invention for commercial use. Printed circuits did not become commonplace in consumer electronics until the mid-1950s, after the Auto-Sembly process was developed by the United States Army. At around the same time in the UK work along similar lines was carried out by Geoffrey Dummer , then at the RRDE . Motorola was an early leader in bringing

2240-453: The chip is mounted on the pinned side, and flip chip construction when the chip is on the top side. Some PGA packages contain multiple dies, for example Zen 2 and Zen 3 Ryzen CPUs for the AM4 socket . A flip-chip pin grid array (FC-PGA or FCPGA) is a form of pin grid array in which the die faces downwards on the top of the substrate with the back of the die exposed. This allows the die to have

2304-757: The circuit, but manufacturing and assembly can be automated. Electronic design automation software is available to do much of the work of layout. Mass-producing circuits with PCBs is cheaper and faster than with other wiring methods, as components are mounted and wired in one operation. Large numbers of PCBs can be fabricated at the same time, and the layout has to be done only once. PCBs can also be made manually in small quantities, with reduced benefits. PCBs can be single-sided (one copper layer), double-sided (two copper layers on both sides of one substrate layer), or multi-layer (outer and inner layers of copper, alternating with layers of substrate). Multi-layer PCBs allow for much higher component density, because circuit traces on

2368-539: The circuit. Some of these dielectrics are polytetrafluoroethylene (Teflon), FR-4, FR-1, CEM-1 or CEM-3. Well known pre-preg materials used in the PCB industry are FR-2 (phenolic cotton paper), FR-3 (cotton paper and epoxy), FR-4 (woven glass and epoxy), FR-5 (woven glass and epoxy), FR-6 (matte glass and polyester), G-10 (woven glass and epoxy), CEM-1 (cotton paper and epoxy), CEM-2 (cotton paper and epoxy), CEM-3 (non-woven glass and epoxy), CEM-4 (woven glass and epoxy), CEM-5 (woven glass and polyester). Thermal expansion

2432-431: The components, test points , or identifying text. Originally, silkscreen printing was used for this purpose, but today other, finer quality printing methods are usually used. Normally the legend does not affect the function of a PCBA. A printed circuit board can have multiple layers of copper which almost always are arranged in pairs. The number of layers and the interconnection designed between them (vias, PTHs) provide

2496-464: The desired final thickness and dielectric characteristics. Available standard laminate thickness are listed in ANSI/IPC-D-275. The cloth or fiber material used, resin material, and the cloth to resin ratio determine the laminate's type designation (FR-4, CEM -1, G-10 , etc.) and therefore the characteristics of the laminate produced. Important characteristics are the level to which the laminate

2560-554: The desktop Nehalem architecture . On January 4, 2010, the range was expanded with Core i3, i5, and i7 processors using the 32 nm Arrandale core and based on the Westmere architecture . On March 28, 2010, low-end Arrandale-based CPUs were released as the Pentium P6x00 series and Celeron P4x00 series. Further Clarksfield-based processors were released as the i7-740QM, 840QM, and 940XM on June 21, 2010. All Socket G1 processors, except for

2624-492: The development of printed components and conductors on a common insulating substrate. Rubinstein was honored in 1984 by his alma mater, the University of Wisconsin-Madison , for his innovations in the technology of printed electronic circuits and the fabrication of capacitors. This invention also represents a step in the development of integrated circuit technology, as not only wiring but also passive components were fabricated on

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2688-403: The dielectric constant). The reinforcement type defines two major classes of materials: woven and non-woven. Woven reinforcements are cheaper, but the high dielectric constant of glass may not be favorable for many higher-frequency applications. The spatially nonhomogeneous structure also introduces local variations in electrical parameters, due to different resin/glass ratio at different areas of

2752-405: The finished multilayer board) are plated-through, before the layers are laminated together. Only the outer layers need be coated; the inner copper layers are protected by the adjacent substrate layers. "Through hole" components are mounted by their wire leads passing through the board and soldered to traces on the other side. "Surface mount" components are attached by their leads to copper traces on

2816-447: The inner layers would otherwise take up surface space between components. The rise in popularity of multilayer PCBs with more than two, and especially with more than four, copper planes was concurrent with the adoption of surface mount technology . However, multilayer PCBs make repair, analysis, and field modification of circuits much more difficult and usually impractical. The world market for bare PCBs exceeded $ 60.2 billion in 2014 and

2880-427: The internal layers is used as ground plane or power plane, to achieve better signal integrity, higher signaling frequencies, lower EMI, and better power supply decoupling. In multi-layer boards, the layers of material are laminated together in an alternating sandwich: copper, substrate, copper, substrate, copper, etc.; each plane of copper is etched, and any internal vias (that will not extend to both outer surfaces of

2944-498: The material can be subjected to before suffering a breakdown (conduction, or arcing, through the dielectric). Tracking resistance determines how the material resists high voltage electrical discharges creeping over the board surface. Loss tangent determines how much of the electromagnetic energy from the signals in the conductors is absorbed in the board material. This factor is important for high frequencies. Low-loss materials are more expensive. Choosing unnecessarily low-loss material

3008-491: The materials and along the reinforcement. Epoxies of the FR-4 materials are not too susceptible, with absorption of only 0.15%. Teflon has very low absorption of 0.01%. Polyimides and cyanate esters, on the other side, suffer from high water absorption. Absorbed water can lead to significant degradation of key parameters; it impairs tracking resistance, breakdown voltage, and dielectric parameters. Relative dielectric constant of water

3072-498: The need for additional discrete components. High density interconnects (HDI) PCBs have tracks or vias with a width or diameter of under 152 micrometers. Laminates are manufactured by curing layers of cloth or paper with thermoset resin under pressure and heat to form an integral final piece of uniform thickness. They can be up to 4 by 8 feet (1.2 by 2.4 m) in width and length. Varying cloth weaves (threads per inch or cm), cloth thickness, and resin percentage are used to achieve

3136-471: The point-to-point chassis construction method remained in common use in industry (such as TV and hi-fi sets) into at least the late 1960s. Printed circuit boards were introduced to reduce the size, weight, and cost of parts of the circuitry. In 1960, a small consumer radio receiver might be built with all its circuitry on one circuit board, but a TV set would probably contain one or more circuit boards. Originally, every electronic component had wire leads , and

3200-629: The printed circuit as part of a radio set while working in the UK around 1936. In 1941 a multi-layer printed circuit was used in German magnetic influence naval mines . Around 1943 the United States began to use the technology on a large scale to make proximity fuzes for use in World War II. Such fuzes required an electronic circuit that could withstand being fired from a gun, and could be produced in quantity. The Centralab Division of Globe Union submitted

3264-474: The process into consumer electronics, announcing in August 1952 the adoption of "plated circuits" in home radios after six years of research and a $ 1M investment. Motorola soon began using its trademarked term for the process, PLAcir, in its consumer radio advertisements. Hallicrafters released its first "foto-etch" printed circuit product, a clock-radio, on November 1, 1952. Even as circuit boards became available,

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3328-403: The protruding wires are cut off and discarded. From the 1980s onward, small surface mount parts have been used increasingly instead of through-hole components; this has led to smaller boards for a given functionality and lower production costs, but with some additional difficulty in servicing faulty boards. In the 1990s the use of multilayer surface boards became more frequent. As a result, size

3392-441: The resin matrix, and the associated local variations in the dielectric constant, are gaining importance. The circuit-board substrates are usually dielectric composite materials. The composites contain a matrix (usually an epoxy resin ) and a reinforcement (usually a woven, sometimes nonwoven, glass fibers, sometimes even paper), and in some cases a filler is added to the resin (e.g. ceramics; titanate ceramics can be used to increase

3456-478: The same side of the board. A board may use both methods for mounting components. PCBs with only through-hole mounted components are now uncommon. Surface mounting is used for transistors , diodes , IC chips , resistors , and capacitors. Through-hole mounting may be used for some large components such as electrolytic capacitors and connectors. The first PCBs used through-hole technology , mounting electronic components by lead inserted through holes on one side of

3520-408: The simplest boards to produce is the two-layer board. It has copper on both sides that are referred to as external layers; multi layer boards sandwich additional internal layers of copper and insulation. After two-layer PCBs, the next step up is the four-layer. The four layer board adds significantly more routing options in the internal layers as compared to the two layer board, and often some portion of

3584-414: The size and weight of through-hole components, and passive components much cheaper. However, prices of semiconductor surface mount devices (SMDs) are determined more by the chip itself than the package, with little price advantage over larger packages, and some wire-ended components, such as 1N4148 small-signal switch diodes, are actually significantly cheaper than SMD equivalents. Each trace consists of

3648-422: The substrate. Chemical etching divides the copper into separate conducting lines called tracks or circuit traces , pads for connections, vias to pass connections between layers of copper, and features such as solid conductive areas for electromagnetic shielding or other purposes. The tracks function as wires fixed in place, and are insulated from each other by air and the board substrate material. The surface of

3712-402: The term "printed circuit board" most commonly means "printed circuit assembly" (with components). The IPC preferred term for an assembled board is circuit card assembly ( CCA ), and for an assembled backplane it is backplane assembly . "Card" is another widely used informal term for a "printed circuit assembly". For example, expansion card . A PCB may be printed with a legend identifying

3776-419: The thickness and stresses the plated-through holes. Repeated soldering or other exposition to higher temperatures can cause failure of the plating, especially with thicker boards; thick boards therefore require a matrix with a high T g . The materials used determine the substrate's dielectric constant . This constant is also dependent on frequency, usually decreasing with frequency. As this constant determines

3840-511: The weave pattern. Nonwoven reinforcements, or materials with low or no reinforcement, are more expensive but more suitable for some RF/analog applications. The substrates are characterized by several key parameters, chiefly thermomechanical ( glass transition temperature , tensile strength , shear strength , thermal expansion ), electrical ( dielectric constant , loss tangent , dielectric breakdown voltage , leakage current , tracking resistance ...), and others (e.g. moisture absorption ). At

3904-440: The weight of copper per area (in ounce per square foot) which is easier to measure. One ounce per square foot is 1.344 mils or 34 micrometers thickness. Heavy copper is a layer exceeding three ounces of copper per ft , or approximately 0.0042 inches (4.2 mils, 105 μm) thick. Heavy copper layers are used for high current or to help dissipate heat. On the common FR-4 substrates, 1 oz copper per ft (35 μm)

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3968-433: Was assigned to the U.S. Army. With the development of board lamination and etching techniques, this concept evolved into the standard printed circuit board fabrication process in use today. Soldering could be done automatically by passing the board over a ripple, or wave, of molten solder in a wave-soldering machine. However, the wires and holes are inefficient since drilling holes is expensive and consumes drill bits and

4032-490: Was developed jointly by the Interuniversity Microelectronics Centre (IMEC) and Laboratory for Production Technology , Siemens AG . The reduced pin grid array was used by the socketed mobile variants of Intel's Core i3/5/7 processors and features a reduced pin pitch of 1   mm, as opposed to the 1.27   mm pin pitch used by contemporary AMD processors and older Intel processors. It is used in

4096-426: Was further minimized and both flexible and rigid PCBs were incorporated in different devices. In 1995 PCB manufacturers began using microvia technology to produce High-Density Interconnect (HDI) PCBs. Recent advances in 3D printing have meant that there are several new techniques in PCB creation. 3D printed electronics (PEs) can be utilized to print items layer by layer and subsequently the item can be printed with

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