DE102019206248A1 - METHOD FOR HEATING A VARIETY OF ELECTRICALLY CONDUCTIVE STRUCTURES AND DEVICE FOR USE IN THE METHOD - Google Patents

Abstract

A method of heating a plurality of electrically conductive structures (2, 4) disposed on an electrically non-conductive first substrate (1), comprising the steps of:
- Providing a first inductor (6) having a plurality of juxtaposed inductor elements (30), wherein each inductor element at least a first connecting portion (31) and at least two legs (32), wherein the first connecting portion (31), the two legs (32 ) of the inductor element (30), and wherein the inductor elements (30) are connected to each other in series by second connecting sections (33),
Arranging the first inductor (6) above or below the first substrate (1) such that
o each inductor element (30) at least partially overlaps with an edge (5) of at least one electrically conductive structure (2, 4) and / or
o each inductor element extends at least in regions parallel to the edge (5) of the electrically conductive structure (2, 4),
- Applying the first inductor (6) with an alternating current or applying an alternating voltage to the first inductor (6) and
- Inducing eddy currents in the electrically conductive structures (2, 4).

Description

Many novel products in microsystem technology represent a major technological challenge for current bonding and joining processes.

Today's assembly and connection technology (AVT) aims at ever smaller and more complex components and microsystems. For the purposes of the present specification, the term "micro" means that there is at least one extension of the corresponding component or microsystem which is between 0.1 μm and 10 mm, typically between 1 μm and 1 mm. The aim is to keep the thermal and mechanical influence of the component during the joining process as low as possible in order not to damage sensitive elements. Consequently, joining pressure and temperature input should be distributed homogeneously into the joining components. Furthermore, some joining processes place high demands on the surface qualities of the joining partners. The joint connection is to hermetically seal components with high mechanical strengths. Other important requirements are the integration density, the variety of materials, the accessibility of the joints (eg 3D integration), as well as process and cycle times.

Although established, hermetically sealed joints joining processes or wafer bonding process in microsystem technology such as anodic bonding, the low-temperature silicon direct bonding, glass frit bonding or eutectic bonding connect reliably, but there prevail over a longer period temperatures of up to 400 ° C before. The temperatures have a global effect on the complete joint structure (substrates, functional elements and layers, contacts, bonding layer) via heating chucks with integrated heating conductors. The heating conductors are traversed by a current and their Joule heating is transmitted via heat conduction first into the surface of the Heizchucks and subsequently into the Fügeeaufbau. These high and relatively long-acting temperatures can damage sensitive components or materials. Furthermore, it is complicated due to the differences in the thermal expansion coefficients, various substrates, such as silicon, metals, ceramics or polymers to connect dense over a large area.

On the other hand, it becomes increasingly difficult to connect complex products and their cases automatically, reliably and tightly. In addition to temperature-sensitive sensors, there are always shaded joints that are not easily accessible with welding and soldering tools.

For this reason, in recent years research has been increasingly focused on technologies that allow selective energy input only at the required joint on square-micron-sized surfaces.

Thus, methods have been developed that use a local source of energy that allows the energy to act directly on the connection. For example, reactive powders are used which produce a self-propagating reaction, but which is difficult to control and to control. In addition, there are in the prior art reactive multilayer systems consisting of a plurality of thin, alternating layers, which allow by their reaction properties, a control of very high but briefly released thermal energy. In such processes, the preparation is laborious and structuring complicated, which makes such processes relatively complex and expensive. For example, the DE 10 2009 006 822 A1 a method for producing a microstructure with at least one bond substrate and a reactive multilayer system.

The documents US Pat. No. 7,064,004 B2 and US Pat. No. 7,332,411 B2 describe the bonding of substrates by means of metallic solder balls or metallic frame structures, wherein eddy currents are generated in the metal used by generating a time-varying electromagnetic field by means of a coil (induction) and the temperature of the metal increases by Joule heat. However, it has been found that with the methods described therein, the heating of the metal is not sufficiently homogeneous, whereby local overheating may occur.

In the publication DE 10 2006 034 600 A1 For example, a method of making a solder joint will be described. Two soldering partners are provided, which are to be connected to each other at a predetermined joint. Further, a metallic intermediate plate and a soldering device with an inductor are provided. By the inductor eddy currents are generated in the intermediate plate, as a result of which the intermediate plate is heated, so that the standing in thermal contact with this solder melts. The heating of the solder and the soldering partners is thus not directly by the inductor, but indirectly via the intermediate plate heated by the inductor. Consequently, the heat input into the solder is realized by said intermediate plate via heat conduction.

The invention aims to overcome at least one or more problems of the prior art. This object is achieved by a method for heating a plurality of electrically conductive structures according to the main claim and an apparatus for use in said method according to the independent claim. Further developments are described by the following description and the dependent claims.

• Bereitstellen eines ersten Induktors mit einer Vielzahl von nebeneinander angeordneten Induktorelementen, wobei jedes Induktorelement mindestens einen ersten Verbindungsabschnitt und mindestens zwei Schenkel aufweist, wobei der erste Verbindungsabschnitt die beiden Schenkel des Induktorelements miteinander verbindet, und wobei die Induktorelemente miteinander durch zweite Verbindungsabschnitte in Serie verbunden sind,
• Anordnen des ersten Induktors oberhalb oder unterhalb des ersten Substrats, derart, dass
• jedes Induktorelement jeweils zumindest bereichsweise mit einem Rand mindestens einer elektrisch leitfähigen Struktur überlappt und/oder
• jedes Induktorelement zumindest bereichsweise parallel zu dem Rand der elektrisch leitfähigen Struktur verläuft,
• Beaufschlagen des ersten Induktors mit einem Wechselstrom und/oder Anlegen einer Wechselspannung an den ersten Induktor und
• Induzieren von Wirbelströmen in den elektrisch leitfähigen Strukturen.

The method for heating a plurality of electrically conductive structures, which are arranged on an electrically non-conductive first substrate, comprises the following steps:

• Providing a first inductor having a plurality of inductor elements arranged side by side, each inductor element having at least a first connection section and at least two legs, the first connection section connecting the two legs of the inductor element, and wherein the inductor elements are connected to each other in series by second connection sections,
• Arranging the first inductor above or below the first substrate such that
• each inductor element at least partially overlaps with an edge of at least one electrically conductive structure and / or
• each inductor element extends at least in regions parallel to the edge of the electrically conductive structure,
• Energizing the first inductor with an alternating current and / or applying an alternating voltage to the first inductor and
• Inducing eddy currents in the electrically conductive structures.

The inventors have recognized that an adaptation of the inductor shape to the geometry of the electrically conductive structures and a corresponding arrangement of the inductor above and / or below the substrate in accordance with the geometry of the electrically conductive structures allows a particularly homogeneous heating of the electrically conductive structures.

In addition, a further homogenization of the temperature by a partial increase of the inductor elements in z Direction, ie perpendicular to the substrate, and / or be achieved by the partial use of field-guiding elements on the inductor elements.

With the proposed method, the electrically conductive structures can be heated homogeneously. By virtue of the homogeneous heating of the electrically conductive structures, in turn local temperature peaks can be reduced, whereby in particular damage to temperature-sensitive components can be avoided. The described method can preferably be carried out with the device described below.

By applying an alternating voltage or applying an alternating current, the inductor typically generates electromagnetic alternating fields which generate eddy currents in the electrically conductive structures. The eddy currents induced in the electrically conductive structures in turn ensure a temperature increase in the electrically conductive structures. The eddy currents induced in the conductive structures can in particular be induced directly and / or primarily by the magnetic field generated by the inductor.

By heating the electrically conductive structures, a cohesive connection of the electrically conductive structures to the first substrate and / or further components (see below) can be formed. The cohesive connection can z. Example, by soldering, welding, sintering and / or diffusion of the material of the electrically conductive structures in the first substrate or the respective other components. In one variant, the electrically conductive structures are at least partially melted by the eddy currents induced in the electrically conductive structures. As a rule, the electrically conductive structures are heated exclusively or at least primarily by the eddy currents induced in the electrically conductive structures.

In a variant of the method, only electrically non-conductive elements are arranged between the inductor and the electrically conductive structures. For example, no electrically conductive elements are arranged between the inductor and the electrically conductive structures. Thus, the electric conductive structures not shielded, whereby the heating of the electrically conductive structures is more effective.

The terms "electrically conductive" and "electrically non-conductive" in the sense of the present specification mean that the first substrate has an electrical conductivity that is at least fifty times or a hundred times or a thousand times smaller than the electrical conductivity of the electrically conductive structures. The conductivity of the first substrate should be less than 2 * 10 ⁴ S / m (corresponds to the conductivity of highly doped silicon), z. B. less than 100 S / m or less than 10 S / m or less than 1 S / m, so that no or only a few eddy currents are induced in the first substrate.

The material of the first substrate may, for. Silicon, glass, ceramic, FR4. FR4 denotes a class of flame retardant and flame retardant composites comprising or consisting of epoxy resin and glass fiber fabric. The first substrate may be made of a semiconductor material. The semiconductor material should be low doped to keep the conductivity of the first substrate low, i. significantly smaller than the electrical conductivity of the electrically conductive structures.

The electrically conductive structures may in particular be metallic. As metals come z. As aluminum, silver, copper, gold, tin, nickel, or an alloy of at least one of these metals in question. Furthermore, materials which are used for soldered joints (eg tin-silver) are suitable. The electrically conductive structures usually touch the first substrate and are thus arranged directly on the first substrate.

In a further development, each inductor element extends in the region of the overlap with the electrically conductive structure parallel to the edge of the electrically conductive structure. This further contributes to a homogeneous heating of the electrically conductive structure.

The edge of the structure can be considered as the outer boundary of the structure. A dimension of the edge of the electrically conductive structure, for example a ridge width, may in one spatial direction comprise up to 50% or 40% or 30% or 20% or 10% of the dimension of the structure in this spatial direction. For example, a dimension of a left-hand edge and / or a dimension of a right-hand edge of the structure each comprise at most 50%, or 40% or 30% or 20% or 10% of the dimension of the structure in the selected spatial direction.

In one embodiment, the first inductor comprises a first group and a second group of inductor elements arranged side by side. The first group and the second group may be connected in parallel with each other.

In one embodiment, the first inductor comprises a first group. In addition, there are a number n further groups of inductor elements arranged side by side. The number n can be a positive integer greater than or equal to one. The first group and the further group (s) may be connected in parallel with each other.

The inductor elements can together form a conductor loop. The conductor loop surrounds an inner region of the conductor loop, wherein an outer region of the conductor loop lies outside the conductor loop. Preferably, the first inductor is arranged such that all electrically conductive structures to be heated lie within a projection of the inner region onto the substrate or within a projection of the outer region onto the substrate. By means of this design of the method, a degree of homogenization of the heating of the electrically conductive structures can be increased.

Typically, field strength and flux density of the electromagnetic field induced by the first inductor are greater in the inner region of the conductor loop than in the outer region of the conductor loop. For an effective heating of the electrically conductive structures, it is thus advantageous if the electrically conductive structures to be heated lie within the projection of the inner region on the substrate.

As a rule, a number of the electrically conductive structures on the first substrate may be at least 10, 20, 50, 100, 200, 500 or even more than 1000. The electrically conductive structures are usually arranged at regular intervals on the first substrate.

The edge of the electrically conductive structures may, for. B. each circular, rectangular or cuboid. Further, depending on the application, the electrically conductive structures may be annular, frame-shaped, plate-shaped or disk-shaped.

It can be provided that each electrically conductive structure has a plurality, for. B. 2, 3, 4, 5, or 6 comprises interconnected webs. The webs may be arranged like a frame. The webs may each have a straight or curved course. Said edge may be formed by the webs.

To improve the generation of the eddy currents and thus the heating, the electrically conductive structures can be connected to each other via electrically conductive connecting bridges or be. The electrically conductive connection bridges can, for. B. may be arranged on the first substrate.

The electrically conductive structures can each form a closed conductor loop. The eddy currents induced by the first inductor can be formed particularly well in such a conductor loop. In addition, such a closed conductor loop can be used for encapsulation of a structure to be encapsulated (see below). The closed conductor loop can z. B. be frame-shaped or ring-shaped (see above). Said edge can be formed by the closed conductor loop.

Functional elements or microsystems may be arranged on the first substrate which are smaller in their lateral dimensions than the electrically conductive structures to be heated. For example, the functional elements may have dimensions that are at most 50%, 40%, 30%, 20% or 10% of a lateral or lateral extent of the electrically conductive structures.

A winding width typically includes two leg widths and a leg spacing of two adjacent legs of an inductor element. The winding width can be at most as large as the sum of two lateral extensions of the electrically conductive structures and a lateral / lateral spacing of the electrically conductive structures. The functional elements or microsystems can z. B. may be disposed within the closed conductor loop on the first substrate. In terms of their lateral dimensions, the functional elements or microsystems are usually smaller than the winding width of the inductor elements. Typically, the functional elements have dimensions that are at most 50%, 40%, 30%, 20% or 10% of a closed conductor loop width.

In one embodiment, a leg width (width of a leg) is at most as large as an extension of the electrically conductive structures in a spatial direction, for. B. in the lateral direction. For example, a leg width corresponds to a width of the webs of the electrically conductive structure.

The frequency of the alternating current and / or the alternating voltage should be chosen so that eddy currents are generated in the electrically conductive structures, whereby heat is generated. In this case, if the dimensions of the structures to be heated are reduced, ever higher frequencies are advantageous in order to ensure effective heating of the structures.

Depending on the dimensions of the electrically conductive structures, the alternating current or the alternating voltage z. B. have a frequency of at least 100 kHz, 200 kHz, 500 kHz or 1000 kHz. Furthermore, the frequency of the alternating current or the frequency of the alternating voltage may be at most 15 GHz, 1 GHz, 500 MHz, 200 MHz, 100 MHz, 50 MHz, 20 MHz or 10 MHz.

The current in the inductor can z. B. greater than 10 A, 20 A, 50 A or 100 A. In addition, the current z. B. less than 1000 A, 750 A, 500 A or 200 A. The voltage applied to the first inductor voltage may, for. B. greater than 10 V, 20 V, 50 V, 100 V, 150 V, 200 V or 300 V. In addition, the voltage may be less than 1500V, 1000V, 800V or 600V.

The duration of the energization of the first inductor may be at least 0.01 s, 0.1 s, 0.5 s or 1 s. A maximum duration of the energization of the first inductor can be at most 60 s, 45 s, 30 s or 15 s. In some embodiments, the duration of the energization is 30 to 60 minutes.

The inductor elements may be formed by hollow tubes, whereby a cooling fluid, such as. As water flows. The cooling fluid can cool the inductor elements from the inside. However, the inductor elements can also be cooled by the cooling medium from the outside or passively cooled by heat conduction.

It can be provided that the first inductor is connected to a power source, which operates as an AC power source and / or AC voltage source.

Usually, the first inductor is arranged such that the inductor elements each extend along a complete longitudinal direction of at least one electrically conductive structure. In other words, the respective inductor element can run along the entire length of the electrically conductive structure. This makes it possible to make the heating of the structures more homogeneous and effective.

Since the shape of the inductor and the arrangement of the inductor with respect to the substrate are adapted to the geometry of the electrically conductive structures, the inductor should be with respect to the substrate during the loading of the first inductor with an alternating current and / or the application of an alternating voltage do not move to the inductor.

• Bereitstellen eines zweiten Substrats.

The method may additionally comprise the following step:

• Providing a second substrate.

The first substrate and the second substrate may be identical or different. For example, the second substrate may be provided with or without electrically conductive structures. The first substrate and / or the second substrate may, for. B. be formed as a wafer or as a chip. In the case where both substrates are wafers, the method preferably includes the step of wafer bonding. In the case where at least one substrate is a chip, the method preferably includes the step of chip bonding. The first substrate and / or the second substrate may predominantly, for. B. at least 80%, or be made entirely of silicon, glass, ceramics, plastics, FR4 or the like. For the features of the second substrate, reference may be made to the above description of the features of the first substrate.

• vor dem Schritt des Anordnens des Induktors oberhalb oder unterhalb des ersten Substrats: Ausrichten des zweiten Substrats in Bezug auf das erste Substrat. Beispielsweise können die elektrisch leitfähigen Strukturen des ersten Substrats und des zweiten Substrats miteinander in Kontakt gebracht werden. Das zweite Substrat kann derart angeordnet werden, dass das zweite Substrat die elektrisch leitfähigen Strukturen des ersten Substrats berührt. Nach dem Schritt des Ausrichtens können das erste Substrat und das zweite Substrat aneinander befestigt, gepresst oder geklammert werden, z. B. mittels Klemmen oder Klammern (Clamps).

The method may additionally comprise the following step:

• before the step of placing the inductor above or below the first substrate: aligning the second substrate with respect to the first substrate. For example, the electrically conductive structures of the first substrate and the second substrate may be brought into contact with each other. The second substrate may be arranged such that the second substrate contacts the electrically conductive structures of the first substrate. After the alignment step, the first substrate and the second substrate may be attached, pressed or stapled together, e.g. B. by means of clamps or clamps (Clamps).

Subsequently, the first inductor can be arranged as described above. As a result of the heating of the electrically conductive structures, a cohesive connection of the first substrate to the second substrate can take place by means of the electrically conductive structures. The cohesive connection can z. Example, by soldering, welding, sintering and / or diffusion of the material of the electrically conductive structures in the second substrate. The electrically conductive structures are in particular at least partially melted by the eddy currents induced in the electrically conductive structures, whereby the second substrate can be connected to the first substrate.

At least one microsystem to be encapsulated may be encapsulated by at least one electrically conductive structure, the first substrate and the second substrate. Typically, the microsystem is hermetically, e.g. B. airtight or waterproof, encapsulated. The microsystems to be encapsulated z. As integrated circuits (IC), micro-electro-mechanical systems (MEMS), micro-opto-electro-mechanical systems (MOEMS), microprocessors or microcontroller.

• Anordnen eines zweiten Induktors unterhalb oder oberhalb des ersten Substrats,
• wobei der zweite Induktor in Bezug auf den ersten Induktor auf der gegenüberliegenden Seite vom ersten Substrat angeordnet wird, und der zweite Induktor in Bezug auf den ersten Induktor parallel oder um 90° oder 180° gedreht ausgerichtet wird.

The method may have further steps:

• Arranging a second inductor below or above the first substrate,
• wherein the second inductor is positioned with respect to the first inductor on the opposite side of the first substrate, and the second inductor is aligned parallel or rotated 90 ° or 180 ° with respect to the first inductor.

• Anordnen eines zweiten Induktors unterhalb oder oberhalb des zweiten Substrats,
• wobei der zweite Induktor in Bezug auf den ersten Induktor auf der gegenüberliegenden Seite vom zweiten Substrat angeordnet wird, und der zweite Induktor in Bezug auf den ersten Induktor parallel oder um 90° oder 180° gedreht ausgerichtet wird.

The method may have further steps:

• Arranging a second inductor below or above the second substrate,
• wherein the second inductor is disposed opposite the second substrate with respect to the first inductor, and the second inductor is aligned parallel or rotated 90 ° or 180 ° with respect to the first inductor.

The first inductor and the second inductor may be different or identical. For the features of the second inductor, reference is made to the above and below description of the first inductor.

The voltages and currents used for the two inductors should be matched to each other or synchronized with each other.

Further, an apparatus for use in the above-mentioned method is proposed. The device has at least one first inductor. The first inductor comprises a multiplicity of inductor elements arranged side by side, wherein each inductor element has at least one first connecting section and at least two legs. The first connecting portion connects the two legs of the inductor element with each other. In addition, the inductor elements are connected to each other by second connecting portions in series.

In one embodiment, the inductor elements are arranged in meandering fashion. The first inductor can thus have a meandering shape.

The legs can be arranged in a plane. The legs usually extend substantially in a longitudinal direction. A lateral direction is perpendicular to the longitudinal direction. It can be provided that adjacent legs of adjacent inductor elements and / or adjacent legs of an inductor element in the longitudinal direction are substantially parallel to one another. For example, the longitudinal directions of the legs of each inductor element are substantially parallel to one another.

As a rule, a projection of the legs of each inductor element on the substrate in the lateral direction includes at most two electrically conductive structures to be heated, preferably an electrically conductive structure to be heated. For example, a projection of the legs of each inductor element on the substrate in the lateral direction includes at most two rows of electrically conductive structures to be heated, preferably one row. If the inductor element has more than two legs, closing a projection of the outer legs of the inductor element on the substrate z. B. in the lateral direction at most two to be heated, electrically conductive structures, preferably an electrically conductive structure to be heated. If the inductor element has more than two legs, closing a projection of the outer legs of the inductor element on the substrate z. B. in the lateral direction at most two rows to be heated, electrically conductive structures, preferably a number to be heated electrically conductive structures. A series of electrically conductive structures to be heated typically includes an array of at least two electrically conductive structures arranged along a line, such as a line. B. a spatial direction, are aligned, for. B. in the longitudinal direction, transverse direction, x Direction or in y direction.

A leg width may be smaller than an extension of a to be heated, electrically conductive structure in a spatial direction, for. B. in the lateral direction, his. Depending on the design of the structures to be heated, the leg width can optionally be constant or variable in the longitudinal direction of the leg.

In one embodiment, a leg distance defines a maximum distance in the lateral direction between the two legs of an inductor element. The leg distance between two adjacent legs can be constant. The leg spacing may be constant in each inductor element. Further, the leg spacing in each inductor element may be the same. Alternatively, it may be provided that there are at least two inductor elements which have a different leg spacing. The leg spacing within an inductor element may be greater than the leg spacing between two adjacent inductor elements.

The first connecting portion and / or the second connecting portion may be formed as arcuate portions, for. As arcuate or straight sections, be formed. With the high voltage used, voltage flashovers can be avoided.

It can be provided that at least one inductor element has more than two legs, which are connected by means of a plurality of first connecting portions with each other in series, wherein the number of Leg of the inductor an even number 2n is, and the number of first connection sections 2n-1 is.

Typically, the legs are formed substantially straight in the longitudinal direction. A leg cross section may be round, oval, square or rectangular.

The device may comprise an electrical energy source. Further, the apparatus may include an AC power source for supplying the first inductor with an AC current or an AC power source for applying an AC voltage to the first inductor. The AC power source or the AC voltage source may be configured such that the AC or the AC voltage have a frequency of at least 100 kHz and / or at most 15 GHz. The frequency of the alternating current or the alternating voltage can be constant or vary here. The first inductor, and, if provided, other inductors, may or may be connected by leads to the AC source or AC source.

The device may comprise a second inductor aligned parallel or at an angle of 90 ° or 180 ° to the first inductor. The second inductor and the first inductor may optionally be identical or different. For the features of the second inductor, reference is made to the above description of the first inductor. The second inductor may be connected to said electrical energy source. Alternatively, a second electrical energy source for the second inductor may also be present.

Usually, a control device is provided, which controls the electrical energy source or the electrical energy sources.

A temperature sensor may be provided which is designed to measure a temperature of the electrically conductive structures and / or the first substrate and / or the second substrate. The temperature sensor is preferably connected to the control device. The control device may be configured to evaluate measured values or data provided by the temperature sensor. If the temperature measured by the temperature sensor of said components exceeds a limit, the energization of the first inductor and / or the second inductor can be switched off. It is also possible to measure the temperature of different regions of the electrically conductive structures and / or the first substrate and / or the second substrate. If a temperature gradient exceeds a predetermined value, the energization of the inductor can be switched off. The control device may also set or determine a current duration of the first inductor and / or the second inductor. The control device may, for. B. be a processor. Furthermore, a storage medium can be present in that, for example, voltage values, current values, alternating current frequencies, alternating voltage frequencies, energization periods, temperature profiles and / or temperature gradients of known material combinations can be stored. The storage medium is preferably connected to the control device.

The device described can be used in particular in the method described above for heating a plurality of electrically conductive structures.

It should be emphasized at this point that features which have been mentioned only in relation to the device can also be claimed for the said method and vice versa.

• 1 eine Aufsicht auf ein Substrat mit einer Vielzahl von elektrisch leitfähigen Strukturen und Funktionselementen;
• 2 Detail X der 1;
• 3 eine Aufsicht auf zwei verschiedene elektrisch leitfähige Strukturen;
• 4 ein Teil einer Seitenansicht auf das Substrat der 1;
• 5 eine Seitenansicht einer Konfiguration von zwei Substraten, welche mittels elektrisch leitfähiger Strukturen miteinander verbunden sind;
• 6 eine weitere Ausführungsform eines Substrats mit Rahmen, elektrisch leitfähigen Strukturen sowie elektrisch leitfähigen Verbindungsbrücken in der Aufsicht;
• 7 eine weitere Ausführungsform eines Substrats mit elektrisch leitfähigen Strukturen und elektrisch leitfähigen Verbindungsbrücken in der Aufsicht;
• 8 eine Aufsicht auf einen mäanderförmigen Induktor;
• 9 eine Aufsicht auf mehrere parallelgeschaltete mäanderförmige Induktoren;
• 10 eine Anordnung eines Induktors und eines Substrats gemäß einer Ausführungsform;
• 11 eine Anordnung eines Induktors und eines Substrats gemäß einer weiteren Ausführungsform;
• 12 eine Anordnung eines Induktors und eines Substrats gemäß einer weiteren Ausführungsform;
• 13 eine Anordnung eines Induktors und eines Substrats gemäß einer weiteren Ausführungsform;
• 14 eine Anordnung eines Induktors und eines Substrats gemäß einer weiteren Ausführungsform;
• 15 eine Anordnung eines Induktors und eines Substrats gemäß einem Vergleichsbeispiel;
• 16 eine Anordnung eines Induktors und eines Substrats gemäß einem Vergleichsbeispiel;
• 17 eine Anordnung eines Induktors und eines Substrats gemäß einem Vergleichsbeispiel; und
• 18 eine Anordnung eines Induktors und eines Substrats gemäß einem Vergleichsbeispiel.

The invention will be explained with reference to the accompanying figures. In the figures shows

• 1 a plan view of a substrate having a plurality of electrically conductive structures and functional elements;
• 2 detail X of the 1 ;
• 3 a plan view of two different electrically conductive structures;
• 4 Part of a side view of the substrate 1 ;
• 5 a side view of a configuration of two substrates, which are interconnected by means of electrically conductive structures;
• 6 a further embodiment of a substrate with frame, electrically conductive structures and electrically conductive connecting bridges in the plan view;
• 7 a further embodiment of a substrate having electrically conductive structures and electrically conductive connection bridges in the plan view;
• 8th a plan view of a meandering inductor;
• 9 a view of several parallel meandering inductors;
• 10 an arrangement of an inductor and a substrate according to an embodiment;
• 11 an arrangement of an inductor and a substrate according to another embodiment;
• 12 an arrangement of an inductor and a substrate according to another embodiment;
• 13 an arrangement of an inductor and a substrate according to another embodiment;
• 14 an arrangement of an inductor and a substrate according to another embodiment;
• 15 an arrangement of an inductor and a substrate according to a comparative example;
• 16 an arrangement of an inductor and a substrate according to a comparative example;
• 17 an arrangement of an inductor and a substrate according to a comparative example; and
• 18 an arrangement of an inductor and a substrate according to a comparative example.

In the figures, recurring features are given the same reference numerals.

Before discussing the method according to the invention, the structures and devices used in the method will first be explained.

The 1 shows a plan view of a substrate 1 with a variety of electrically conductive structures 2 , which at regular intervals 99 on the substrate 1 are arranged. The 2 shows a section here X of the 1 ,

The production of electrically conductive structures 2 . 4 on the substrate 1 takes place for. B. by physical vapor deposition (PVD) and photolithographic structuring. Such a procedure is familiar to the person skilled in the art; alternative method for applying the electrically conductive structures 2 . 4 on the substrate 1 are also possible. The electrically conductive structures 2 . 4 (hereinafter also "structures" 2 called) are so cohesively with the substrate 1 connected.

In the embodiment of 1 are 37 structures 2 on the substrate 1 arranged. The number of structures can be higher or lower as needed. So z. B. 10, 100, 200, 500, 1000 or even more structures 2 on the substrate 1 be arranged. The structures 2 comprise four interconnected webs 97 , which are arranged in a frame shape. The edge 5 a structure 2 is z. Square ( 2 ) or rectangular ( 3 Left). The square structures 2 have dimensions of 15 mm × 15 mm (y-direction or x-direction). The bridges 97 have a width b of 3 mm and a height H (in the z-direction) of 1.5 microns (see. 4 ). In the 4 is a part of a side view of the substrate 1 of the 1 shown. For a better view, the height H the structures 2 Enlarged in z-direction. The width b and height H may be much smaller in other embodiments. So the webs can be a width b of 0.5 mm or smaller and have a height of 0.2 μm or smaller.

The structures 2 are preferably metallic and can be formed, for example, from aluminum, silver, copper, gold, tin, lead, or an alloy of at least one of the above metals. The bridges 97 the structure 2 thus each form a closed electrical conductor loop.

The substrate 1 is in the embodiment shown, a wafer made of a semiconductor material, such as. B. silicon. The substrate has an electrical conductivity at least fifty times smaller than that of the structures 2 ,

It is also on the substrate 1 a variety of microsystems 3 which may be implemented as integrated circuits, integrated circuits, microprocessors, microelectromechanical systems (MEMS), microcontrollers or sensors. The microsystems 3 are each within the frame shape of the electrically conductive structure 2 positioned. The microsystems 3 be in the process below by the substrate 1 , the structures 2 and another substrate 100 encapsulated. The microsystems 3 can be a set of different functional elements 22 exhibit. The dimensions of the functional elements 22 the microsystems 3 are usually smaller than the width b of the electrically conductive structures 2 , For example, the dimensions of the functional elements are at most 10% of the width b the structures 2 ,

The 5 shows a side view of a configuration of two substrates 1 and 100 , which by means of electrically conductive structures 2 connected to each other. The substrates 1 . 100 and the structures 2 enclose the microsystems 3 , By separating the substrates 1 . 100 can be a variety of separate encapsulated microsystems 3 to be obtained.

The 6 and 7 show two further embodiments of substrates 1 on which electrically conductive structures 2 are arranged. The electrically conductive structures 2 . 4 of the 6 and 7 are interconnected via electrically conductive connection bridges 23 connected. The electrically conductive connection bridges 23 are also on the substrate 1 arranged.

The 3 shows a plan view of two alternative electrically conductive structures 2 . 4 , Unlike the structures 2 of the 1 . 2 and 3 left, are the electrically conductive structures 4 of the 3 right and 7 not frame-shaped but flat. So you have in particular no central opening. The structures 4 can z. B. be referred to as "pads".

Below are various inductors 6 for heating the structures 2 . 4 described in more detail.

The 8th to 14 show various embodiments of inductors 6 , For better intuition are in the 10 . 11 . 12 and 14 slice AA the respective 10 . 11 . 12 respectively. 14 displayed.

By applying an alternating voltage or applying an alternating current, the inductors 6 generate electromagnetic fields, which in turn with appropriate arrangement of the inductors 6 Eddy currents in the electrically conductive structures 2 . 4 to generate. As the inductor material, various electrically conductive materials (usually metals such as copper, aluminum, silver or their alloys) may be used.

The manufacture of the inductor 6 can be done by forming (bending), cutting (milling, laser cutting, water jet cutting, shear cutting, eroding), prototyping (3D printing / selective laser sintering, casting) or coating (Aerosoljet, screen printing, galvanic). The inductor 6 can be actively cooled, passively cooled or uncooled. A cooling of the inductor 6 can be done using heat transfer fluids or gases (eg cooling water, compressed air). The cooling can be integrated internally cooled (eg inductor as a hollow tube) or externally cooled (eg inductor enclosed by cooling water).

The in the 8-14 shown inductor 6 has a plurality of juxtaposed inductor elements 30 on. Each inductor element 30 has at least one (first) connection section 31 and at least two thighs 32 on, wherein the (first) connecting section 31 the two thighs 32 connects with each other. The inductor elements 30 are connected to each other via second connecting sections 33 connected in series. inductor 30 Together they form a conductor loop that forms an interior area 7 and an outdoor area 8th having. Typically, electromagnetic field strength and flux density of the inductor 6 caused electromagnetic field or river indoors 7 of the inductor 6 bigger than outdoors 8th of the inductor 6 ,

The thigh 32 the inductor elements 30 are arranged in a plane parallel to the substrate 1 is (see below). The thigh 32 are along a longitudinal direction y essentially straight and run parallel to each other. A lateral direction x stands here perpendicular to the longitudinal direction y , The connecting sections 31 and 33 are arcuate, so that the inductor 6 or the inductor elements 30 has or have a meandering structure as a whole.

As in the cuts AA of the 10 . 11 . 12 and 14 it can be seen, have the thighs 32 the inductor elements 30 a square cross section. Alternatively, the cross section of the legs 32 z. B. also oval, round or rectangular.

The thigh 32 each individual inductor element 30 of the 8th . 9 . 10 . 11 and 14 have a constant and equal leg distance 9 . 13 in x Direction / lateral direction x to each other. One turn width 98 is typically composed of two leg widths 11 . 15 and a leg distance 9 . 13 , In the 10 corresponds to the winding width 98 about a lateral extent an electrically conductive structure 2 , In the 11 is the winding width 98 as large as two lateral extensions of the structures 2 and a distance 99 between the structures 2 ,

In the 12 and 13 is a leg distance ( 12 : Thigh distance 19 . 20 ) within a single inductor element 30 while constant and equal; however, the leg spacing is in the various inductor elements 30 differently. There are thus at least two inductor elements 30 that have a different thigh distance 19 . 20 exhibit.

In the 12 There are several inductor elements 30 , each with more than two legs 32 exhibit. Here are in the 12 sections 16 and 17 shown in addition to the outer thighs 32 the inductor elements 30 another two or four legs 32 indoor 7 exhibit. Next are in the section 18 two additional thighs 32 outside 8th shown. The number of thighs 32 the respective inductor element 30 this is an even number 2n wherein the number of the first connecting sections 2n - 1 is. This ensures that the current direction in the inductor 6 not vice versa.

The thigh 32 of the 8-14 have a constant leg width 11 . 15 . 21 , Alternatively, the leg width 11 . 15 . 21 also along the longitudinal direction y the thigh 32 vary. The thigh width 11 . 15 . 21 corresponds to a web width b of the bridges 97 of the electrically conductive structures 2 , The leg width is thus smaller than half the sum of the dimensions of the structures 2 and the structure distance 99 in the lateral direction x ,

From the 8th to 14 shows that a projection of the thighs 32 each inductor element 31 on the substrate 1 in the lateral direction x at most two to be heated, electrically conductive structures 2 includes.

A leg distance or distance between adjacent inductor elements 30 is also constant and in the 8th . 9 . 10 and 14 with the reference numerals 10 and 14 characterized.

The embodiment of the in the 13 shown inductor 6 is a mixed form of the inductors of the embodiments of 10 and 11 , Other mixed forms are also possible.

The Indian 9 shown inductor 6 thus differs from the in the 8th . 10-14 shown inductors, as the inductor 6 three groups 36 . 37 . 38 of inductor elements 30 having, where the groups 36 . 37 . 38 are connected in parallel to each other. There may be two groups or more than three groups.

The inductor 6 from the 8-14 is via supply lines 34 with an electrical energy source 35 connected, wherein the electrical energy source 35 may be an AC power source or an AC power source. The electrical energy source is designed to be an alternating voltage or an alternating current for the inductor 6 provide. A frequency of the AC voltage or AC is dependent on the particular application and can, for. B. at least 100 kHz and / or at most 15 MHz. The electrical energy source 35 can supply a voltage of about 100 to 900 V to the inductor 6 invest. The through the inductor 6 flowing electricity has a current of about 300 - 500 A.

A control device, not shown, is provided, which is formed, the electrical energy source 35 head for. Optionally, a temperature sensor may be provided which is configured, a temperature of the electrically conductive structures 2 and / or the first substrate 1 and / or the second substrate 100 to measure. The temperature sensor is connected to the control device, wherein the control device is configured to evaluate measured values or data of the temperature sensor. In addition, a storage medium connected to the control device is provided, in which voltage profiles, current characteristics, AC frequencies, AC voltage frequencies, energization periods and / or temperature profiles of previously known material combinations are stored.

The in the 1-7 shown electrically conductive structures 2 can be preferably by means of in the 8-14 shown inductors 6 heat.

For this purpose, the inductor 6 initially above or below the substrate 1 arranged, s. 10-14 , The inductor 6 is arranged such that each inductor element 30 each with an edge of at least one electrically conductive structure 2 overlaps. Next is the inductor 6 arranged so that the respective inductor element 30 parallel to the edge of the electrically conductive structure 2 runs. Here, each runs inductor 30 , especially the thighs 32 , preferably in the region of the overlap parallel to the edge of the respective electrically conductive structure 2 , The inductor elements 30 , especially the thighs 32 , each can be along a complete length in the longitudinal direction y the electrically conductive structure 2 extend.

After arranging the inductor 6 above or below the substrate 1 becomes the inductor 6 with an alternating current by means of the electrical energy source 35 applied. Alternatively or additionally, an alternating voltage is applied to the inductor 6 by means of the electric energy source 35 created. As a result, eddy currents in the electrically conductive structures 2 generated. The eddy currents are typically directly through the alternating magnetic field of the inductor 6 in the electrically conductive structures 2 induced. The eddy currents heat the electrically conductive structures 2 according to the first law of Joule. The frequency of the alternating current and / or the alternating voltage are matched to the dimensions of the electrically conductive structures, so that the generation of eddy currents is as effective and efficient.

As the electrically conductive structures to be heated 2 within the projection of the interior 7 on the substrate 1 can be heated more strongly than within the projection of the exterior 8th on the substrate 1 , becomes the inductor 6 arranged so that the electrically conductive structures 2 within the projection of the interior 7 on the substrate 1 lie (cf. 10-14 ).

Because the shape and the spatial arrangement of the inductor 6 in relation to the substrate 1 to the geometry and arrangement of the electrically conductive structures 2 on the substrate 1 adjusted, the inductor should be 6 in relation to the substrate 1 during inducing the eddy currents in the electrically conductive structures 2 and the heating of the electrically conductive structures 2 dont move.

The substrate 1 can be due to the heating of the electrically conductive structures 2 with another substrate 100 be connected, see eg. 5 , For details, the expert takes z. B. the publication US Pat. No. 7,332,411 B2 , which is made by referencing fully incorporated into the present application.

The first substrate 1 and the second substrate 100 can be identical or different. For example, the second substrate 100 with or without electrically conductive structures 2 be provided. While the first substrate 1 usually formed as a wafer or printed circuit board, the second substrate 100 z. As a glass or even a wafer or a printed circuit board. The invention is not limited to a particular form of the substrates 1 . 100 limited. For the features of the second substrate 100 Incidentally, the above description of the features of the first substrate 1 to get expelled.

Before the step of placing the inductor 6 above or below the first substrate 1 becomes the second substrate 100 with respect to the first substrate 1 aligned. The expert speaks here of bond alignment. For example, the electrically conductive structures 2 of the first substrate 1 and the second substrate 100 , if present, are positioned one on top of the other. The second substrate 100 can be arranged such that the second substrate 100 the electrically conductive structures 2 of the first substrate 1 touched, s. 5 , After the alignment step, the first substrate may be 1 and the second substrate 100 attached, pressed or stapled together, e.g. B. by means of clamps.

After that, the inductor 6 arranged as described above. By heating or heating of the electrically conductive structures 2 , a cohesive connection of the two substrates 1 . 100 getting produced. So can the electrically conductive structures 2 be melted by the generated temperature increase. The cohesive connection can z. B. by soldering, welding, sintering and / or diffusion.

The above-described method is particularly suitable for the encapsulation of microsystems 3 , By connecting the two substrates 1 . 100 by means of the electrically conductive structures 2 becomes the intermediate microsystem 3 hermetically encapsulated.

In order to increase the efficiency or the homogeneity of the heating, a second inductor can also be used 60 be used, cf. 14 , If the first inductor 6 above the first substrate 1 is arranged, the second inductor 60 below the first substrate 1 arranged. The second inductor 60 can z. B. with respect to the first inductor 6 be aligned parallel or rotated by 90 ° or 180 °. Of the first inductor 6 and the second inductor 60 can be designed differently or identically. For the characteristics of the second inductor 60 Turns to the above description of the first inductor 6 directed.

At this point it should be emphasized that a use of two inductors 6 . 60 with two substrates 1 . 100 is also possible.

In addition to the above embodiments, further homogenization of the temperature of the electrically conductive structures 2 . 4 by a partial increase of the inductor elements 30 in z Direction, ie perpendicular to the substrate 1 . 100 , and / or by the partial use of field-guiding elements over the inductor elements 30 be achieved.

Below are the application examples 1 - 4 compared to each other. The 15 to 18 show arrangements of each of an inductor and a substrate according to the application examples 1 - 4 , In the lower graphs of 15-18 are spatial temperature profiles during the heating of the electrically conductive structures 2 shown.

• ■ Querschnitt der Induktorschenkel: Quadratisch, 4 mm × 4 mm
• ■ Induktormaterial: Cu-ETP
• ■ Herstellung des Induktors: Umformen (Biegen)
• ■ Kühlung des Induktors: innengekühlt mit Wasser
• ■ Material der induktiv zu erwärmende Strukturen: Aluminium, Dicke: 1,5 µm
• ■ Geometrie der zu erwärmenden Strukturen: Rahmen, 15 mm × 15 mm, Stegbreite: 3 mm
• ■ Induktiv nicht zu erwärmendes Substrat: Silizium, ∅ 150 mm, Dicke: 675 µm, p(100), p = 10...20 Ω·cm
• ■ Induktiv nicht zu erwärmende Funktionselemente: keine vorhanden
• ■ Verbindungsbrücken: keine vorhanden
• ■ Generatorparameter: f_Res = 1400 kHz, HF-Spannung: 436 V, HF-Stromstärke: 151 A
• ■ Heizdauer: 3 Sekunden

In Comparative Examples 1-4, the following parameters were used:

• ■ Cross section of the inductor legs: Square, 4 mm × 4 mm
• ■ Inductor material: Cu-ETP
• ■ manufacture of the inductor: forming (bending)
• ■ Cooling of the inductor: internally cooled with water
• ■ Material of the inductively heated structures: aluminum, thickness: 1.5 μm
• ■ Geometry of the structures to be heated: frame, 15 mm × 15 mm, web width: 3 mm
• ■ Indirectly non-heating substrate: silicon, ∅ 150 mm, thickness: 675 μm, p (100), p = 10 ... 20 Ω · cm
• ■ Functional elements not to be heated inductively: none available
• ■ Connecting bridges: none available
• ■ Generator parameters: f _Res = 1400 kHz, RF voltage: 436 V, RF current: 151 A
• ■ Heating time: 3 seconds

The comparative examples differ only in the form of the inductor 6 and the arrangement of the inductor 6 above the substrate 1 ,

In the 15 was a meandering inductor according to the embodiment of 10 selected. It can be seen that the shape and the arrangement of the inductor are adapted to the specific shape of the electrically conductive structures.

The Indian 16 inductor shown is also meandering. The in the 17 and 18 Inductors shown are annular or spiral. The in the 16 to 18 Inductor geometries shown are not adapted to the specific frame-shaped geometry of the electrically conductive structures.

By means of thermography was a temperature of the arrangements of 15-18 measured and in the lower representations of the 15-18 visualized.

The following minimum and maximum temperatures T _min and T _max in ° C were measured: ◯ 15 : _Tmin = 197 ° C; _Tmax = 218 ° C (ΔT = 21 K, ± 5%) ◯ 16 : T _min = 109 ° C; T _max > 300 ° C (ΔT> 191 K, ± 34%) ◯ 17 : T _min = 162 ° C; T _max > 300 ° C (ΔT> 138 K, ± 25%) ◯ 18 : T _min = 60 ° C; _Tmax = 246 ° C (ΔT = 186 K, ± 41%)

The temperature difference between T _max and T _min is here indicated as ΔT in K. While the temperature difference ΔT of the example of 15 is only 21 K, the temperature differences ΔT of the examples are 16-18 significantly larger than 100 K. Consequently, the frame-shaped structures can be replaced by the Inductor the 15 are heated homogeneously (ie, ΔT is, for example, less than 50 K, 40 K or 30 K), while the 16-18 have inhomogeneous temperature profiles of the frame-shaped structures.

LIST OF REFERENCE NUMBERS

1

substratum

2

electrically conductive structures

3

microsystems

4

electrically conductive structures

5

edge

6

first inductor

7

interior

8th

outdoors

9

Leg distance between two legs of an inductor element

10

Leg distance between two adjacent inductor elements

11

leg width

12

Expansion of an electrically conductive structure in x -Direction

13

Leg distance between two legs of an inductor element

14

Leg distance between two adjacent inductor elements

15

leg width

16

inductor

17

inductor

18

inductor

19

Leg distance between two legs of an inductor element

20

Leg distance between two legs of an inductor element

21

leg width

30

inductor

31

first connection section

32

leg

33

second connection section

34

supply

35

electrical energy source

36

Group of inductor elements

37

Group of inductor elements

38

Group of inductor elements

60

second inductor

97

web

98

coil width

99

pattern pitch

100

another substrate

b

Width of the electrically conductive structure

H

Height of the electrically conductive structure

x

lateral direction

y

longitudinal direction

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102009006822 A1 [0006]
• US 7064004 B2 [0007]
• US 7332411 B2 [0007, 0100]
• DE 102006034600 A1 [0008]

Claims (15)

A method of heating a plurality of electrically conductive structures (2, 4) disposed on an electrically non-conductive first substrate (1), comprising the steps of: - Providing a first inductor (6) having a plurality of juxtaposed inductor elements (30), wherein each inductor element at least a first connecting portion (31) and at least two legs (32), wherein the first connecting portion (31), the two legs (32 ) of the inductor element (30), and wherein the inductor elements (30) are connected to each other in series by second connecting sections (33), Arranging the first inductor (6) above or below the first substrate (1) such that o each inductor element (30) at least partially overlaps with an edge (5) of at least one electrically conductive structure (2, 4) and / or o each inductor element extends at least in regions parallel to the edge (5) of the electrically conductive structure (2, 4), - Applying the first inductor (6) with an alternating current or applying an alternating voltage to the first inductor (6) and - Inducing eddy currents in the electrically conductive structures (2, 4). Method according to Claim 1 in which each inductor element (30) extends in the region of the overlap with the electrically conductive structure (2, 4) parallel to the edge of the electrically conductive structure (2, 4). Method according to one of the preceding claims, characterized in that the inductor elements (30) together form a conductor loop and surround an inner region (7) of the conductor loop, wherein an outer region (8) lies outside the conductor loop, and the first inductor is arranged such that all to be heated electrically conductive structures (2, 4) within a projection of the inner region (7) lie on the first substrate (1). Method according to one of the preceding claims, wherein the first inductor (6) is arranged such that the inductor elements (30) each extend along a complete longitudinal direction of at least one electrically conductive structure (2, 4). Method according to one of the preceding claims, wherein the eddy currents induced in the conductive structures (2, 4) are induced directly and / or primarily by the magnetic field generated by the inductor. Apparatus for use in a method according to any one of Claims 1 to 4 comprising said first inductor (6), wherein a projection of the legs (32) of each inductor element (30) on the substrate (1) in the lateral direction includes at most two rows of electrically conductive structures (2, 4) to be heated. Device after Claim 5 , characterized in that the inductor elements (30) are arranged meander-shaped. Device according to one of Claims 5 to 7 , characterized in that the legs (32) are arranged in a plane. Device according to one of Claims 5 to 8th , characterized in that longitudinal directions of the legs of each inductor element are substantially parallel to each other. Device according to one of Claims 5 to 10 , characterized in that a leg width (11, 15, 21) is smaller than a lateral extent of an electrically conductive structure (2, 4) to be heated. Device according to one of Claims 5 to 11 wherein a leg distance (9, 13, 19) defines a maximum distance in the lateral direction between the two legs (32) of an inductor element (30), wherein the leg distance (9) in each inductor element (30) is equal and / or constant. Device according to one of Claims 5 to 12 , wherein a leg distance (9) defines a maximum distance in the lateral direction between the two legs (32) of an inductor element (30), characterized in that there are at least two inductor elements (30) having a different leg distance (9). Device according to one of Claims 5 to 13 , characterized in that the first connecting portion (31) and / or the second connecting portion (33) are formed as arcuate or straight sections. Device according to one of Claims 5 to 13 wherein the first inductor (6) comprises a first group and a second group of juxtaposed inductor elements (36, 37, 38), the first group and the second group being connected in parallel. Device according to one of Claims 5 to 14 characterized by a second inductor (60) aligned parallel or at an angle of 90 ° or 180 ° to the first inductor (6).

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