Apparatus and method for soldering, fusing or brazing

Claim 2

Method as in claim 1, wherein: h. the operation performed on the article is soldering with solder, i. the boiling point of said primary liquid is at least equal to the melting point of said solder.

Claim 3

Method as in claim 3, wherein the article to be soldered is a printed circuit board having electrical components mounted thereon and wherein: j. said primary liquid is electrically non-conductive, k. said primary vapor is chemically inert.

Claim 4

Method as in claim 1, wherein: h. the operation to be performed on the article is fusing a coating of solder thereon, i. the boiling point of said primary liquid is at least equal to the melting point of said solder.

Claim 5

Method as in claim 1, wherein: h. the operation to be performed on the article is brazing, i. the boiling point of the primary liquid is at least equal to the melting point of the material being brazed.

Claim 6

Method as in claim 1, wherein: h. said saturated primary vapor is chemically inert.

Claim 7

Method for performing on an article at elevated temperature on operation comprising the melting of material, said method comprising: a. establishing substantially at atmospheric pressure a body of saturated primary vapor extending to a first predetermined height over a primary liquid having a boiling point at least equal to said elevated temperature and the melting point of said material by continuously boiling said primary liquid; b. applying a first cooling medium to said body of saturated primary vapor at said first predetermined height to condense saturated primary vapor at said first predetermined height; c. generating a body of secondary vapor from a secondary liquid, said secondary liquid having a lower atmospheric boiling point than said primary liquid; d. maintaining said body of secondary vapor floating on said body of saturated primary vapor, said body of secondary vapor preventing an interface between said body of saturated primary vapor and the atmosphere thereby substantially to prevent losses of primary vapor to the atmosphere; e. applying a second cooling medium to said body of secondary vapor at a second predetermined height over said first predetermined height to condense secondary vapor at said second predetermined height and to restrict said secondary vapor from rising above said second predetermined height; f. transporting said article from the atmosphere through the body of secondary vapor into the body of saturated primary vapor below said first predetermined height; g. condensing saturated primary vapor directly on said article thereby to heat said article at least to said elevated temperature by transfer of latent heat of vaporization of said condensed saturated primary vapor to said article; h. performing said operation on said article; i. thereafter, transporting said article from said body of saturated primary vapor through said body of secondary vapor into the atmosphere.

Claim 8

Method as in claim 8, further comprising: j. returning to said primary liquid condensed primary vapors resulting from steps (b) and (g).

Claim 9

Method as in claim 8, wherein: j. the temperature of said second cooling medium is lower than the temperature of said first cooling medium; said method further comprising: k. collecting condensed secondary vapor resulting from step (e) and contacting said condensed secondary vapor with condensed primary vapor resulting from step (b), thereby to reboil and revaporize said condensed secondary vapor.

Claim 10

Method as in claim 8, wherein: j. the operation performed on the article is soldering with solder, k. the boiling point of the primary liquid is at least equal to the melting point of said solder.

Claim 11

Method as in claim 11, wherein the article to be soldered is a printed circuit board having electrical components mounted thereon and wherein: l. said primary liquid is electrically non-conductive, m. said primary vapor is chemically inert.

Claim 12

Method as in claim 8, wherein: j. the operation performed on the article is fusing a coating of solder thereon, k. the boiling point of the primary liquid is at least equal to the melting point of said solder.

Claim 13

Method as in claim 8, wherein: j. the operation to be performed on the article is brazing, k. the boiling point of said primary liquid is at least equal to the melting point of the material being brAzed.

Claim 14

Method as in claim 8, wherein: j. said saturated primary vapor is chemically inert.

Claim 15

Method as in claim 8, wherein: j. said saturated primary vapor is denser than air at ambient temperature and atmospheric pressure, k. said seondary vapor has a density intermediate the density of the saturated primary vapor and the density of air at ambient temperature and atmospheric pressure.

Claim 16

Wave soldering an article according to the method of claim 8, further comprising: j. generating a solder wave extending into said body of saturated primary vapor below said first predetermined height, k. passing said article through said solder wave.

Claim 17

Method according to claim 17, wherein: i. the temperature of said solder wave is higher than the temperature of said body of saturated primary vapor.

Claim 18

Apparatus for heating an article to an elevated temperature, said apparatus comprising: a. a vessel open to the atmosphere and adapted to contain a primary liquid having a boiling point at least equal to said elevated temperature, b. heating means adjacent the lower end of said vessel and adapted to boil said primary liquid to produce primary vapor therefrom, c. primary condensing means at a first elevation above the bottom of said vessel and adapted to condense primary vapor to primary liquid at said first elevation, d. primary condensate collecting means associated with said primary condensing means and adapted to collect condensed primary vapor therefrom, e. a first conduit communicating between said primary condensate collecting means and the lower portion of said vessel and adapted to convey condensed primary vapor from said primary condensate collecting means to the lower portion of said vessel, f. means to establish a body of secondary vapor in said vessel above said primary vapor, g. secondary condensing means at a second elevation above said first elevation and adapted to condense secondary vapor to secondary liquid at said second elevation, h. secondary condensate collecting means associated with said secondary condensing means and adapted to collect condensed secondary vapor therefrom, i. a second conduit communicating between said secondary condensate collecting means and said primary condensate collecting means and adapted to convey condensed secondary vapor from said secondary condensate collecting means to said primary condensate collecting means, j. a secondary liquid supply tank adapted to contain secondary liquid, k. a third conduit communicating between said secondary liquid supply tank and said primary condensate collecting means and adapted to convey secondary liquid from said secondary liquid supply tank to said primary condensate collecting means.

Claim 19

Apparatus as in claim 19, further comprising:

Claim 20

Method as in claim 21, wherein: h. the density of the secondary vapor is intermediate the density of the saturated primary vapor and the density of air at ambient temperature and at atmospheric pressure, i. said body of secondary vapor floats on said body of primary vapor.

Claim 21

Method as in claim 21, wherein: h. the operation performed on the article is wave soldering.

Claim 22

Method for heating an article to an elevated temperature and performing an operation on said article, said method comprising: a. establishing substantially at atmospheric pressure a body of saturated primary vapor extending to a first predetermined height over a primary liquid having a boiling point at least equal to said elevated temperature by continuously boiling said primary liquid; b. applying a first cooling medium to said body of saturated primary vapor at said first predetermined height to condense saturated primary vapor at said first predetermined height; c. generating a body of secondary vapor from a secondary liquid, said secondary liquid having a lower atmospheric boiling point than said primary liquid; d. maintaining said body of secondary vapor floating on said body of saturated primary vapor, said body of secondary vapor preventing an interface between said body of saturated primary vapor and the atmosphere thereby substantially to prevent losses of primary vapor to the atmosphere; e. applying a second cooling medium to said body of secondary vapor at a second predetermined height over said first predetermined height to condense secondary vapor at said secondary height and to restrict said secondary vapor from rising above said second predetermined height; f. transporting said article from the atmosphere through the body of secondary vapor into the body of saturated primary vapor below said first predetermined height; g. condensing saturated primary vapor directly on said article thereby to heat on said article at least to said elevated temperature by transfer of latent heat of vaporization of said condensed saturated primary vapor to said article; h. performing said operation on said article; i. thereafter, transporting said article from said body of saturated primary vapor through said body of secondary vapor into the atmosphere.

Claim 23

Method as in claim 24, further comprising: j. returning to said primary liquid condensed primary vapors resulting from steps (b) and (g).

Claim 24

Method as in claim 24, wherein: j. the temperature of said second cooling medium is lower than the temperature of said first cooling medium; said method further comprising: k. collecting condensed secondary vapor resulting from step (e) and contacting said condensed secondary vapor with condensed primary vapor resulting from step (b), thereby to reboil and revaporize said condensed secondary vapor.

Claim 25

Method as in claim 24, wherein: j. said saturated primary vapor is denser than air at ambient temperature and atmospheric pressure, k. said secondary vapor has a density intermediate the density of the saturated primary vapor and the density of air at ambient temperature and atmospheric pressure.

Claim 26

Method as in claim 24, wherein: j. the operation performed on the article is wave soldering.