Selenia Industrie Elettroniche Associate

Selenia Industrie Elettroniche Associate S.p.a.

Sergio Moretti

Antonio Cetronio

Vittoria Compagnucci

Ugo Fracassi

Maurizio Di Bona

An apparatus for applying a soldering alloy to an element to be soldered including an open-channeled member having a receiving region for holding the element, a vacuum system connected to the member for creating a negative pressure through the open channel and at the receiving region sufficient to retain the element against the receiving region, a heating coil connected to the member for conducting heat to the element at a soldering temperature, and a gas distribution and heating system for providing heated gas to a soldering alloy at a temperature sufficient to melt and provide at least one soldering connection on the heated element. The invention also comprises a method for providing heat to an element to be soldered substantially by conduction and heat to a soldering alloy substantially by convection employing a heated gas all at temperatures sufficient to provide a soldered connection without damaging the element being soldered.

Soldering method employing provision of heated gas to a soldering alloy

A technique utilizing conventional photolithography to manufacture GaAs MESFET devices having sub-micrometric gate and variable length recessed channel. The structure of these devices consists of two photopolymeric layers separated by a metal interface. The upper, stencil layer sets the aperture of the submicrometric gate. The lower planarizing layer defines the recessed channel, through the metal interface, which acts as a template. The length of such channel may be varied through suitable choice of exposure time of the planarizing photopolymer. By adopting such multilayer structures it is possible to obtain gate lengths of .about.b .mu.m and recessed channel lengths form 0.8 to 3 .mu.m, with a process yield typically better than 90%, simultaneously. Furthermore, by using a thicker planarizing layer in this structure it is possible to obtain a relatively thick metal deposit (typically about 0.8 .mu.m), such as a Ti/Pt/Au overlayer over ohmic contacts and gate pads.

Multi layer photopolymeric structure for the manufacturing of MESFET

A method of making semiconductive developments, especially MESFETs, which applies a template to a surface of the substrate previously formed with circuit elements in alignment with these elements and so bonds the template to the substrate that the template can be utilized as a holder for the substrate. The rear surface is then coated with a resist and a second template aligned externally with the first utilizing markings exterior to the substrate to form the structure on the rear surface which can include throughholes for a metal deposit extending through the preferably GaAs substrate.

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Rome, Italy

Sergio Moretti