Various apparatus and methods are disclosed. In one aspect, a method of manufacturing a thermal interface material on a semiconductor chip is provided. The method includes placing a preform of a combination of a first metal and a second metal on one of the semiconductor chip or a lid. The preform is liquid phase sintered to cause the combination to evolve to an equilibrium composition and bond to the semiconductor chip.

A brazed heat exchanger includes plates that are stacked or nested to define flow channels for multiple media. Inserts are arranged within at least some of the flow channels. Two different braze alloys having compositions based on different metals are used to form braze joints between the plates and the inserts. In some cases, a copper-based braze alloy is used for joints corresponding to flow channels for one of the media in order to provide high pressure-resisting strength to those flow channels, while an iron-based braze alloy is used for joints corresponding to flow channels for another of the media where dissolved copper is undesirable.

Methods of making solder preforms are disclosed. A ribbon of raw material is received, and a first annular solder preform is formed by laser cutting the ribbon. The edges of the first annular solder preform can then be cleaned. The cutout section removed from the middle of the first annular solder preform can then be laser cut to form a second annular solder preform that is smaller than the first annular solder preform.

A screen (24A-H) of a specified thickness (T) for insertion in a gap (32) between surfaces of workpieces (32, 34) to be joined by brazing. The screen thickness determines and maintains the gap thickness during brazing. The screen has a higher melting point than the braze filler material (22), is wettable by a melt of the braze filler material, and may have a higher tensile strength than the braze filler material at operating temperatures of the braze joint. The screen may include electrical resistance heating wires (52, 62) to melt the filler material (46). The screen may be covered by the filler material, forming a brazing foil (20B). The screen may include electrically conductive insulated wires (92, 93) connected to a sensor (95) such as a thermocouple or strain gauge to monitor a condition of the braze joint during subsequent operation.

Disclosed is an amorphous, ductile brazing foil with a composition consisting essentially of Ni.sub.restCr.sub.aB.sub.bP.sub.cSi.sub.d with 2 atomic percent≦a≦30 atomic percent; 0.5 atomic percent≦b≦14 atomic percent; 2 atomic percent≦c≦20 atomic percent; 0 atomic percent≦d≦14 atomic percent; incidental impurities≦0.5 atomic percent; rest Ni, where c>b>c/15 and 10 atomic percent≦b+c+d≦25 atomic percent. Also disclosed is amorphous, ductile Ni-based brazing foil having a composition consisting essentially of Ni.sub.restCr.sub.aB.sub.bP.sub.cSi.sub.dC.sub.eX.sub.fY.sub.g wherein a, b, c, d, e, f, and g are numbers such that 2 atomic percent≦a≦30 atomic percent; 0.5 atomic percent≦b≦14 atomic percent; 2 atomic percent≦c≦20 atomic percent; 0 atomic percent≦d≦14 atomic percent; 0 atomic percent≦e≦5 atomic percent; 0 atomic percent≦f≦5 atomic percent; 0 atomic percent≦g≦20 atomic percent; wherein incidental impurities are present, if at all, in amounts≦0.5 atomic percent; wherein rest indicates that the balance of the composition is Ni; wherein c>b>c/15; wherein 10 atomic percent≦b+c+d≦25 atomic percent, wherein X is one or more of the elements Mo, Nb, Ta, W and Cu; and wherein Y is one or both of the elements Fe and Co. Also disclosed are methods for making and using these brazing foils, and brazed objects produced therefrom.

A method for brazing is provided, in which an amorphous or partially amorphous brazing foil, having a composition with a metalloid content of 10 to 30 at. %, is arranged at a joining point of two or more parts. The brazing foil is in the form of a wound ring-shaped strip which has a short-circuited current path between at least two layers lying one on top of the other. The brazing foil inductively heated, melted and a brazed connection of the parts is produced.

A method for joining heat transfer plates, comprising: applying a melting depressant composition on individual application areas of a first metal sheet, each application area comprising a mid-section and two end-sections; pressing ridges and grooves in the metal sheet, the ridges extending in a direction that extends between the end-sections of the application areas, such that the application areas are located on top of the ridges; bringing the metal sheet into contact with a second, pressed metal sheet, such that contact points are formed where the mid-sections of the application areas re located; heating the sheets until melted metal is formed at the application areas where the melting depressant composition is applied; and allowing the melted metal to solidify such that a joint is obtained at the contact points.

A brazing sheet (1) includes a core material (11) composed of an Al alloy that contains 0.20-3.0 mass % of Mg; and a filler material (12) layered on the core material and composed of an Al alloy that contains Mg, 6.0-13.0 mass % of Si, and more than 0.050 mass % and 1.0 mass % or less of Bi. The Mg concentration of the filler material becomes continuously lower in a direction from a boundary (122) with the core material to an outermost surface (121). The Mg concentration of the filler material is 0.150 mass % or less at a first depth from the outermost surface that is ⅛ of a thickness (t.sub.f) of the filler material and is 5-90% of the amount of Mg in the core material at a second depth from the outermost surface that is ⅞ of the thickness of the filler material.

Electrical insulating properties between adjacent copper plates are improved while a defect of a bonded substrate which is caused by concentration of stress to end portions of the copper plates is prevented. A bonded substrate includes a silicon nitride ceramic substrate, a copper plate, and a bonding layer. The copper plate and the bonding layer are disposed on the silicon nitride ceramic substrate. The bonding layer bonds the copper plate to the silicon nitride ceramic substrate. The bonding layer includes: an interplate portion between the silicon nitride ceramic substrate and the copper plate; and a protruding portion protruding from between the silicon nitride ceramic substrate and the copper plate. Exposure of the silicon nitride ceramic substrate is prevented at a position where the protruding portion is disposed.

A composite member having an excellent heat resistance is provided. The composite member includes: a substrate composed of a composite material including a non-metal phase and a metal phase; and a metal layer that covers at least a portion of a surface of the substrate, wherein a metal included in each of the metal phase and the metal layer is mainly composed of Ag, and a ratio of a content of Cu to a total content of Ag and Cu in a boundary region of the metal layer with the substrate is less than or equal to 20 atomic %.