Flip chip technology is a way to connect different types of electronic components directly by using conductive solder bumps instead of wires. Older technologies used chips that had to be mounted faceup, and wires were used to connect them to external circuits. Flip chip technology replaces wire bonding technologies and allows integrated circuit chips and microelectromechanical systems to be directly connected with external circuits through conductive bumps present on the chip's surface. It is also called a direct chip attach or controlled collapse chip connection (C4) and is becoming very popular because it reduces packaging size, is more durable, and offers better performance.
This type of microelectronic assembly is called as flip chip technology because it requires the chip to be flipped over and placed facedown onto the external circuit it needs to connect to. The chip has solder bumps on the appropriate connective spots, and it is then aligned in such a way that these spots meet the corresponding connectors on the external circuit. Solder is applied to the point of contact, and the connection is completed. While it is primarily used to connect semiconductor devices, electronic components such as detector arrays and passive filters are also being connected with flip chip technology. It is also used to affix chips to carriers and other substrates.
Introduced by IBM in the early 1960s, flip chip technology has become more popular with every passing year and is being integrated into many common devices such as cell phones, smart cards, electronic watches, and automotive components. It offers many advantages, such as the elimination of bond wires, that reduce the amount of board area needed by up to 95 percent, allowing the overall size of the chip to be smaller. The presence of a direct connect via solder increases the performance speed of the electrical devices, and it also permits a greater degree of connectivity because more connections can be fitted into a smaller area. Not only does flip chip technology lower the overall costs during automated production of interconnected circuitry, it's also quite durable and can survive a great deal of hard use.
Some of the disadvantages of using flip chips include the necessity of having really flat surfaces for the chips to be mounted onto external circuitry; this is difficult to arrange in every situation. They also don't lend themselves to manual installation as the connections are made by soldering two surfaces. The elimination of wires means that it cannot be replaced easily if there is a problem. Heat also becomes a major issue because the points soldered together are quite stiff. If the chip expands due to heat, the corresponding connectors also need to be designed to thermally expand to the same degree, otherwise the connections between them will break.
