Motorola Corporation

Western Electric Company, Inc.

Robert C Pfahl, Jr

James A Wrezel

Lawrence R Hagner

A distillable, non-azeotropic solvent mixture for electronic assembly cleaning in order to adequately remove solder flux and other residues traditionally removed using CFC-based azeotropes. The mixture is heated to at least the boiling point of component A but less than the boiling point of component B. Component A vaporizes (102), forming a vapor layer above the mixture (103). Condensing elements (101) near the top of the cleaning apparatus condense the vapor (102), returning it to the heated mixture (103) to be vaporized again. The assembly (104) to be cleaned is lowered through the vapor and then immersed in the mixture (103) before being positioned in the vapor (102).

Method for electrical assembly cleaning using a non-azeotropic solvent

Non-azeotropic solvent composition for cleaning and defluxing electrical

The apparatus of the present invention uses a vessel with a sump for containing a liquid (103). The vessel has one or more downward angled openings (101). A heating device (104) boils the liquid to produce a vapor and a condensing apparatus (102), in the opening or in a separate chamber, prevents any vapor from exiting the apparatus. The apparatus contains a condensable liquid having a vapor density less than that of the ambient atmosphere by producing a stably stratified interface between the condensable vapor and the ambient atmosphere. The apparatus can be used for such manufacturing processes as cleaning or coating with vapors that are less dense than air.

Vapor containment apparatus

Several methods and apparatus (10, 60) are disclosed for vapor condensation heating only a selected underside surface area of an article (18, 18') while continuously minimizing loss of the generated vapor (26b, 26b') to the atmosphere. In accordance with several preferred embodiments, a composite vessel (11, 11') is formed with a lower stationary sidewall section (14), including venting means (28, 29, 31, 32, 34), and a channel (41) adapted to telescopically receive an upper, internally cooled and retractable sidewall section (13, 44, 13', 44') in a manner that establishes a vapor barrier (27) of controllable volume therewithin. As such, an article (18, 18') to be heated, when initially mounted on the top of the upper sidewall section (13, 13') may thereafter be readily displaced downwardly such that only a selected underside surface area thereof is controllably brought into contact with, and heated by, a single heat transfer liquid (26)--generated body of hot vapor (26b, 26b') confined therebelow.

Methods and apparatus for heating articles selectively exposed to a

This disclosure is directed to the vapor condensation heating of articles to an elevated temperature so as to perform, for example, a soldering, brazing or fusing operation thereon, without requiring the immersion of the articles within the heat transfer liquid-generated body of hot saturated vapor. This is accomplished in accordance with several methods and apparatus which allow the saturated body of vapor to controllably rise to and heat only a selected underside surface area (or areas) of each article, in succession, while minimizing the loss of any vapor to the atmosphere at all times.

Method and apparatus for generating a controllably exposed vapor body

A heat transfer liquid having a boiling point at atmospheric pressure at least equal to the temperature at which a soldering, fusing or brazing operation is to be performed, is floated on a pool of a liquifiable metal having a density greater than, a melting point below, and a heat of vaporization above, that of the liquid. The metal is heated to a temperature between its melting and boiling points, and at least to the boiling point of the liquid, to continuously boil the liquid to establish a body of hot, saturated vapor having a density greater than that of air at atmospheric pressure. An article on which the soldering, fusing or brazing operation is to be performed is extended into the body of vapor to condense the vapor thereon. The latent heat of vaporization of the condensing vapor heats the article to the temperature for the operation, and the article is then withdrawn from the vapor for cooling.

Growing community of inventors

Glen Ellyn, IL, United States of America

Robert C Pfahl, Jr