Computer hardware consists of physical parts of the computer which includes CPU’s (central processing units), motherboard, graphics card, CPU cooler, hard drive or SSD (solid state drive), RAM (random access memory) as well as, computer peripherals which include: monitors, computer mouse, and the keyboard. The use of chemistry makes it possible to improve computer hardware by the use of chemical metals and non-metals such as lead, mercury, polychlorinated biphenyls (PCB’s) among many others.
Computer Monitors
The first computer monitors available were CRT monitors or (cathode ray tube) which is also known as a vacuum tube that contains one or more electron guns and a phosphorescent screen which is used to display images. Phosphorescent is an important material that makes it possible for a CRT screen to work. Phosphorescent contains many chemical elements and compounds. Starting with the phosphorescent pigments which include zinc sulphide and strontium aluminate and the phosphorescent itself which contains calcium sulphide.
With the use of chemistry, it was possible to manufacture CRT monitors, LED monitors and radar screens by using a transition metal compound named phosphor. Phosphor is a compound that “exhibits the phenomenon of luminescence.” [Wiki Phosphor, Pg. 1, Line 1]. CRT monitors produce single-generated light patterns usually in a round or rectangular format. [Wiki Phosphor, Cathode Ray Tubes, Line 1]. The light patterns that are used in a CRT monitor with colour are; white, which has a “mix of zinc cadmium sulfide silver, the ZnS: Ag+(Zn, Cd)S: Ag is the white P4 phosphor used in black and white television screens”, [ Wiki phosphor, Cathode Ray Tubes, Line 6] as well as computer monitors. “Red: Yttrium oxide-sulfide activated with europium is used as the red phosphor in colour CRT’s.”[Wiki Phosphor, Cathode Ray Tubes, Line 8] (YVO₄:Eu³). “Yellow: When mixed with Cadmium sulfide, the resulting zinc cadmium sulfide (Zn, Cd)S:Ag, provides strong yellow light.” [Wiki Phosphor, Cathode Ray Tubes, Line 10]. “Green: Combination of zinc sulfide with copper, the P31 phosphor or ZnS:Cu, provides green light peaking at 531 nm, with long glow.” [Wiki phosphor, Cathode Ray Tubes, Line 11]. “Blue: Combination of zinc sulfide with few ppm of silver, the ZnS:Ag, when excited by electrons, provides strong blue glow with maximum at 450 nm, with short afterglow with 200 nanosecond duration. It is known as the P22B phosphor. This material, zinc sulfide silver, is still one of the most efficient phosphors in cathode ray tubes. It is used as a blue phosphor in colour CRT’s.” [Wiki Phosphor, Cathode Ray Tubes, Line 12]. The standard phosphor type for a computer display has a composition of InBO₃:Tb+InBO₃:Eu.
Today, the use of LED (light emitting diode) monitors have largely replaced CRT monitors because of the improved technology. “Light emitting diodes is a semiconductor light source that emits light when current flows through it”. [Wiki LED, Line 1].
The newest type of LED screens are named OLED (organic light emitting diode). They were developed by the chemists Ching Wan Tang and Steven Van Slyke in 1987. The OLED is made up of a layer of organic materials which are situated between two electrodes, the anode and cathode, and they are deposited on a substrate. “The organic molecules are electrically conductive as a result of delocalization of pi electrons caused by conjugation over part or all of the molecule”. [Wiki OLED, Working principle, Line 2].
OLED’s are still being improved and are currently one of the leading technologies for full-colour display panels and OLED’s are also very eco-friendly lighting sources because of their mercury-free manufacture and superior colour quality.
Flexible OLED panels is an emerging technology that will be available to the public in the future. Research in the field of chemistry has made it possible to produce flexible OLED panels. The material used for this technology is polyethylene terephthalate (PET). The chemical formula is C₁₀H₈O₄. The main issue that needs to be solved for the flexible OLED technology is to reduce the residual stress on the device as well as reducing the external stress from bending. There is ongoing research and development in chemistry to improve computer monitors.
Motherboards
Computer components such as the motherboard have been advancing in technology, this has been made possible with the use of chemistry. Components that make up the motherboard have become smaller and sleeker.
The two main materials that a motherboard is made up of is fiberglass and copper. Fiberglass provides extensive insulation and copper forms conductive pathways. Chemical etching is a vital process that allows communication pathways of wires integrated into the circuit. “Photoresist is applied to both sides of the copper-clad laminate, coating the layers of the copper.” [Qual-Tech, The importance of Chemical Etching, Line 2]. “A pattern is then placed over the laminate before the component is exposed to ultraviolet light.” {Qual-Tech, The important of Chemical Etching, Line 3]. “The chemicals polymerised when the photo-resist is exposed to the ultraviolet light - the board is immersed in a chemical solution to develop the image.” {Qual-Tech, The importance of Chemical Etching, Line 4]. “The unexposed photoresist is washed away, and any remaining polymerised portions of the photoresist are etched away. [Qual-Tech, The importance of Chemical Etching, Line 5]. The entire process of chemical etching makes it possible for all the additional components added to the motherboard such as capacitors, and various expansion slots. The process is vital for the motherboard to work properly.
In addition, the use of chemistry is an important for computer engineering when manufacturing motherboards because, there are many chemical processes happening when the motherboard is being built. Chemical processes such as producing fiberglass and chemical etching would not be possible without the use of chemistry and working with chemists. Therefore, chemistry is vital for computer science and computer engineers.
Liquid Coolant
Chemistry has made it possible to effectively build liquid cooling systems used to cool CPU’s (Central process units. Liquid cooling is a very effective method of removing heat in a computer caused by the CPU (Central Processing Unit) and GPU (Graphics processing unit). The most common type of fluid used is distilled water. However, liquid nitrogen is also used extensively by companies to cool the CPU when they are trying to measure the peak performance of the CPU.
Although, using a standard liquid cooling system with distilled water is still popular, a new method of liquid cooling computer parts using thermosiphon has been introduced to the public. With a normal liquid cooling system, the problem arises that occasionally the CPU will produce a lot of heat and the distilled water in the cooling system will vaporize leaving with less liquid available to transfer the heat. With the thermosiphon “liquid in the evaporator portion near the CPU works much like a heat pipe, in that the liquid is in a sealed metallic body and is heated into a vapor state.” [pcworld, line 7]. “The heated vapor travels to the condensers through channels where it cools off and reverts to liquid form.” [pcworld, line 8]. This unique innovation has allowed liquid cooling systems to retain water that is evaporated.
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Using thermal paste is another form of liquid cooling. With the use of chemistry in computer science and computer engineering, thermal paste had been manufactured to fill air gaps between the CPU and the CPU fan. Thermal paste acts as an effective cooling agent for the CPU combined with a liquid cooling system or CPU fan. Thermal paste “is a thermally conductive (but usually electrically insulating) compound, which is commonly used as an interface between heatsinks and heat sources such as high-power semiconductor devices.” [wiki Thermal Paste, Line 1]. “The main role of thermal paste is to eliminate air gaps or spaces which act as thermal insulation from the interface area in order to maximize heat transfer and dissipation.” [wiki Thermal Paste, Line 3].
Thermal paste consists of polymerizable liquid and has large volume fractions of electrically insulating and thermally conductive filter. The matrix materials of the thermal paste are epoxies, silicones, urethanes and acrylates. Adhesives are also used such as hot melt adhesives, solvent based systems and pressure sensitive adhesive tapes. The fillers that are used for the adhesives are aluminium oxide, boron nitride, zinc oxide, and aluminium nitride.
Manufacturing liquid cooling systems for PC’s depends heavily on the use of chemistry. Only individuals with chemistry background have expertise to identify what will happen to the liquid when the microprocessor reaches higher temperatures. For the Liquid cooling system to work properly it needs to be extensively tested in a controlled environment so there are absolutely no faults with the product. Overtime, water leaking out of the liquid cooling system and air pockets are common consequences. Hopefully, in the future new research in chemistry may come up with an improved type of liquid compound to replace water. Thermal paste, a product to reduce heat on a CPU has also been manufactured with the use of chemistry. This ties into computer science and chemistry because without thermal paste, CPU’s would have an excessive amount of heat and would fail completely. The use of chemistry has made it possible to produce thermal paste so the CPU can run smoothly without any heat spikes.
Central Processing Units (CPU’s)
The central processing unit is a type of electronic circuitry that executes instructions and calculates mathematical operations very quickly. A central processing unit is one of the most fundamental computer parts in computer electronics. Central processing units are made up of mostly silicon, which is an important element used as a conductor when voltage is applied to the material. The first stages of production start with making chemical wafers which is where the CPU will be produced on. The process starts with melting polysilicon together with amounts of electrically active elements such as boron, arsenic, and phosphorus. Once the chemical process is complete the next step is to lower a silicon seed crystal, into the melt. Crystal growth begins around the seed immediately once the temperature reduces. The seed is then slowly extracted from the melt. “The temperature of the melt and the speed of extraction govern the diameter of the ingot, and the concentration of an electrically active element in the melt governs the electrical properties of the silicon wafers to be made from the ingot.” [CPU Shack, Line 11].
Next, a layer of oxide is added onto the wafer and a layer of organic photoresist is applied. A mask is then applied to the wafer and UV light is shown through the gaps. UV light is mainly used because of the shorter wavelength it produces. Using a shorter wavelength means it can pass through a smaller mask without any problems. “The UV light hardens (fixes) the photoresist.” [CPU Shack, Page 2, Line 6-9]. After this process, chemical etching is used to etch away the Silicon Oxide with Hydrofluoric acid. Hydrofluoric acid is an inorganic compound and it does not remove the photoresist. The remaining photoresist is removed by washing it off and the wafer is then complete. The material is ready for doping and another type of silicon.
The next step is to make the transistor for the wafer. “A p-type wafer (silicon doped with boron) has a epilayer of n-type (silicon doped with Phosphorus or Arsenic).” [CPU Shack, Page 2, Line 11]. After the two processes are complete a mask is used to implant silicon dioxide and then it is used for the insulator. Acceptor atoms, mainly boron are diffused into the window in the compound silicon dioxide. By using another mask additional Silicon Dioxide is grown and donor atoms like arsenic with an excess amount of electrons are then implanted. Once the Silicon Dioxide is complete then, a new mask is used to grow additional silicon dioxide. The final process is to use the last mask which is used to implant evaporated Aluminium or Copper for the contacts. [CPU Shack, Making the transistor, Lines 1-6].
The final step is the production of the microprocessor. “Silicon-on-Insulator (SOI) is a manufacturing technology where an insulating layer is created in a silicon wafer, isolating the top layer of silicon where the active transistors will be manufactured from the rest of the bulk silicon wafer.” [CPU Shack, Page 4, Line 2]. “The buried oxide layer acts as a barrier that reduces electrical leakage from the transistors, resulting in semiconductor devices that are faster and more power efficient.” [CPU Shack, Page 4, Line 3]. “Immersion lithography is a projection enhancement methodology that places a liquid between the lens and the wafer” [CPU Shack, Page 4, Line 11]. “Low-k dielectrics are used to form insulation between interconnections in integrated circuits.” [CPU Shack, Page 4, Line 12]. Finally, the final process is using Strained germanium, EUV -Extreme ultraviolet light and Separation-by-Implantation-of-Oxygen. [CPU Shack, Page 4].
Semiconductors
A semiconductor by definition in computer electronics is a solid substance that has a conductivity centered between an insulator and that of metals. The properties are either due to impurity of the chemical substance or the effects of temperature. Semiconducting properties have many elements and compounds such as silicon and germanium. Binary compounds such as gallium arsenide and silicon carbide. The process of manufacturing semi-conductors undergoes many different types of chemical processes. One of the most fundamental chemical process is to have a high degree of crystalline perfection since any faults with the crystal structure will cause major defectors to the semi-conductors. Once the crystalline perfection has been achieved, there is a combination of chemical processes that is used to make the semi-conductor materials into an integrated circuit. The chemical process is called thermal oxidation which forms silicon dioxide, on the surface of the silicone. The silicon dioxide is then used as a gate insulator and field oxide. The other processes are known as photomasks and photolithography, which creates the patterns on the circuitry in the integrated circuit. Ultraviolet light and a photoresist layer is used to create a chemical change that creates patterns for the circuit. Plasma etching is an important process used to complete the semi-conductor. “Plasma etching involves an etch gas pumped in a low-pressure chamber to create plasma.” [Wiki Semi-conductor, Materials, Line 18]. “A common etch gas is chlorofluorocarbon, or more commonly known Freon.” [Wiki Semi-conductor, Materials, Line 19]. “A high-frequency voltage between the cathode and anode is what creates the plasma in the chamber.”
Semiconductors are essential components of most electronic circuits and silicon has been always at the forefront of the semiconductor manufacturing. There are many reasons why silicon is the preferred element for use as semiconductors. Silicon can be easily separated from silica sand and is an economical choice for the computer electronics industry.
Silicon is also not without problems. It turns out that it is rather inefficient at converting light into an electrical signal, or at turning electricity back into light. Researchers in the field of chemistry wanted to move beyond the use of silicon in semiconductors and developed the use of new elements instead of silicon.
They researched related elements from group IV of the periodic table where each element forms bonds by sharing four electrons. The elements are carbon, tin, and lead besides silicon and germanium. As stated previously, silicon is very inefficient at converting electricity to light and so is germanium. The scientists decided to check elements from group III and V column. This experimentation resulted in GaAs Gallium Arsenide. Also, another reason why silicon is preferred over germanium is that germanium has a higher electron mobility and causes reverse current to flow.
Overall, the electronics and semiconductor manufacturers are trying to move away from silicon as it requires a number of harmful chemical substances for its processing. These harmful chemical substances cause health hazards to the people working in semiconductor manufacturing. Below are some examples listed of the harmful chemicals used in producing semiconductors. List of chemicals and health problems linked to exposure to those chemicals:
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