Manufacturing a power module

Abstract

Manufacturing a Power Module The invention relates to a method for manufacturing a power electronic module (100) comprising a substrate (110) having at least one stack (111) of several layers, the method further comprising: - a step of arranging or fixing on one (112b) of the layers of said at least one stack (111) a spacer element (115, 215, 315, 415, 515, 615, 715), the spacer element having a thickness greater than or equal to 200 µm, - a step of fixing at least one connector (120) on the spacer element (115, 215, 315, 415, 515, 615, 715). Figure for the abstract: Fig 1.

Description

Title of the invention: Fabrication of a power module technical field

[0001] The present invention relates to the manufacture of a power electronic module. The invention finds particular application in the field of aeronautics where high reliability and relative compactness are required. Previous technique

[0002] Power electronic modules are present in aircraft and allow the integration of numerous electronic components within a single assembly. Thus, functions of varying degrees of complexity can be performed in this type of module.

[0003] Such modules generally comprise a substrate, semiconductors, and / or other components assembled on the substrate. Power connections are also located on the substrate. Power electronic modules also include electrical and mechanical interconnection means and a housing that structures the entire power module. Encapsulation solutions may also be present in the power modules to ensure electrical isolation between different potentials and to protect the components from environmental stresses.

[0004] In the context of the manufacture of power electronic modules, "SMI" insulated metallic substrates or ceramic substrates may be used.

[0005] SMI substrates and ceramic substrates have the advantage of having excellent thermal conductivity and high dielectric strength against high voltages.

[0006] The assembly of power connectors on SMI substrates or on ceramic substrates can be carried out by different techniques such as: brazing, sintering, ultrasonic welding and laser welding.

[0007] It happens that in some cases, the power connectors are not suitable for assembly on the SMI substrate or on the ceramic substrate.

[0008] In such cases, one solution proposes integrating threaded pads onto the SMI or ceramic substrate by brazing and screwing the power connectors onto these pads. However, this option involves positioning and screwing the connectors, which can be time-consuming and complex to implement. These operations make the substrate manufacturing process lengthy and expensive. These manipulations can also generate inhomogeneity in the arrangement of the encapsulation solution. Indeed, the manipulations are generally carried out before the polymerization of the encapsulation solution within the module. Furthermore, during During the manufacturing of the power electronic module, the substrate containing the threaded pads and the unpolymerized encapsulation solution is moved from the encapsulation solution filling unit to the polymerization unit. Depending on the nature of the encapsulation solution, this movement can cause leakage of the encapsulation solution outside the module or towards electrical contact areas. Similarly, this operation can render the encapsulation solution non-homogeneous.

[0009] Furthermore, the bulky geometry of the pads can degrade the switching inductance of the power electronic module and reduce its compactness. Indeed, a power module connects its output(s) to several power inputs depending on the control signals received. At each switching operation, the output current is redirected from one power input to another. This generates a change in the magnetic fields of the current conductors and a transfer of magnetic energy. This phenomenon is known as parasitic switching inductance.

[0010] A larger pin geometry requires more energy to redirect the output current from one input to another because the distance between the conductors is greater. This results in higher parasitic switching inductance, as well as losses and overvoltages in the switches, which heat the power module. Consequently, the system becomes less efficient.

[0011] Another solution proposes to perform the bond between the power connector and the SMI substrate by laser fusion. However, this solution can lead to high and deep heating of the ceramic substrate or the SMI substrate, which can damage it. This is particularly the case when the substrate layer to which the bond is made is thin.

[0012] There is therefore a real need for a manufacturing process for a power module that allows better control of the link between the power connector and the SMI substrate or the ceramic substrate, without the drawbacks inherent in the aforementioned known methods. Description of the invention

[0013] The invention is specifically aimed at meeting the needs stated above.

[0014] According to a first aspect, the invention proposes a method for manufacturing a power electronic module comprising a substrate having at least one stack of several layers, characterized in that the method further comprises: - a step of arranging or fixing on one of the layers of said at least one stack of a spacer element, the spacer element comprising a thickness greater than or equal to 200 pm, - a step of fixing at least one connector onto the spacer element.

[0015] Thus, the process makes it possible to obtain a module with superior mechanical and electrical properties compared to the prior art. Such a process also makes it possible to obtain a module into which one or more power connectors can be integrated using techniques involving high and deep heating, such as laser melting, without risk of damage. Indeed, the stacking layer adjacent to the stacking layer on which the spacer element is located does not suffer degradation when said connector is attached to the substrate. This is possible thanks to the presence of the spacer element, which protects said layer from the substrate. Furthermore, the arrangement of the spacer element makes it possible to increase the local thickness of the substrate, and more specifically, at least partially, the thickness of the stacking layer on which the spacer element is located.

[0016] Moreover, such a method allows for a robust connection of the power connector in a simpler way because it does not require any positioning and screwing of the connectors.

[0017] According to a particular characteristic, at least one of the layers of the stack is an electrically insulating layer.

[0018] According to a particular feature of the process, the process may comprise the following steps: - the provision of a fixing material on one of the layers of said at least one stack, - the fixing of the 1st spacer element, - the implementation of a heat treatment to bond the spacer element with the stack.

[0019] Indeed, such a method ensures robust attachment of the spacer element to the stack. Furthermore, the method allows for faster and more economical manufacturing of power electronic modules, particularly because no delicate and complex manual operations are required to adapt the substrate for receiving the connectors.

[0020] According to a particular feature of the method, the spacer element may further comprise several protrusions of a determined height, said protrusions being in contact with said layer on which the spacer element is fixed.

[0021] Indeed, such protrusions ensure the stability of the spacer element, particularly when the process includes a step of arranging a fixing material between the spacer element and the substrate stack. This is especially true when the fixing material can be arranged in the form of a semi-solid composition. In fact, when arranging the fixing material on the stack, inhomogeneous flatness may occur. Such protrusions can penetrate the fixing material to make contact with the stack. Similarly, they allow for better control and distribution of the fixing material. Thus, the desired flatness can be achieved.

[0022] According to another particular feature of the method, the spacer element may comprise a first leg, a second leg and a central part included between the first leg and the second leg, the first leg and the second leg being integral with the central part and fixed or arranged on one of the layers of said at least one stack, the central part being raised relative to the first leg and the second leg, forming a recess between the stack and the raised central part.

[0023] Such a configuration makes it possible to improve the thermal decoupling between the central part of the spacer element and the first and second legs of the spacer element, in particular when attaching the connector to the central part of the spacer element.

[0024] According to a particular feature of the method, each of the legs among the first leg and the second leg of the spacer element can form a damping spring extending under the central part of the spacer element.

[0025] Thus, it is possible to reduce the mechanical stress on the stack when attaching the connector to the spacer element. Indeed, the curvatures of the damping spring provide elasticity to the spacer element.

[0026] According to a particular feature of the process, the spacer element can be made of an electrically conductive material.

[0027] According to a particular feature of the process, the spacer element may comprise an electrically conductive material selected from copper, brass, nickel-plated aluminum, constantan, or a mixture thereof.

[0028] This helps to limit the thermal expansion of the spacer element during a temperature change.

[0029] According to a particular characteristic, the electrically conductive material can be the constantan.

[0030] This helps to limit thermal cycle failures, to further limit the thermal expansion of the spacer element and to have good electrical conductivity in the module.

[0031] According to a particular characteristic, the electrically conductive material can be copper.

[0032] This makes it possible to further limit thermal cycle failures, to further limit the thermal expansion of the spacer element and to improve the electrical conductivity of the module.

[0033] According to a particular feature of the process, each of the steps of the process can be carried out for a plurality of substrates simultaneously, said substrates being mechanically coupled together to form a single panel.

[0034] Thus, it is possible to manufacture a plurality of modules in a fast and more economical way.

[0035] According to a particular feature, the process may further include a step of decoupling a substrate from the panel.

[0036] According to a particular feature of the process, the step of fixing at least one connector is carried out by laser welding.

[0037] Thus, the process makes it possible to obtain a power electronics module with improved mechanical and electrical properties compared to prior art solutions. Indeed, the process allows for a robust connection between said at least one connector and the substrate, in particular because laser welding has the advantage of being free of intermetallics that weaken the mechanical assembly while ensuring good electrical conductivity. Furthermore, the process makes it possible to obtain an electronic module with a high power density, thanks to the presence of the compact power connector. Such a module can therefore reliably supply power to numerous components.

[0038] According to another aspect of it, the invention proposes a power electronic module characterized in that it comprises a substrate having at least one stack of several layers, a spacer element disposed or fixed on one of the layers of the stack, the spacer element having a thickness greater than or equal to 200 pm, at least one power connector and, in that the power electronic module (100) is obtained by the process according to the invention.

[0039] Such a power electronic module has a robust connection between the power connector and the substrate, as well as superior mechanical and electrical properties compared to the prior art. Indeed, in such a configuration, the properties of the stacking layer on which the spacer element is located are not degraded during the step of bonding the connector to the substrate. Similarly, in such a module configuration, the module encapsulation solution optimally protects the components because the substrate is not subjected to any complex and delicate handling that could affect the arrangement of said encapsulation solution.

[0040] According to a particular feature of the module, the spacer element may further comprise several protrusions of a determined height, said protrusions being in contact with the layer on which the spacer element is fixed. Brief description of the drawings

[0041] [Fig-1] Fig. 1 schematically represents a power electronic module in accordance with one embodiment of the invention,

[0042] [Fig.2] Fig.2 is a flowchart of the steps in a manufacturing process of a power electronic module according to one embodiment of the invention,

[0043] [Fig.3] Fig.3 schematically represents the substrate of the electronic module of power of the [Fig.1],

[0044] [Fig.4] Fig.4 schematically represents a substrate in accordance with a second embodiment of the invention,

[0045] [Fig. 5] Fig. 5 schematically represents a power electronic module in accordance with a second embodiment of the invention,

[0046] [Fig.6] Fig.6 schematically represents an example of an electronic module of power according to a third embodiment of the invention,

[0047] [Fig.7] Fig.7 schematically represents an electronic module in accordance with a fourth embodiment of the invention,

[0048] [Fig.8] Fig.8 schematically represents an electronic module in accordance with a fifth embodiment of the invention,

[0049] [Fig.9] Fig.9 schematically represents an electronic module in accordance with a sixth embodiment of the invention. Description of the implementation methods

[0050] The invention is now described by means of figures, which are provided for descriptive purposes to illustrate certain embodiments of the invention and which should not be interpreted as limiting the latter.

[0051] Figure 1 represents a power electronic module 100 according to an embodiment of the invention. Such a module 100 comprises a substrate 110 and at least one power connector 120.

[0052] Said substrate 110 comprises a stack 111 and a spacer element 115. As illustrated in [Fig. 1], the spacer element 115 may be a layer. The stack 111 comprises two conductive layers 112a and 112b and an electrically insulating layer 113. The electrically insulating layer 113 is situated between the two conductive layers 112a and 112b. In another mode of The stacking can include a conductive layer between two electrically insulating layers.

[0053] In the example shown in [Fig. 1], the power electronic module 100 comprises a stack 111, but this is not a limitation of the invention. Thus, the power module 100 may comprise several stacks 111.

[0054] In an embodiment not shown, the stack 111 can be arranged on a heat-dissipating base. Such a base can comprise a matrix of aluminum-silicon carbide alloy, copper, molybdenum, aluminum, or a mixture thereof. The stack 111 can be arranged on the heat-dissipating base by a method such as brazing, sintering, or bonding.

[0055] The conductive layers 112a and 112b comprise an electrically and thermally conductive material while the insulating layer 113 comprises an electrically insulating material.

[0056] The electrically and thermally conductive material of the conductive layers 112a and 112b can be chosen from copper, alloys comprising copper and nickel, alloys comprising aluminum and nickel, gold-plated nickel-plated copper or a mixture thereof.

[0057] The electrically insulating material of the insulating layer 113 can be chosen from: organic materials for example based on epoxy resin (of type FR4 and its derivatives), variously charged materials (glass fiber, ceramics), materials based on aluminium oxide (Al2O3), aluminium nitride (NiA) or silicon nitride (Si3N4).

[0058] This allows a good compromise to be obtained between the coefficient of expansion, thermal performance and resistance to mechanical stress within the stack 111. In addition, such an electrically insulating material has the advantage of not being very expensive.

[0059] The spacer element 115 covers at least partially one of the conductive layers, here layer 112b. Such a spacer element 115 makes it possible to locally increase the thickness of the substrate 110 at the point where the connection with said at least one power connector 120 will be made. Moreover, such a spacer element 115 is even more advantageous when the conductive layer 112b of the stack 111, which is at least partially covered by the spacer element, has a small thickness. Thus, said electrically insulating layer 113 is protected because the thickness of the conductive layer 112b is locally increased by the spacer element 115 and does not suffer any degradation of its mechanical and electrical properties when the connector 120 is connected to the stack 111. Such degradation is possible, for example, when the connection between the The connection and the substrate is made by laser welding and, that heating produced by the laser damages at least partially the conductive layer 112b.

[0060] According to a particular characteristic of the substrate, at least one of the conductive layers 112a or 112b of the stack 111 may comprise a thickness less than or equal to 500 pm.

[0061] In the example illustrated in [Fig. 1], the spacer element 115 is a layer that partially covers the conductive layer 112b, but this is not limiting. In an embodiment other than the one shown, the spacer element 115 may completely cover one of the conductive layers 112a or 112b.

[0062] For the sake of simplification, an embodiment is described below which includes only a stack 110 and a conductive layer 112b which is partially covered by the spacer element 115.

[0063] According to a particular feature, the spacer element 115 may comprise an electrically conductive material.

[0064] According to a particular feature, the spacer element 115 may comprise an electrically conductive material selected from copper, brass, silver, aluminum, gold, constantan or a mixture thereof.

[0065] According to a particular feature, a fixing layer 114 may be located between the spacer element 115 and the conductive layer 112b, as illustrated in [Fig. 1], but this is not restrictive. Thus, in embodiments illustrated in Figures 5 and 6, the substrate 110 lacks the fixing layer 114.

[0066] Such a bonding layer 114 allows the spacer element 115 to be bonded to the stack 111. Indeed, the layer 114 is notably present when the manufacturing process of the power electronics module 100 involves a step of bonding the spacer element 115 by a method such as sintering or brazing. A bonding layer 114 may also be provided when the manufacturing process of the power electronics module is carried out using an electrically conductive adhesive.

[0067] Depending on a characteristic of the substrate or the process, the fixing layer 114 may comprise a material chosen from lead-free solders, for example of the SAC or SnAg type, or even the old leaded solders.

[0068] According to a particular feature, the spacer element 115 may further comprise several protrusions 116, as illustrated in Figures 1 and 3. Such protrusions help to ensure the stability of the spacer element 115. This is particularly the case when a fixing material 114 is required for bonding the spacer element 115 to the stack 111. The protrusions 116 are even more advantageous when the fixing layer 114 is assembled in a liquid or semi-solid state.

[0069] Indeed, the fixing layer 114 can be arranged in the form of a semi-solid fixing material. The distribution of the fixing layer 114 on said at least one conductive layer 112b can, under certain conditions, be inhomogeneous. When the spacer element 115 is fixed, the protrusions 116 pass through the fixing layer 114 until they are in contact with the conductive layer 112b. Thus, the flatness of the connection between the spacer element 115 and the stack 111 is ensured. The protrusions 116 also make it possible to position the spacer element 115 parallel to the conductive layer 112b, and to control the thickness of the fixing layer 114 at the points of contact between the spacer element 115 and the conductive layer 112b. The protrusions 116 can be made by punch and stamping die or by ploughing the corners or edge of layer 115 in order to reduce manufacturing costs.When protrusions are formed by a punch and a stamping die, the protrusionless spacer 115 is placed on the stamping die, which comprises a first protruding portion and a second protruding portion. The first protruding portion is positioned opposite the second protruding portion. A recess separates the first protruding portion from the second protruding portion. The punch applies pressure to the spacer element so that the lower surface of the spacer element, parallel to the surface on which the pressure is applied, conforms to the shape of the die. This lower surface is deformed under the effect of the applied pressure. The protrusion is thus formed in the recess separating the two protruding portions of the stamping die.

[0070] The presence of the protrusions 116 is not limiting. Thus, as illustrated in [Fig.4], the spacer element 215 of the electronic module 100 is a layer that may be devoid of protrusions 116.

[0071] The advantages described here for embodiments in which the substrate 110 comprises several stacks 111, or in which one or more layers 112a, 112b would be covered entirely by the spacer element 115 can be transposed to these embodiments.

[0072] Figure 7 illustrates a power electronic module 100 according to another embodiment. As shown in Figure 7, the spacer element 515 comprises a first leg 516, a second leg 517, and a central portion 518. The first leg 516 comprises a first end 5160 and a second end 5162, and the second leg 517 comprises a first end 5170 and a second end 5172. The central portion 518 is integral with the second end 5162 of the first leg 516 and integral with the first end 5170 of the second leg 517.

[0073] The first leg 516 is separated from the second leg 517 by a distance at least equal to the length of the central part 518. The central part 518 is raised relative to the first leg 516 and the second leg 517, generating a recess 800 between the central part 518 of the spacer element 515 and the stack 111. The connection 120 is fixed to the central part 518 of the spacer element 515.

[0074] This embodiment facilitates the protection of the electrically insulating layer 113 of the stack 111 when one or more power connections are fixed using techniques involving high and deep heating. Indeed, the raised central portion 518 increases the distance between the conductive layer 112b of the stack 111 and the connection 120. Consequently, the distance between the electrically insulating layer 113 of the stack 111 and the connection 120 is also increased.

[0075] This embodiment is most advantageous when the process involves the use of a fixing material to fix the spacer element 515, as illustrated in [Fig. 7]. In this case, the fixing material forms a first fixing layer 114a and a second fixing layer 114b. The first fixing layer 114a is interposed between the first leg 516 of the spacer element 515 and the layer 112b of the stack 111. The second fixing layer 114b is interposed between the second leg 517 of the spacer element 515 and the layer 112b of the stack 111. Thus, when the connector 120 is fixed to the central part 518 of the spacer element 515, the fixing layers 114a, 114b, the layer 112b and the electrically insulating layer 113 are protected from any possible heating related to the fixing of the connector 120 to the central part 518 of the spacer element 515.

[0076] In such an embodiment, the bonding layers 114a and 114b can be a brazing composition, a sintering composition or even micro-pastes or nano-pastes of silver or copper. The spacer element 515 can be fixed to the stack 111 by a heat treatment such as welding, sintering or brazing.

[0077] The embodiment illustrated in [Fig. 8] differs from that illustrated in [Fig. 7] in that the first end 6160 of the first leg 616 of the spacer element 615 is opposite the second end 6172 of the second leg 617 of the spacer element 615. The first leg 616 comprises a horizontal portion 6165 extending parallel to and below the central portion 618 and a vertical portion 6167 extending between the horizontal portion 6165 and the central portion 618. The second leg 617 comprises a horizontal portion 6175 extending parallel and under the central part 618 and a vertical portion 6177 extending between the horizontal part 6175 and the central part 618.

[0078] Such a configuration further improves the thermal decoupling between the central part 618, the first leg 616 and the second leg 617 of the spacer element 615, without increasing the horizontal footprint of the spacer element 615.

[0079] This embodiment is also most advantageous when the process involves the use of a fixing material to fix the spacer element 615, as illustrated in [Fig. 8]. In this case, the first fixing layer 114a is intercalated between the horizontal portion 6165 of the first leg 616 of the spacer element 615 and the conductive layer 112b of the stack 111. The second fixing layer 114b is intercalated between the horizontal portion 6175 of the second leg 617 of the spacer element 615 and the conductive layer 112b of the stack 111.

[0080] The example of power electronic module 100 illustrated in [Fig.9] differs from that of [Fig.7] in that the first leg 716 forms a first damping spring 7161 and the second leg 717 forms a second damping spring 7171. Each of the springs 7161 and 7171 extends under the central part 718 of the spacer element 715.

[0081] The first res sort 7161 comprises a first horizontal portion 7162, a The first spring 7161 comprises a first vertical portion 7163 and a second vertical portion 7165. The first vertical portion 7163 is not integral with the second vertical portion 7165.

[0082] The first horizontal portion 7162 is coupled to the second horizontal portion 7164 by the first vertical portion 7163. The second horizontal portion 7164 is coupled to the third horizontal portion 7166 by the second vertical portion 7165.

[0083] The second spring 7171 comprises a first horizontal portion 7172, a second horizontal portion 7174 and a third horizontal portion 7176. The second spring 7171 comprises a first vertical portion 7173 and a second vertical portion 7175. The first vertical portion 7173 is not integral with the second vertical portion 7175.

[0084] The first horizontal portion 7172 is coupled to the second horizontal portion 7174 by the first vertical portion 7173. The second horizontal portion 7174 is coupled to the third horizontal portion 7176 by the second vertical portion 7175.

[0085] Such a configuration makes it possible to reduce the mechanical stress experienced by the stack 111 when the connector 120 is attached to the spacer element 715. Indeed, when the tool for attaching the connector 120 is in contact with The spacer element 715 can be subjected to high mechanical stress by the tool. This mechanical stress can damage the bearing points of the stack 111 on which the spacer element 715 is fixed or positioned, and damage the electrical connection between the spacer element 715 and the conductive layer 112b, particularly at the fixing layers 114a and 114b. The presence of the damping springs 7161 and 7171 therefore limits the mechanical stress on these bearing points and consequently provides greater protection for the fixing of the spacer element 715 to the stack 111.

[0086] The advantages described here for embodiments in which the substrate 110 comprises several stacks 111 can be transposed to these embodiments.

[0087] An example of the manufacturing process for a power electronics module 100 is now described. This process allows, for example, the production of the substrate equipped with the power electronics module illustrated in [Fig. 1]. The steps of such a process are illustrated in [Fig. 2].

[0088] In a first step E1, a fixing material can be placed on the stack 111. In the embodiments shown in Figures 1, 3, and 4, the fixing layer 114 is formed by said fixing material. This is also the case for layers 114a and 114b in the embodiments illustrated in Figures 7 to 9.

[0089] The stack 111 comprises two conductive layers 112a, 112b and an electrically insulating layer 113. The electrically insulating layer 113 is situated between the two conductive layers 112a and 112b.

[0090] According to a particular feature of the process, at least one of the conductive layers 112a or 112b of the stack 111 may comprise a thickness less than or equal to 500 pm.

[0091] It is indeed for such stacks that the process is particularly advantageous because an even greater degradation of the mechanical and electrical properties is observed when making the connection of a connector on a substrate in prior art processes.

[0092] According to another particular feature of the method, it can be devoid of the step El of arranging a fixing material on the stack 111. In such an embodiment, the spacer element 315, 415 can be arranged on the stack 111 and on it the power connector 120. Figures 5 and 6 illustrate examples of this embodiment.

[0093] Such a method makes it possible to ensure the protection of the insulating layer 113 of the stack 111 and to increase the local thickness of the substrate 110 by the arrangement or fixing of a single layer on the stack 111. Thus, it is possible to obtain a method that is even easier to implement.

[0094] In [Fig. 5], the spacer element 315 corresponds to a layer that is fixed to the conductive layer 112b of the stack 111. In such an embodiment, the spacer element 315 can be a plate generated by the growth of an electrically conductive material. In this case, the spacer element 315 can be formed by electroplating or by additive manufacturing using a metal powder bed. The metal powder used in additive manufacturing can include aluminum. The plate forming the spacer element 315 can comprise a metallic material selected from copper, zinc, brass, tin, aluminum, silver, or a mixture thereof. The spacer element 315 can be fixed to the stack 111 by a heat treatment such as electric welding or ultrasonic welding.

[0095] In [Fig.6], the spacer element 415 is contained within a region of one of the layers of the stack 111. Here, the spacer element 415 is part of a first region 1121b of the conductive layer 112b of the stack 111. In such an embodiment, the spacer element 415 can be manufactured by chemical etching or by mechanical machining of the conductive layer 112b of the stack 111.

[0096] Before the manufacture of the spacer element 415, the conductive layer 112b has a constant thickness el. The value of the thickness el is defined so as to protect the insulating layer 113 during chemical etching or mechanical machining of the conductive layer 112b.

[0097] When the conductive layer 112b is chemically etched or mechanically machined, the conductive layer 112b comprises a first region 1121b of thickness e1 and a second region 1122b of thickness e2. The thickness e2 of the second region 1122b is less than the thickness e1 of the first region 1121b. The first region 1121b includes the spacer element 415 of thickness e3, such that e1 = e2 + e3.

[0098] The presence of the second region 1122b makes it possible to reduce the stresses induced by the expansion of the conductive layer 112b during a change in temperature, to reduce the total mass and total volume of the module and to improve the fineness of the etching of the tracks on the substrate.

[0099] According to a particular feature of the method, when a fixing material has been placed on the stack, a spacer element 115 can then be fixed in a step E2. The spacer element 115 is then placed on said fixing layer 114. The spacer element 115 has an internal surface 117 and an external surface 118.

[0100] According to a particular feature, the spacer element 115 may comprise a metallic material selected from copper, brass, Invar®, Nilo 42®, silver, gold or nickel-plated aluminum.

[0101] According to a particular feature of the process, the step of fixing a spacer element 115 can be followed by a heat treatment step E3. The heat treatment can include a reflow soldering step, a soldering iron step, or a selective wave soldering step. Such heat treatment makes it possible to bond the spacer element 115 to the stack 111. Figures 3 and 4 illustrate examples of a substrate 110 obtained after step E3.

[0102] According to a particular feature, the E3 heat treatment step can be carried out simultaneously for a plurality of the substrates 110. Thus, it is possible to manufacture a plurality of the power electronic modules 100 at the same time and consequently obtain a more economical and faster process.

[0103] According to a particular feature of the process, said step E3 can be carried out under an atmosphere of nitrogen N2 or under vacuum.

[0104] According to a particular feature of the process, a manufacturing step of several protrusions 116 on the internal surface 117 of the spacer element 115 can be carried out, and this before the fixing or arrangement step of the spacer element E2. [Fig.3] illustrates a substrate 110 which can be obtained as a result of such a process.

[0105] The fabrication of such protrusions 116 on the internal surface 117 of the spacer element 115 ensures the stability of the spacer element 115. The protrusions 116 are even more advantageous when a fixing layer 114 is disposed on one of the conductive layers during the fabrication of the electronic module 100.

[0106] Depending on a particular characteristic of the substrate and the process, the protrusions can have a height of between 40 µm and 150 µm. Such a height makes it possible to ensure that the thermomechanical stresses of the product in its use are compatible with the mechanical performance of the brazing.

[0107] According to a particular feature of the process, a twisting step of the spacer element can be carried out, so as to form a central part, a first leg and a second leg, and this before the fixing or arrangement step of the spacer element E2. Figures 7 and 8 illustrate a module 100 which can be obtained at the end of such a process.

[0108] According to a particular feature of the method, a step of forming a first damping spring 7161 and a second damping spring 7171 can be carried out before the step of fixing or arranging the element E2 spacing. [Fig.9] illustrates a module 100 which can be obtained as a result of such a process.

[0109] According to a particular feature of the process, each of the steps of the process can be carried out simultaneously for a plurality of the substrates 110. In this context, the substrates 110 can be mechanically coupled together to form a single panel.

[0110] Such a configuration of the process steps makes it possible to manufacture a plurality of substrates 110 simultaneously. Thus, the process can be faster and more economical.

[0111] The heat treatment step E3 is followed by a laser welding step E4 of at least one power connector 120 on at least one spacer element 115.

[0112] This step makes it possible to obtain a robust connection between said at least one connector and the substrate. Indeed, laser welding has the advantage of high precision and allows for deep welding without intermetallics and without molten material spatter. Thus, it is possible to obtain a power electronics module with improved mechanical and electrical properties compared to prior art solutions.

[0113] According to a particular feature of the process, said step E4 can be carried out at a temperature between 150°C and 300°C.

[0114] According to a particular feature of the process, said step E4 can be carried out under standard or controlled atmosphere.

[0115] According to a particular feature of the process, said laser welding step E4 can be carried out simultaneously for a plurality of substrates 110.

[0116] Thus, it is possible to manufacture a plurality of 100 power electronic modules at the same time and consequently obtain a more economical and faster process.

[0117] When the substrates 110 are mechanically coupled together to form a single panel, the process may further include a step of decoupling a substrate 110 from the panel. In this case, the step of decoupling a substrate 110 is carried out before the laser welding step E4.

[0118] When the process includes a heat treatment step E3, the decoupling step of a substrate 110 can be carried out after the heat treatment step E3 and before the laser welding step E4.

Claims

Demands

1. A method for manufacturing a power electronic module (100) comprising a substrate (110) having at least one stack (111) of several layers, characterized in that the method comprises: - a step of arranging or fixing on one (112b) of the layers of said at least one stack (111) of a spacer element (115, 215, 315, 415, 515, 615, 715), the spacer element having a thickness greater than or equal to 200 pm, - a step of fixing at least one connector (120) on the spacer element (115, 215, 315, 415, 515, 615, 715).

2. A method according to claim 1, wherein the method further comprises the following steps: - the disposition of a fixing material on one (112b) of the layers of said at least one stack (111), - the fixing of the spacer element (115, 215, 515, 615, 715), - the carrying out of a heat treatment to bond said stack (111) with said spacer element (115,215,515, 615,715).

3. A method according to claim 1 or 2, wherein the spacer element (515, 615, 715) comprises a first leg (516, 616, 716), a second leg (517, 617, 717), and a central portion (518, 618, 718) situated between the first leg (516, 616, 716) and the second leg (517, 617, 717), the first leg (516, 616, 716) and the second leg (517, 617, 717) being integral with the central portion (518, 618, 718) and fixed or arranged on one of the layers of said at least one stack (111), the central portion (518, 618, 718) being raised relative to the first leg (516, 616, 716) and the second leg (517, 617, 717), forming a recess (800) between the stack (111) and the raised central part (518, 618, 718).

4. Method according to claim 3, wherein each of the legs among the first leg (716) and the second leg (717) of the spacer element (715) forms a damping spring (7161, 7171) extending under the central part (718) of the spacer element (715).

5. A method according to any one of claims 1 to 4, wherein the spacer element (115) further comprises several protuberances (116) of a determined height, said protuberances (116) being in contact with the layer (112b) on which the spacer element (115) is fixed.

6. A method according to any one of claims 1 to 5, wherein each of the steps of said method is carried out for a plurality of substrates (110) simultaneously, said substrates (110) being mechanically coupled together to form a single panel.

7. Method according to claim 6, further comprising a step of decoupling a substrate 110 from the panel.

8. A method according to any one of claims 1 to 7, wherein the step of fixing at least one connector is carried out by laser welding.

9. Power electronic module (100) characterized in that it comprises a substrate having at least one stack (111) of several layers, a spacer element (115, 215, 315, 415, 515, 615, 715) disposed or fixed on one of the layers of the stack (111), the spacer element (115, 215, 315, 415, 515, 615, 715) having a thickness greater than or equal to 200 pm, at least one power connector (120) and, in that the power electronic module (100) is obtained by a process according to any one of claims 1 to 8.

10. Module according to claim 9, wherein said spacer element (115) further comprises several protrusions (116) of a determined height, said protrusions (116) being in contact with the layer on which the spacer element (115) is fixed.

Images