Television circuit boards

Shredded circuit boards. Circuit boards are metal boards that hold computer chips, thermostats, batteries, and other electronic components. Circuit boards can be found in computers, televisions, radios, and other electronic equipment. When this equipment is thrown away, these boards can be removed and recycled. Whole circuit boards meet the definition of scrap metal, and are therefore exempt from hazardous waste regulation when recycled. On the other hand, some recycling processes involve shredding the board. Such shredded boards do not meet the exclusion for recycled scrap metal. In order to facilitate the recycling of such materials, U.S. EPA excluded recycled shredded circuit boards from the definition of solid waste, provided that they are stored in containers sufficient to prevent release to the environment, and are free of potentially dangerous components, such as mercury switches, mercury relays, nickel-cadmium batteries, and lithium batteries. 

The total content of Lead and PBDEs in the TVs has been calculated. In the case of Lead, Fig. 6 presents the distribution of this compound in the different parts of a TV set. It is important to mention that due to the lack of data on the Pb content in Printed Circuit Board (PCBs), this element has not been taken into account for televisions. 

Fabrics and polyurethane furniture, circuit boards, high-impact plastic casings around electronic equipment such as televisions, telephones, computers, hair dryers, etc., are sources of flame retardants such as PBDEs, HBCD, TBBPA and new generation flame retardants bis(2,4,6-tribromophenoxy)ethane (BTBPE), (2-ethyUiexyl)tetrabromophtha-late (TBPH), decabromodiphenyl ethane (DeBDethane) and 2,4,6-tribromophenol (2,4,6-TB) (see Chapters 2, 5, 7 and 8) (Kemmlein et al, 2003 Stapleton et al, 2008 Takigami et al, 2008, 2009 Kolic et al, 2009). Traces of PBDD/F can... 

Different fractions of electronic scrap were tested and pyrolysed. Figures 20.3-20.6 show feed materials and their related residues. In the case of populated and nonpopulated computer circuit boards as well as in the case of television boards a non-sticky residue results. 

As worked out for several reaction temperatures and residence times, different materials such as populated and nonpopulated circuit boards from computers or television sets as well as housing fractions from computers or monitors can be processed at two distinct... 

Figure 20.5 Television printed circuit boards, pyrolysed at 350 and 450°C, 2 h at each stage and the related residues...

Brominated flame retardants have been used extensively for many years in high impact polystyrene, ABS and similar styrene polymers, especially in housings for televisions, computers, audio and video equipment. Replacing them by nonhalogen systems has proved difficult because of inability to match their effectiveness and their freedom from technical problems. Difficulties have also arisen in finding appropriate replacements for use in PBT connectors and epoxy printed circuit boards. 

Polymers can also be used in many applications and a few examples are electrical cable and wire insulations, electrical systems and components, automotive ignition, switches, relays, capacitors, transformers, resistors, printed circuit boards, bush holders, terminal blocks, electric motor parts, capacitors, telecommunications equipment, ignition components, television and radio location. 

Telephones, televisions, audiovisual equipment, computers, computer components, circuit boards, and handheld devices that store music and books are all examples of products that are disposed of by businesses and individual consumers as electronic wastes (e-wastes) when they become obsolete. E-wastes,... 

TBBPA has found use as a reactive flame retardant in the production of epoxy and polycarbonate resins added to circuit boards used in computers and in many other devices. In about 10% of cases TBBPA is used as an additive flame retardant, especially in the production of acrylonitrile-butadiene-styrene polymers, polystyrene, papers, textiles, televisions, office equipment and others. 

What resources are moved in a supply chain Obviously, when we initially think of a supply chain, we think of materials or parts moving from one location to another and eventually ending up in the hands of a customer. For example, when we think of the supply chain for a television, we go all the way back to the mine that dug up the raw materials, then to the refinery where we process the steel or the chemicals, and next to the factory where we form the parts and assemble them into products such as circuit boards or screens. From the assembly plant that put the television together we go to the shipping company that packaged the product and delivered it to a warehouse, and finally to a retailer. The retail store puts the television on the shelf where the customer selects the product, purchases it, and takes it home. This process involves literally thousands of steps, and each step becomes critical to the success of the overall process. The customer interprets a failure in any of these steps as a failure of the entire supply chain. 

A potentially new and novel source of resin for compression molders is e-waste, which represents material in the components of electronic devices— personal computers, laptop computers, monitors, telephones, cellular telephones, radios, copiers, printers, fax machines, televisions, hard drives, media players/recorders—at the end of their useful life. Once the most valuable, mainly metallic, materials are removed from circuit boards and wiring, the remainder is plastic (e-plastics). This is a mixed stream of predominantly engineered thermoplastics such as ABS, nylon, polycarbonate, polyethylene, polypropylene, polystyrene, and various blends. However, thermosets (epoxy and phenol-formaldehyde for instance) and elastomers may also be present in small quantities. Unfortunately, material separation, although desirable, is a costly and formidable task. Due to the composition variability and unpredictability. 

The ability of a solder mask to protect conductors from physical and chemical deterioration and to insulate adjacent circuitry is a major consideration of PCB manufacturers. The Institute for Interconnecting and Packaging Electronic Circuits (IPC) has defined the requirements for the qualification and performance of solder masks in the Standard Specification IPC-SM-840 (A). The specification defines classes (1, 2, and 3) to reflect progressive increases in sophistication, functional performance, and testing methods. These classes try to provide PCB manufacturers with assurances of reliability. For example, Class 1 requirements provide the reliability needed by commercial boards used in radios, televisions, and small appliances. Class 2 is for computers and Class 3 for military and life-dependent products. 

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