Component Package Types

Pad shapes and sizes must be uniform, particularly for each component package type. Variation in pad size and shape within a component package type forces longer and more difficult development of inspection programs for each printed circuit assembly type. 

Around 1945, acrylic-type plastics were introduced as restorative materials.These materials, prepared as a two-component package, were semi-II IPNs based on linear poly(methyl methacrylate) as polymer I, and MMA monomer plus crosslinking agents as network II. 

As the name imphes, this package type contains surface-mount parts on both sides, as well as through-hole parts such as connectors. In most cases, the surface-moimt components on one... 

Over time, a wide assortment of packages has been developed to house components. Selecting the correct package type for each component is one of the most important parts of the design process. Package types chosen affect ease of design, assembly, test, and rework, as well as prodnct cost and component availabUity. 

In addition, there has been a steady increase of odd-shaped devices that include inductors as well as LEDs, surface-mount connectors,etc. The result has been circuit boards with a greater mix of package types and sizes. Consequently, it is considerably less expensive and time-consuming to reprogram a computer-based, machine vision system to recognize these components than it is to retool a machine based on mechanical relays, detents, and such for component placement. 

Component installation or placement is the first step in the assembly of the PCBA. It may begin by preparation of the leads of a given package type in order to provide the correct lead... 

For data input in fixed cycle operation the AMI and Siemens package type 1907 shown in Fig. 28 has been designed. With this device and a few additional components a pulse counter, frequency meter, chronometer or digital voltmeter can be built. 

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