Method for joining two components in the region of a joint zone by means of at least one laser beam, and method for generating a continuous joint seam

Abstract

A method is disclosed for joining two components (1, 2), a first component (I) and a second component (2), in the region of a joint zone by means of at least one laser beam. In a first phase, the first component (I) is melted, and a melt lens is formed in the first component (I) from the molten material (9). In a second phase, at least one pressure pulse is applied to the melt in the direction of the second component (2) until the melt lens is deflected into the joint gap as a result of the pressure pulse, bridges the joint gap, and comes into contact with the second component (2), and energy is transmitted to the second component (2) as a result of the melt lens coming into contact with the second component. A temperature curve results in the second component (2) as a result of the energy transmission such that the melting temperature is reached on the upper face of the second component (2), and a melt film is formed. The heat penetration depth is set such that a damaging temperature which damages the second component (2) is not exceeded at a specified depth. A method for generating a continuous joint seam is also disclosed.

Claims

1. Method for joining two components having a thickness in a region of a joint zone defining free surfaces of the two components to be joined together by means of at least one laser beam comprising, the method comprising: positioning a first component in the region of the joint zone, thermally separated at a distance from a second component, viewed in a direction of the thickness of the components, forming a joint gap, the second component having a metallic layer on a side facing the first component, in a first phase, directing the at least one laser beam in the direction of the thickness of the components onto a surface of the first component facing away from the second component, wherein a surface irradiated by the at least one laser beam is referred to as an irradiated surface (A.sub.L), and melting the first component locally, at least in accordance with a size of the joint zone, over its entire thickness, an energy (Q.sub.L,a) absorbed by the laser beam in the first component being selected such that a condition
absorbed energy=Q.sub.L,a={dot over (Q)}.sub.L,adt=Q.sub.B1+{dot over (Q)}.sub.kond1dt+dH.sub.M1+Q.sub.B2+{dot over (Q)}.sub.kond2dt+dH.sub.M2 is fulfilled, where Q.sub.L,a={dot over (Q)}.sub.L,adt energy absorbed in the first component Q.sub.B1=.sub.1.Math.A.sub.1.Math.s.sub.B1.Math.c.sub.p1.Math.(T.sub.m1T.sub.0) energy required to generate a local melt lens in the first component where .sub.1=density of the first component, A.sub.1=area of the melt lens projected in the direction of the laser beam s.sub.B1=thickness of the first component, c.sub.1=thermal capacity of the first component, T.sub.m1=melting temperature of the first component, T.sub.0=ambient temperature {dot over (Q)}.sub.cond2dt=Q.sub.cond2 conductive heat conduction losses in the first component dH.sub.M1 enthalpy for a material phase change in the first component Q.sub.B2=.sub.2.Math.A.sub.2.Math.s.sub.B2.Math.c.sub.p2.Math.(T.sub.m2T.sub.0) energy required to generate a local melt film in the second component where .sub.2=density of the second component, A.sub.2=area of the melt lens projected in the direction of the laser beam s.sub.B2=thickness of the melt film in the second component c.sub.2=thermal capacity of the second component, T.sub.m2=melting temperature of the second component, T.sub.0=ambient temperature {dot over (Q)}.sub.cond2dt=Q.sub.cond2 conductive heat conduction losses in the second component dH.sub.M2 enthalpy for a material phase change in the second component whereby a melt lens is formed in the first component from molten material, then, in a second phase, applying at least one pressure pulse to the melt lens in a direction of the second component until the melt lens deflects into the joint gap due to the pressure pulse, bridges the joint gap and comes into contact with the second component, and energy is transferred to the second component by the contact of the melt lens with the second component, and such a temperature curve is generated by the energy transfer in the second component that on an upper side of the second component a melting temperature thereof is reached, a melt film is formed and a heat penetration depth, defined by
d.sub.w={square root over (4t.sub.contakt)}, =thermal conductivity into the second component due to a contact time (t.sub.contakt), referred to as a time between a first contact of the melt lens with the second component and solidification of material melted in the melt lens, is set such that a damage temperature (T.sub.damage) damaging the second component is not exceeded at a predetermined depth of the second component, wherein the damage temperature (T.sub.damage) in the second component is defined as a temperature T in a depth (z.sub.crit,B2) of the second component viewed in a direction of the thickness of the second component, at which either damage to a material lying under the metallic layer of the second component occurs or a detachment of the metallic layer on the second component from an underlying material occurs.

2. Method as in claim 1, wherein the at least one pressure pulse is carried out by a further laser beam superimposed on the at least one laser beam, wherein the at least one laser beam and the further laser beam have different intensities, focus diameters, pulse lengths (ms pulse, ns pulse) and/or wavelengths.

3. Method as in claim 2, wherein the further laser beam is focused above the first workpiece.

4. Method as in claim 2, wherein the further laser beam has a wavelength which has an increased absorption in an ambient atmosphere/plasma cloud above the first component.

5. Method as in claim 1, wherein the pressure pulse(s) applied in the second phase is/are triggered by different modulation of laser radiation of the at least one laser beam.

6. Method as in claim 5, wherein a surface temperature generated by the at least one laser beam in the first component is temporally modulated in the second phase by increasing and decreasing a size of the irradiated surface with approximately a same laser power as a function of a process phase.

7. Method as in claim 1, wherein energy input into the melt lens in the second phase is carried out such that the laser beam passes through the first component without first generating a melt in the second component, and the temperature of the melt lens bridging the gap is not further increased, and wherein the second component is then heated by thermal energy stored in the melt located in the joint gap and melted on an upper side of the second component so that melts of both components connect, and that then a pressure puke on the melt lens in the first component is triggered by material evaporation.

8. Method as in claim 1, wherein joining is carried out in an ambient atmosphere which is matched to a desired surface tension distribution of the melt lens, wherein a flow of a melt in a center of the melt lens and in a direction of the second component is generated by the selected ambient atmosphere.

9. Method as claim 1, wherein a measurement of the temperature or a variable correlating to the temperature of the first component is carried out in the region of the melt lens, and wherein a time of contact of the melt lens in the joint gap with the second component is derived from a drop in the temperature or a drop in the correlating variable and at this time a further absorption of the energy (Q.sub.L,a) into the first component is reduced or ended.

10. Method as in claim 1, wherein a movement of the melt lens on the upper side of the first component is detected in the region of the irradiated surface and an extent of the absorbed energy (Q.sub.L,a) is adjusted as a function of the detected movement of the melt lens.

11. Method for generating a continuous joint seam by combining spot welds produced by the method according to claim 1 by means of overlapping to form a continuous joint seam, by offsetting the laser beam step by step along the joint seam to be produced and spot welding at each of the offset positions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic representation to explain the method for joining two components according to the invention.

(2) FIG. 2 shows a diagram presenting the temperature T as a function of the penetration depth z in the second component.

(3) FIG. 3 shows a bonded joint between a 200 m thick Cu substrate on a 35 m thin metallization and an Si substrate.

(4) FIG. 4 shows three phases (a), (b) and (c) for joining two components using local power modulation.

(5) FIG. 5 shows three phases (a), (b) and (c) for joining two components using temporal focus modulation via a change in the irradiated surface.

(6) FIG. 6 shows three phases (a), (b) and (c) for joining two components using a temporal power modulation with a temperature increase and a pressure pulse caused by evaporation.

(7) FIG. 7 shows three possible power profiles (a), (b) and (c) for a temporal power modulation of the laser radiation.

DESCRIPTION OF THE PREFERRED EMBODIMENT

(8) The preferred embodiments of the present invention will now be described with reference to FIGS. 1-7 of the drawings. Identical elements in the various figures are designated with the same reference numerals.

(9) FIG. 1 schematically shows a joining process according to the method according to the invention for joining two components, an upper first component 1 and a lower second component 2. The index B1 is assigned to the upper component 1 in the sizes used, while the index B2 is assigned to the lower component 2.

(10) At the beginning of the joining process, the two components 1, 2 are positioned thermally separated from each other at a distance so that a joint gap 4 remains between components 1, 2, in the direction of their thickness indicated by the direction arrow 3. The second component 2 uses a metallic layer 5 on its side facing the first component 1, which is to form a material connection with the melt of the first component. The width 6 of the joint gap 4 is dimensioned such that it has the smallest possible dimension at which a thermal separation of the joining partners, i.e. component 1 and component 2, is still achieved.

(11) A laser beam 7 is then directed in the direction of the thickness of components 1, 2 onto surface 8 of the first component 1 facing away from the second component 2. The surface irradiated by the laser beam 7 or by more laser beams is referred to as irradiated surface A.sub.L and depends on the diameter of the laser beam 7 with which it impacts the surface 8 of the second component 2. The energy Q.sub.L,a introduced and absorbed in the first component 1 melts the first component 1 locally over its entire thickness. Due to the thermal separation of components 1, 2 via the joint gap 4, less energy is required overall in the melting phase of the upper component 1, since firstly no conductive heat conduction takes place from the first component 1 to the second component 2 and secondly the second component is not thermally influenced by the melting of the first component.

(12) The size of the melting zone, viewed in the direction of surface 8 of the first component 1, should be at least the size of a joint zone to be produced.

(13) The joint zone is the region of the two components 1, 2, in which the two components 1, 2 are joined together by fusion.

(14) The energy Q.sub.L,a absorbed by the at least one laser beam in the first component 1 is set so that it fulfills the condition
absorbed energy=Q.sub.L,a={dot over (Q)}.sub.L,adt=Q.sub.B1+{dot over (Q)}.sub.kond1dt+dH.sub.M1+Q.sub.B2+{dot over (Q)}.sub.kond2dt+dH.sub.M2
where Q.sub.L,a={dot over (Q)}.sub.L,adt energy absorbed in the first component Q.sub.B1=.sub.1.Math.A.sub.1.Math.s.sub.B1.Math.c.sub.p1.Math.(T.sub.m1T.sub.0) energy required to generate a local melt lens in the first component
where .sub.1=density of the first component, A.sub.1=area of the melt lens projected in the direction of the laser beam s.sub.B1=thickness of the first component, c.sub.1=thermal capacity of the first component, T.sub.m1=melting temperature of the first component, T.sub.0=ambient temperature {dot over (Q)}.sub.cond2dt=Q.sub.cond2 conductive heat conduction losses in the first component dH.sub.M1 enthalpy for a material phase change in the first component Q.sub.B2=.sub.2.Math.A.sub.2.Math.s.sub.B2.Math.c.sub.p2.Math.(T.sub.m2T.sub.0) energy required to generate a local melt film in the second component
where .sub.2=density of the second component, A.sub.2=area of the melt lens projected in the direction of the laser beam s.sub.B2=thickness of the melt film in the second component c.sub.2=thermal capacity of the second component, T.sub.m2=melting temperature of the second component, T.sub.0=ambient temperature {dot over (Q)}.sub.cond2dt=Q.sub.cond2 conductive heat conduction losses in the second component dH.sub.M2 enthalpy for a material phase change in the second component

(15) This concludes the first phase of the method.

(16) Now, in a second phase, at least one pressure pulse is applied to the melted material 9 or the melt lens 10 in the direction (direction arrow 3) of the second component 2 until the melt lens 10 deflects into the joint gap 4 as a result of the pressure pulse.

(17) The joint gap 4 is then bridged by the melt lens 10 and comes into contact with the second component 2, as shown in FIG. 1. The contact of the melt lens 10 with the second component 2 causes an energy transfer to the second component 2. The energy Q.sub.B2 transferred to the second component 2 and thus the energy transfer to the second component 2 results in such a temperature curve in the second component 2 that the melting temperature is reached on its upper side, which is covered by the metallic layer 5.

(18) The melt film of the metallic layer 5 then forms a material bond with the melt lens 10, which solidifies when cooled and connects the two components.

(19) The depth of heat penetration into the second component 2 is adjusted due to a contact time t.sub.contakt, referred to as the time between a first contact of the melt lens 10 with the second component 2 and the solidification of the material 9 melted in the melt lens 10, so that a damage temperature T.sub.damage damaging the second component 2 is not exceeded at a predetermined depth of the second component 2. The conductive heat conduction losses
{dot over (Q)}.sub.cond2dt=Q.sub.cond2
in the second component 2 are taken into account.

(20) The damage temperature T.sub.damage in the second component 2 is defined as the temperature T at the depth z.sub.crit of the second component (z.sub.crit,B2) viewed in the direction of its thickness 12, at which either the material under the metallic layer 5 of the second component 2 is damaged or the metallic layer 5 on the upper side of the second component 2 becomes detached from the underlying material 13 (base material).

(21) The melting of the upper joining partner, i.e. the upper component 1, by means of the laser radiation is carried out with defined overheating of the melt in a range between the melting and evaporation temperature in coordination with the joining partners, components 1 and 2. A defined overheating means that the energy Q.sub.L,a absorbed in the first component 1 does not lead to complete evaporation of the melt lens, but is so large that after contact of the melt lens with the metal layer 10 of the second component and the associated energy dissipation into component 2, the melt lens does not solidify immediately, but solidifies only after a material connection of the two components has been made.

(22) The deflection of the melt 9 or the melt lens 10 over the joint gap 4 to the lower component 2 by means of a transfer technique, for example a modulation of the laser radiation, is carried out under introduction of energy into the melt 9 such that the lower region of the melt lens 10 comes into contact with the upper side of the second component 2 and a melt transfer is achieved. The energy input and thus the increase in temperature at the interface between the melt lens 10 and the upper side of the second component 2 is reduced after deflection of the melt 9 or the melt lens 10 and their contact with the second component 2 such that sufficient mixing of the joining partners occurs without, however, exceeding the critical temperature at the interface between the metal layer on the second component 2 and the respective substrate material.

(23) The method according to the invention utilizes defined melt overheating to heat the lower component 2 as a joining partner above the melting temperature T.sub.m2. The required energy surplus in the melt lens is calculated as E.sub.m= c.sub.pVT; E.sub.m is the energy required to produce a thin melting film in the metal layer of component 2, p is the density of the metal layer of component 2, c.sub.p is the specific heat of the metal layer of component 2, V is the volume of the melting film and T is given by T=(T.sub.m, lower, joining partner+temperature increase) to compensate for heat losses by heat conduction and melt enthalpy in the lower joining partner. The melt (molten material) 9 is overheated with adaptation to the required melt volume and the required energy E.sub.m for melting the lower metallization (metallic layer 5). For example, metallic layer 5 could be a 20 m thick metallization on a temperature-sensitive substrate. According to the method, the lower joining partner, the second component 2, is melted only with the energy Q.sub.B2 contained in the melt 9.

(24) To minimize the energy input in the deflection phase, the process is controlled such that the melt deflection is the smallest deflection that still allows the melt to be connected to the lower component across the selected gap.

(25) The connection of the melt to the lower component and thus the joining process is essentially only achieved by the energy present in the melt 9, so that the total energy input into the two components and the energy input into the lower, second component 2 is kept at a minimum value.

(26) The modulation technique used according to the method according to the invention for deflecting the melt lens 10 into the joining gap 4 towards the second component is carried out such that the intensity of the laser radiation, designated as 12, in the deflection phase falls below a limit value, designated as I.sub.limit value (I.sub.2<I.sub.limit value), which would otherwise lead to a significant penetration of the laser beam or of the laser radiation through the melt lens 10 and exceed the energy load limit of the lower component 2. The limit value I.sub.limit value depends, among other things, on the geometry and material of the joining partners 1, 2 and the modulation technique/beam guidance.

(27) In a bonding phase, the deflected melt leads to wetting of the melt with the metal layer of the second component 2 and to a joint between the two components 1 and 2 across the joint gap 4. The external energy input via the laser radiation is terminated, as already mentioned above, with or shortly after the contact of the melt with the lower, second component 2, whereby the energy input into the lower component 2 primarily occurs only by the energy (Q.sub.B2) contained in the melt 9.

(28) FIG. 2 shows a diagram illustrating the temperature T (in the second component 2) as a function of the penetration depth z in the second component 2. In this diagram, the curve, which is shown as a broken line and designated as t.sub.contakt, indicates the temporal progression of the penetration depth z into the second component 2 from a first contact of the melt lens 10 with the second component 2. The other two curves for t.sub.max as a solid line and for t.sub.min as a dotted line indicate the minimum and maximum times to be observed for firstly reaching the melting temperature at the surface of the second component and secondly for reaching a critical damage temperature at the depth z.sub.crit in the second component.

(29) The curves are derived from the one-dimensional heat equation

(30) $T\left(z,t\right)-T_{}=\frac{2.Math.\left(q_F+I_{L,t}\right)}{.Math.c_P}\sqrt{\frac{t}{}}i\mathrm{erfc}\left(\frac{z}{\sqrt{4t}}\right)$
where T(z,t): Temperature curve in the second component at depth z at time t T.sub.z,t: ambient temperature ierfc: integral error function complement q.sub.F: heat input into the second component 2 where q.sub.F={dot over (Q)}/A.sub.Kontakt=.Math.(T.sub.1T.sub.2) I.sub.L,I: intensity of the laser radiation 7 transmitted through the melt 9 : heat transfer coefficient between the first and second components 1, 2 T.sub.1: temperature in the first component 1 at the time of melt 9 contact with the second component 2 T.sub.2: temperature in the second component 2 at the time of melt 9 contact with the second component 2 t: time from a first contact of melt 9 with component 2 A.sub.contact: contact area between melt 9 and metal layer on component 2 : Thermal conductivity of the lower (second) component 2 : density of the lower (second) component 2 c.sub.p: heat capacity of the lower (second) component 2 z: depth in the component measured from the upper side of the second component 2.

(31) On the temperature axis, the temperatures T.sub.damage, B2(z=z.sub.crit, B2) and T.sub.melt, B2(z=0) are marked; the temperature T.sub.damage, B2(z=z.sub.crit,B2) indicates the temperature at which at the depth z.sub.crit (z.sub.crit,B2), measured from the upper side of the second component 2, and which is indicated in FIG. 1, damage occurs while T.sub.melt,B2(z=0) indicates the melt temperature at the surface of the second component 2, i.e., at a depth z=0.

(32) It can be seen that by setting the heat input qF and the contact time t.sub.contakt via the component depth even in the maximum case without conductive losses at Q(t)=const; Q.sub.B2(t=t.sub.contakt)=Q.sub.B2(t=t.sub.solidification) also in the cooling phase at any time t the damage temperature T.sub.damage in the component depth z.sub.krit,B2 of the second component 2, viewed in the direction of its thickness, is not exceeded. The graph in FIG. 2 also shows that the temperature gradient is set to the depth of component 2 in such a way that the critical damage temperature is not exceeded at any time after heating of the metal layer of component 2. The energy input into component 2 is distributed via conductive heat conduction such that the temperature in component 2 balances out without exceeding the critical temperature at the interface between metallization and substrate.

(33) FIG. 3 schematically shows a bonded joint over a joint gap 4, which was created between an upper, first component 1 and a lower, second component 2 according to the method according to the invention. The upper, first component 1 is a 200 m thick Cu contact and the lower, second component 2 is a silicon substrate coated on its upper side with a 35 m thick metallization of copper (metallic layer 5). This illustration shows that for thick-melt contacting of a thick terminal contact with a thin metallization on a temperature-sensitive substrate, the energy transfer is minimized by introducing the essential energy portion for melt formation in the terminal contact without a thermal contact for thin metallization. When the melt contacts the metallization, the hot melt melts the metal layer, but when it cools down, the energy introduced into the melt goes into the terminal contact and not into the temperature-sensitive component.

(34) FIG. 4 shows three phases (a), (b) and (c) for joining two components 1, 2 using local power modulation. In these figures, the metallic layer 5 on the upper side of the second component 2 is not shown. At the beginning of the joining process (phase (a)), the two components 1, 2 are spaced so that a joint gap 4 with a defined distance 6 (width of the joint gap) is formed between them. The laser beam 7 or the laser radiation used is guided over the surface 8 of the first component 1 in a circular motion with respect to an axis 14, so that the material of the first component 1 is melted in a circular shape. Accordingly, the zone of molten material 13 progresses faster in the outer area viewed perpendicular to axis 14 than in a central area near axis 14. With a progressing energy input via multiple laser rotations in accordance with the circular movement, the inner region is also melted via heat conduction, so that a homogeneous melting phase is produced. In phase (b), the radius of the circular movement of the laser beam 7 is then reduced in comparison to the radius in phase (a), so that the temperature in the middle of the melt is suddenly increased and the evaporation threshold is exceeded.

(35) The melt deflection is achieved by evaporation due to an increase in temperature by a movement of the laser beam 7 in micro-rings and successive changes in the diameter of the circular movement (transition from phase (a) to phase (b)). In phase (a), preheating with a large circular diameter of the beam movement of, for example, 200 m can be realized and then for phase (b), the deflection of the molten material 9 over the decreasing diameter of the circular movement with a diameter of 50 m. Consequently, the diameter of the original circular motion is reduced by a factor of about 4. To prevent uncontrolled evaporation, the intensity of the laser radiation between phase (a) and phase (b) is kept constant or even reduced in the deflection phase (phase (a)) compared to the preheating phase (phase (b)). This achieves a homogeneous transition between melt formation and evaporation with controlled pressure formation, which transfers the melt into the joint gap.

(36) When the molten material 9 reaches the underside of the first component 1, the molten material 9 bridges the joint gap 4 until the melt lens 10 strikes the top of the second component 2. This moment in time is measured using various methods as described above, so that the power of the laser beam is reduced or completely switched off at this time. This ensures that the molten material 9 only slightly melts the second component 2 and connects with this melt of the second component 2, so that after cooling a joint is formed, which is shown in phase (c) of FIG. 4.

(37) FIG. 5 shows three phases (a), (b) and (c) for joining two components 1, 2 using temporal focus modulation of the laser radiation and via a change in the irradiated surface. Again, phase (a) is the warm-up phase, phase (b) is the deflection phase and phase (c) is the connection phase.

(38) It is essential that with a temporal focus modulation the intensity of the laser radiation 7 is changed by means of dynamic change of the focus, for example via an electromagnetic telescope, at a constant power of the laser radiation.

(39) In the preheating phase (a), component 1 is irradiated with a large beam diameter of the laser radiation 7, so that a melt lens 10 is formed that is determined according to the beam diameter and the heat conduction, the diameter 15 of the laser beam 7 being set so that no evaporation occurs at surface 8 and no capillary is formed either. Again, molten material 13 is formed in the first component 1 until this material reaches the underside of component 1.

(40) In the subsequent deflection phase (b), the diameter 15 of the laser beam 7 is reduced in such a way that the intensity for reaching the evaporation temperature is reached and a vapor cloud 16 forms above component 1, which exerts a vapor pressure on the melt (melt lens 10). Alternatively, this can also be done by enlarging the laser beam 7 and the associated reduced lateral heat dissipation, so that an evaporation beam or lobe forms in the middle of the melt lens 10, which presses the melt in the direction of component 2.

(41) In the connection phase (c), in which the melt lens 10 bridges the joint gap 4, the diameter 15 of the laser beam 7 is increased again in order to avoid the formation of a vapor capillary, which would otherwise influence component 2 thermally. Depending on the joint geometry and material, laser radiation is still briefly applied to the bonded joint until a homogeneous, molten zone is formed at the interface between the two components 1,2, which solidifies after the laser beam 7 is switched off. Such a temporal focus modulation by changing the irradiated surface of the laser radiation 7 into the first component 1 has the advantage that a constant power of the laser radiation 7 is used and the local distribution of the intensity with which the laser radiation 7 strikes the upper side of the first component 1 is carried out by dynamically changing the focus.

(42) FIG. 6 shows again three phases (a), (b) and (c) for joining two components 1, 2 using temporal power modulation with a temperature increase and a pressure pulse caused by evaporation. In phase (a), the laser beam 7 is directed at the upper side 8 of the first component 1 so that molten material 9 is formed in the first component 1 according to the phase (a) described in FIG. 5 above. During the entire joining process, laser beam 7 remains unchanged with respect to its size.

(43) In phase (b), the power is increased to exceed the evaporation temperature so that the melt lens 10 is moved to component 2 via the vapor pressure that forms, thereby bridging the joint gap 4.

(44) In phase (c), laser radiation 7 is briefly applied to the bonded joint until a homogeneous molten zone is formed at the interface between the two components 1, 2, which solidifies after the laser beam is switched off. FIG. 7 now shows three possible power profiles (a), (b) and (c) for temporal power modulation of the laser radiation, which is preferably used when the different heat dissipation conditions of component 2 have to be taken into account in order to generate a homogeneous melt in component 1. In these profiles, the power of the laser radiation is applied over time, i.e. the time of the joining process.

(45) Profile (a) shows a rectangular profile with again a constant power in the preheating phase and a stepped increase in power for the connection phase, which is then kept constant in the connection phase.

(46) Profile (b) shows a profile, which can be called a peak profile, with a constant power in the preheating phase and increasingly higher power peaks during the connection phase.

(47) Profile (c) shows a ramp profile in which the power of the laser radiation is kept constant over the preheating phase (VWP) corresponding to phases (a) of FIGS. 5 and 6, while the power for the connection phase following the preheating phase is ramped up.

(48) Of these profiles, profile (a) should be used if the geometry of component 1 is only slightly larger than the metallization of component 2 and the associated energy input into component 2 prevents the critical temperature in component 2 from being exceeded. In contrast, a peak profile (b) is to be preferred for cases in which a high heat dissipation in component 2 does not permit a homogeneous and sufficient formation of the melt lens. Here, a controlled energy deposition and controlled evaporation is possible by a fast power modulation with increasing peak power, without the laser beam passing through the melt lens of the first component. Ramp profile (c) is to be preferred if metrological instruments are used to control the process or if the heat dissipation in component 2 becomes so high after contact of the melt lens with component 2 that the melt solidifies too quickly, so that sufficient mixing and joining strength is not achieved. Here, the necessary energy is dosed by the additional energy deposition.

(49) There has thus been shown and described a novel method for joining two components in the region of a joint zone by means of at least one laser beam, and method for generating a continuous joint seam, which fulfills all the objects and advantages sought therefor. Many changes, modifications, variations and other uses and applications of the subject invention will, however, become apparent to those skilled in the art after considering this specification and the accompanying drawings which disclose the preferred embodiments thereof. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention, which is to be limited only by the claims which follow.