Chip carriers

Electronic-Grade MMCs. Metal-matrix composites can be tailored to have optimal thermal and physical properties to meet requirements of electronic packaging systems, eg, cotes, substrates, carriers, and housings. A controUed thermal expansion space tmss, ie, one having a high precision dimensional tolerance in space environment, was developed from a carbon fiber (pitch-based)/Al composite. Continuous boron fiber-reinforced aluminum composites made by diffusion bonding have been used as heat sinks in chip carrier multilayer boards. 

Fig. 1. The different levels of electronic packaging (0) chip (1) chip carrier (2) printed circuit board (electronic card assembly) (3) rack and (4) system (2).

In appUcations in which electrical conductivity is required, metals, copper, tungsten, molybdenum, and Kovar [12606-16-5] are the preferred chip-carrier materials. Metals have exceUent thermal conductivities. Tables 2 and 3 Ust the various materials used for substrates, along with their mechanical, electrical, and thermal properties. 

Wire Interconnect Materials. Wire-bonding is accompHshed by bringing the two conductors to be joined into such intimate contact that the atoms of the materials interdiffuse (2). Wire is a fundamental element of interconnection, providing electrical connection between first-level (ie, the chip or die) and second-level (ie, the chip carrier, or the leadframe in a single-chip carrier) packages. 

Recently, the telecommunication industry has undergone rapid expansion, and a strong consumer trend towards smaller and lighter telecommunication devices, such as cellular phones and notebook computers, is indicated. Small connection sockets and chip carriers are micro-injection-molded parts requiring the high flowability, high mechanical properties and dimensional stability of LCPs. These merits are now thought to be another application field for LCPs in the electronics industry. 

Sockets, switches, relays, electrical and electronic connectors, fuse holders, closures... Chip carriers... 

Resins are used in electromc/electncal applications (connectors, circuit boards that are vapor and wave solderable, microwave transparent radomes, integrated circuit chip carriers, miniature switches, explosion proof enclosures, lamp reflectors, and high-precision fiber optic components). Polyetherimide is used for medical components (hat require all forms of sterilization. Other uses are found in the transportation field, dual-ovenable cookware, as well as bearings, fasteners, and advanced composites. 

With the conventional technology, ICs are mounted individually in plastic or ceramic single-chip packages (SCPs), such as dual-in-line packages (DIPs) or chip carriers, and the SCPs are interconnected on printed wiring boards (PWBs). The number of pins on SCPs has increased significantly, and line widths on PWBs, like IC feature sizes, have followed a historical downward trend (2). However, the basic SCP-on-PWB approach has remained predominant. 

Chip carriers are square ceramic or plastic packages with leads on four... 

Figure 5. Plastic-leaded chip carrier with J-shaped leads. (Reproduced with permission from reference 28. Copyright 1985 Institute of Electrical and Electronics Engineers.)...

Pin Grid Arrays. Standard chip carriers are limited to ICs with 124... 

Mixer top side layer material Alumina Chip carrier material PPMA PEEK... 

Major polymer applications aerospace, electronics (mostly films and coatings), photosensitive materials for positive imaging, solar cells, hollow fiber membranes, composites. unclear power plants, space shuttle, microprocessor chip carriers, structural adhesives... 

Major polymer applications automotive lighting, ignition and braking systems, carburetor parts, fuel components, chip carriers, phone jacks, IC card connectors, transistor encapsulation, tape recorder head moimts, relay components, motor fans, coil bobbins, sockets, relay units, food choppers, steam hair drier parts, lamp sockets, microwave oven components, pump housings, impeller diffusers, oil well valves, halogen lamp sockets... 

Integrated circuit device burn-in test sockets. These chip carriers must survive high continuous test oven temperatures. 

The need for accommodating a higher number of leads resulted in development of chip carriers with contact pads on four sides. The example shown in Figure 2 is leadless, but several lead... 

Figure 2. Conventional chip carrier. This example with a lid is for hermetic applications. (Reproduced with permission from Ref. 4. Copyright 1988 BPA [Technology and Management, Ltd.].)...

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