DE102019108977B4 - Method for connecting two power electronic connection partners - Google Patents

Abstract

A method for connecting a first connection partner to a second connection partner within a power electronics arrangement, the respective connection partner being designed as a power electronics substrate (1) or as a power semiconductor component (2) or as a power electronics connection device (5), with the following method steps: a) Providing the first Connection partner; b) Sequential application in layers of a connection means designed as a sintering paste with metal particles in the form of a connection means arrangement (3) on a first connection surface of a first surface of the first connection partner by means of a print head (6) which can be moved at a distance from the first connection partner and is designed for this purpose selectively from a A plurality of printhead openings (60) in individual dosing processes per printhead opening (60) to dispense in each case individual connector portions (30); multiple repetition of this method step, whereby with each execution of the method step different partial connecting means arrangements are generated, which together produce the connecting means arrangement (3) with a minimum thickness (306) and a maximum thickness (308), and wherein the connecting means arrangement (3) has a three-dimensional surface contour (300); c) arranging the second connection partner in such a way that its second connection surface, at least partially, comes to rest on the connection means arrangement (3); d) forming a material connection.

Description

The invention describes a method for connecting a first connection partner to a second connection partner within a power electronics arrangement.

For the connection of any two connection partners, it is customary in the art to arrange a mostly flat layer of a connection means on one of the connection partners, then to arrange the second connection partner, possibly also subjected to pressure or temperature, and thus to form a material connection. Such connections are generally known in the form of adhesive connections. In particular in the technical field of power electronics, so-called pressure sintered connections are also described by way of example in FIG DE 10 2009 024 371 A1 , known.

From the DE 10 2014 222 819 A1 Furthermore, a power semiconductor contact structure for power semiconductor modules is known which has at least one substrate and a shaped metal body as an electrode, which are sintered onto one another by means of an essentially closed sintered layer with regions of varying thickness. The shaped metal body is in the form of a flexible contacting film with a thickness such that it is essentially completely sintered onto the areas of varying thickness of the sintered layer with its side facing the sintered layer. Furthermore, a method is described for forming a power semiconductor contact structure in a power semiconductor module, which has a substrate and a shaped metal body. The formation of the power semiconductor contact structure is first carried out by applying a layer of sintered material with locally varying thickness to either the metal molding or the substrate, followed by sintering the contacting foil with the substrate via the connection-promoting properties of the sintered material layer, the contacting foil corresponding to the varying thickness of the layer of the Sintered material gets its shape pronounced.

From de U.S. 5,681,757 A A method is known for connecting microchips to integrated semiconductor circuits with adhesive which is deposited by microjets in a precise pattern. A printhead technology similar to that used in inkjet printers is used to apply the adhesive substance (most commonly an epoxy). The use of microjets in an “array print head” to deposit an adhesive pattern is advantageous because it can control the position and size of the adhesive droplets with a high degree of precision. The method also provides for an individual actuation of the microjets, which makes it possible to quickly switch from pattern to pattern without having to change and clean heads and devices or have to provide several heads. The method is used both in standard connection and in the "flip-chip" method using "bumped dies". The high level of precision enables adhesive to be printed between the soldering points of a "bumped die", creating a stronger connection and underfilling without affecting the electrical connection created by the soldering points.

From the DE 10 2017 117 668 B3 a method and an arrangement produced therewith is known, which is formed with a substrate, with a power semiconductor component and an adhesive layer arranged therebetween, the substrate having a first surface facing the power semiconductor component, the power semiconductor component having a third surface facing the substrate, the Adhesive layer has a second surface, which is in, preferably full-area, contact with the third surface and has a first continuous surface contour with a first roughness and wherein a fourth surface of the power semiconductor component, which is opposite the third, has a second surface contour with a second roughness, wherein this second surface contour follows the first surface contour.

From the US 2017/0 309 549 A1 an integrated circuit chip is known which has a plurality of contacts. A metal post can be formed on each of the multiple contacts. A plurality of bumps may be formed on a plurality of contact areas of a leadframe or on the posts in which the plurality of bumps are formed with a material containing metal nanoparticles. The IC chip can be attached to the leadframe by aligning the metal posts on the leadframe and sintering the metal nanoparticles in multiple bumps to form a sintered metal bond between each metal post and the corresponding contact area of the leadframe.

In the essay "Development and Application by Ink-Jet Printing of Advanced Packaging Materials" (DJ Hayes, ME Grove and WR Cox, Proceedings International Symposium on Advanced Packaging Materials. Processes, Properties and Interfaces, IEEE Cat. No.99TH8405, 1999, p. 88 -93. IEEE Xplore [online]. DOI: 10.1109 / isapm.1999.757293 , In: IEEE, high-temperature ink printing processes and custom-made polymer formulations for the production of high-density microelectronic and optoelectronic packaging presented.

With knowledge of the state of the art, the invention is based on the object of presenting a method which allows the greatest possible freedom in the specific configuration of material connections between two power electronic connection partners.

1. a) Bereitstellen des ersten Verbindungspartners;
2. b) Sequentielles schichtweises Aufbringen eines als Sinterpaste mit Metallpartikeln ausgebildeten Verbindungsmittels in Form einer Verbindungsmittelanordnung auf einer ersten Verbindungsfläche einer ersten Oberfläche des ersten Verbindungspartners mittels eines beabstandet vom ersten Verbindungspartner verfahrbaren Druckkopfes, der dazu ausgebildet ist selektiv aus einer Mehrzahl von Druckkopföffnungen in einzelnen Dosierungsvorgängen pro Druckkopföffnung jeweils einzelne Verbindungsmittelportionen abzugeben; diese Verbindungsmittelportionen werden somit matrixartig angeordnet; mehrfaches wiederholen dieses Verfahrensschritts, wobei bei jeder Ausführung des Verfahrensschritts voneinander unterschiedliche Teilverbindungsmittelanordnungen erzeugt werden die gemeinsam die Verbindungsmittelanordnung mit einer minimalen Dicke und einer maximalen Dicke erzeugen und wobei die Verbindungsmittelanordnung eine dreidimensionalen Oberflächenkontur aufweist;
3. c) Anordnen des zweiten Verbindungspartners derart, dass seine zweite Verbindungsfläche, zumindest teilweise, auf der Verbindungsmittelanordnung zu liegen kommt;
4. d) Ausbilden einer stoffschlüssigen Verbindung.

According to the invention, this object is achieved by a method for connecting a first connection partner to a second connection partner within a power electronics arrangement, the respective connection partner being designed as a power electronics substrate or as a power semiconductor component or as a power electronics connection device, with the following method steps:

1. a) providing the first connection partner;
2. b) Sequential layer-by-layer application of a connecting means designed as a sinter paste with metal particles in the form of a connecting means arrangement on a first connecting surface of a first surface of the first connecting partner by means of a printhead which can be moved at a distance from the first connecting partner and which is designed to selectively from a plurality of printhead openings in individual dosing processes per printhead opening to deliver individual lanyard portions; these connector portions are thus arranged like a matrix; repeating this method step several times, with each execution of the method step generating different partial connecting means arrangements which together produce the connecting means arrangement with a minimum thickness and a maximum thickness and wherein the connecting means arrangement has a three-dimensional surface contour;
3. c) arranging the second connection partner in such a way that its second connection surface comes to rest, at least partially, on the connection means arrangement;
4. d) Forming a cohesive connection.

It is advantageous here if the power electronic substrate has a plurality of conductor tracks; the power semiconductor component is designed as a power semiconductor switch; the power electronic connection device is film-based.

Here and in the following, the term “paste” is used in connection with the sintering paste and the soldering paste due to its customary use, although, as described below, the connecting means advantageously has a lower viscosity than is generally known for pastes. The term paste is used here synonymously for suspension.

The sintering paste advantageously has a viscosity of 1 to 50 mPa s, preferably 20 to 40 mPa s.

The mean size of the metal particles of the sintering paste is advantageously between 0.01 and 1 μm, preferably between 0.05 and 0.5 μm. It is also advantageous if the diameter of the respective print head opening is between 20 and 100 times the mean particle size.

It can also be preferred if in process step d) the material connection is formed under the action of heat or mechanical pressure on one of the connection partners or under a combination of both.

Within the scope of the invention, the print head can be displaceable in one or two axes in a plane parallel to the first surface on which the first connecting surface is arranged. Advantageously, the print head can also be moved in a direction normal to the first surface.

It is often preferred if the relative positioning of the connection means arrangement on the first surface of the first connection partner takes place during operation by means of a control device before method step b) is carried out. In particular, method step c) and here the relative position of the second connection partner relative to the first connection partner can be dependent on the position of the connection means arrangement.

It is particularly advantageous if the print head openings of the print head are arranged in a row or in several rows offset from one another and each print head opening can be controlled independently of the others.

The respective connector portion is advantageously between 1 and 100 pl, preferably between 20 and 50 pl.

In principle, the print head can be controlled in such a way that only a defined, non-variable connector portion is dispensed per dosing process.

It can also be advantageous if the print head is heated to a stable operating temperature between 40 and 120 ° C., preferably between 60 and 80 ° C., in the area of the print head openings.

• 1 zeigt zwei Verbindungspartner unmittelbar vor dem Verfahrensschritt c) einer ersten Ausgestaltung des erfindungsgemäßen Verfahrens.
• 2 zeigt den Abschluss des Verfahrensschritts b) der ersten Ausgestaltung des erfindungsgemäßen Verfahrens.
• 3 zeigt den Verfahrensschritt b) einer zweiten Ausgestaltung des erfindungsgemäßen Verfahrens.
• 4 zeigt den Verfahrensschritt b) einer dritten Ausgestaltung des erfindungsgemäßen Verfahrens.
• 5 zeigt den Verfahrensschritt b) einer vierten Ausgestaltung des erfindungsgemäßen Verfahrens.
• 6 zeigt den Abschluss des Verfahrensschritts b) der vierten Ausgestaltung des erfindungsgemäßen Verfahrens.

Further explanations of the invention, advantageous details and features emerge from the following description of the FIGS 1 until 6th schematically illustrated embodiments of the invention, or of respective parts thereof.

• 1 shows two connection partners immediately before method step c) of a first embodiment of the method according to the invention.
• 2 shows the conclusion of method step b) of the first embodiment of the method according to the invention.
• 3 shows method step b) of a second embodiment of the method according to the invention.
• 4th shows method step b) of a third embodiment of the method according to the invention.
• 5 shows method step b) of a fourth embodiment of the method according to the invention.
• 6th shows the conclusion of method step b) of the fourth embodiment of the method according to the invention.

1 shows in cross section two connection partners immediately before method step c) of a first embodiment of the method according to the invention. A customary power electronic substrate is shown here 1 with an insulating body 10 and a conductor track 12th . Such substrates are customary in the art 1 a plurality of mutually electrically insulated conductor tracks arranged.

On this track 12th and a power semiconductor component is connected to it in an electrically conductive manner 2 , here purely by way of example a power diode. This power diode 2 indicates the substrate 1 opposite a surface 220 with a load connection surface. The surface 220 the power diode here forms the first surface of the first connection partner. The load connection area forms the first connection area.

In the context of the method according to the invention and by repeating method step b), cf. 2 , applied a lanyard, which is now called a lanyard arrangement 3 is present. In this embodiment, the connecting means is in the form of a sintering paste with an average size of the metal particles, here more precisely silver particles, of 0.3 μm. This sinter paste usually consists of a solvent in addition to the silver particles.

In the same way, namely the multiple execution of method step b), an adhesive was arranged all the way around the power diode and also covering it in the edge area. This adhesive thus consists of a further connecting means and forms a further connecting means arrangement 4th the end.

The second connection partner is designed here as a conventional film stack 5 of two electrically conductive foils 50, 54 and an electrically insulating foil arranged between them 52 . The two electrically conductive foils 50, 54 are in one section by means of plated-through holes through the electrically insulating foil 52 electrically connected to each other. That of the power diode 2 facing electrically conductive film 50 assigns a section 500 on, the surface of which forms the second connection surface of the second connection partner.

When the next method steps c) and d) are carried out, the second connection surface comes up 500 on the surface facing you 300 the lanyard assembly 3 , here the sinter paste. A sintered connection is then formed in a manner customary in the art. Due to the small mean size of the silver particles, this sintered connection can take place entirely without the usual application of pressure. A temperature application in the purely exemplary temperature range around 120 ° C. is preferred here for the formation of the sintered connection. In principle, an embodiment of the sintering method is not restricted by the inventive method, in particular with regard to the arrangement of the sintering paste.

At the same time as the sintered connection, an adhesive connection is thus formed here between the substrate as the first connection partner and the film stack as the second connection partner. This further connection is made by the adhesive as a further connecting means.

2 shows the conclusion of method step b) of the first embodiment of the method according to the invention. The power semiconductor component is again shown in cross section here 2 , designed as a power diode that forms the first connection partner. On the first interface 220 , here the cathode of the power diode 2 , is the lanyard assembly 3 shown. This was created by applying the connecting means in layers in individual partial connecting means arrangements. The printhead is used for this 6th , see also 3 , here a plurality of printhead openings arranged in a row 60 has multiple over the power diode 2 has been proceeded and has applied the connecting means, in each case sequentially. Are purely schematic here individual lanyard portions 30th shown, the respective volume of which is around 40 pl. In this configuration of the print head 6th the preferred particle size is in the lower single-digit percentage range of the diameter of the printhead opening 60 .

Since, with the sequential application of several layers, the number and position of the connector portions in the direction of travel of the print head 6th can vary, a connecting means arrangement is created 3 with, depending on the viscosity of the sinter paste, which is around 35 mPa s, a three-dimensional surface that is largely arbitrary 300 . The surface contour shown is therefore purely exemplary.

The accuracy and flexibility of the application of the sintering paste as an exemplary connecting means is further increased here by the print head 6th can be moved not only in the xy plane, but also in the z direction, that is, in the normal direction N of the power diode.

3 shows method step b) of a second embodiment of the method according to the invention. A substrate is shown that is basically similar to that shown in FIG 1 , with an insulating body 10 and here two conductor tracks 12th , on which power semiconductor components are to be arranged.

This is done on both conductor tracks 12th , which here forms the first connection partner, a connecting means arranged sequentially in a respective section, which thus forms the first connection surface. This sequential arrangement takes place by means of a print head 6th that has a variety of printhead openings 60 , only a few are shown.

The printhead 6th is moved in a first travel in the x direction over the substrate and in particular over the first connecting surfaces, with first connecting means portions in each case 32 be deposited on the first interface. These individual lanyard portions 32 overlap in the x-direction and in this case each form a row of connecting means, that is to say a partial connecting means arrangement. In a further travel in the x-direction and with an offset of the print head 6th in the y-direction by half the distance between the printhead openings 60 second lanyard portions are deposited as further rows between the existing rows. In this way, a thin, rectangular arrangement of connecting means with a wavy surface contour is created.

The connecting means used here is a sintering paste, but it can also be a soldering paste or an adhesive. In a next step, a power semiconductor component is then placed on the respective connecting means arrangement 3 arranged and connected to this.

4th shows method step b) of a third embodiment of the method according to the invention. The printhead used for this 6th has a plurality of rows of printhead openings 60 on. This printhead 6th has the advantage that, in contrast to the configuration according to 3 when the print head moves 6th in the x-direction already a surface is created, not just rows of connecting means spaced apart from one another. Basically, the single-layer fastener arrangements produced in this way are similar 3 the end 3 and 4th . If greater layer thicknesses are required, the process step can be carried out several times.

5 shows method step b) of a fourth embodiment of the method according to the invention. The first connection partner is here as well as with 2 a power semiconductor component 2 , here a power transistor with a large emitter connection surface 222 and a smaller gate pad.

Furthermore, but shown purely schematically, the individual connector portions generated in different runs, that is, journeys, of the printing process are on the connection surfaces of the power transistor 2 . Those lanyard portions for the first trip are shown as black circles 32 shown, those of the second journey as circles 34 with close hatching, those of the third trip as circles 36 with further hatching and finally those of the fourth journey as circles 38 without hatching.

Of course, not all connector portions are shown for reasons of clarity.

In this exemplary embodiment, the entire emitter connection area is used during the first and second travel 222 printed with a partial connection arrangement, while on the third and fourth journey only the edge areas of the emitter connection surface are of different widths 222 are printed with a partial connecting means arrangement. The four journeys result in a profile according to line AA 6th . This configuration is also purely exemplary, since the printing process as such basically means any three-dimensional surface contour 300 is possible. Ultimately, this is only limited by the viscosity of the connecting agent used. Depending on the viscosity of the connecting means, the structures generated without taking this flow effect into account run, of course also intended to achieve a certain homogeneity of the surface.

6th shows the conclusion of method step b) of the fourth embodiment of the method according to the invention. That under 3 The described course can be clearly seen here, especially in the middle area.

Otherwise, it is basically shown here that an almost arbitrary surface contour 300 the lanyard assembly 3 is possible by the method according to the invention. In particular, even in the case of several first connection surfaces to be printed, the method according to the invention allows an individual configuration of the connection means arrangement and in particular its surface contour for each of these first connection surfaces 300 .

the 5 and 6th show some more typical technical parameters: The distance 302 in the y-direction corresponds to the distance between these print head openings in the case of a single-row printhead, which therefore has only one row of printhead openings. The distance 304 in the x-direction is determined from the speed of the movement of the print head in the x-direction and the ability of the print head to dispense another portion of the connecting means after dispensing. The minimum thickness 306 a connecting means arrangement is only determined by the mean size of the particles of the connecting means and is therefore almost arbitrarily small from a technical point of view. The maximum thickness 308 a connector arrangement is determined by the mean size of the particles of the connector and by its viscosity. The roughness 310 the surface 300 the lanyard assembly 3 is of the order of magnitude of the above-mentioned distances between the connector portions in the x and y directions. The difference in altitude 312 between the minimum and maximum thickness 306 , 308 a lanyard assembly 3 is ultimately only determined by the mean size of the particles and the viscosity of the connecting agent.

Claims (14)

Method for connecting a first connection partner to a second connection partner within a power electronics arrangement, the respective connection partner being designed as a power electronics substrate (1) or as a power semiconductor component (2) or as a power electronics connection device (5), with the following method steps: a) providing the first connection partner; b) Sequential, layer-by-layer application of a connecting means designed as a sinter paste with metal particles in the form of a connecting means arrangement (3) on a first connecting surface of a first surface of the first connecting partner by means of a print head (6) which can be moved at a distance from the first connecting partner and is designed to selectively from a plurality of To dispense printhead openings (60) in individual dosing processes per printhead opening (60) in each case individual connector portions (30); multiple repetition of this method step, whereby with each execution of the method step different partial connecting means arrangements are generated, which together produce the connecting means arrangement (3) with a minimum thickness (306) and a maximum thickness (308), and wherein the connecting means arrangement (3) has a three-dimensional surface contour (300); c) arranging the second connection partner in such a way that its second connection surface comes to rest, at least partially, on the connection means arrangement (3); d) Forming a cohesive connection. Procedure according to Claim 1 , wherein the power electronic substrate (1) has a plurality of conductor tracks (12). Procedure according to Claim 1 , wherein the power semiconductor component (2) is designed as a power semiconductor switch. Procedure according to Claim 1 , wherein the electronic power connection device (5) is film-based. Procedure according to Claim 1 , the sintering paste having a viscosity of 1 to 50 mPa s, preferably 20 to 40 mPa s. Procedure according to Claim 5 , the mean size of the metal particles of the sintering paste being between 0.01 and 1 μm, preferably between 0.05 and 0.5 μm. Method according to one of the preceding claims, wherein in method step d) the material connection is formed under the action of heat or mechanical pressure on one of the connection partners or under a combination of both. Method according to one of the preceding claims, wherein the print head (6) can be moved in one or two axes in a plane parallel to the first surface on which the first connecting surface is arranged. Procedure according to Claim 8 , wherein the print head (6) can be moved in a normal direction (N) of the first surface. Method according to one of the preceding claims, wherein the relative positioning of the connection means arrangement (3) on the first surface of the first connection partner takes place during operation by means of a control device before performing method step b). Procedure according to Claim 10 , wherein the method step c) and here the relative position of the second connection partner relative to the first connection partner is dependent on the position of the connection means arrangement. Method according to one of the preceding claims, wherein the printhead openings (60) of the printhead (6) are arranged in a row or in several mutually offset rows and each printhead opening (60) can be controlled independently of the others. Method according to one of the preceding claims, wherein the respective connector portion (30) is between 1 and 100 pl, preferably between 20 and 50 pl. Method according to one of the preceding claims, wherein the print head (6) is controlled in such a way that only one defined, non-variable connector portion (30) is dispensed per dosing process.

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