romikgosai/squad_modified huggingface dataset:
Each trace consists of a flat, narrow part of the copper foil that remains after etching. The resistance, determined by width and thickness, of the traces 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 the form of stripline and 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; but they can be used as a deliberate part of the circuit design, obviating the need for additional discrete components.

Questions and answers:
['
Q: What process is a trace left over from?
A: etching', '
Q: Along with thickness, what determines the resistance of a trace?
A: width', '
Q: What type of trace is often narrower than a ground trace?
A: signal', '
Q: In a multi-layer board, what metal would a ground plane be mostly made out of?
A: copper', '
Q: What type of circuits use a stripline and microstrip format?
A: microwave circuits']
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 is fire retardant, the dielectric constant (er), the loss factor (tδ), the tensile strength, the shear strength, the glass transition temperature (Tg), and the Z-axis expansion coefficient (how much the thickness changes with temperature).

Questions and answers:
['
Q: What element of a laminate is designated by the cloth to resin ratio, among other things?
A: type designation', "
Q: What's the name for the measurement of a laminate's change in thickness as its temperature changes?
A: Z-axis expansion coefficient", "
Q: What's the abbreviation for the glass transition temperature of a laminate?
A: Tg"]
There are quite a few different dielectrics that can be chosen to provide different insulating values depending on the requirements of 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 is an important consideration especially with ball grid array (BGA) and naked die technologies, and glass fiber offers the best dimensional stability.

Questions and answers:
["
Q: What's the common name of polytetrafluoroethylene?
A: Teflon", '
Q: What pre-preg material is designated by "FR-2"?
A: phenolic cotton paper', '
Q: To what type of packaging is thermal expansion particularly critical?
A: ball grid array', '
Q: What material delivers optimum dimensional stability?
A: glass fiber', '
Q: What dielectric is matte glass and polyester?
A: FR-6']
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 the weave pattern. Nonwoven reinforcements, or materials with low or no reinforcement, are more expensive but more suitable for some RF/analog applications.

Questions and answers:
['
Q: Along with the non-woven class, what makes up the reinforcement type materials?
A: woven', '
Q: Which is the more expensive reinforcement type?
A: non-woven', '
Q: What type of structure do woven reinforcements have that cause them to have variation in their electrical parameters?
A: spatially nonhomogeneous', '
Q: Which ratio varies because of the structure of woven reinforcements?
A: resin/glass', '
Q: For what kind of applications are non-woven reinforcement materials better than woven ones?
A: RF/analog']
At the glass transition temperature the resin in the composite softens and significantly increases thermal expansion; exceeding Tg then exerts mechanical overload on the board components - e.g. the joints and the vias. Below Tg 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 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 high Tg matrix.

Questions and answers:
["
Q: What's the temperature at which resin softens and expands called?
A: glass transition temperature", '
Q: Along with vias, what makes up the components of a board?
A: joints', '
Q: What will happen to the components when the temperature of resin goes above that of glass transition?
A: mechanical overload', '
Q: What do thick boards require to resist plating failure?
A: high Tg matrix', '
Q: When resin stays below Tg, its thermal expansion is similar to that of copper and what other material?
A: glass']
Moisture absorption occurs when the material is exposed to high humidity or water. Both the resin and the reinforcement may absorb water; water may be also soaked by capillary forces through voids in the materials and along the reinforcement. Epoxies of the FR-4 materials aren't 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 is about 73, compared to about 4 for common circuitboard materials. Absorbed moisture can also vaporize on heating 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.

Questions and answers:
['
Q: What will happen to the materials when a board gets wet or is in a humid area?
A: Moisture absorption', '
Q: If materials absorb moisture and then are heated enough to vaporize the water, the board might show delamination or what other type of damage?
A: cracking', '
Q: What percentage absorption do F-4 epoxies have?
A: 0.15%', "
Q: What's the approximate relative dielectric constant of most materials in circuit boards?
A: 4", '
Q: What material has an absorption rate of only 0.01%?
A: Teflon']
The printed circuit board industry defines heavy copper as layers exceeding three ounces of copper, or approximately 0.0042 inches (4.2 mils, 105 μm) thick. PCB designers and fabricators often use heavy copper when design and manufacturing circuit boards in order to increase current-carrying capacity as well as resistance to thermal strains. Heavy copper plated vias transfer heat to external heat sinks. IPC 2152 is a standard for determining current-carrying capacity of printed circuit board traces.

Questions and answers:
['
Q: What\'s the minimum amount of copper a layer in a PCB can have to be considered "heavy copper"?
A: three ounces', '
Q: About how thick would a PCB layer be if it contained three oz. of copper?
A: 0.0042 inches', '
Q: What will a circuit board with heavy copper carry very well?
A: current', '
Q: What would a PCB designer use heavy copper to make their circuit board resist?
A: thermal strains', '
Q: Where does the heat go when it leaves heavy copper-plated vias?
A: external heat sinks']
Since it was quite easy to stack interconnections (wires) inside the embedding matrix, the approach allowed designers to forget completely about the routing of wires (usually a time-consuming operation of PCB design): Anywhere the designer needs a connection, the machine will draw a wire in straight line from one location/pin to another. This led to very short design times (no complex algorithms to use even for high density designs) as well as reduced crosstalk (which is worse when wires run parallel to each other—which almost never happens in Multiwire), though the cost is too high to compete with cheaper PCB technologies when large quantities are needed.

Questions and answers:
['
Q: What arduous aspect of the process can designers skip in Multiwire?
A: routing of wires', '
Q: What does the machine create by drawing a straight line between two points on the board?
A: a connection', '
Q: Along with quick design times, what problem does Multiwire cut down on?
A: crosstalk', '
Q: What makes Multiwire impractical to use when large quantities of a board are needed?
A: cost', '
Q: In simple language, what are the interconnections in an embedding matrix?
A: wires']
Cordwood construction can save significant space and was often used with wire-ended components in applications where space was at a premium (such as missile guidance and telemetry systems) and in high-speed computers, where short traces were important. In cordwood construction, axial-leaded components were mounted between two parallel planes. The components were either soldered together with jumper wire, or they were connected to other components by thin nickel ribbon welded at right angles onto the component leads. To avoid shorting together different interconnection layers, thin insulating cards were placed between them. Perforations or holes in the cards allowed component leads to project through to the next interconnection layer. One disadvantage of this system was that special nickel-leaded components had to be used to allow the interconnecting welds to be made. Differential thermal expansion of the component could put pressure on the leads of the components and the PCB traces and cause physical damage (as was seen in several modules on the Apollo program). Additionally, components located in the interior are difficult to replace. Some versions of cordwood construction used soldered single-sided PCBs as the interconnection method (as pictured), allowing the use of normal-leaded components.

Questions and answers:
['
Q: What type of construction is best for applications that need to portion space carefully?
A: Cordwood', '
Q: What gets mounted in the middle of two parallel planes in a cordwood construction?
A: axial-leaded components', '
Q: What type of component has to be used in cordwood construction to its detriment?
A: nickel-leaded', '
Q: What do insulating cards prevent between interconnection layers?
A: shorting', '
Q: What force caused the physical damage to components that affected the Apollo program?
A: Differential thermal expansion']
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 a print-and-etch method in Britain, and in the United States Max Schoop obtained a patent to flame-spray metal onto a board through a patterned mask. Charles Ducas in 1927 patented a method of electroplating circuit patterns.

Questions and answers:
['
Q: Who was the German inventor who wrote in 1903 about conductors being laminated in layers to a board?
A: Albert Hanson', '
Q: What material did Thomas Edison experiment with by trying to chemically attach conductors to it?
A: linen paper', '
Q: What year did Arthur Berry patent his print-and-etch method?
A: 1913', "
Q: In Max Schoop's method, what was used to create the flame-sprayed pattern on the board?
A: a patterned mask", '
Q: Who obtained a patent in 1927 for his method of electroplating circuit patterns?
A: Charles Ducas']
The Austrian engineer Paul Eisler invented the printed circuit as part of a radio set while working in England around 1936. Around 1943 the USA began to use the technology on a large scale to make proximity fuses for use in World War II. After the war, in 1948, the USA 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 Britain work along similar lines was carried out by Geoffrey Dummer, then at the RRDE.

Questions and answers:
['
Q: What was Paul Eisler making when he came up with the printed circuit?
A: a radio set', '
Q: What event prompted the United States to adopt the printed circuit to make proximity fuses?
A: World War II', '
Q: When was the printed circuit released for commercial use in the U.S.?
A: 1948', '
Q: Who was working on the same type of large-scale application of printed circuits as the U.S. in Britain in the mid-1950s?
A: Geoffrey Dummer', '
Q: What process was created by the U.S. Army that led to innovation in consumer electronics?
A: Auto-Sembly']
During World War II, the development of the anti-aircraft proximity fuse 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 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 Mr. Harry W. Rubinstein, the former head of Globe Union's Centralab Division, its coveted Cledo Brunetti Award for early key contributions to the development of printed components and conductors on a common insulating substrate. As well, Mr. 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.

Questions and answers:
['
Q: What company developed the first electronic circuit that could be mass produced and was durable enough to be fired from a gun?
A: Globe Union', '
Q: Who was in charge of the Centralab Division of Globe Union when the PCB used in anti-aircraft fuses was invented?
A: Harry W. Rubinstein', '
Q: Where did Harry Rubinstein attend college?
A: University of Wisconsin-Madison', '
Q: What was the plate used for anti-aircraft proximity fuses in World War II made out of?
A: ceramic', '
Q: What award did Rubinstein win in 1984 for his contributions?
A: Cledo Brunetti Award']
Originally, every electronic component had wire leads, and the PCB had holes drilled for each wire of each component. The components' leads were then passed through the holes and soldered to the PCB trace. 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 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 wasteful since drilling holes is expensive and the protruding wires are merely cut off.

Questions and answers:
['
Q: What type of construction was originally used for all electronic components?
A: through-hole', '
Q: In what year was the Auto-Sembly process created?
A: 1949', '
Q: What year was the patent for the Auto-Sembly process granted?
A: 1956', '
Q: Although two men developed the Auto-Sembly process, to whom was the patent officially granted?
A: U.S. Army', '
Q: Which part of the Auto-Sembly manufacturing process is the most costly?
A: drilling holes']
The Premier League is a corporation in which the 20 member clubs act as shareholders. Seasons run from August to May. Teams play 38 matches each (playing each team in the league twice, home and away), totalling 380 matches in the season. Most games are played on Saturday and Sunday afternoons; others during weekday evenings. It is currently sponsored by Barclays Bank and thus officially known as the Barclays Premier League and is colloquially known as the Premiership. Outside the UK it is commonly referred to as the English Premier League (EPL).

Questions and answers:
['
Q: How many club members are there?
A: The Premier League is a corporation in which the 20 member clubs act as shareholders', '
Q: How many matches does each team play?
A: Teams play 38 matches each (playing each team in the league twice, home and away), totalling 380 matches in the season.', '
Q: What days are most games played?
A: Most games are played on Saturday and Sunday afternoons; others during weekday evenings', '
Q: Who sponsors the Premier League?
A: It is currently sponsored by Barclays Bank and thus officially known as the Barclays Premier League and is colloquially known as the Premiership.', '
Q: What name is the Premier League known as outside of the United Kingdom?
A: Outside the UK it is commonly referred to as the English Premier League (EPL).', '
Q: How many member clubs are shareholders in the Premier League?
A: 20', '
Q: When do Premier League seasons run from?
A: August to May', '
Q: How many matches do each team play?
A: 38', '
Q: Who sponsors the Premier League?
A: Barclays Bank', '
Q: What is the Premier League commonly referred to outside the UK?
A: English Premier League']
The competition formed as the FA Premier League on 20 February 1992 following the decision of clubs in the Football League First Division to break away from the Football League, which was originally founded in 1888, and take advantage of a lucrative television rights deal. The deal was worth £1 billion a year domestically as of 2013–14, with BSkyB and BT Group securing the domestic rights to broadcast 116 and 38 games respectively. The league generates €2.2 billion per year in domestic and international television rights. In 2014/15, teams were apportioned revenues of £1.6 billion.

Questions and answers:
['
Q: What date was the Premier League formed?
A: The competition formed as the FA Premier League on 20 February 1992', '
Q: Who secured the domestic rights to broadcast games 116 and 38 respectively?
A: BSkyB and BT Group securing the domestic rights to broadcast 116 and 38 games respectively.', '
Q: How much was the deal worth?
A: The deal was worth £1 billion a year domestically as of 2013–14', '
Q: How much revenue does the league generate in domestic and international television rights?
A: The league generates €2.2 billion per year in domestic and international television rights', '
Q: In 2014/15, how much were the teams apportioned in revenues?
A: In 2014/15, teams were apportioned revenues of £1.6 billion.', '
Q: When was the Premier League originally formed?
A: 20 February 1992', '
Q: When was the Football League originally founded?
A: 1888', '
Q: How many games were secured to broadcast by BSkyB?
A: 116', '
Q: How many games were secured to broadcast by BT Group?
A: 38', '
Q: How much income does the Premier League generate per year in worldwide television rights?
A: €2.2 billion']
The Premier League is the most-watched football league in the world, broadcast in 212 territories to 643 million homes and a potential TV audience of 4.7 billion people. In the 2014–15 season, the average Premier League match attendance exceeded 36,000, second highest of any professional football league behind the Bundesliga's 43,500. Most stadium occupancies are near capacity. The Premier League rank second in the UEFA coefficients of leagues based on performances in European competitions over the past five seasons.

Questions and answers:
['
Q: Is the Premier League the most watched football league in the world?
A: The Premier League is the most-watched football league in the world,', '
Q: How many territories is the Premier League broadcast to?
A: broadcast in 212 territories', '
Q: What is the potential television audience of the Premier League?
A: a potential TV audience of 4.7 billion people', "
Q: What is the Premier League's UEFA co-efficients of leagues rank?
A: The Premier League rank second in the UEFA coefficients of leagues", '
Q: What is the average game attendance for the league?
A: the average Premier League match attendance exceeded 36,000', '
Q: To how many homes is the Premier League broadcast to?
A: 643 million', '
Q: What average attendance number was exceeded by the Premier League in the 2014-15 season?
A: 36,000', '
Q: Which league has the highest average attendance in professional football?
A: Bundesliga', '
Q: To how many territories is the Premier League broadcast to?
A: 212', '
Q: What is the potential television audience of the Premier League?
A: 4.7 billion']
Despite significant European success during the 1970s and early 1980s, the late '80s had marked a low point for English football. Stadiums were crumbling, supporters endured poor facilities, hooliganism was rife, and English clubs were banned from European competition for five years following the Heysel Stadium disaster in 1985. The Football League First Division, which had been the top level of English football since 1888, was well behind leagues such as Italy's Serie A and Spain's La Liga in attendances and revenues, and several top English players had moved abroad.

Questions and answers:
["
Q: When was the low point for English football?
A: the late '80s had marked a low point for English football", '
Q: Why was there a low point for English football?
A: Stadiums were crumbling, supporters endured poor facilities, hooliganism was rife', "
Q: Why were the English clubs banned from European competition in the 1980's?
A: English clubs were banned from European competition for five years following the Heysel Stadium disaster in 1985.", '
Q: Had the Football League First Division ever been in the top level?
A: The Football League First Division, which had been the top level of English football since 1888', '
Q: In which year were English football clubs banned from competition in Europe?
A: 1985', '
Q: How long were the clubs banned for?
A: five years', '
Q: What did English players do after the ban?
A: moved abroad', '
Q: When attendance dropped to the Football League First Division, what else decreased?
A: revenues']