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WO2004050286A1 - Method for the application of solder material, use of a system for laser-aided direct metal deposition and contact surfaces with solder material - Google Patents

Method for the application of solder material, use of a system for laser-aided direct metal deposition and contact surfaces with solder material Download PDF

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Publication number
WO2004050286A1
WO2004050286A1 PCT/DE2003/003944 DE0303944W WO2004050286A1 WO 2004050286 A1 WO2004050286 A1 WO 2004050286A1 DE 0303944 W DE0303944 W DE 0303944W WO 2004050286 A1 WO2004050286 A1 WO 2004050286A1
Authority
WO
WIPO (PCT)
Prior art keywords
solder
contact surface
powder particles
produced
solder powder
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/DE2003/003944
Other languages
German (de)
French (fr)
Inventor
Klaus-Peter Galuschki
Martin Schäfer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Siemens Corp
Original Assignee
Siemens AG
Siemens Corp
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 Siemens AG, Siemens Corp filed Critical Siemens AG
Publication of WO2004050286A1 publication Critical patent/WO2004050286A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

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
    • B23K3/00—Tools, devices, or special appurtenances for soldering, e.g. brazing, or unsoldering, not specially adapted for particular methods
    • B23K3/06—Solder feeding devices; Solder melting pans
    • B23K3/0607—Solder feeding devices
    • B23K3/0623—Solder feeding devices for shaped solder piece feeding, e.g. preforms, bumps, balls, pellets, droplets
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
    • H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
    • H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
    • H05K3/3457—Solder materials or compositions; Methods of application thereof
    • H05K3/3485—Applying solder paste, slurry or powder
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/02—Fillers; Particles; Fibers; Reinforcement materials
    • H05K2201/0203—Fillers and particles
    • H05K2201/0263—Details about a collection of particles
    • H05K2201/0272—Mixed conductive particles, i.e. using different conductive particles, e.g. differing in shape
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/01—Tools for processing; Objects used during processing
    • H05K2203/0104—Tools for processing; Objects used during processing for patterning or coating
    • H05K2203/0126—Dispenser, e.g. for solder paste, for supplying conductive paste for screen printing or for filling holes
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/04—Soldering or other types of metallurgic bonding
    • H05K2203/0425—Solder powder or solder coated metal powder
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/10—Using electric, magnetic and electromagnetic fields; Using laser light
    • H05K2203/107—Using laser light
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
    • H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
    • H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
    • H05K3/3494—Heating methods for reflowing of solder

Definitions

  • the invention relates to a method for applying solder material to a contact area.
  • a method for applying solder material to a contact area is described, for example, in US Pat. No. 5,977,512.
  • contact surfaces of components are provided with solder deposits, in that in a first step the solder material later forming the solder deposit, for example in the form of a solder ball, is applied to the contact surface by means of a device provided specifically for this purpose and held there.
  • the solder depot is then produced in a second step by remelting the solder ball on the contact surface into the solder depot by means of a laser beam. Due to the surface tension of the liquefied solder material spherical solder deposits which may for example form the contact bumps on the underside of a flip chip 'arising thereby.
  • the object of the invention is to provide a method for applying solder material to a contact surface, with the aid of which solder deposits can be produced with a comparatively large design freedom with regard to their geometry.
  • solder material is supplied to the contact surface in the form of solder powder particles with an energy input such that the solder powder particles at least on their surface the melting temperature can be warmed up.
  • the solder powder particles are thus melted at least on the surface during the supply to the contact surface, upon impacting or directly after impacting on the contact surface or on solder material already on the contact surface, so that the individual solder powder particles during Impact on the intended location can be fixed immediately. After the required amount of solder powder particles have been fed in, it is therefore advantageously no longer necessary to further melt the solder deposit produced in this way.
  • the solder depot can be designed specifically in any desired geometry, since the solder deposit is only melted at the location where the solder powder particles strike. In particular, it is therefore also possible to deviate from a spherical configuration of the solder deposits as contact bumps.
  • solder deposits with the most varied requirements for their geometry can thus advantageously be produced in one operation, for example on a printed circuit board.
  • solder deposits with very large and very small volumes can be produced in one operation, such as, for. B. occur in the combination of components such as resistors and capacitors with components of high integration density such as chip size packages and flip chips on a circuit board.
  • solder deposits can also advantageously be produced on spatially structured circuit carriers, which are manufactured, for example, using MID technology (Molded Interconnected Devices).
  • One embodiment of the invention provides for the solder powder particles to be fed to the contact surface by means of a nozzle. Compared to other feed options, such as. B. the sprinkling of the contact surface, the supply by means of a nozzle has the advantage that this supply can take place in a targeted manner in a locally narrowly defined area.
  • Another embodiment of the invention provides that the energy input is carried out by means of a laser beam.
  • a laser beam In comparison to, for example, induction heating of the solder powder particles, a laser beam has the advantage that the energy for melting with a high energy density can be introduced in a small place.
  • the laser beam is directed onto the contact area and the energy input into the contact area is limited in such a way that the heating of the contact area remains below its melting temperature. Melting of the contact surface must be avoided so that the solder material does not mix with the material of the contact surface at the point of contact with the contact surface and alloys with an undesirable composition are formed in the transition area between the contact surface and the solder depot. Heating the contact surface below its melting temperature has the advantage that the adhesion of the solder powder particles to the contact surface is improved, so that a particularly reliable fixation of the solder deposit on the contact surface is produced by means of this embodiment of the invention.
  • Another embodiment of the invention provides that a mixture of solder powder particles with different chemical compositions is used. As a result, partial depots of solder are produced, the final alloy composition of which only results from the complete melting of the solder deposit during the soldering process.
  • the alloy composition can advantageously be produced continuously using appropriate mixtures of different solder powders.
  • the number of solder powders to be stored can advantageously be kept to a minimum.
  • a solder depot can also be produced, which has a high-melting core and a low-melting cap.
  • a solder depot with a porous structure is produced by melting the supplied solder powder particles on the surface due to the energy input.
  • the shape of the solder powder particles essentially remains, so that when adjacent solder powder particles are deposited, there are gaps which result in the porous structure of the solder deposit.
  • the energy input for example by the laser, can be limited to a minimum, as a result of which the thermal load on the contact area also remains very small. This is particularly advantageous when using the method for repair soldering, since there is a conductor to be repaired on the plate in the vicinity of the repair site are often already thermally sensitive components.
  • Another embodiment of the invention provides that a massive solder depot is produced by dimensioning the energy input in such a way that the solder powder particles supplied in each case are melted completely by the energy input.
  • this advantageously makes it possible to produce solder deposits with almost any geometry, for example by using a solder powder jet to generate the geometry in one or more layers by completely melting the particles that have just been supplied.
  • an optimal amount of solder material can advantageously be accommodated in a solid solder depot in relation to its volume.
  • a solder depot with a curved surface is produced in that the solder depot that forms is kept in the molten state by the energy input during the supply of the solder powder particles.
  • the curved surface is formed by the surface tension of the solder deposit which is in the liquid state.
  • Spherical solder deposits are z. B. can be generated on the underside of flip chips.
  • solder deposits with a lens-like curvature on one side and a planar side towards the contact surface can also be formed. Solder deposits with a curved surface can thus advantageously be produced by means of the method according to the invention in combination with the solder deposits of another geometry already described.
  • the invention further relates to a contact area with a solder depot.
  • a solder deposit is for example in the aforementioned US Pat. No. 5,977,512.
  • the solder deposits described there form so-called contact bumps with a curved, almost spherical surface.
  • Another object of the invention is to provide contact areas with solder deposits in which the solder deposits are comparatively well adapted to the component to be fastened.
  • this object is achieved by a contact surface with a solder depot having pores, which is formed by solder powder particles which are connected to one another by melting their surface. Since the solder powder particles are only melted, the solder depot can be built up from powder particles with different alloy compositions, so that a final alloy formation of the solder joint to be formed is only achieved during the actual soldering process. This allows, for example, the required soldering temperature of the solder depot to be reduced, which also reduces the thermal load on the component to be soldered.
  • solder additive it is advantageously possible to fill the pores with a solder additive.
  • a flux can be used as the solder additive, which advantageously improves the quality of the soldered connections to be formed.
  • a contact area with a solid solder deposit is formed by a plurality of layers superimposed on one another.
  • These layers can be produced, for example, by the method already described, in that the application of solder powder is repeated several times, the first layer being applied directly to the contact surface and the following layers each to the previous layer.
  • very high solder deposits can advantageously also be produced in relation to the base area.
  • at least some layers can advantageously have different properties.
  • the layers can have different alloy compositions. It is also possible, for example, to connect a solid layer to a porous layer, so that, as already mentioned, a flux can be introduced into the porous layer.
  • the invention relates to the use of a system for laser-assisted direct metal deposition.
  • This process is described in "Proceedings of the 2001 ASME Design Engineering Technical Conferences and Computers and Information in Engineering Conference", Volume 2, published in 2001 by “The American Society of Mechanic Engineers", pages 333 to 338 and as "Laser aided direct metal deposition "(LADMD).
  • LADMD Laser aided direct metal deposition
  • Any three-dimensional structures made of solid metal can be produced by means of this method, whereby three-dimensional CAD data can be used as the basis for the manufacturing process.
  • the basic principle of so-called “laser cladding” is used in the production of the three-dimensional structure.
  • a local melt pool is created on the surface of the component to be produced, which forms the three-dimensional structure, into which the metal powder is added.
  • Another object of the invention is to provide solder deposits for contact areas which can be produced with a comparatively large design freedom with regard to the geometry of the solder connection.
  • LADMD laser-assisted direct metal deposition
  • the energy input by the laser overall having to be dimensioned sufficiently high so that the supplied solder powder particles are melted at least on their surface in order to ensure sufficient adhesion of the solder powder particles to one another and on the other hand can be reached on the contact surface.
  • the component to be produced is therefore not used in the invention produced exclusively from the powder, but the already existing contact surfaces are only provided in the system with the solder deposits produced from solder powder particles, the component to be produced containing the contact surfaces and the solder deposits produced on them.
  • the contact areas can, for example, be part of a circuit carrier, a component such as a flipchip or also a so-called “lead frame”, that is to say a rib-like conductor track structure with the associated contact areas, the modules mentioned being able to be produced by any method generated solder deposits have already been described in connection with the method according to the invention.
  • FIG. 1 shows an exemplary embodiment of the method according to the invention for applying solder powder particles
  • FIGS. 2 to 5 show different exemplary embodiments of solder deposits that are produced using the method according to the invention
  • FIG. 6 shows an exemplary embodiment for a system for
  • a circuit carrier 11 with a contact surface 12 is shown schematically in FIG.
  • a solder powder jet 13 is directed onto the contact surface and emerges from a nozzle opening (not shown).
  • the solder powder jet 13 contains solder powder particles 14, which pass through a laser beam 15 shortly before hitting the contact surface 12 and are at least melted on the surface.
  • the solder distribute 14 both on the contact surface 12 and on adjacent solder powder particles 14, whereby a solder depot 16 is generated.
  • the laser beam 15 and the solder powder beam 13 are guided over the contact surface at a suitable speed, so that the entire surface to be soldered is successively
  • a porous solder deposit 16a on the contact surface 12 is formed by solder powder particles 14a, 14b, which were only melted on the surface during the manufacture of the solder deposit. Therefore, the shape of the individual solder powder particles in the solder depot 16a has remained essentially unchanged, so that pores 17 are formed in the spaces between the individual solder powder particles 14a, 14b.
  • the pores 17 are by a solder additive 18 such. B. filled a flux.
  • the solder additive can be introduced into the pores 17 of the solder deposit 16a, for example, by an impregnation process.
  • the solder filler material 18 is indicated by cross hatching.
  • the solder powder particles 14a have a different alloy composition than the solder powder particles 14b. A final alloy composition of the solder deposit is therefore only achieved when it is melted to produce the solder connection.
  • the different alloy compositions of the solder powder particles 14a, 14b are indicated by hatching of different orientations.
  • FIG. 3 shows a planar solder deposit 16b which adheres to the contact surface 12 as a solid block.
  • Such a solder depot can be produced by completely melting the solder powder particles so that they unite on the contact surface with the solder deposit 16b. The planar formation of the solder depot is ensured in that the solder depot 16b that is formed is only ever melted at the point of the current solder powder supply.
  • a solder deposit 16c is formed on the contact surface 12, which is made up of several layers 19a, 19b.
  • the individual layers are produced using the method described for FIG. 3.
  • a solder powder with a higher melting point is used for the layers 19a than for the layers 19b.
  • the solder depot 16c thus has a cap 20 that melts lower than the rest of the solder depot.
  • a solder depot 19d is designed on the contact surface 12 as a contact bump.
  • This solder depot 19d is produced in that the entire amount of the solder powder already supplied to the contact surface 12 is kept in the melt until the solder depot is completed, so that the surface tension of the liquid solder material leads to the configuration of the geometry shown.
  • a LADMD system 21 is shown schematically in FIG. This has a process space 22 which is filled with a protective gas which prevents the oxidation of liquid solder material.
  • the circuit carrier 11 with the contact surfaces 12 is introduced in the process space 22.
  • the solder powder particles 14 can be one of the Contact surfaces 12 are supplied.
  • Via a semitransparent mirror 24 and an optical system 25, a laser can be used to generate a laser beam.
  • the metal powder feed 23 consists of a powder supply 29, the solder powder particles being fed from the powder supply 29 to a nozzle 31 via a conveying device 30.
  • the nozzle also carries the optics 25 for the laser beam. In order to completely provide all contact surfaces 12 of the circuit carrier 11 with solder powder particles 14, either the nozzle 31 or the circuit carrier 11 can be moved.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Mechanical Engineering (AREA)
  • Electric Connection Of Electric Components To Printed Circuits (AREA)

Abstract

The invention relates to a method wherein a solder deposit is formed on a contact surface (12), e.g. a circuit carrier (11), such that a beam (13) of solder powder particles (14) is directed at the contact surface (12) and the solder powder particles (14) are at least melted during or shortly after the delivery thereof to the contact surface (12). Targeted movement of the beam of solder powder (13) and the laser beam (15) enable solder deposits of any particular geometry, especially those with extremely different volumes, to be produced in a single work procedure on the various surfaces of the circuit carrier (11). As a result, solder deposits having very low volumes (e.g. for flipchips) and those having very large volumes (e.g. for capacitors and resistors) can be combined with each other on said circuit carrier in an advantageous manner. The invention also relates to solder deposits which have a porous or layered structure and which can, more particularly, be produced according to the above-mentioned manner. The invention further relates to the use of a laser-aided metal deposition (LADMD) system for the above-mentioned method.

Description

Beschreibung description

Verfahren zum Aufbringen von Lotmaterial, Verwendung einer Anlage zur laserunterstützten direkten Metallabscheidung hierfür und Kontaktflächen mit LotdepotsProcess for applying solder material, use of a system for laser-assisted direct metal deposition therefor and contact areas with solder deposits

Die Erfindung bezieht sich auf ein Verfahren zum Aufbringen von Lotmaterial auf eine Kontaktfläche. Ein solches Verfahren ist beispielsweise in der US-Patentschrift 5,977,512 be- schrieben. Mit diesem Verfahren werden Kontaktflächen von Bauelementen mit Lotdepots versehen, indem in einem ersten Schritt der später das Lotdepot bildende Lotwerkstoff beispielsweise in Form einer Lotkugel mittels einer speziell hierfür vorgesehenen Vorrichtung auf die Kontaktfläche aufge- bracht und dort gehalten wird. Anschließend wird in einem zweiten Schritt das Lotdepot erzeugt, indem die Lotkugel auf der Kontaktfläche durch einen Laserstrahl in das Lotdepot umgeschmolzen wird. Aufgrund der Oberflächenspannung des verflüssigten Lotwerkstoffes ergeben sich dabei kugelförmige Lotdepots, die beispielsweise die Kontaktbumps auf der Unterseite eines Flipchips' bilden können.The invention relates to a method for applying solder material to a contact area. Such a method is described, for example, in US Pat. No. 5,977,512. With this method, contact surfaces of components are provided with solder deposits, in that in a first step the solder material later forming the solder deposit, for example in the form of a solder ball, is applied to the contact surface by means of a device provided specifically for this purpose and held there. The solder depot is then produced in a second step by remelting the solder ball on the contact surface into the solder depot by means of a laser beam. Due to the surface tension of the liquefied solder material spherical solder deposits which may for example form the contact bumps on the underside of a flip chip 'arising thereby.

Die Aufgabe der Erfindung besteht darin, ein Verfahren zum Aufbringen von Lotmaterial auf einer Kontaktfläche anzugeben, mit dessen Hilfe sich Lotdepots mit vergleichsweise großem Gestaltungsspielraum hinsichtlich ihrer Geometrie erzeugen lassen.The object of the invention is to provide a method for applying solder material to a contact surface, with the aid of which solder deposits can be produced with a comparatively large design freedom with regard to their geometry.

Diese Aufgabe wird erfindungsgemäß durch ein Verfahren zum Aufbringen von Lotmaterial auf eine Kontaktfläche gelöst, bei dem das Lotmaterial der Kontaktfläche in Form von Lotpulverteilchen unter einem solchen Energieeintrag zugeführt wird, dass die Lotpulverteilchen zumindest an ihrer Oberfläche über die Schmelztemperatur hinaus erwärmt werden. Bei der Durchführung des Verfahrens werden also die Lotpulverteilchen während der Zuführung zur Kontaktfläche, beim Auftreffen oder direkt nach dem Auftreffen auf die Kontaktfläche bzw. auf be- reits auf der Kontaktfläche befindliches Lotmaterial zumindest an der Oberfläche zum Schmelzen gebracht, so dass die einzelnen Lotpulverteilchen beim Auftreffen auf den vorgesehenen Ort sofort fixiert werden. Nach dem Zuführen der erforderlichen Menge an Lotpulverteilchen ist daher vorteilhafter- weise eine weitere Aufschmelzung des so entstandenen Lotdepots nicht mehr notwendig. Durch eine gezielte Führung des Lotpulverstrahls kann daher das Lotdepot gezielt in jeder gewünschten Geometrie gestaltet werden, da lediglich an dem Ort des Auftreffens der Lotpulverteilchen eine AufSchmelzung des Lotdepots bewirkt wird. Insbesondere kann daher auch von einer kugelförmigen Ausbildung der Lotdepots als Kontaktbumps abgewichen werden.This object is achieved according to the invention by a method for applying solder material to a contact surface, in which the solder material is supplied to the contact surface in the form of solder powder particles with an energy input such that the solder powder particles at least on their surface the melting temperature can be warmed up. When carrying out the method, the solder powder particles are thus melted at least on the surface during the supply to the contact surface, upon impacting or directly after impacting on the contact surface or on solder material already on the contact surface, so that the individual solder powder particles during Impact on the intended location can be fixed immediately. After the required amount of solder powder particles have been fed in, it is therefore advantageously no longer necessary to further melt the solder deposit produced in this way. By specifically guiding the solder powder jet, the solder depot can be designed specifically in any desired geometry, since the solder deposit is only melted at the location where the solder powder particles strike. In particular, it is therefore also possible to deviate from a spherical configuration of the solder deposits as contact bumps.

Durch das erfindungsgemäße Verfahren können damit Lotdepots mit den unterschiedlichsten Anforderungen an deren Geometrie vorteilhaft in einem Arbeitsgang beispielsweise auf einer Leiterplatte hergestellt werden. Insbesondere können in einem Arbeitsgang Lotdepots mit sehr großen und sehr kleinen Volumina hergestellt werden, wie sie z. B. bei der Kombination von Bauelementen wie Widerständen und Kondensatoren mit Bauelementen hoher Integrationsdichte wie Chip-Size-Packages und Flipchips auf einer Leiterplatte auftreten. Durch die gezielte Aufbringung mit gleichzeitiger Fixierung durch Anschmelzen der Lotpulverteilchen können weiterhin vorteilhaft auch Lot- depots auf räumlich strukturierten Schaltungsträgern, die beispielsweise in MID-Technik (Moulded Interconnected Devices) hergestellt sind, erzeugt werden. Eine Ausgestaltung der Erfindung sieht vor, die Lotpulverteilchen der Kontaktfläche mittels einer Düse zuzuführen. Im Vergleich zu anderen Zuführmöglichkeiten, wie z. B. dem Be- rieseln der Kontaktfläche, hat die Zuführung mittels einer Düse den Vorteil, dass diese Zuführung gezielt auf einem örtlich eng begrenzten Gebiet erfolgen kann.By means of the method according to the invention, solder deposits with the most varied requirements for their geometry can thus advantageously be produced in one operation, for example on a printed circuit board. In particular, solder deposits with very large and very small volumes can be produced in one operation, such as, for. B. occur in the combination of components such as resistors and capacitors with components of high integration density such as chip size packages and flip chips on a circuit board. Through the targeted application with simultaneous fixation by melting the solder powder particles, solder deposits can also advantageously be produced on spatially structured circuit carriers, which are manufactured, for example, using MID technology (Molded Interconnected Devices). One embodiment of the invention provides for the solder powder particles to be fed to the contact surface by means of a nozzle. Compared to other feed options, such as. B. the sprinkling of the contact surface, the supply by means of a nozzle has the advantage that this supply can take place in a targeted manner in a locally narrowly defined area.

Eine andere Ausgestaltung der Erfindung sieht vor, dass der Energieeintrag mittels eines Laserstrahls vorgenommen wird.Another embodiment of the invention provides that the energy input is carried out by means of a laser beam.

Im Vergleich beispielsweise zu einer induktiven Erwärmung der Lotpulverteilchen hat ein Laserstrahl den Vorteil, dass die Energie zur AufSchmelzung mit hoher Energiedichte auf einen kleinen Ort beschränkt eingebracht werden kann.In comparison to, for example, induction heating of the solder powder particles, a laser beam has the advantage that the energy for melting with a high energy density can be introduced in a small place.

Es ist vorteilhaft, wenn der Laserstrahl auf die Kontaktfläche gerichtet wird und der Energieeintrag in die Kontaktfläche derart begrenzt wird, dass die Erwärmung der Kontaktfläche unterhalb von deren Schmelztemperatur bleibt. Die Auf- Schmelzung der Kontaktfläche muss vermieden werden, damit sich der Lotwerkstoff an der Auftreffstelle zur Kontaktfläche nicht mit dem Material der Kontaktfläche vermischt und so im Übergangsbereich zwischen Kontaktfläche und Lotdepot Legierungen mit einer unerwünschten Zusammensetzung entstehen. Die Erwärmung der Kontaktfläche unterhalb von deren Schmelztemperatur hat den Vorteil, dass die Haftung der Lotpulverteilchen auf der Kontaktfläche verbessert wird, so dass mittels dieser Ausgestaltung der Erfindung eine besonders zuverlässige Fixierung des Lotdepots auf der Kontaktfläche erzeugt wird.It is advantageous if the laser beam is directed onto the contact area and the energy input into the contact area is limited in such a way that the heating of the contact area remains below its melting temperature. Melting of the contact surface must be avoided so that the solder material does not mix with the material of the contact surface at the point of contact with the contact surface and alloys with an undesirable composition are formed in the transition area between the contact surface and the solder depot. Heating the contact surface below its melting temperature has the advantage that the adhesion of the solder powder particles to the contact surface is improved, so that a particularly reliable fixation of the solder deposit on the contact surface is produced by means of this embodiment of the invention.

Eine andere Ausgestaltung der Erfindung sieht vor, dass ein Gemisch von Lotpulverteilchen mit unterschiedlicher chemischer Zusammensetzung verwendet wird. Hierdurch können vor- teilhaft Lotdepots hergestellt werden, deren endgültige Legierungszusammensetzung sich erst durch das vollständige Aufschmelzen des Lotdepots während des Lötvorganges ergibt. Dabei kann die Legierungszusammensetzung vorteilhaft stufenlos durch entsprechende Mischungen aus verschiedenen Lotpulvern erzeugt werden. Die Zahl der zu bevorratenden Lotpulver kann dabei vorteilhafterweise auf ein Minimum beschränkt bleiben.Another embodiment of the invention provides that a mixture of solder powder particles with different chemical compositions is used. As a result, partial depots of solder are produced, the final alloy composition of which only results from the complete melting of the solder deposit during the soldering process. The alloy composition can advantageously be produced continuously using appropriate mixtures of different solder powders. The number of solder powders to be stored can advantageously be kept to a minimum.

Es ist gemäß einer ähnlichen Ausgestaltung der Erfindung auch möglich, dass ein Lotdepot mit Schichten unterschiedlicherAccording to a similar embodiment of the invention, it is also possible that a solder depot with layers of different

Eigenschaften erzeugt wird, indem die Schichten jeweils durch Lotpulverteilchen mit unterschiedlichen Eigenschaften gebildet werden. Hierdurch können vorteilhaft im Lotdepot Zonen mit unterschiedlichen Eigenschaften, also z. B. unterschied- liehen Legierungszusammensetzungen gebildet werden. Es ist beispielsweise auch ein Lotdepot herstellbar, welches einen hochschmelzenden Kern und eine niedrig schmelzende Kappe aufweist .Properties is generated in that the layers are each formed by solder powder particles with different properties. This can advantageously zones in the solder depot with different properties, so z. B. different alloy compositions are formed. For example, a solder depot can also be produced, which has a high-melting core and a low-melting cap.

Eine andere Ausgestaltung der Erfindung sieht vor, dass ein Lotdepot mit poröser Struktur erzeugt wird, indem die zugeführten Lotpulverteilchen durch den Energieeintrag jeweils an der Oberfläche angeschmolzen werden. Durch die Anschmelzung lediglich an der Oberfläche der Lotpulverteilchen bleibt die Form der Lotpulverteilchen im Wesentlichen bestehen, so dass sich bei der Anlagerung benachbarter Lotpulverteilchen Zwischenräume ergeben, die die poröse Struktur des Lotdepots ergeben. Bei dem Verfahren gemäß dieser Ausgestaltung der Erfindung kann der Energieeintrag beispielsweise durch den La- ser auf ein Minimum begrenzt werden, wodurch auch die thermische Belastung der Kontaktfläche sehr klein bleibt. Dies ist bei einer Anwendung des Verfahrens zum Reparaturlöten besonders vorteilhaft, da sich auf einer zu reparierenden Leiter- platte in der Nachbarschaft der Reparaturstelle oft bereits thermisch empfindliche Bauelemente befinden.Another embodiment of the invention provides that a solder depot with a porous structure is produced by melting the supplied solder powder particles on the surface due to the energy input. As a result of the melting only on the surface of the solder powder particles, the shape of the solder powder particles essentially remains, so that when adjacent solder powder particles are deposited, there are gaps which result in the porous structure of the solder deposit. In the method according to this embodiment of the invention, the energy input, for example by the laser, can be limited to a minimum, as a result of which the thermal load on the contact area also remains very small. This is particularly advantageous when using the method for repair soldering, since there is a conductor to be repaired on the plate in the vicinity of the repair site are often already thermally sensitive components.

Eine andere Ausgestaltung der Erfindung sieht vor, dass ein massives Lotdepot erzeugt wird, indem der Energieeintrag derart bemessen wird, dass die jeweils zugeführten Lotpulverteilchen durch den Energieeintrag vollständig aufgeschmolzen werden. Hierdurch lassen sich vorteilhaft - wie bereits erwähnt - Lotdepots mit annähernd beliebiger Geometrie erzeu- gen, indem beispielsweise mittels eines Lotpulverstrahls die Geometrie in einer oder mehreren Schichten durch vollständiges Aufschmelzen der gerade zugeführten Teilchen erzeugt wird. Weiterhin lässt sich vorteilhafterweise in einem massiven Lotdepot im Verhältnis zu dessen Volumen eine optimale Menge von Lotwerkstoff unterbringen.Another embodiment of the invention provides that a massive solder depot is produced by dimensioning the energy input in such a way that the solder powder particles supplied in each case are melted completely by the energy input. As already mentioned, this advantageously makes it possible to produce solder deposits with almost any geometry, for example by using a solder powder jet to generate the geometry in one or more layers by completely melting the particles that have just been supplied. Furthermore, an optimal amount of solder material can advantageously be accommodated in a solid solder depot in relation to its volume.

Gemäß einer wieder anderen Ausgestaltung der Erfindung wird ein Lotdepot mit gewölbter Oberfläche erzeugt, indem das sich bildende Lotdepot während der Zuführung der Lotpulverteilchen durch den Energieeintrag im geschmolzenen Zustand gehalten wird. Dabei wird die gewölbte Oberfläche durch die Oberflächenspannung des sich im flüssigen Zustand befindlichen Lotdepots gebildet. Dabei sind kugelförmige Lotdepots z. B. an der Unterseite von Flipchips erzeugbar. Alternativ können auch Lotdepots mit einer linsenartigen Krümmung auf der einen Seite und einer planaren Seite zur Kontaktfläche hin gebildet werden. Damit können vorteilhaft Lotdepots mit gekrümmter 0- berfläche mittels des erfindungsgemäßen Verfahrens in Kombination mit den bereits beschriebenen Lotdepots anderer Geo- metrie hergestellt werden.According to yet another embodiment of the invention, a solder depot with a curved surface is produced in that the solder depot that forms is kept in the molten state by the energy input during the supply of the solder powder particles. The curved surface is formed by the surface tension of the solder deposit which is in the liquid state. Spherical solder deposits are z. B. can be generated on the underside of flip chips. Alternatively, solder deposits with a lens-like curvature on one side and a planar side towards the contact surface can also be formed. Solder deposits with a curved surface can thus advantageously be produced by means of the method according to the invention in combination with the solder deposits of another geometry already described.

Die Erfindung bezieht sich weiterhin auf eine Kontaktfläche mit einem Lotdepot. Ein solches Lotdepot ist beispielsweise in der eingangs erwähnten US-Patentschrift 5,977,512 beschrieben. Die dort beschriebenen Lotdepots bilden sogenannte Kontaktbumps mit einer gekrümmten, fast kugelförmigen Oberfläche.The invention further relates to a contact area with a solder depot. Such a solder deposit is for example in the aforementioned US Pat. No. 5,977,512. The solder deposits described there form so-called contact bumps with a curved, almost spherical surface.

Eine weitere Aufgabe der Erfindung besteht darin, Kontaktflächen mit Lotdepots anzugeben, bei denen die Lotdepots vergleichsweise gut an das zu befestigende Bauteil angepasst sind.Another object of the invention is to provide contact areas with solder deposits in which the solder deposits are comparatively well adapted to the component to be fastened.

Diese Aufgabe wird erfindungsgemäß durch eine Kontaktfläche mit einem Poren aufweisenden Lotdepot gelöst, welches durch Lotpulverteilchen gebildet ist, die durch Anschmelzen ihrer Oberfläche untereinander verbunden sind. Da die Lotpulver- teilchen lediglich angeschmolzen werden, kann das Lotdepot aus Pulverteilchen mit unterschiedlichen Legierungszusammensetzungen aufgebaut werden, so dass eine endgültige Legierungsbildung der zu bildenden Lötverbindung erst während des eigentlichen Lötvorganges erzielt wird. Hierdurch lässt sich beispielsweise die erforderliche Löttemperatur des Lotdepots senken, wodurch auch die thermische Belastung des zu verlötenden Bauelementes verringert wird.According to the invention, this object is achieved by a contact surface with a solder depot having pores, which is formed by solder powder particles which are connected to one another by melting their surface. Since the solder powder particles are only melted, the solder depot can be built up from powder particles with different alloy compositions, so that a final alloy formation of the solder joint to be formed is only achieved during the actual soldering process. This allows, for example, the required soldering temperature of the solder depot to be reduced, which also reduces the thermal load on the component to be soldered.

Weiterhin ist es vorteilhaft möglich, die Poren mit einem Lotzusatzstoff auszufüllen. Als Lotzusatzstoff kann insbesondere ein Flussmittel zum Einsatz kommen, welches vorteilhaft die Qualität der zu bildenden Lötverbindungen verbessert.Furthermore, it is advantageously possible to fill the pores with a solder additive. In particular, a flux can be used as the solder additive, which advantageously improves the quality of the soldered connections to be formed.

Gemäß einer alternativen Lösung der letztgenannten Aufgabe ist eine Kontaktfläche mit einem massivern Lotdepot durch mehrere übereinander gelagerte Schichten gebildet. Diese Schichten lassen sich beispielsweise durch das bereits beschriebene Verfahren erzeugen, indem das Aufbringen von Lot- pulver mehrfach wiederholt wird, wobei die erste Schicht direkt auf die Kontaktfläche und die folgenden Schichten jeweils auf die vorhergehende Schicht aufgebracht werden. Damit lassen sich vorteilhaft auch im Verhältnis zur Grundfläche sehr hohe Lotdepots erzeugen. Weiterhin können vorteilhaft zumindest einige Schichten unterschiedliche Eigenschaften aufweisen. Z. B. können die Schichten unterschiedliche Legierungszusammensetzungen aufweisen. Es ist auch möglich beispielsweise eine massive Schicht mit einer porösen Schicht zu verbinden, so dass in die poröse Schicht, wie bereits erwähnt, ein Flussmittel eingebracht werden kann.According to an alternative solution to the latter task, a contact area with a solid solder deposit is formed by a plurality of layers superimposed on one another. These layers can be produced, for example, by the method already described, in that the application of solder powder is repeated several times, the first layer being applied directly to the contact surface and the following layers each to the previous layer. In this way, very high solder deposits can advantageously also be produced in relation to the base area. Furthermore, at least some layers can advantageously have different properties. For example, the layers can have different alloy compositions. It is also possible, for example, to connect a solid layer to a porous layer, so that, as already mentioned, a flux can be introduced into the porous layer.

Zuletzt bezieht sich die Erfindung auf eine Verwendung einer Anlage zur laserunterstützten direkten Metallabscheidung. Dieses Verfahren ist in „Proceedings of the 2001 ASME Design Engineering Technical Conferences and Computers and Information in Engineering Conference", Band 2, herausgegeben 2001 durch "The American Society of Mechanic Engineers", Seiten 333 bis 338 beschrieben und als „Laser aided direct metal deposition" (LADMD) bezeichnet. Mittels dieses Verfahrens lassen sich beliebige dreidimensionale Strukturen aus massivem Metall fertigen, wobei als Grundlage für den Fertigungs- prozess dreidimensionale CAD-Daten Verwendung finden können. Bei der Herstellung der dreidimensionalen Struktur wird das Grundprinzip des sogenannten „Laser cladding" verwendet. Bei .dem Laser cladding wird auf der Oberfläche des zu erzeugenden, die dreidimensionale Struktur bildenden Bauteils mittels eines Lasers ein lokales Schmelzbad erzeugt, in das das Metallpulver zugegeben wird. Hierdurch entsteht auf dem zu er- zeugenden Bauteil eine Schicht aus dem zugeführten, aufgeschmolzenen Metallpulver. Durch eine die erwähnten CAD-Daten berücksichtigende Führung von Laserstrahl und Pulverzuführung kann das Bauteil mit einer definierten Geometrie erzeugt werden. Dabei wird Schicht für Schicht übereinander gelagert. Eine weitere Aufgabe der Erfindung besteht darin, Lotdepots für Kontaktflächen bereitzustellen, welche mit einer ver- gleichsweise großen Gestaltungsfreiheit hinsichtlich der Geometrie der Lotverbindung herstellbar sind.Finally, the invention relates to the use of a system for laser-assisted direct metal deposition. This process is described in "Proceedings of the 2001 ASME Design Engineering Technical Conferences and Computers and Information in Engineering Conference", Volume 2, published in 2001 by "The American Society of Mechanic Engineers", pages 333 to 338 and as "Laser aided direct metal deposition "(LADMD). Any three-dimensional structures made of solid metal can be produced by means of this method, whereby three-dimensional CAD data can be used as the basis for the manufacturing process. The basic principle of so-called “laser cladding” is used in the production of the three-dimensional structure. In laser cladding, a local melt pool is created on the surface of the component to be produced, which forms the three-dimensional structure, into which the metal powder is added. This creates a layer of the supplied, melted metal powder on the component to be produced by guiding the laser beam and powder supply taking into account the CAD data mentioned the component can be created with a defined geometry. Layer by layer is stacked on top of each other. Another object of the invention is to provide solder deposits for contact areas which can be produced with a comparatively large design freedom with regard to the geometry of the solder connection.

Diese weitere Aufgabe wird erfindungsgemäß durch die Verwendung einer Anlage zur laserunterstützten direkten Metallab- Scheidung (LADMD) mit einer Zuführvorrichtung, mit der Metallpulver einem zu erzeugenden Bauteil zugeführt wird und einem auf die Zuführstelle des Metallpulvers am zu erzeugenden Bauteil gerichteten Laser, mit dem das Metallpulver aufgeschmolzen wird, gelöst, indem diese Anlage für die Abschei- düng von Lotpulverteilchen auf einer Kontaktfläche eingesetzt wird, wobei der Energieeintrag durch den Laser in die Kontaktfläche derart begrenzt wird, dass die Erwärmung der Kontaktfläche unterhalb von deren Schmelztemperatur bleibt. Die erfindungsgemäße Verwendung der Anlage sieht also vor, dass von dem Prinzip des Laser claddings, das zu erzeugende Bauteil bei der Zuführung des Pulvers lokal anzuschmelzen, be- wusst abgewichen wird, um ein Aufschmelzen der Kontaktfläche, auf der das Lotdepot erzeugt werden soll, zu verhindern. Dies wird durch die bereits erwähnte Begrenzung des Energieein- trags durch den Laser erreicht, wobei der Energieeintrag durch den Laser insgesamt genügend hoch bemessen, werden muss, damit die zugeführten Lotpulverteilchen zumindest an ihrer Oberfläche angeschmolzen werden, um eine genügende Haftung der Lotpulverteilchen einerseits untereinander und anderer- seits auf der Kontaktfläche zu erreichen.This further object is achieved according to the invention by the use of a system for laser-assisted direct metal deposition (LADMD) with a feed device with which metal powder is fed to a component to be produced and with a laser directed at the feed point of the metal powder on the component to be produced with which the metal powder is melted, solved by using this system for the deposition of solder powder particles on a contact surface, the energy input by the laser into the contact surface being limited in such a way that the heating of the contact surface remains below its melting temperature. The use of the system according to the invention therefore provides that there is a deliberate departure from the principle of laser cladding, that the component to be produced is melted locally when the powder is supplied, in order to melt the contact surface on which the solder depot is to be produced prevent. This is achieved by the already mentioned limitation of the energy input by the laser, the energy input by the laser overall having to be dimensioned sufficiently high so that the supplied solder powder particles are melted at least on their surface in order to ensure sufficient adhesion of the solder powder particles to one another and on the other hand can be reached on the contact surface.

Das zu erzeugende Bauteil wird also im Unterschied zum LADMD- Verfahren gemäß dem Stand der Technik bei der Erfindung nicht ausschließlich aus dem Pulver erzeugt, sondern die bereits bestehenden Kontaktflächen werden in der Anlage lediglich mit den aus Lotpulverteilchen erzeugten Lotdepots versehen, wobei das zu erzeugende Bauteil die Kontaktflächen und die auf die- sen erzeugten Lotdepots enthält. Die Kontaktflächen können beispielsweise Teil eines Schaltungstragers, eines Bauelementes wie einem Flipchip oder auch eines sogenannten „lead frame", also einer gerippeartigen Leiterbahnstruktur mit den zugehörigen Kontaktflächen, sein, wobei die genannten Bau- gruppen nach einem beliebigen Verfahren hergestellt werden können. Die Vorteile der erzeugten Lotdepots sind im Zusammenhang mit dem erfindungsgemäßen Verfahren bereits beschrieben worden.In contrast to the LADMD method according to the prior art, the component to be produced is therefore not used in the invention produced exclusively from the powder, but the already existing contact surfaces are only provided in the system with the solder deposits produced from solder powder particles, the component to be produced containing the contact surfaces and the solder deposits produced on them. The contact areas can, for example, be part of a circuit carrier, a component such as a flipchip or also a so-called “lead frame”, that is to say a rib-like conductor track structure with the associated contact areas, the modules mentioned being able to be produced by any method generated solder deposits have already been described in connection with the method according to the invention.

Weitere Einzelheiten der Erfindung werden im Folgenden anhand der Zeichnung beschrieben. Hierbei zeigenFurther details of the invention are described below with reference to the drawing. Show here

Figur 1 ein Ausführungsbeispiel des erfindungsgemäßen Verfahrens zum Aufbringen von Lotpulverteilchen, die Figuren 2 bis 5 verschiedene Ausführungsbeispiele von Lotdepots, die mit dem erfindungsgemäßen Verfahren hergestellt sind, und Figur 6 ein Ausführungsbeispiel für eine Anlage zur1 shows an exemplary embodiment of the method according to the invention for applying solder powder particles, FIGS. 2 to 5 show different exemplary embodiments of solder deposits that are produced using the method according to the invention, and FIG. 6 shows an exemplary embodiment for a system for

Bildung von Lotdepots auf Kontaktflächen.Formation of solder deposits on contact areas.

In Figur 1 ist ein Schaltungsträger 11 mit einer Kontaktfläche 12 schematisch dargestellt. Auf die Kontaktfläche ist ein Lotpulverstrahl 13 gerichtet, der aus einer nicht dargestellten Düsenöffnung austritt. Der Lotpulverstrahl 13 enthält Lotpulverteilchen 14, die kurz vor dem Auftreffen auf die Kontaktfläche 12 durch einen Laserstrahl 15 hindurchtreten und dabei zumindest an der Oberfläche angeschmolzen werden. Beim Auftreffen auf die Kontaktfläche 12 haften die Lotpul- verteilchen 14 sowohl auf der Kontaktfläche 12 als auch an benachbarten Lotpulverteilchen 14 an, wodurch ein Lotdepot 16 erzeugt wird. Der Laserstrahl 15 und der Lotpulverstrahl 13 werden dabei mit geeigneter Geschwindigkeit über die Kontakt- fläche geführt, so dass sukzessive die gesamte zu belotendeA circuit carrier 11 with a contact surface 12 is shown schematically in FIG. A solder powder jet 13 is directed onto the contact surface and emerges from a nozzle opening (not shown). The solder powder jet 13 contains solder powder particles 14, which pass through a laser beam 15 shortly before hitting the contact surface 12 and are at least melted on the surface. When hitting the contact surface 12, the solder distribute 14 both on the contact surface 12 and on adjacent solder powder particles 14, whereby a solder depot 16 is generated. The laser beam 15 and the solder powder beam 13 are guided over the contact surface at a suitable speed, so that the entire surface to be soldered is successively

Fläche der Kontaktfläche mit Lotpulverteilchen 14 versehen wird.Surface of the contact surface is provided with solder powder particles 14.

In den folgenden Figuren sind sich entsprechende Zeichnungs- elemente mit gleichen Bezugszeichen versehen und werden nur insoweit genauer erläutert, wie sich Abweichungen zu dem bereits Ausgeführten ergeben.In the following figures, corresponding drawing elements are provided with the same reference symbols and are only explained in more detail to the extent that there are deviations from what has already been stated.

Ein poröses Lotdepot 16a auf der Kontaktfläche 12 ist durch Lotpulverteilchen 14a, 14b gebildet, die bei der Herstellung des Lotdepots nur an der Oberfläche angeschmolzen wurden. Daher ist die Form der einzelnen Lotpulverteilchen in dem Lotdepot 16a im Wesentlichen unverändert geblieben, so dass Poren 17 in den Zwischenräumen zwischen den einzelnen Lotpul- verteilchen 14a, 14b entstehen. Die Poren 17 sind durch einen Lotzusatzstoff 18 wie z. B. ein Flussmittel ausgefüllt. Die Einbringung des Lotzusatzstoffes in die Poren 17 des Lotdepots 16a kann beispielsweise durch einen Imprägnierungsvorgang erfolgen. Der Lotzusatzwerkstoff 18 ist durch eine Kreuzschraffur angedeutet.A porous solder deposit 16a on the contact surface 12 is formed by solder powder particles 14a, 14b, which were only melted on the surface during the manufacture of the solder deposit. Therefore, the shape of the individual solder powder particles in the solder depot 16a has remained essentially unchanged, so that pores 17 are formed in the spaces between the individual solder powder particles 14a, 14b. The pores 17 are by a solder additive 18 such. B. filled a flux. The solder additive can be introduced into the pores 17 of the solder deposit 16a, for example, by an impregnation process. The solder filler material 18 is indicated by cross hatching.

Die Lotpulverteilchen 14a haben eine andere Legierungszusammensetzung als die Lotpulverteilchen 14b. Eine endgültige Legierungszusammensetzung des Lotdepots stellt sich daher erst beim Aufschmelzen desselben zur Herstellung der Lotverbindung ein. Die unterschiedlichen Legierungszusammensetzungen der Lotpulverteilchen 14a, 14b sind durch Schraffuren unterschiedlicher Ausrichtung angedeutet. In Figur 3 ist ein planares Lotdepot 16b dargestellt, welches als massiver Block auf der Kontaktfläche 12 haftet. Ein solches Lotdepot kann durch vollständiges Aufschmelzen der Lotpulverteilchen erzeugt werden, so dass diese sich auf der Kontaktfläche zum Lotdepot 16b vereinigen. Die planare Ausbildung des Lotdepots wird dadurch gewährleistet, dass das sich bildende Lotdepot 16b immer nur an der Stelle der aktuellen LotpulverZuführung aufgeschmolzen wird.The solder powder particles 14a have a different alloy composition than the solder powder particles 14b. A final alloy composition of the solder deposit is therefore only achieved when it is melted to produce the solder connection. The different alloy compositions of the solder powder particles 14a, 14b are indicated by hatching of different orientations. FIG. 3 shows a planar solder deposit 16b which adheres to the contact surface 12 as a solid block. Such a solder depot can be produced by completely melting the solder powder particles so that they unite on the contact surface with the solder deposit 16b. The planar formation of the solder depot is ensured in that the solder depot 16b that is formed is only ever melted at the point of the current solder powder supply.

In Figur 4 ist ein Lotdepot 16c auf der Kontaktfläche 12 gebildet, welches aus mehreren Schichten 19a, 19b aufgebaut ist. Die einzelnen Schichten werden mit dem zu Figur 3 beschriebenen Verfahren hergestellt. Dabei wird für die Schich- ten 19a ein Lotpulver mit einem höheren Schmelzpunkt verwendet als für die Schichten 19b. Das Lotdepot 16c weist also eine im Vergleich zum restlichen Lotdepot niedriger schmelzende Kappe 20 auf.In FIG. 4, a solder deposit 16c is formed on the contact surface 12, which is made up of several layers 19a, 19b. The individual layers are produced using the method described for FIG. 3. A solder powder with a higher melting point is used for the layers 19a than for the layers 19b. The solder depot 16c thus has a cap 20 that melts lower than the rest of the solder depot.

Gemäß Figur 5 ist ein Lotdepot 19d auf der Kontaktfläche 12 als Kontaktbump ausgeführt. Dieses Lotdepot 19d wird dadurch erzeugt, dass die gesamte Menge des bereits der Kontaktfläche 12 zugeführten Lotpulvers bis zur Fertigstellung des Lotdepots in der Schmelze gehalten wird, so dass die Oberflächen- Spannung des flüssigen Lotwerkstoffes zu der dargestellten Ausbildung der Geometrie führt.According to FIG. 5, a solder depot 19d is designed on the contact surface 12 as a contact bump. This solder depot 19d is produced in that the entire amount of the solder powder already supplied to the contact surface 12 is kept in the melt until the solder depot is completed, so that the surface tension of the liquid solder material leads to the configuration of the geometry shown.

In Figur 6 ist eine LADMD-Anlage 21 schematisch dargestellt. Diese weist einen Prozessraum 22 auf, der mit einem die Oxi- dation von flüssigen Lotwerkstoff verhindernden Schutzgas gefüllt ist. In dem Prozessraum 22 wird der Schaltungsträger 11 mit den Kontaktflächen 12 eingebracht. Mittels einer Metallpulverzuführung 23 können die Lotpulverteilchen 14 einer der Kontaktflächen 12 zugeführt werden. Über einen halbdurchlässigen Spiegel 24 und eine Optik 25 kann ein durch einen LaserA LADMD system 21 is shown schematically in FIG. This has a process space 22 which is filled with a protective gas which prevents the oxidation of liquid solder material. The circuit carrier 11 with the contact surfaces 12 is introduced in the process space 22. By means of a metal powder feed 23, the solder powder particles 14 can be one of the Contact surfaces 12 are supplied. Via a semitransparent mirror 24 and an optical system 25, a laser can

26 erzeugter, nicht näher dargestellter Laserstrahl auf die Zuführstelle 27 für das Lotpulver auf der Kontaktfläche 12 projiziert werden. Der Temperaturverlauf an der Zuführstelle26 generated laser beam, not shown, are projected onto the feed point 27 for the solder powder on the contact surface 12. The temperature curve at the feed point

27 kann über ein Pyrometer 28 überwacht werden.27 can be monitored via a pyrometer 28.

Die Metallpulverzuführung 23 besteht aus einem Pulvervorrat 29, wobei die Lotpulverteilchen aus dem Pulvervorrat 29 über eine Fördervorrichtung 30 einer Düse 31 zugeführt werden. Die Düse trägt gleichzeitig die Optik 25 für den Laserstrahl. Um alle Kontaktflächen 12 des Schaltungsträgers 11 vollständig it Lotpulverteilchen 14 zu versehen, kann entweder die Düse 31 oder der Schaltungsträger 11 bewegt werden. The metal powder feed 23 consists of a powder supply 29, the solder powder particles being fed from the powder supply 29 to a nozzle 31 via a conveying device 30. The nozzle also carries the optics 25 for the laser beam. In order to completely provide all contact surfaces 12 of the circuit carrier 11 with solder powder particles 14, either the nozzle 31 or the circuit carrier 11 can be moved.

Claims

Patentansprüche claims 1. Verfahren zum Aufbringen von Lotmaterial auf eine Kontaktfläche (12) , bei dem das Lotmaterial der Kontaktfläche (12) in Form von Lotpulverteilchen (14, 14a, 14b) unter einem solchen Energieeintrag zugeführt wird, dass die Lotpulverteilchen (14, 14a, 14b) zumindest an ihrer Oberfläche über die Schmelztemperatur hinaus erwärmt werden.1. A method for applying solder material to a contact surface (12), in which the solder material is supplied to the contact surface (12) in the form of solder powder particles (14, 14a, 14b) with an energy input such that the solder powder particles (14, 14a, 14b ) are heated at least on their surface above the melting temperature. 2. Verfahren nach Anspruch 1, d a d u r c h g e k e n n z e i c h n e t, dass die Lotpulverteilchen (14, 14a, 14b) der Kontaktfläche2. The method according to claim 1, which also includes the solder powder particles (14, 14a, 14b) of the contact surface (12) mittels einer Düse (31) zugeführt werden.(12) are fed by means of a nozzle (31). 3. Verfahren nach einem der vorangehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t, dass der Energieeintrag mittels eines Laserstrahls (15) vorgenommen wird.3. The method according to any one of the preceding claims, that the energy input is carried out by means of a laser beam (15). 4. Verfahren nach Anspruch 3, d a d u r c h g e k e n n z e i c h n e t, dass der Laserstrahl auf die Kontaktfläche gerichtet wird und der Energieeintrag in die Kontaktfläche derart begrenzt wird, dass die Erwärmung der Kontaktfläche (12) unterhalb von deren Schmelztemperatur bleibt.4. The method according to claim 3, so that the laser beam is directed onto the contact area and the energy input into the contact area is limited in such a way that the heating of the contact area (12) remains below its melting temperature. 5. Verfahren nach einem der vorangehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t, dass ein Gemisch von Lotpulverteilchen (14a, 14b) mit unter- schiedlicher chemischer Zusammensetzung verwendet wird.5. The method according to any one of the preceding claims, that a mixture of solder powder particles (14a, 14b) with a different chemical composition is used. 6. Verfahren nach einem der vorangehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t, dass ein Lotdepot (16c) mit Schichten (19a, 19b) unterschiedlicher Eigenschaften erzeugt wird, indem die Schichten jeweils durch Lotpulverteilchen (14) mit unterschiedlichen Eigenschaften gebildet werden.6. The method according to any one of the preceding claims, characterized in that a solder depot (16c) with layers (19a, 19b) with different properties is produced by the layers being formed in each case by solder powder particles (14) with different properties. 7. Verfahren nach einem der vorangehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t, dass ein Lotdepot (16a) mit poröser Struktur erzeugt wird, indem die zugeführten Lotpulverteilchen (14, 14a, 14b) durch den Energieeintrag jeweils nur an der Oberfläche angeschmolzen werden.7. The method as claimed in one of the preceding claims, that a solder deposit (16a) with a porous structure is produced by melting the supplied solder powder particles (14, 14a, 14b) only on the surface due to the energy input. 8. Verfahren nach einem der Ansprüche 1 bis 6, d a d u r c h g e k e n n z e i c h n e t, dass ein massives Lotdepot (16b) erzeugt wird, indem der E- nergieeintrag derart bemessen wird, dass die jeweils zugeführten Lotpulverteilchen (14, 14a, 14b) durch den Energieeintrag vollständig aufgeschmolzen werden.8. The method according to any one of claims 1 to 6, characterized in that a solid solder deposit (16b) is generated by the energy input is dimensioned such that the respectively supplied solder powder particles (14, 14a, 14b) are completely melted by the energy input , 9. Verfahren nach einem der Ansprüche 1 bis 6, d a d u r c h g e k e n n z e i c h n e t, dass ein Lotdepot (16d) mit gewölbter Oberfläche erzeugt wird, indem das sich bildende Lotdepot (16d) während der Zuführung der Lotpulverteilchen durch den Energieeintrag im ge- schmolzenen Zustand gehalten wird.9. The method according to any one of claims 1 to 6, so that a solder depot (16d) with a curved surface is produced by the solder depot (16d) that is formed being kept in the molten state by the energy input during the supply of the solder powder particles. 10. Kontaktfläche mit einem Poren (17) aufweisenden Lotdepot (16a) , welches durch Lotpulverteilchen (14, 14a, 14b) gebildet ist, die durch Anschmelzen ihrer Oberfläche untereinander verbunden sind. 10. Contact surface with a pore (17) having solder depot (16a) which is formed by solder powder particles (14, 14a, 14b) which are connected to one another by melting their surface. 11. Kontaktfläche nach Anspruch 10, d a d u r c h g e k e n n z e i c h n e t, dass die Poren (17) mit einem Lotzusatzstoff (18) ausgefüllt sind.11. Contact surface according to claim 10, so that the pores (17) are filled with a solder additive (18). 12. Kontaktfläche mit einem massiven Lotdepot (16c), welches durch mehrere übereinandergelagerte Schichten (19a, 19b) gebildet ist.12. Contact surface with a solid solder deposit (16c), which is formed by several superimposed layers (19a, 19b). 13. Kontaktfläche nach Anspruch 12, d a d u r c h g e k e n n z e i c h n e t, dass zumindest einige Schichten (19a, 19b) unterschiedliche13. Contact surface according to claim 12, so that at least some layers (19a, 19b) are different Eigenschaften aufweisen.Have properties. 14. Verwendung einer Anlage zur laserunterstützten direkten Metallabscheidung (LADMD) mit14. Use of a system for laser-assisted direct metal deposition (LADMD) - einer Zuführvorrichtung (23), mit der Metallpulver einem zu erzeugenden Bauteil zugeführt wird, und einem auf die Zuführstelle des Metallpulvers am zu erzeu- genden Bauteil gerichteten Laser, mit dem das Metallpulver aufgeschmolzen wird, für die Abscheidung von Lotpulverteilchen (14, 14a, 14b) auf einer Kontaktfläche (12), wobei der Energieeintrag durch den Laser in die Kontaktfläche derart begrenzt wird, dass die Er- wärmung der Kontaktfläche (12) unterhalb von deren Schmelztemperatur bleibt. - A feed device (23), with which metal powder is fed to a component to be produced, and a laser, aimed at the feed point of the metal powder on the component to be produced, with which the metal powder is melted, for the deposition of solder powder particles (14, 14a, 14b) on a contact surface (12), the energy input by the laser into the contact surface being limited such that the heating of the contact surface (12) remains below its melting temperature.
PCT/DE2003/003944 2002-12-03 2003-11-26 Method for the application of solder material, use of a system for laser-aided direct metal deposition and contact surfaces with solder material Ceased WO2004050286A1 (en)

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