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== Wire Bonding==
Wire bonding is the manufacturing process for creating metallurgical bond connections between a thin wire (12.5 – 50 µm for gold fine-wires and 150 – 500 µm for aluminum thick-wires) and a suitably coated circuit carrier through friction welding. In principle , this process method consists of pressure welding with the aid help of ultrasound. The metallurgical bond is mainly caused by frictional heat , created through the relative movement between the two bonding partner materials. To achieve high reliability over longer time and under difficult environmental conditions , high quality requirements regarding material and mechanical strength properties must be met by the surfaces of the bonding partners. Multiple silicon chips are combined to a functional unit on a circuit carrier (for example PCB board, DCB substrate, thick film ceramic) which is mostly encased in a hybrid housing for environmental protection. The metallic conductors mounted inside the housing then serve as connections to the outside. If higher current carrying capacity is needed, as for example in power electronics, Al thick-wire bonding is employed ''(Fig. 9.1)''. 2 bilder
Multiple silicon chips are combined to a functional unit on a circuit carrier (for example PCB board, DCB substrate, thick film ceramic) which is mostly encased in a hybrid housing for environmental protection. The metallic conductors attached inside the housing then serve as the connection to the outside. If a higher current carrying capacity is required, such as in power electronics, the Al thick wire connection is used (<xr id="fig:Bond_connection_Al_thick_wire_on_clad_AlSi"/><!--(Fig. 9.1)-->).<figure id="fig:Bond_connection_Al_thick_wire_on_clad_AlSi">[[File:Bond connection Al thick wire on clad AlSi.jpg|right|thumb|Figure 1: Bond connection: Al thick-wire on clad AlSi; (a) Macro photograph,b) micro structure with ruptured wire.]]</figure>
==AlSi Clad Strip for Bond Connections==
Besides electroplated or chemically deposited gold coatings, AlSi clad semi- finished materials are used for layered systems on circuit carriers and in hybrid housings (or for lead frames). These strip materials are manufactured by cold roll cladding of an AlSi1 alloy material onto Cu or Cu alloy strip (<xr id="fig:Examples of AlSi clad strips for bond connections"/>) (see chapter [[Manufacturing_of_Semi-Finished_Materials|Manufacturing of Semi-Finished Materials]]).
Mechanical strength and dimensional tolerances for AlSi clad strips mostly follow the standards EN 1652, EN 1654, and EN 1758 for Cu and Cu alloys. Depending on the end application the following parameters for the coating layer are tested for and documented during manufacturing:
*Layer thickness *Adhesion strength*Bond properties *Solderability
==Electroless Metal Deposition on Printed Circuit Boards==
<figure id="fig:Electroless deposition on a printed circuit board">
[[File:Electroless deposition on a printed circuit board.jpg|right|thumb|Figure 3: Electroless deposition on a printed circuit board]]
</figure>
==References==
Ganz, J.; Kaspar, F.: AlSi-plattierte Bänder für Bondverbindungen mit hoher Zuverlässigkeit in der Gehäusetechnik. PLUS 11 (2005) 2057 -2058
[[de:Anwendungen_in_der_Aufbau_und_Verbindungstechnik]]