Wire bonding types

EIA/JESD51-4, E.J.S., Thermal Test Chip Guideline (Wire Bond-Type Chip), Eebruary, 1997. 

This is the last bond type to be considered. Let s start with a question What holds a metal together A bar of copper or magnesium has properties that are entirely different from substances held together by ionic or covalent bonds. Metals are dense structures that conduct electricity readily. They are malleable, which means that they can be easily twisted into shapes. They are ductile, which allows them to be drawn into wires. No substances with ionic or covalent bonds, such as salt or water, behave anything like metals. 

Flex interposer-based CSPs. This CSP type uses a flexible circuit having solder balls or metal bumps as an interconnect interposer between the chip and the next circuit board level. The bare chip is attached facedown and wire-bonded to the interposer. A thin elastomer, sandwiched between the chip and interposer, cushions the chip and the solder-ball interconnects, relieving stresses (see Fig. 1.13). The interposer generally consists of a metallized, flexible polyimide tape on which are formed electrical connections by photolithographic processes. As a final step, the exposed wire bonds and edges of the chip are molded with epoxy. 

New High TCE Ceramic Material for Wire Bonded Chip Assembly Type CSP with Potting Compound... 

Evaluation of Temperature Cycling Test for wire bonded chip assembly type CSP... 

FIGURE 1.1.9 Photograph of cross-sectional SEM of solder joints of TCT (—40 to 123°C) samples of wire bonded chip assembly type CSP made of the 11.3 ppm/° C material after 1000 cycles. 

FIGURE 58.1 Diagram of a quad flat pack. Note the copper (Cu) leads that are attached by gold wire bonds to the die.This is the primary (or first-level interconnect) between the die and the package.The second-level interconnect will be created when the Cu leadframe is soldered to a motherboard via some type of surface-mount attach process. (Courtesy ofAmkor Technology, Inc.)... 

Polyphenylene sulphide has been used commercially to encapsulate ceramic capacitors for several years and mica capacitors encapsulated in Phillips Ryton BR61B have recently received the British Standard 9000 approval (BS9070-N-002). More recently, attempts have been made to encapsulate wire-bonded integrated circuits, which is one of the most difficult applications to successfully mould with a thermoplastic material because of problems with wire-bond sweep. By paying particular attention to the melt viscosity of the PPS and having careful control of the moulding parameters it has been shown that it is possible to mould successfully both TTL and linear operational amplifier type devices. 

The space needed by the bond head during the process is another aspect that has to be taken into account for US wire bonding on 3D-MID. Deep-access bond heads of some types can bond inside recesses. This permits a high level of 3D design freedom. On the horizontal plane, approximately 1.2 mm of clearance is typically required between the second bond and the next raised object (component, MID wall, etc.). 

Ultrasonic wire bonding on MID has to allow for other factors influencing bond-ability that are of minor significance at best in the context of conventional printed-circuit boards or ceramic substrates. For example, the thickness of the plating, metallization surface roughness, and the type of substrate structuring are all of crucial importance. With two-shot MID the structural design and the mechanical... 

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