Contact system comprising a component, and method for applying sintering agent

Abstract

The invention relates to a contact system. The contact system has a circuit carrier and at least one component. The component is electrically and integrally connected to the circuit carrier by means of a sintered connection, in particular at least one or just one sintered connection. The sintered connection in the contact system is created by means of two complementary sinter interlayers with complementary surface geometries. One of the complementary sinter interlayers is connected to the circuit carrier, and the other of the complementary sinter interlayers is connected to the component, wherein, in order to form the integral joining connection, one of the sinter interlayers is inserted into the complementary solid sinter interlayer, that has in particular been solidified by means of a drying process, in such a manner that protruding regions of the sinter interlayer are inserted into recesses of the solid sinter interlayer by means of material deformation of the sinter interlayer, that is in particular flowable.

Description

[0001] Description

[0002] title with a component and method for Si

[0003] State of the art

[0004] Disclosure of the invention

[0005] The invention relates to a contact system. The contact system comprises a circuit carrier and at least one component. The component is electrically and materially connected to the circuit carrier by means of a sintered connection, in particular at least one or only one.

[0006] The sintered connection in the contact system is created by means of two mutually complementary sintered layers with mutually complementary surface geometries. Of the mutually complementary sintered layers, one sintered layer is bonded to the circuit carrier, and the other sintered layer is bonded to the component. To form the integral joint, one of the sintered layers is inserted into the complementary solid sintered layer, in particular solidified by drying, in such a way that projection areas of the sintered layer are inserted into the recesses of the solid sintered layer by material deformation of the sintered layer, in particular the flowable sintered layer.

[0007] Advantageously, a gap-free, pore-free, or bubble-free sintered bond, in particular a complete sintered compound layer, can be formed from the mutually complementary sintered compound layers. Furthermore, this can advantageously ensure good heat transfer between the component and the circuit carrier.It has been recognized that by means of the interlocking joining technique, in which projection areas, in particular bumps of the sintering agent layer engage in a further sintering agent layer and there in correspondingly shaped recesses in the further sintering agent layer, a sintering layer result of the sintered connection that is in particular free of voids can be produced if a sintering agent layer, in particular sintering paste layer, of the sintering agent layers has previously been solidified in particular by drying, and projection areas complementary to the recesses are inserted into the solidified sintering agent layer in which recesses are formed in the further sintering agent layer.The further sintering agent layer, in particular the projection areas or bumps, are still viscous and / or pasty during the joining of the joining partners, in particular the circuit carrier and the component, so that during joining, in particular pressing together of the joining partners, the flowable, in particular pasty sintering agent layer can flow into the recesses to completely fill them.

[0008] Preferably, no interruptions in the sintering agent layer are formed by webs in a template for applying the sintering agent. This advantageously allows for the formation of a void-free final layer after sintering.

[0009] Another advantage is that when the sintering paste is applied by a doctor blade, no exhaustion of the sintering paste with the associated formation of a trough can occur due to large openings in the template, so that the layer thickness of the sintering agent, in particular of the sintering paste, can have a constant layer thickness over the wetted surface on the joining partner.

[0010] Furthermore, by drying the applied sintering paste on at least one joining partner or on both joining partners, the probability of crack formation during subsequent sintering is reduced.

[0011] It was further recognized that with the contact system formed in this way, no special or additional process is necessary during assembly to prevent slipping of the joining partners before sintering - in particular in a sintering device, in particular sintering plant or sintering furnace - / sEpi In a preferred embodiment, the sintering agent layers, in particular sintering paste layers, comprise silver and / or copper, or are formed by a silver-containing and / or copper-containing alloy.

[0012] The sintering agent layer, in particular the sintering paste layer, preferably comprises solid metal particles, in particular silver particles or silver alloy particles, and a matrix material, in particular a solvent, preferably a low-viscosity solvent. After the sintering agent layer has been produced on the circuit carrier and / or the component, the sintering paste layer, produced, for example, by printing or doctoring, can be dried. Drying can take place, for example, in an oven. During the drying process, the matrix components evaporate, so that after the matrix has been baked, preformed molded bodies are formed from the sintered particles. During a further baking process, in particular after the joining partners have been joined, the sintered bond can be created by forming a material bond between the particles during the sintering process.The sintering process may comprise a heat supply, for example by means of a furnace, and / or a pressure treatment of the joining partners, in particular pressing the joining partners.

[0013] In a preferred embodiment of the contact system, the formed sintered layer has, in particular, positive cylindrical protrusions, star-shaped protrusions, or flower-shaped protrusions. The complementary sintered layer preferably has corresponding, in particular negative, recesses. Advantageously, the star shape or flower shape can thus be used to form an enlarged edge area between the sintered parts of the sintered layers.

[0014] In another embodiment, webs are formed on one joining partner by means of the sintered layer, and groove-shaped recesses are formed in the complementary sintered layer on the complementary joining partner. Advantageously, the interlocking can thus be formed with low cost and further advantageously prevent deflection of the layered composite in one direction. In a preferred embodiment, the circuit carrier is a ceramic circuit carrier, and the at least one component is a semiconductor switch, in particular a packageless semiconductor switch, also called a bare die. The semiconductor switch is, for example, a field-effect transistor or an IGBT (IGBT = insulated-gate bipolar transistor).

[0015] In a preferred embodiment of the contact system, a switching path connection, in particular a drain connection of the semiconductor switch, is integrally connected to the circuit carrier, in particular an electrically conductive layer of the circuit carrier, by means of the sintering agent layer formed from the two sintering agent layers.

[0016] The invention also relates to an inverter, in particular an inverter with a contact system of the type described above.

[0017] Preferably, the circuit carrier in the inverter is a ceramic circuit carrier, and the at least one component is a semiconductor switch. The inverter has a control unit connected to the at least one semiconductor switch and configured to control the semiconductor switch to generate an alternating current.

[0018] The semiconductor switches preferably form at least one, more preferably three, semiconductor switch half-bridges. Advantageously, a half-bridge module can be formed as the joining partner or a B6 bridge module can be formed as the joining partner.

[0019] The invention also relates to a method, in particular for producing a sintered connection between two joining partners, namely one joining partner and another joining partner, in particular for producing a contact system of the type described above.

[0020] In this process, a sintering agent, in particular a sintering paste, is applied to the joining partners, in particular by printing or doctoring. The sintering pastes thus applied have complementary surface geometries, in particular surface topographies, with projections and complementary recesses. The sintering paste can be applied, for example, by doctoring and stencil printing, by screen printing, by dispensing, in particular needle dispensing or slot mask dispensing, by lamination, or by preform printing.

[0021] In this process, the sintering agent, in particular sintering paste, applied to the joining partner is solidified by drying. In a further step, the further joining partner is joined to the joining partner using the particularly flowable, deformable sintering agent, in particular sintering paste, in such a way that the flowable sintering agent, in particular sintering paste, is introduced into the recesses of the solidified sintering agent, in particular sintering paste, and the recess is filled by flow deformation of the flowable sintering agent, in particular sintering paste.

[0022] Preferably, the bond of the joining partners thus created is subsequently dried so that any remaining solvent or binder can evaporate or outgas from the sintering agent, in particular the sintering paste.

[0023] In a further step, the resulting joining partner composite can be sintered in a sintering device, in particular a sintering plant or a sintering furnace, particularly by pressing or additional heating. During sintering, a material-to-material bond is created between the joining partners using the sintering paste. The material-to-material bond is preferably electrically conductive.

[0024] In a preferred embodiment of the method, the deformable sintering paste has a greater layer thickness than the sintering paste that has been solidified, in particular by drying. This advantageously allows the recesses to be filled reliably. The deformable bumps of the sintering paste are preferably narrower than the recesses, so that for complementary mold filling and production of a particularly homogeneous sintering bonding layer formed from the sintering paste layers, the volumes of the deformable sintering paste bumps and the complementary recesses in the solidified sintering paste layer are each equal. In a preferred embodiment, the deformable sintering paste layer has bumps, wherein a circumferential gap is formed between the bumps and the complementary recesses in the solidified sintering paste layer, which gap is at least partially or completely filled during the deforming of the deformable sintering paste layer.This advantageously allows a void-free sintered connection to be created between the joining partners.

[0025] In a preferred embodiment of the method, the deformable sintering paste bumps have a serrated or wavy edge. This advantageously allows for a large surface connection to be formed in the edge region between the bumps and the recesses.

[0026] In a preferred embodiment of the method, one of the joining partners is formed by a circuit carrier, in particular a ceramic circuit carrier, and the other joining partner is formed by a component, in particular a semiconductor switch. The ceramic circuit carrier preferably has at least one electrically insulating ceramic layer and at least one electrically conductive layer, in particular a copper layer.

[0027] The joining partners are preferably formed by a power semiconductor and a circuit carrier.

[0028] In another embodiment, one joining partner is formed by a semiconductor power module, in particular a semiconductor switch half-bridge or B6 bridge, and the other joining partner is formed by a heat sink, in particular a heat sink or a heat spreader plate. For this purpose, the power module has a thermal contact surface, in particular a metal surface, designed for sintering with the heat sink.

[0029] In another embodiment, the aforementioned joining partners, in particular those with sintering agent protrusions, can be sintered with previously dried sintering agent protrusions. The spreading of the sintering paste in the toothing can thus occur by diffusion during sintering. The invention will now be described below with reference to figures and further exemplary embodiments. Further advantageous embodiments result from a combination of the features described in the figures and in the dependent claims.

[0030] Figure 1 shows an embodiment of a method and a contact system with two joining partners that can be joined together by means of two sintering agent layers;

[0031] Figure 2 shows the contact system shown in Figure 1, in which the joining partners have been pressed together except for a small gap;

[0032] Figure 3 shows the contact system shown in Figure 2, in which the joining partners have been pressed together so that the deformable sintering paste can fill recesses in the solidified sintering paste;

[0033] Figure 4 shows an embodiment of a contact system with two joining partners, namely a circuit carrier and a component, which have been joined together by means of cylindrically deformable sintered paste bumps printed on one joining partner and a recess formed on the other joining partner in a solidified sintered paste layer corresponding to the sintered paste bumps;

[0034] Figure 5 shows an embodiment of a contact system with two joining partners, namely a circuit carrier and a component, which have been joined together by means of deformable sintered paste bumps, in particular flower-shaped, printed on one joining partner, with a corrugated edge and a corrugated recesses formed on the other joining partner corresponding to the sintered paste bumps in a solidified sintered paste layer.

[0035] Figure 1 shows an exemplary embodiment of a contact system 1. The contact system 1 comprises a circuit carrier 2. In this exemplary embodiment, the circuit carrier 2 is a ceramic circuit carrier and comprises two electrically conductive layers 3 and 4, which sandwich an electrically insulating ceramic layer 5. The electrically conductive layer 4 forms a rewiring layer and is designed to be electrically connected to a component, in particular a semiconductor switch 6, by means of sintering.

[0036] In the contact system 1, the component 6 has a sintering agent layer 8 designed for the material-to-material connection to the circuit carrier 2. In this exemplary embodiment, the sintering agent layer 8 has recesses, of which one recess 7 is designated as an example. In this exemplary embodiment, the recess 7 extends as far as the component 6, in particular an electrical connection 12 of the component 6, so that the recess is formed free of sintering paste in this exemplary embodiment. In another embodiment, the recess 7 can have a thin sintering paste layer that covers the electrical connection of the component 6.

[0037] In this exemplary embodiment, the electrically conductive layer 4 of the circuit carrier 2 has a deformable sintered paste layer comprising a plurality of sintered paste moldings that are applied, in particular printed, to the electrically conductive layer 4 of the circuit carrier 2. The sintered paste moldings, which are connected to the circuit carrier 2, each face a recess formed in the sintered paste layer 8, so that when the joining partners formed by the component 6 and the circuit carrier 2 are joined, the deformable sintered paste moldings can engage in the recesses in the sintered paste layer 8.

[0038] A deformable sintered paste molded part 10 of the sintered paste molded parts connected to the circuit carrier 2 is designated as an example.

[0039] In this exemplary embodiment, a diameter 11 of the deformable sintered paste molded part 10 is smaller than a diameter 9 of the recess 7. The recess 7 and the sintered paste molded part 10 have the same volume in this exemplary embodiment, so that a vertical extension 13 of the deformable sintered paste molded part 10 is larger than a vertical extension 14 of the recess 7 in the sintered paste layer 8.

[0040] The sintering paste layer 8 has been solidified, for example, in a drying process, for example by heating in a drying oven or by means of hot air. During the solidification process, the sintering paste layer 8 is solidified to such an extent that the sintering paste layer, in particular a geometric shape or texture of the sintering paste layer, can no longer be deformed non-destructively upon contact.

[0041] Figure 2 shows the contact system 1 illustrated in Figure 1, in which the joining partners, formed by the component 6 and the circuit carrier 2, have been almost pressed together - in particular except for a small gap 15. It can be seen that the deformable sinter paste layer applied to the circuit carrier 2, which in this exemplary embodiment is formed by the deformable sinter paste moldings, can completely fill the recess 7 when the joining partners are pressed together laterally and thus spreading in the direction of a flat extension of the circuit carrier. The sinter paste molding 10 in Figure 2 has been deformed in a mushroom shape into a deformed sinter paste molding 10'. While the sinter paste layer 8' can still retain its dimensional stability - generated in particular by the drying process - in the position pressed against the circuit carrier 2.The lateral deformation of the deformed sintered paste molded part 10' is shown as an example in Figure 2 by means of a lateral arrow 16.

[0042] Figure 3 shows the contact system already illustrated in Figure 2, in which the component 6, in particular the semiconductor switch, has been completely pressed onto the circuit carrier 2 in such a way that the deformable sintered paste moldings in the recesses are deformed such that the recesses are completely filled by the deformable sintered paste moldings. In Figure 3, the sintered paste molding 10 has been deformed into a sintered paste molding 10" that completely fills the recess 7. The parts of the sintered paste layer 8" illustrated in Figure 3 retain their shape almost completely or have been deformed only slightly.

[0043] The contact system shown in Figure 3 can be tempered in a further step in a sintering device to create a material-to-material bond between the component 6 and the circuit carrier 2. In this process, a residual solvent can be expelled from the deformable sintering paste layer, and the sintered particles of the sintering paste layers can be sintered to form a sintered bonding layer.

[0044] Figure 4 shows a contact system 20. The contact system 20 has two joining partners, namely a particularly ceramic circuit carrier 21 and a component 22. The joining partners are materially connected to one another by means of a sintering agent layer 24 comprising two complementary sintering agent layers. For this purpose, recesses are formed in a sintering agent layer 24 applied to the component 22, into which sintering agent protrusions formed on the circuit carrier 21 engage in a form-fitting manner. A recess 23 and a sintering agent protrusion 25 inserted into the recess 23 are designated by way of example. In this exemplary embodiment, the recesses and / or the sintering agent protrusions are designed, in particular, as circular cylinders. The sintering agent protrusions can be formed by flowing into the recesses or by pre-dried sintering agent shaped elements which, when the joining partners are joined, interlock with one another in the opposing recesses.

[0045] Figure 5 shows a contact system 30. The contact system 30 has two joining partners, namely a particularly ceramic circuit carrier 26 and a component 27. The joining partners are materially connected to one another by means of a sintered layer consisting of two complementary sintered layers. For this purpose, recesses are formed in a sintered layer 28 applied to the component 27, into which sintered bumps formed on the circuit carrier 26 engage in a form-fitting manner. A recess 29 and a sintered bump 31 inserted into the recess 29 are shown as examples. In this exemplary embodiment, the sintered bumps are designed, in particular, as cylinders with corrugated edges. This can facilitate the expulsion of air during assembly.

[0046] When the sintering agent layer joined in this way is sintered between the joining partners, the outline of the star-shaped recesses forms a grain boundary after sintering. Although the crystalline alignment of the sintered bond at the grain boundary can be detected in a cross-sectional image, its electrical and thermal properties differ little or nothing from those of a sintering paste printed in a continuous layer. Using the sintering agent layer produced in this way, a sintering agent layer, for example the sintering agent layer with the recesses, can be pre-dried, and the sintering agent layer with the bumps can be inserted into the recesses in a deformable, particularly solvent-containing, wet state. This avoids applying the sintering agent over a large area to a joining partner, which could cause drying channels or cracks when the solvent is expelled.

Claims

Claims 1 . Contact system (1, 20, 30) with a circuit carrier (2, 21, 26) and at least one component (6, 22, 27), wherein the component is electrically and materially connected to the circuit carrier (2, 21, 26) by means of a sintered connection (8”, 10”, 24, 25, 28, 31), wherein the sintered connection (8”, 10”, 24, 25, 28, 31) is produced by means of two mutually complementary sintered layers (8, 10, 24, 25, 28, 31) with mutually complementary surface geometries, wherein one sintered layer (8, 24, 28) of the sintered layers (8”, 10”, 24, 25, 28, 31) is connected to the circuit carrier and the further sintered layer (10, 25, 31) is connected to the component (6, 22, 27), wherein, to form the material-locking joint, one of the sintering agent layers (10) is inserted into the complementary solid sintering agent layer (8), which is particularly solidified by drying, in such a way that projection areas of the sintering agent layer (10, 25, 31) are inserted into the recesses (7,23, 29) of the solid sintered layer by means of material deformation of the sintered layer (10).

2. Contact system (1, 20, 30) according to claim 1, characterized in that the sintering agent layers (8, 10, 24, 25, 28, 31) comprise silver and / or copper or are formed by a silver-containing and / or copper-containing alloy.

3. Contact system (1, 20, 30) according to one of the preceding claims 1 or 2, characterized in that the solid sintered layer (8, 24, 28), in particular solidified by drying, is connected to the component and the sintered layer, in particular formed by flowing, is connected to the circuit carrier (2, 21, 26).

4. Contact system (1, 20, 30) according to one of the preceding claims, characterized in that the formed sintered layer has, in particular, positive star-shaped or flower-shaped bumps and the sintered layer complementary thereto has corresponding, in particular, negative recesses.

5. Contact system (1, 20, 30) according to one of the preceding claims, characterized in that the circuit carrier (2, 21, 26) is a ceramic circuit carrier and the component (6, 22, 27) is a semiconductor switch.

6. Inverter with a contact system (1, 20, 30) according to claim 5, wherein the circuit carrier (2, 21, 26) is a ceramic circuit carrier and the at least one component (6, 22, 27) is a semiconductor switch, wherein the inverter has a control unit which is connected to the at least one semiconductor switch and is designed to control the semiconductor switch to generate an alternating current.

7. Method, in particular for producing a sintered connection between two joining partners, namely one joining partner and another joining partner, in particular for producing a contact system (1, 20, 30) according to one of the preceding claims, in which a sintering agent (8, 10), in particular sintering paste, is applied to the joining partners (6, 2), in particular printed or doctored on wherein the sintering means (8, 10) have mutually complementary surface geometries with projections (10) and complementary recesses (7), and the sintering means (8) applied to the joining partner (6) is solidified, in particular by means of drying, and the further joining partner (2) is joined to the joining partner (6) with the, in particular, flowable, deformable sintering means (10) in such a way that the flowable sintering means (10) is introduced into the recesses (7) of the solidified sintering means (8') and the recess (7) is filled by means of flow forming of the deformable, in particular flowable sintering means (10').

8. Method according to claim 7, characterized in that the deformable sintering agent (10, 10') has a greater layer thickness (13, 14) than the sintering agent (8') which is solidified in particular by drying.

9. The method according to claim 7 or 8, characterized in that the sintering agent (8, 10) is a sintering paste and the deformable sintering paste layer (10) has bumps (10), wherein between the bumps and the recesses (7) complementary thereto in the solidified sintering paste layer (8) a circumferential gap is formed, which is at least partially or completely filled during the forming of the deformable sintering paste layer (10, 10').

10. Method according to claim 9, characterized in that the deformable sintering paste bumps (10) are cylindrical or web-shaped. 5

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