Consumer electronic assemblies

Because the conductivity of polymer electrolytes is generally low, thin batteries are assembled (50-200 pm) with electrolyte thickness ranging from 20 to 50 pm. Conventional polymer electrolytes based on PEO and lithium salts, owing to their high crystallinity, reach useful conductivity values only at temperatures above 60 °C, i.e., above the melting temperature of the crystalline phase. If the low conductivity at room temperature prevents their application for consumer electronics, this does not represent an obstacle for electric vehicles, for which an operating temperature higher than that of the transition in the amorphous phase is expected. 

Assembly line refers to a facility in which products are made from component parts by a process in which discrete units of product move along an essentially continuous line through a sequence of installation, joining, and finishing processes. Examples are automobiles, industrial equipment, small and large apphances, computers, consumer electronics, toys, and some furniture and clothing. 

Mechanical attachment of components, devices, and other parts of an electronic assembly is the prime function of adhesives. Although adhesives are expected to bond a wide variety of materials for electronic applications, they do not need to be structural. They should, however, meet minimum tensile and shear strengths in order to withstand mechanical shock, thermal shock, thermal cycling, and vibration as specified for the intended application. For consumer and commercial products, these stresses may be minimal. For high reliability aerospace and medical systems, more severe tests as defined in MIL-STD-883 and other documents must be used. 

The decision to rework electronic devices or assemblies depends on the cost of reworking versus the value of the part. Consumer electronics, due to their low cost, are considered throwaways and seldom reworked. For some, such as plastic-encapsulated microcircuits (PEMs) that are produced in high volumes, rework is impractical because of the difficulty in removing the plastic encapsulant without destroying the components. However, for high-value assemblies, such as densely populated PWBs and MCMs, where the final value may be as high as 10,000 or more, the ability to rework is essential. In such cases, rework may be necessary to meet schedules when small numbers of assemblies are produced. 

It must be kept in mind that design for manufacture and assembly and design for disassembly may sometimes be in conflict with each other. For example, snap-fits may accelerate the assembly process but impede rapid disassembly if they are not designed properly. Furthermore, safety rules and regulations, such as for consumer electronics and household appliances, require the protection of electrical circuits to avoid accidents. In other products, easy access may also encourage the theft of valuable components [32]. 

The two main approaches to explain nanotechnology to the general public have been oversimplified and have become known as the top-down approach and the bottom-up approach. The top-down approach involves fabrication of device structures via monolithic processing on the nanoscale. This approach has been used with spectacular success in the semiconductor devices used in consumer electronics. The bottom-up approach involves the fabrication of device structures via systematic assembly of atoms, molecules or other basic units of matter. This is the approach... 

In one of its final assembly factories, Maxtor Corporation offers a component-level product. Hard Disk Drive (HDD), to its customers for further assembly of desktop PCs, high-end servers, consumer electronics products, network attached storage (NAS) server appliances, etc. (see www.maxtor.com). Maxtor has partnership-based B2B relationships with its customers. In this setting, customer orders are not given as specific order quantities and order due dates. Instead, only the total order quantity in each week is specified with permitted minimum and maximum quantity limits. In its order promising and fulfillment processes, Maxtor does not postpone customer orders to later weeks (i.e. no backorders), but it may deny customer orders subject to liability and/or penalties. While customer orders are promised weekly, the order fulfillment process is executed daily to provide accurate resource utilization and production schedules (see Ali, et al. 1998). 

There are manufacturers focusing on low value mass production parts and manufacturers doing their own R D and providing high value specialized parts as well as those focusing on assembly (e.g., FoxCram ). In consumer electronics products, the final assembly cost often is just 5-10 % of the cost of the part used in the assembly. 

All component leads attach to the PCB by being inserted into holes that pass through the PCB.The components may be secured by wave soldering or by pressing into holes that result in an interference fit (press fit). Assembly involves a component placement operation followed by a wave-soldering operation. This method is still the workhorse of the low-cost consumer electronics industry. 

Several machine types are available. The turret-style chip shooter and the gantry-style or flexible fine-pitch (FFP) machines have both been nsed extensively in the assembly of consumer electronics, telecommunications, mainframe and server computers, as well as for lower volume, high-reliability electronic products. However, the demands for even higher production volumes as well as the flexibility to change product fines rapidly have caused manufacturers to consider alternative machine architectures that include high-speed stepper motors and optical sensors as well as highly parallel methodologies that place multiple components at the same time. 

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