International Business Machines Corporation

Societe' Nazionale Industria Applicazioni Viscosa S.p.a. (snia Viscosa)

Vittorio Sirtori

Franco Zambon

Pietro Luigi Cavallotti

Michele Monopoli

Giovanni Zangari

Lorenza Lombardi

Fabio Mauri

Giovanni Cattaneo

Adelio Monzani

Luigi Giussani

Paul Joseph Hart

Luca Magagnin

Pletro Luigi Cavallotti

Fiavio Cereda

Seba Calgari

Ignazio R Bellobono

Roberto Mazzoni

Marino Verderio

Sergio Varinelli

Flavio Cereda

Pietro Luigi Cavalloti

The method according to a preferred embodiment of the present invention mitigates the problem of gold contamination during the SMT assembly operations in the manufacture of Hybrid Multi Chip Modules (HMCM), achieving a high assembly process yield. This target is accomplished by protecting, at the first process step, the gold with a thin layer (0.02&#x2013;0.03 millimeter) of a paste very soluble in water and washing it off. The protective layer obtained with the above described method is very strong. Furthermore it is very easy to remove, since it is soluble in water.

Ball grid array module

A method of pretreating a copper surface for protecting the surface from oxidation, by immersing the surface in a solution containing organic solderabilty preservatives, such as BenzoTriAzole, with the addition of a zinc salt. The method is particularly useful in the manufacturing of electronic Printed Circuit Boards for protecting the copper surfaces during the solder processes when the PCB undergoes high temperature. The addition of the zinc salts also gives the additional advantage of increasing the solderabilty properties of the copper surface (i.e. wettability and adhesion).

Copper preservative treatment

The method according to a preferred embodiment of the present invention mitigates the problem of gold contamination during the SMT assembly operations in the manufacture of Hybrid Multi Chip Modules (HMCM), achieving a high assembly process yield. This target is accomplished by protecting, at the first process step, the gold with a thin layer (0.02-0.03 millimeter) of a paste very soluble in water and washing it off. The protective layer obtained with the above described method is very strong. Furthermore it is very easy to remove, since it is soluble in water.

A method and system for estimating the roughness and the contamination of a surface. A preferred embodiment of the present invention makes use of a mathematical model which gives indications of the metal roughness, expressed as the ratio of metal volume to air volume, and the contamination thickness values of a metal substrate (e.g. gold) for a determined contamination (e.g. organic). This model is based on a series of tables which represent the expected values of &psgr;, i.e. the ratio between the amplitudes of the incident beam on the two polarization planes multiplied by the ratio of the amplitudes of the reflected beam on the polarization planes, and &Dgr;, i.e. the difference between the phases on the two polarization planes of the incident beam and the reflected beam, for a gold substrate having a predetermined roughness and a predetermined type of contamination (organic). Each table is built for a roughness value &phgr; expressed as the ratio of metal volume to air volume and gives the values of &psgr; and &Dgr; for a range of possible contaminations expressed as thickness of the contaminant film. Each table shows, for a predetermined value of &phgr;, the expected values of &psgr; and &Dgr; for an organic contaminant film having a thickness of 0, 10 . . . 100 Angstrom.

Surface analysis using ellipsometry

A method and a bath for protecting a Zn or Zn alloy surface against the corrosion and oxidation and for improving the wettability characteristics of a Zn or Zn alloy surface with a Sn solder alloy. The method is particularly useful in the manufacture of electronic components, when the deposition of a thin layer of Zn or Zn alloy is needed before the deposition of the Sn alloy (particularly Pb free) to improve the solderability characteristics of the Cu surface.

Protective treatment of a zinc or a zinc alloy surface

A method for decontaminating the copper surfaces (e.g. circuits) of an electronic card from copper salts which can be formed after the soldering of the electronic components onto the substrate employing a water free solution which comprises an alcohol and at least one neutral ammonium salt of an organic acid.

Decontamination of electronic cards from copper salts

A method for removing thermal grease from an electronic card having plated via holes and including electronic components thereon, the method including the steps of providing a substantially water free solution having an alcohol and at least one compound of a neutral ammonium salt of an organic acid and immersing the electronic card in the solution for a predetermined period of time remove the thermal grease from the electronic card.

Removing thermal grease from electronic cards

A water free solution for decontaminating copper surfaces (e.g. circuits of an electronic card) from copper salts which includes an alcohol and at least one neutral ammonium salt of an organic acid.

Solution for removing copper salts from a copper surface comprising an

An electronic device has a layer of high wettability tin-bismuth solder alloy on component leads and substrate pads. The solder is electrodeposited onto copper with an electrodeposition bath containing a zinc salt, although no zinc is co-deposited on the copper. The tin-bismuth layer has a low quantity of oxygen thereby increasing the wettability and decreasing the oxidation at the surface after reflowing.

Electronic device with high wettability solder pads

A method and a bath for autocatalytic chemical deposition of a Sn Zn alloy on a catalytic surface. The method is particularly useful in the manufacture of electronic components, when the deposition of a thin layer of Sn Zn alloy is needed before the deposition of the Sn alloy (particularly Pb free) to improve the solderability characteristics of the Cu surface. The Cu surface must be made catalytic before immersion in the autocatalytic bath, e.g. by depositing a thin film of metallic Sn.

Autocatalytic chemical deposition of zinc tin alloy

Method of manufacturing a printed circuit board

An electrodeposition bath for depositing a Sn alloy onto a Cu substrate containing a Zn salt. This bath is particularly useful for Pb free alloy, such as a Sn--Bi alloy. The presence of Zn in the elctrodeposition bath greatly influence the bath behaviour and the characteristics of the deposited alloy, even if no Zn is codeposited on the Cu substrate.

Electrodeposition bath

A soldering method for soldering electronic components onto a copper (Cu) substrate using a tin (Sn) solder alloy. The method comprises in pretreating the Cu substrate by depositing a thin layer of zinc (Zn) before the deposition of the Sn solder alloy. This method greatly enhances the mechanical and electrical properties of the solder alloy, allowing the use of lead (Pb) free alloys such as tin-bismuth (Sn--Bi).

Solder method

A cell for the direct conversion of radiant energy to electrical energy for arrying the process is characterized in that it comprises two layer-like zones each comprising a transparent material and at least one photochromic compound, electrical conduction means between said two zones, and two electrodes. The two layer-like zones may be constituted by different portions of a same layer. The photochromic compounds used are preferably spiro-2H-pyranes and the electrodes are metals having a standard oxidation potential higher than--2.5V or their oxides or photoactive semi-conductors.

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Milan, Italy

Vittorio Sirtori