DE102021117530A1 - Process for joining at least two joining partners - Google Patents

Abstract

The present invention relates to a method for joining at least two joining partners (3, 8) using ultra-short laser pulses of a laser beam (5) from an ultra-short pulse laser (4), with at least one of the joining partners (3, 8) being transparent for the laser wavelength used, with the joining partners (3, 8) are joined together by means of ultra-short laser pulses of the laser beam (5) along at least one joining seam trajectory (90), the strength of the joint (9) being lower than the strength of the weakest joining partner (3, 8).

Description

technical field

The present invention relates to a method for joining at least two joining partners by means of ultra-short laser pulses of a laser beam from an ultra-short-pulse laser and a container for medical and/or chemical preparations produced therewith.

State of the art

To join two parts to be joined, it is known to apply a laser beam to the respective parts to be joined in order to generate a melt through energy absorption in the zone exposed to the laser beam, which melt forms a weld seam between the parts to be joined after the melt has solidified. Joining using ultra-short laser pulses enables a stable connection of the joining partners without the use of additional material.

It is known to place the focus or focal zone of the laser beam in the boundary surface or in an area around the common boundary surface of the two joining partners for joining a transparent joining partner with a non-transparent joining partner or for welding two transparent joining partners. The processing laser beam passes through one of the transparent joining partners and generates a melt in the area of the interface between the two joining partners.

If you focus ultra-short laser pulses, i.e. laser pulses in the picosecond range or in the femtosecond range (e.g. 50 fs to 50 ps), in the volume of a material, the high intensity in the focus can lead to non-linear absorption processes. If the time between the successive ultra-short laser pulses is shorter than the heat diffusion time, this leads to heat accumulation or a temperature rise in the material in the focus area. With each of the successive pulses, the temperature can then be increased to the melting temperature of the material and finally the material can be locally melted.

A particular problem also arises when closing glass containers, such as vials or ampoules. The closure of such containers, which often contain chemical and/or medicinal preparations, requires complex manufacturing methods, such as adhesives and/or complex sample preparation. In particular, the preparations contained in the containers must not be damaged by the manufacture of a closure. Furthermore, to open the containers, predetermined breaking points are often introduced into the containers by mechanical scoring. When a force is applied, the container then breaks along the predetermined breaking point so that the preparation can be removed.

US 2013/0068384 A1 shows a device and a method for joining two joining partners, whereby a certain region can be enclosed and sealed by the joining seam.

Presentation of the invention

Proceeding from the known prior art, it is an object of the present invention to provide an improved method for joining two joining partners.

The object is achieved by a method for joining two joining partners with the features of claim 1. Advantageous developments result from the dependent claims, the description and the figures.

Accordingly, a method for joining at least two joining partners using ultrashort laser pulses of a laser beam from an ultrashort pulse laser is proposed, with at least one of the joining partners being transparent to the laser wavelength used, with the joining partners being joined to one another using ultrashort laser pulses of the laser beam along at least one joining seam trajectory. According to the invention, the strength of the joint is designed to be lower than the strength of the weakest joining partner.

In this way, a connection can be made between the joining partners, which can be separated again when a predetermined force is applied, without one of the joining partners breaking. Correspondingly, for example, a lid can be applied to a container, which can then be opened again by applying a corresponding force, in that the joint connection is separated again—for example by breaking open. However, the joining partners are not substantially damaged and, for example, the lid and the container remain structurally undamaged.

The ultra-short pulse laser makes the ultra-short laser pulses of the laser beam available, with the individual laser pulses forming the laser beam in the beam propagation direction.

Instead of individual laser pulses, the laser can also provide bursts, with each burst comprising the transmission of a number of laser pulses. In this case, for a specific time interval, the transmission the laser pulses follow one another very closely, a few picoseconds up to hundreds of nanoseconds apart. The bursts can in particular be so-called GHz bursts, in which the sequence of the successive laser pulses of the respective burst takes place in the GHz range.

In this context, a sequence of individual pulses means that the laser emits several individual pulses one after the other. A sequence of individual pulses therefore includes at least two individual pulses. A sequence of bursts means that the laser emits several bursts one after the other. A sequence of bursts therefore includes at least two bursts. In particular, the bursts or individual pulses of the sequence can each be of the same type. The bursts or individual pulses are identical if the laser pulses used have essentially the same properties, ie approximately the same pulse energy, the same pulse length and—in the case of bursts—also the same pulse spacing within the burst.

The transparency of the at least one joining partner has the advantage that the joining laser can be focused through the transparent joining partner, so that the joining area can be localized at the interface between the two joining partners - i.e. on the inside - between the two joining partners.

The first joining partner can be transparent, for example, and the second joining partner can be opaque to the wavelength of the laser. However, both joining partners can also be transparent.

A first joining partner can preferably comprise a metal or consist of metal and a further joining partner comprise glass or consist of glass, or at least two joining partners joined together comprise plastic or glass or consist of plastic or glass. For example, the first joining partner can consist of quartz glass and the second can consist of aluminum.

The joining partners are arranged one on top of the other, so that the boundary surfaces of the joining partners, across which the joining partners are to be joined, face one another. The abutting surface is the surface on which the joining partners are in contact.

In the joining area, heat is accumulated as a result of successive absorption of the ultra-short laser pulses, provided the pulse rate of the laser beam is greater than the rate of heat dissipation through material-specific heat transport mechanisms, in particular through heat diffusion. Due to the increasing temperature in the material of at least the first joining partner from joining pulse to joining pulse or from burst to burst, the melting temperature of the material of the joining partner can finally be reached, which leads to local melting of the material of the joining partner.

The joining area is therefore understood to be that area of the joining partner in which the ultra-short laser pulses are introduced and in which the material is melted. Alternatively, the entirety of the locally melted material in the joining area can also be referred to as a melt bubble. Irrespective of the name, the resulting melt can bridge the common interface of the joining partners and permanently connect the joining partners to one another when cooling down. In particular, the network structure of the joining partners can also change. The joint seam is then referred to as the cooled melt which connects the joint partners to one another or results in the joint connection.

The joining area is the entire cross-sectional area of the joining area in the plane of the abutting surface of the joining partners. In other words, the joining surface is the part of the interface via which the joining partners are connected to one another by the melt bubble.

In order to melt the material in the joining area, individual pulses and/or bursts can be introduced into the material and successively absorbed. This large number of ultra-short individual pulses and/or bursts introduced at a position is also called a laser spot, with the number of ultra-short individual pulses and/or bursts per laser spot N being given by the product of spot size SG and repetition rate P per feed rate VG: N = SG * P / VG. The spot size describes the spatial area over which the ultra-short laser pulses and/or bursts are emitted into the material.

The size of the joining area is additionally determined by the beam geometry, in particular the size of the focal zone of the focused laser beam. The beam geometry describes the spatial configuration of the laser beam and other beam properties such as certain diffraction properties of the laser beam, see below.

According to the invention, the strength of the joint is lower than that of the weakest joint partner. In other words, when a force is applied to the joint partners being joined, the joint connection breaks first. The surface of the separated joining partners is essentially undamaged apart from (shell) eruptions at the location of the joint.

A predetermined breaking point of the joined joining partners is accordingly provided by the defined joining connection.

The strength of the joint can be adjusted by the proportion of the joint surface covered by the joint to the entire abutting surface, the abutting surface being defined by the surface on which the joint partners rest against one another.

For example, with two fixed joining partners, a stronger joint can be created, which can still function as a predetermined breaking point. Therefore, in order to achieve such allowable higher strength, the joining area can be increased. On the other hand, the strength of the joint connection also depends on the material combination of the joint partners, so that a desired joint connection strength can be generated by adjusting a joint surface independently of the material of the joint partners.

In particular, the proportion of the joint surface to the entire joint surface can be less than 50%, preferably less than 25%, provided that a first joint partner is metal and another joint partner is glass, with the joint surface being defined by the surface on which the joint partners meet issue.

For example, an abutting surface of two joining partners can be 20mm ² in size. The joining area can then be smaller than 10 mm ² , for example. If one of the joining partners is metal and another joining partner is glass, the joining area can preferably be smaller than 5 mm ² . However, the joining surface can also be smaller than 5mm ² if none of the joining partners is metal.

The proportion of the joint surface of the joint connection to the entire abutment surface can be adjusted by introducing several joint seams.

In particular, the joint is produced by the large number of joint seams.

For example, a first strength of the joint connection can be generated by a first joint seam. A second joint seam running parallel to the first joint seam can likewise produce a first strength of the joint connection. Overall, the joint connection—consisting of the first and second joint seam—can have a strength of two first strengths.

However, it can also be the case that the first joint seam creates a first strength of the joint connection and the second joint seam creates a second strength of the joint connection, so that the strength of the joint seam—consisting of the first and second joint seam—has a strength of the first and second strength .

However, it is also possible that the strengths do not add up directly, but rather accumulate in a different way. The person skilled in the art can easily find this out by carrying out suitable tests with the joining partners.

The strength of the joint connection can accordingly provide a force for breaking the joint connection, with the joint connection being designed as a predetermined breaking point between the joint partners.

At least one seam can be closed along a seam trajectory or more than 50% closed along the seam trajectory.

The joining seam trajectory is the trajectory along which the joining modifications or a joining seam are introduced. A joining seam trajectory is closed, for example, if the starting point and the end point of the joining seam trajectory are on top of each other. For example, a circular joint trajectory is closed. A joint trajectory can also be closed if the joint trajectory sweeps over a point twice.

If the joint seam is closed for more than 50% of the joint seam trajectory, this can mean that the joint seam is perforated, so that joint modifications are introduced, for example, at the same or different distances.

At least one of the joining partners can enclose a volume and another joining partner can hermetically seal the volume through the joint connection, with the enclosed volume being able to contain in particular a medical and/or chemical preparation.

For example, the first joining partner can be cylindrical and contain a medical and/or chemical preparation. The second joining partner can be a plate that covers the opening of the cylinder. The volume with the medical and/or chemical preparation can be hermetically sealed by the joint connection, so that the preparation can neither outgas nor leak and can be damaged by environmental influences such as high humidity.

In particular, by joining the joining partners and the design of the joining seam, a strong and tight, in particular also gas-tight connection can be produced, which, however, acts as a predetermined breaking point under load.

The invention therefore enables components, for example sleeves, ampoules and/or containers for medical and/or chemical preparations, to be closed in a gas-tight manner and without the use of additional materials and adhesives and then opened again in a defined manner.

Due to the high strength of laser-welded samples, new (slim) design options are conceivable. In particular, mechanical scoring of the containers is no longer necessary and there is no thermal impairment of the preparation when the containers are closed.

The average power of the laser spot can be between 0.5W and 50W.

The average power of the laser spot Ls is defined for a single pulse as the product of pulse energy E, repetition rate P _E of the single pulse and number of single pulses N _E : L _S,E = E * P _E * N _E

The average power of the laser spot in a burst is defined as the product of the pulse energy E, the number of pulses per burst N _P , the number of bursts N _E and the repetition rate at which the bursts are emitted P _E : L _S,P = E * N _P * P _E * N _E . The average power of the laser spot during a burst is thus scaled only with the number of laser pulses per burst compared to the average power of a single pulse: L _S,P = L _S,E * N _P .

The power can be reduced and/or adjusted, for example, inside the laser or externally by polarization optics.

The pulse energy of the laser pulses can be modulated over time, preferably with the average power remaining the same, with the modulation frequency preferably being between 100 Hz and 10 kHz.

Temporally modulated means that the pulse energy is changed during a modulation period, the modulation period being given by the inverse modulation frequency. The modulation frequency indicates the time scale on which the modulation form is repeated. In particular, a modulation of the pulse energy means that the pulse energy can become larger or smaller during the modulation period. The modulation form indicates which mathematical function the pulse energy follows during the modulation period.

The modulated pulse energy from pulse to pulse means that there are times when less pulse energy is introduced into the joining partner(s) and temperature relaxation can take place. There may also be times when more energy can be injected than without the modulation.

For example, a temporal modulation can be achieved by varying the intensity of the joining pulses. For example, a strong joining pulse can be emitted followed by two joining pulses with half the intensity. However, the temporal modulation also means that the laser then emits a strong joining pulse, followed by two weakened joining pulses.

The laser pulses of a burst can each have a time interval of at most 1 µs, preferably between 0.05 ns and 1000 ns, and the bursts of the sequence of bursts can each have a time interval of at least 2 µs, preferably between 2 µs and 1000 µs, and/or the individual pulses of the sequence of individual pulses can each have a time interval of at least 0.02 μs, preferably between 0.02 μs and 1000 μs, from one another.

This has the advantage that suitable joining parameters can be found for many different materials, so that the strength of the joint can be set particularly easily. In particular, the cooling phases of the joining partners or the accumulation of heat in the joining area are controlled by the time intervals, so that particularly high-quality and in particular stress-free and crack-free joining seams and joints can be produced.

The time intervals between the laser pulses of all bursts used for joining can be the same length and/or the time intervals between the bursts for all bursts used for joining can be the same length and/or all time intervals between all the individual pulses used for joining can be the same length.

The time intervals between the laser pulses can thus be determined by a fixed repetition frequency. In particular, the operation of the laser system can be stabilized by using a fixed repetition frequency.

For example, the laser pulses of a burst can then have a repetition frequency between 50 GHz and 1 MHz and the bursts of the sequence of bursts can have a repetition frequency between 500 kHz and 1 kHz and/or the A sequence of individual pulses can have a repetition frequency between 50 MHz and 1 kHz.

The time intervals between the laser pulses of all bursts used for joining can be the same length and/or the time intervals between the bursts can be the same length for all bursts used for joining and/or all the time intervals between all the individual pulses used for joining can be the same length.

In particular, the pulses can thus be introduced into the joining partners with a predetermined frequency, so that particularly simple control electronics can be used to control the laser or to generate and emit pulses.

The laser wavelength can be between 200nm and 5000nm, preferably 1000nm, and/or the pulse duration of the laser pulses can be between 10fs and 50ps, and/or the laser beam can be focused in a focal zone in the joining partners and the fluence in the focal zone can be greater than 0.01 J/cm ² for a single single pulse or a laser pulse of a burst.

These parameters make it possible to control the accumulation of heat in the joint partners, to reduce stress and to generate higher strengths in the joint. In particular, it is also possible to adapt the process parameters to the respective materials of the joining partners.

For example, the wavelength of the ultra-short laser pulse can be 1030 nm, the pulse duration of a single pulse being 400 fs, the pulse spacing being 20 ns, which corresponds to a repetition rate of 50 MHz, and the fluence in the focus being 75 J/cm ² , for example.

The laser beam and the joining partners can be moved and/or positioned relative to each other with a feed between 0.01 mm/s and 1000 mm/s.

Moving relative to each other can mean that either the laser beam or the joining partners or both the laser beam and the joining partners are moved. In this way it can be achieved that the laser beam introduces joints at different locations of the joint partners. In particular, this makes it possible to produce a continuous weld seam between the two joining partners.

The movement can take place with a feed, with laser pulses or bursts being able to be introduced continuously into the joining partners during the feed. A positioning of the joining partners relative to the laser beam consists in bringing the focus zone of the laser beam into the desired penetration depth and into the desired location.

The laser beam can be a quasi non-diffracting laser beam, preferably a Bessel beam or a Gauss-Bessel beam, and the laser beam can preferably have a focal zone that is elongated in the beam propagation direction.

Non-diffracting rays and/or Bessel-like rays are to be understood in particular as rays in which a transverse intensity distribution is propagation-invariant.

In particular, in the case of non-diffractive beams and/or Bessel-type beams, a transverse intensity distribution is essentially constant along the beam propagation direction.

In addition, the focal zone of the processing laser beam is always understood to mean that part of the intensity distribution of the processing laser beam that is greater than the modification threshold of the material. The word focal zone makes it clear that this part of the intensity distribution is provided in a targeted manner and that an intensity increase in the form of the intensity distribution is achieved by focusing.

With regard to the definition and properties of non-diffracting rays, reference is made to the book "Structured Light Fields: Applications in Optical Trapping, Manipulation and Organization", M. Wördemann, Springer Science & Business Media (2012), ISBN 978-3-642-29322- 1 referenced. This is expressly and fully referred to.

Accordingly, non-diffracting laser beams have the advantage that they can have a focal zone that is elongated in the direction of beam propagation and that is significantly larger than the transverse dimensions of the focal zone. In particular, a material modification that is elongated in the beam propagation direction can be produced in this way, in order to enable a particularly strong joining of the joining partners, for example.

In particular, non-diffracting beams can be used to generate elliptical non-diffracting beams that have a non-radially symmetrical transverse focal zone. For example, elliptical quasi-non-diffracting rays have a main maximum that coincides with the center of the ray. The center of the ray is given by the place where the main axes of the ellipse intersect. In particular, elliptical, quasi non-diffracting beams can result from the superimposition of several intensity measurements xima result, in which case only the envelope of the intensity maxima involved is elliptical. In particular, the individual intensity maxima do not have to have an elliptical intensity profile.

For example, a non-diffracting beam can be generated from a plane wave field or from parallel partial laser beams if all partial laser beams are refracted at the same angle β to the optical axis of the laser beam. As a result, the partial laser beams close to the axis overlap shortly after the processing laser beam shaping optics on the optical axis and thus form an increased laser intensity, while off-axis rays overlap later after the processing laser beam shaping optics and form an increased laser beam intensity. A substantially constant laser intensity can thus be generated over a longitudinal length parallel to the beam propagation direction.

However, the real laser optics can have optical aberrations. In addition, an optical adjustment can be faulty, so that the partial laser beams are refracted at different angles to the optical axis. This can lead to a systematic deviation of the angle of refraction β. Accordingly, the intensity distribution in the focal zone - where the different partial laser beams overlap - can deviate from that of an ideal non-diffracting reference laser beam.

The object set above is also achieved by a container for medical and/or chemical preparations having the features of claim 16. Advantageous developments of the method result from the dependent claims and the present description and the figures.

Accordingly, a container for medical and/or chemical preparations is proposed, comprising a joining partner enclosing a volume and a joining partner serving as a closure, with the volume containing the medical and/or chemical preparation. According to the invention, the joining partners are joined by means of ultra-short laser pulses of a laser beam from an ultra-short pulse laser along at least one joining seam trajectory, with at least one of the joining partners being transparent to the laser wavelength used, at least one joining seam along the at least one joining seam trajectory being closed and the strength of the joint connection being lower than the strength of the weakest joining partner.

A first joining partner preferably comprises a metal or consists of metal and a further joining partner comprises glass or consists of glass, or that at least two joining partners joined together comprise plastic or glass or consist of plastic or glass.

This has the advantage that particularly robust containers can be produced. In particular, containers can also be produced which have little or no chemical interaction with the preparations, so that the preparations can be kept longer inside the container than outside the container.

The strength of the joint can be adjusted by the proportion of the joint surface covered by the joint to the entire abutting surface, the abutting surface being defined by the surface on which the joint partners rest against one another. It can preferably be less than 50%, preferably less than 25%, of the joint surface to the entire joint surface, provided that a first joint partner is a metal and a further joint partner is a glass. The proportion of the joint surface to the entire abutment surface can preferably be adjusted, in particular by introducing several joint seams. The strength of the joining seam can preferably provide a force for breaking the joining seam, with the joining seam being designed as a predetermined breaking point between the joining partners.

By adjusting the strength and the force required as a result to break the connection along the predetermined breaking point, it can be made possible in particular that the container can be opened with just one hand, for example, or can be opened with only two hands. Depending on the preparation contained, appropriate handling of the container may be required.

character list

• 1 einen schematischen Aufbau zur Durchführung des Verfahrens;
• 2A, B, C, D eine schematische Darstellung der Durchführung des Verfahrens und einen entsprechend hergestellten Behälter;
• 3A, B, C, D, E eine schematische Darstellung zur Einstellung der Festigkeit der Fügeverbindung;
• 4A, B, C verschiedene Laserpulskonfigurationen zum Fügen der Fügepartner;
• 5 eine Fügeverbindung bestehend aus mehreren Fügenähten;
• 6A, B, C, D verschiedene mögliche Laserstrahlprofile; und
• 7A, B zeitlich modulierte Laserpulskonfigurationen.

Preferred further embodiments of the invention are explained in more detail by the following description of the figures. show:

• 1 a schematic structure for carrying out the method;
• 2A, B , C , D a schematic representation of the implementation of the method and a correspondingly manufactured container;
• 3A, B , C , D , E a schematic representation for adjusting the strength of the joint;
• 4A, B , C different laser pulse configurations for joining the joining partners;
• 5 a joint connection consisting of several joint seams;
• 6A, B , C , D various possible laser beam profiles; and
• 7A, B time-modulated laser pulse configurations.

Detailed description of preferred embodiments

Preferred exemplary embodiments are described below with reference to the figures. Elements that are the same, similar or have the same effect are provided with identical reference symbols in the different figures, and a repeated description of these elements is sometimes dispensed with in order to avoid redundancies.

In 1 a structure 1 for carrying out the method described below is shown schematically and a very schematic cross section of two parts to be joined 3, 8 to be joined. The parts to be joined 3, 8 are arranged one on top of the other at a common interface 7, with the entire interface being an abutment surface in the present case 70 trains.

An ultra-short pulse laser 4 provides ultra-short laser pulses of a laser beam 5. These can be introduced into the joining partners 3, 8 in the form of a sequence of individual pulses or in the form of a sequence of bursts.

The average power of the laser spot can be between 0.5W and 50W. The laser pulses of a burst can each have a time interval of at most 1 µs, preferably between 0.05 ns and 1000 ns, and the bursts of the sequence of bursts can each have a time interval of at least 2 µs, preferably between 2 µs and 1000 µs, and/or the individual pulses of the sequence of individual pulses can each have a time interval of at least 0.02 μs, preferably between 0.02 μs and 1000 μs, from one another.

The time intervals between the laser pulses of all bursts used for joining can be the same length and/or the time intervals between the bursts for all bursts used for joining can be the same length and/or all time intervals between all the individual pulses used for joining can be the same length.

The laser wavelength can be between 200 nm and 5000 nm, preferably 1000 nm, and/or the pulse duration of the laser pulses can be between 10 fs and 50 ps the area of the intensity increase of the laser beam 5 coincides approximately with the common boundary surface 7 of the two joining partners 3, 8.

For example, the fluence in the focal zone F can be at least 0.01J/cm ² . By focusing with the focusing optics 6, in particular the insertion height of the focal zone F can be determined relative to the first surface of the joining partner 8 in the beam direction. In order to focus the laser beam 5 in the common interface 7 of the joining partners 3 , 8 , the first joining partner 8 in the beam propagation direction must be transparent to the wavelength of the laser 4 .

At the boundary surface 7, successive laser pulses are absorbed in the focus zone F in such a way that the material of the joining partners 3, 8 melts and connects across the boundary surface 7 to the other joining partner 8, 3 in each case. As soon as the melt cools down, a permanent connection is formed between the two parts to be joined 3, 8. In other words, the two parts to be joined 3, 8 are joined to one another in this area by welding. This area, in which the melting and joining of the materials and the subsequent cooling of the melt takes place and in which the actual joining takes place, is also referred to as the joining area. The cooled melt and material connection of the joining partners 3, 8 forms a weld seam.

The laser beam and the joining partners can be moved and/or positioned relative to each other with a feed VG between 0.01 mm/s and 1000 mm/s. For this purpose, the joining partners can be positioned, for example, on a feed device (not shown). As a result, it can be achieved, for example, that the laser beam is moved over the joining partners along a joining seam trajectory, so that the joining partners can be joined along the joining seam trajectory.

In the 2A until 2D the implementation of the proposed method is shown very schematically using a container 2, which is also shown schematically, for receiving medical and/or chemical preparations.

In 2A a first joining partner 3 and a second joining partner 8 are shown, the second joining partner 8 being transparent to the wavelength of the laser 4 . For example, the first joining partner 3 can be a metal, for example aluminum, and the second joining partner 8 can be glass or a plastic. It can also be the case that both parts to be joined 3, 8 are transparent and are made of glass or plastic, for example. If the laser wavelength is selected appropriately, two metals can also be joined together, for example.

In the present case, the first joining partner 3 encloses a volume. In the volume, for example, medical and / or chemical preparations or other substances such as a liquid (not shown) or a powder. The second joining partner 8 is then arranged on the first joining partner 3 so that the second joining partner 8 covers the opening of the first joining partner 3 . In particular, it is also possible to press or clamp the second joining partner 8 onto the first joining partner 3 . The surface on which the two parts to be joined 3.8 bear against one another is called the abutment surface 70 in this case.

Accordingly, the first joining partner 3 and the second joining partner 8 jointly form a container 2 for medical and/or chemical preparations.

In 2 B shows how the laser beam 5 of the ultra-short pulse laser 4 introduces laser pulses along the joining seam trajectory 90, with the effects described above creating a joining seam 9' and thus a joint connection 9 between the joining partners 3, 8. If the joining seam 9' is closed, the volume of the first joining partner 3 can be hermetically sealed. The preparation contained in the volume of the first joining partner 3 is thus protected against environmental influences, which increases the durability of the preparation.

In particular, the strength of the joint 9 is lower than the strength of the weakest joining partner 3, 8. As a result, a predetermined breaking point 94 is formed along the joint 9, which preferably breaks when a force K is applied. Because the strength of the joint connection 9 is lower than the strength of the weakest joint partner 3, 8, only the joint connection 9 is specifically damaged when a force K is applied, with the joint partners 3, 8 not being damaged.

In 2C is shown schematically the application of a force K on the joint partners 3.8 joined together. The joint connection 9 forms a predetermined breaking point 94 along which the joint partners 3.8 are separated by the force K.

The separated state of the previously joined joining partners is in 2D shown. The surface of the separated parts to be joined 3, 8 is essentially undamaged, apart from (shell) breakouts at the location of the joint 9.

In 3 shows how the strength of the joint 9 can be adjusted so that the strength of the joint 9 is lower than the strength of the weakest joint partner 3, 8. In 3A For this purpose, the abutting surface 70 is shown with a single joint seam 9 ′, which produces the joint connection 9 . The ratio of the two areas can be less than 50%, preferably less than 25% if one of the joining partners 3 is metal and the other joining partner 8 is glass.

In particular, the strength of the joint connection 9 depends on the total area covered by the joint connection 9 . The more surface is joined, the stronger the joint 9.

One compared to 3A stronger joint connection 9 can be achieved, for example, in that the individual joint seam 9' is wider. As a result, the joining surface 92 is larger than the joining surface 92 in 3A , so that the ratio of joining surface 9 to abutting surface 70 becomes larger.

But it is also possible, as in 3C shown that the joining surface 92 is increased in that several joining seams 9 'are produced, which together produce the joint connection 9. The joining seams 9' can, for example, run parallel to one another in the abutting surface 70.

For example, the overall joint connection 9 formed 3C three times as strong as the joint 9 from the 3A be, because there are three mutually parallel joining seams 9 'are provided.

In 3D it is shown that the joint seam 9', which produces the joint connection 9, is closed along the joint seam trajectory 90. In particular, the start and end points of the joining seam 9' lie on top of one another. A closed joining seam 9' results in a hermetically sealed connection between the joining partners 3, 8, so that liquids or gases, for example, can also be accommodated and enclosed in a container 2 closed in this way.

In 3E On the other hand, a non-closed joining seam 9 is shown by way of example, which, however, is more than 50% closed along the joining seam trajectory 90 . Such a joining seam 9 cannot, for example, create a gas-tight connection between the two joining partners 3, 8, but an advantageous connection with a predetermined breaking point 94, for example for powdered preparations, can nevertheless result. In particular, it is sufficient for a hermetic seal or a gas-tight seal if at least one of the joining seams 9' that is introduced is closed.

Combinations of at least one closed joint seam and at least one non-closed joint seam are also conceivable.

In 4 different configurations for laser irradiation are shown as examples.

For example, the joining partners 3, 8 can be joined particularly advantageously with a sequence of individual pulses. In this case, the individual pulses have a time interval of at least 0.02 μs, preferably an interval of between 0.02 μs and 1000 μs, from one another. This is very schematic in 4A shown.

However, it is also possible to join the joining partners 3, 8 with a sequence of bursts. For example, a burst can include exactly two laser pulses. The laser pulses of the burst can each have a time interval of at most 1 μs, preferably between 0.05 ns and 1000 ns. The bursts can have a time interval of at least 2 μs, preferably between 2 μs and 1000 μs, from one another. This is very schematic in 4B shown. However, it is also possible for a burst to include more than two laser pulses. This is very schematic in 4C shown.

In particular, the laser pulses within the burst have an equally large time interval, so that a burst repetition frequency is given by the time interval. The time interval between the bursts or the individual laser pulses is also constant, so that the delivery of the laser power can be described with a repetition frequency. In general, however, the individual laser pulses or the bursts can also have different time intervals.

In 5 the top view of the joining partners 3, 8 is shown, with the first joining partner 8, which is transparent to the laser beam 5 in the beam propagation direction, being visible. By means of a feed system (not shown), a large number of spot welds were introduced into the interface 7 of the layered system of joining partners 3, 8 in order to form a joint connection 9. The joining partners and the laser beam 5 were shifted relative to one another at a feed rate VG in order to produce a continuous weld seam.

For example, the feed speed VG, ie the relative speed of movement between the laser beam 5 and the joining partners 3, 8, can be between 0.01 and 1000 mm/s. Furthermore, a sequence of bursts was used, each burst comprising four laser pulses. However, it is also possible to join the joining partners 3, 8 with a sequence of individual pulses.

In particular, three seams 9' were produced, which increased the overall strength of the joint. This makes it possible to specify a force K for separating the joining partners 3, 8.

In 6A the intensity profile and beam cross section of a quasi-non-diffracting laser beam 5 is shown. In particular, the quasi-non-diffractive beam 5 is a Bessel-Gaussian beam. In the beam cross-section in the xy plane, the Bessel-Gauss beam has radial symmetry, so that the intensity of the laser beam only depends on the distance from the optical axis. In particular, the transverse beam diameter d ^ND ₀ is between 0.25 μm and 10 μm.

In 6B shows the longitudinal beam cross-section, i.e. the beam cross-section in the direction of beam propagation. The beam cross-section has an elongated focal zone that is about 300 µm in size. The focus zone F is thus significantly larger in the direction of propagation than the beam cross section in the xy plane, so that there is an elongated focus zone.

In 6C is analogous to 6A a Bessel beam is shown which has a non-radially symmetric beam cross-section. In particular, the beam cross-section appears stretched in the y-direction, almost elliptical.

In 6D shows the longitudinal focal zone of the Bessel beam, which again has a longitudinal extension of about 300 µm. Accordingly, the Bessel beam also has a focal zone that is elongated in the direction of beam propagation.

In 7A a temporal modulation of the pulse energy is shown. The black bars can be understood as single pulses, so that the pulse energy of consecutive single pulses is modulated. The black bars can also be understood as bursts, so that consecutive bursts have different mean energies. In particular, all of the black bars can also be a burst, so that the temporal modulation takes place during a burst. The modulation rate can be between 100 Hz and 10 kHz, for example 1 kHz. For example, with a 200 kHz modulation rate and bursts comprising 2 pulses, 200 bursts can be provided during one period.

The modulation form is sine ² -shaped, so that, for example, the pulse energy of the successive individual pulses differ from one another according to the sine ² function. Analogous to this is in 7B a temporal modulation of the pulse energy is shown, the modulation shape being triangular here. The laser pulse energy follows a triangular function.

The forms of modulation shown make it possible for the joining partners 3, 8 to move between the introduction of the pulses with the maximum shown can cool down easily, so that the joining process can be optimally adapted to the joining partners 3, 8.

As far as applicable, all individual features that are presented in the exemplary embodiments can be combined with one another and/or exchanged without departing from the scope of the invention.

reference list

1

contraption

2

container

3

joining partner

4

laser

5

laser beam

6

focusing optics

7

interface

70

impact surface

8th

joining partner

9

joint connection

9'

joint seam

90

joint trajectory

92

mating surface

94

predetermined breaking point

K

power

f

focus zone

VG

feed rate

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• US20130068384A1 [0006]

Claims (18)

Method for joining at least two joining partners (3, 8) using ultra-short laser pulses of a laser beam (5) from an ultra-short pulse laser (4), with at least one of the joining partners (3, 8) being transparent for the laser wavelength used, with the joining partners (3, 8) are joined together by means of ultra-short laser pulses of the laser beam (5) along at least one joining seam trajectory (90), characterized in that the strength of the joining connection (9) is less than the strength of the weakest joining partner (3, 8). procedure after claim 1 , characterized in that a first joining partner (3, 8) comprises a metal or is made of metal and a further joining partner (8, 3) comprises glass or is made of glass, or that at least two joining partners (3, 8) joined together are plastic or glass or consist of plastic or glass. procedure after claim 1 or 2 , characterized in that the strength of the joint (9) is adjusted by the proportion of the joint surface (92) covered by the joint (9) to the entire abutment surface (70), the abutment surface (70) being given by the surface on which the joining partners (3, 8) rest against one another. Method according to one of the preceding claims, characterized in that the proportion of the joining surface (92) to the entire abutting surface (70) is less than 50%, preferably less than 25%, if a first joining partner (3, 8) comprises a metal or and a further joining partner (8, 3) comprises or is a glass, the abutting surface (70) being defined by the surface on which the joining partners (3, 8) bear against one another. Method according to one of the preceding claims, characterized in that the proportion of the joining surface (92) of the joining connection (9) to the entire abutting surface (70) is adjusted by introducing a plurality of joining seams (9'). Method according to one of the preceding claims, characterized in that at least one seam (9`) of the joint (9) is closed along a seam trajectory (90) or more than 50% is closed along the seam trajectory (90). Procedure according to one of claims 3 until 6 , characterized in that the strength of the joint (9) provides a force for breaking the joint (9), the joint (9) being designed as a predetermined breaking point (94) between the joining partners (3, 8). Method according to one of the preceding claims, characterized in that at least one of the joining partners (3, 8) encloses a volume and another joining partner (8, 3) hermetically seals the volume through the joint (9), the enclosed volume being in particular a medical and/or chemical preparation may contain. Method according to one of the preceding claims, characterized in that the average power of the laser spot is between 0.5W and 50W. Method according to one of the preceding claims, characterized in that the pulse energy of the laser pulses is modulated over time, preferably with the average power remaining the same, the modulation frequency preferably being between 100 Hz and 10 kHz. Method according to one of the preceding claims, characterized in that - the laser pulses of a burst each have a time interval of at most 1 µs, preferably between 0.05 ns and 1000 ns, and the bursts of the sequence of bursts each have a time interval of at least 2 µs, preferably between 2 μs and 1000 μs to one another and/or the individual pulses of the sequence of individual pulses each have a time interval of at least 0.02 μs, preferably between 0.02 μs and 1000 μs, to one another. Method according to one of the preceding claims, characterized in that the time intervals between the laser pulses of all bursts used for joining are the same length and/or the time intervals between the bursts are the same length for all bursts used for joining and/or all time intervals between all of them single pulses used for joining are of the same length. Method according to one of the preceding claims, characterized in that - the laser wavelength is between 200nm and 5000nm, preferably 1000nm, and/or - the pulse duration of the laser pulses is between 10fs and 50ps, and/or - the laser beam and the joining partners relative to each other be moved and/or positioned at a feed between 0.01mm/s and 1000mm/s. Method according to one of the preceding claims, characterized in that the laser beam (5) is focused in a focal zone (F) in the joining partners (3, 8) and the fluence in the focal zone (F) is greater than 0.01 J/cm <sup>2</sup> for a individual single pulse or a laser pulse of a burst. Method according to one of the preceding claims, characterized in that the laser beam (5) is a quasi non-diffracting laser beam, preferably a Bessel beam or a Gauss-Bessel beam, and the laser beam (5) preferably has a focal zone (F ) having. Container (2) for medical and/or chemical preparations, comprising a joining partner (3, 8) enclosing a volume and a joining partner (8, 3) serving as a closure, the volume containing the medicinal and/or chemical preparation, characterized in that at least one of the joining partners (3, 8) is transparent for the laser wavelength used, the joining partners (3, 8) are joined by means of ultra-short laser pulses of a laser beam (5) of an ultra-short-pulse laser (4) along at least one joining seam trajectory (90), at least one joining seam ( 9') is closed along the at least one joining seam trajectory (90), and the strength of the joining connection (9) is lower than the strength of the weakest joining partner (3, 8). container (2) after Claim 16 , characterized in that a first joining partner (3, 8) comprises a metal or is made of metal and a further joining partner (8, 3) comprises glass or is made of glass, or that at least two joining partners (3, 8) joined together are plastic or glass or consist of plastic or glass. container (2) after Claim 16 or 17 , characterized in that the strength of the joint (9) is adjusted by the proportion of the joint surface (92) covered by the joint (9) to the entire abutment surface (70), the abutment surface (70) being given by the surface on which the Joining partners (3, 8) abut one another, with the proportion of the joining surface (92) to the entire abutting surface (70) preferably being less than 50%, preferably less than 25%, provided that a first joining partner (3, 8) is a metal and another joining partner (8, 3) is a glass, with the proportion of the joining surface (92) to the entire abutting surface (70) preferably being able to be adjusted by introducing several joining seams (9`), and with the strength of the joining connection (9) preferably there is a force (K) to break the joint (9), the joint (9) being designed as a predetermined breaking point between the joint partners (3, 8).

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