WO2001038032A1 - Procede et dispositif de brasage sans fondants, avec bain de fusion metallique enrichi par un gaz reactif - Google Patents

Procede et dispositif de brasage sans fondants, avec bain de fusion metallique enrichi par un gaz reactif Download PDF

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Publication number
WO2001038032A1
WO2001038032A1 PCT/EP2000/010993 EP0010993W WO0138032A1 WO 2001038032 A1 WO2001038032 A1 WO 2001038032A1 EP 0010993 W EP0010993 W EP 0010993W WO 0138032 A1 WO0138032 A1 WO 0138032A1
Authority
WO
WIPO (PCT)
Prior art keywords
solder
gas
soldering
hydrogen
outlet opening
Prior art date
Application number
PCT/EP2000/010993
Other languages
German (de)
English (en)
Inventor
Hans-Peter Schmidt
Tilman Schwinn
Original Assignee
Messer Griesheim Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Messer Griesheim Gmbh filed Critical Messer Griesheim Gmbh
Priority to EP00984980A priority Critical patent/EP1233842A1/fr
Publication of WO2001038032A1 publication Critical patent/WO2001038032A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K1/00—Soldering, e.g. brazing, or unsoldering
    • B23K1/20—Preliminary treatment of work or areas to be soldered, e.g. in respect of a galvanic coating
    • B23K1/203—Fluxing, i.e. applying flux onto surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2101/00—Articles made by soldering, welding or cutting
    • B23K2101/36—Electric or electronic devices

Definitions

  • the invention relates to a method and a device for flux-free soldering with reactive gas-enriched metal melts.
  • the wave soldering process is used, in which the components are inserted with their connections through holes in a circuit board and the circuit board is guided along one or two shafts of liquid solder.
  • the solder heated to around 250 ° C, wets the solder joints, and after cooling, there is a firm connection.
  • the object of the present invention is therefore to provide an apparatus and a method for soldering, in particular of electronic components, in which the use of flux is reduced and the risk of oxidation of metal parts or the solder bath is reduced.
  • the soldering device accordingly has a gas supply device by means of which a reducing reactive gas, for example hydrogen, is introduced into the molten solder present in the soldering container and at least partially dissolved therein.
  • a reducing reactive gas for example hydrogen
  • the reactive gas emerges directly at the site of action, namely in the area of the solder contacts. This significantly reduces the amount of reactive gas required.
  • the use of flux can largely be dispensed with.
  • a particularly effective way of introducing gas into the solder is given in a gas electrode, which at least in the area of a gas outlet opening in the Immersed solder and flows around it.
  • the gas emerging from the gas outlet opening is at least partially dissolved in the solder.
  • a catalyst for example made of palladium or platinum, to be arranged in the region in front of the gas outlet opening of the gas electrode, by means of which the formation of atomic reactive gas from the molecular gas that flows out of the gas electrode is improved becomes.
  • Heating the catalyst or the solder in the area in front of the gas outlet opening further increases the solubility of reactive gas in accordance with Sievert's law and improves the effectiveness of the catalyst in the formation of nascent hydrogen.
  • the gas electrode is expediently provided with a tubular casing which is received essentially vertically in the solder container and through which the solder can be guided parallel to the gas bubbles rising from the gas outlet opening.
  • a heater is provided on the catalytic converter or in the region of the gas outlet opening, a convective flow is also brought about, through which the hydrogen-enriched solder is distributed more uniformly in the solder bath.
  • a beading device such as a sieve, a mesh or a frit made of porous material, is provided in the area in front of the gas outlet opening of the gas electrode, by means of which the gas bubbles emerging from the gas outlet opening are converted into smaller gas bubbles , which increases the contact surface between gas and solder.
  • soldering process must take place under protective gas in order to largely prevent possible pre- or post-oxidation of the workpiece or the solder. For this reason, in a further expedient embodiment of the invention, to arrange the solder container in a solder tunnel, which is equipped with a feed for an inert protective gas, such as nitrogen.
  • an inert protective gas such as nitrogen. Examples of soldering tunnels that can be used in the context of the present invention are described in the publications DE 197 49 187 A1, DE 197 49 186 A1 or 197 49 184 A1.
  • a gas purging device which is provided with a suction and a suction device for protective gas, enables the composition of the protective gas to be changed or maintained in a controlled manner during the soldering process.
  • a further embodiment of the device according to the invention provides for the hydrogen content in the protective gas atmosphere to be determined continuously or at predetermined time intervals by a monitoring device, and for the protective gas to be extracted and / or supplied with hydrogen-free protective gas if a certain limit value for the hydrogen concentration is exceeded.
  • the configuration of the device according to the invention as a retrofit kit for existing soldering systems is particularly advantageous.
  • the solder is first heated and melted in a soldering container in a manner known per se.
  • a reducing reactive gas such as hydrogen
  • a reducing reactive gas such as hydrogen
  • the reactive gas dissolved in the solder degasses at least partially and has a reducing effect in the vicinity of the outgassing point, that is to say directly on the workpiece or the wetted solder. In this way, the formation of an oxide layer on the workpiece and / or on the solder surface is effectively prevented.
  • the solder is advantageously circulated continuously or at predetermined time intervals.
  • the reactive gas is expediently introduced into the solder by means of a gas electrode and the solder is heated above the intended soldering temperature at least in the region around a gas outlet opening of the gas electrode.
  • a preferred temperature value is 300 ° C.
  • the reactive gas escaping from the gas electrode but not dissolving in the solder and / or the reactive gas escaping from the wetted, cooling solder according to Sievert's law is used to generate a protective gas atmosphere.
  • the protective gas enriched with reactive gas in this way is particularly well suited to prevent pre-oxidation and post-oxidation on the workpiece or the solder.
  • FIG.1 a gas supply device received in a solder bath in cross section
  • the device 1 for introducing a reducing reactive gas in the exemplary embodiment of hydrogen, comprises a hydrogen electrode 3 accommodated in a solder bath 2 which is filled with solder, from which hydrogen is supplied via a feed line 4, which is connected to a hydrogen supply in a manner not shown here , continuously brought up and introduced into the solder bath 2 via a gas outlet opening 5.
  • the hydrogen escaping from the gas outlet opening is brought into the form of small gas bubbles 7 by means of a frit 6, which is made of a porous material and is arranged directly in front of the gas outlet opening, thereby increasing the contact surface between gas and solder and thus improving the solubility of the gas in the solder.
  • the gas bubbles bubble against the force of gravity in the direction of the bath surface 8 and pass through a catalyst 9, which consists of palladium or platinum and whose task is to break down the hydrogen H 2 emerging in molecular form from the gas outlet opening 5 into the soluble atomic form Reinforce 2H.
  • a catalyst 9 which consists of palladium or platinum and whose task is to break down the hydrogen H 2 emerging in molecular form from the gas outlet opening 5 into the soluble atomic form Reinforce 2H.
  • the gas electrode 3 is surrounded on its front section, which includes the gas outlet opening, by an electrode housing 10, which is received on a holder 11 in the solder bath 2.
  • the electrode housing 10 is dimensioned such that solder can flow through between the gas electrode 3 and the inner wall of the electrode housing 10.
  • the electrode housing 10, which also serves to fasten the catalytic converter 9, is intended to supply the gas bubbling up from the gas outlet opening 5 or the frit 6 to the catalytic converter in order to achieve the most efficient possible solution of gas in the solder in the solder bath 2.
  • gas flows out of the gas outlet opening 5 of the gas electrode 3 and is brought into the form of small gas bubbles 7 in the frit 6.
  • the gas bubbles 7 rise, counter to gravity, upwards in the electrode housing 10 and are guided along the catalyst 9.
  • a heater 13 is mounted on the electrode housing 10.
  • the catalyst 9 is heated by the heater 13, whereby on the one hand the catalyst effect and on the other hand the solubility of the hydrogen in accordance with Sievert's law
  • c (H) denotes the concentration of the hydrogen dissolved in the solder
  • p (H 2 ) denotes the partial pressure of the molecular hydrogen
  • the heater causes a convective flow of the solder in the electrode housing 10 from bottom to top, so that fresh, low-hydrogen solder is constantly flowing through the catalyst 9.
  • a circulation system not shown here, ensures a homogeneous distribution of the dissolved hydrogen in the entire solder bath 2.
  • the solder is shaped into a solder wave in the usual way, for example by means of pumps. After wetting the solder joint on the workpiece, it cools down quickly. As a result of Sievert's law, the previously dissolved hydrogen at least partially emerges from the solder and reduces the oxides that may be present on the workpiece or the surface of the solder.
  • Part of the hydrogen flowing out of the gas electrode 3 is not dissolved in the solder of the solder bath 2. This undissolved hydrogen 14 bubbles to the solder bath surface 8, mixes with the protective gas atmosphere 15 above and there also has a reducing effect.
  • the protective gas atmosphere 15, which consists predominantly of inert N 2 is not shown here by a Maintain solder bath on top of solder bath. Suitable soldering tunnels for this purpose are described, for example, in documents DE 197 49 187 A1, DE 197 49 186 A1 or 197 49 184 A1.
  • the hydrogen content in the protective gas atmosphere should not exceed about 4% by volume, since otherwise there is a risk of explosion. For this reason, the hydrogen content in the protective gas atmosphere 15 is determined continuously or at predetermined time intervals, likewise not shown here. If a certain limit value is exceeded, the protective gas is pumped out of the soldering tunnel and low-hydrogen inert gas is supplied.
  • the device shown in the figures is equally suitable for wave soldering or selective soldering systems and in particular for use in soldering electronic assemblies.
  • the effectiveness of hydrogen as a reducing agent is significantly increased by the direct transfer of the hydrogen via the solder to the soldering point.
  • the reducing effect of hydrogen comes into its own at low soldering temperatures, especially when soldering.
  • the use of flux can thus be largely avoided.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Electric Connection Of Electric Components To Printed Circuits (AREA)
  • Molten Solder (AREA)

Abstract

Lorsqu'on utilise des dispositifs de brasage à la vague conçus suivant l'état de la technique, on a recours à des fondants destinés à empêcher l'oxydation des pièces métalliques à braser ou du bain de brasure (formation de crasse). Ceci entraîne la formation de résidus de fondants susceptibles d'altérer la qualité du joint de brasage ou de la pièce brasée. L'invention vise en conséquence à réduire l'emploi de fondants lors du brasage. A cet effet, l'invention est caractérisée en ce qu'avant de procéder au brasage proprement dit, un gaz réactif réducteur, par exemple, l'hydrogène, est dissous dans l'agent de brasage liquide par l'intermédiaire d'une électrode à gaz introduite dans le bain de brasage. Par refroidissement de l'agent de brasage sur la pièce, une partie du gaz réactif dissous s'évapore et exerce un effet réducteur sur la pièce ou sur l'agent de brasage. Ce procédé permet ainsi de réduire, au moins dans une large mesure, l'utilisation d'un fondant.
PCT/EP2000/010993 1999-11-19 2000-11-08 Procede et dispositif de brasage sans fondants, avec bain de fusion metallique enrichi par un gaz reactif WO2001038032A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP00984980A EP1233842A1 (fr) 1999-11-19 2000-11-08 Procede et dispositif de brasage sans fondants, avec bain de fusion metallique enrichi par un gaz reactif

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19955659A DE19955659A1 (de) 1999-11-19 1999-11-19 Verfahren und Vorrichtung zum flussmittelfreien Löten mit reaktivgasangereicherten Metallschmelzen
DE19955659.8 1999-11-19

Publications (1)

Publication Number Publication Date
WO2001038032A1 true WO2001038032A1 (fr) 2001-05-31

Family

ID=7929596

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2000/010993 WO2001038032A1 (fr) 1999-11-19 2000-11-08 Procede et dispositif de brasage sans fondants, avec bain de fusion metallique enrichi par un gaz reactif

Country Status (3)

Country Link
EP (1) EP1233842A1 (fr)
DE (1) DE19955659A1 (fr)
WO (1) WO2001038032A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0330867A1 (fr) * 1988-02-08 1989-09-06 Praxair Technology, Inc. Application, sans utilisation de flux, d'une couche comprenant du métal
US5205461A (en) * 1988-07-29 1993-04-27 International Business Machines Corporation Method and apparatus for fluxless solder bonding
EP0547860A1 (fr) * 1991-12-16 1993-06-23 Osaka Sanso Kogyo Limited Méthode et appareil de brasage

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2083773B (en) * 1980-08-01 1984-10-24 Aiwa Co A soldering method for electric and/or electronic components
US5509598A (en) * 1994-05-31 1996-04-23 The Boc Group, Inc. Wave soldering apparatus and process

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0330867A1 (fr) * 1988-02-08 1989-09-06 Praxair Technology, Inc. Application, sans utilisation de flux, d'une couche comprenant du métal
US5205461A (en) * 1988-07-29 1993-04-27 International Business Machines Corporation Method and apparatus for fluxless solder bonding
EP0547860A1 (fr) * 1991-12-16 1993-06-23 Osaka Sanso Kogyo Limited Méthode et appareil de brasage

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP1233842A1 *

Also Published As

Publication number Publication date
DE19955659A1 (de) 2001-05-31
EP1233842A1 (fr) 2002-08-28

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