JP6629447B2 - Method for manufacturing an electrical device having a coating - Google Patents

Description

  The present invention relates to a method for manufacturing an electrical device comprising electrical components at least partially covered by a covering and to such an electrical device.

BACKGROUND ART Improving the reliability and efficiency of power electronics modules and rugged sensor systems and reducing costs is of paramount importance today. Current coating materials (epoxy compounds, silicone materials) are limited to a temperature range below 200 ° C. By developing a temperature range of up to 300 ° C. to 350 ° C. for coatings, modern power semiconductors (eg SiC) without having to give up additional functions of the coating (eg protection against environmental conditions, improved thermals) Can be extended to over 200 ° C.

  From DE 102013112267 A1 a semiconductor module with a coating of various types of cement is known for coating semiconductor components. In this case, the coating material has an adhesion-mediating layer, which is applied to the semiconductor component by spraying in a separate manufacturing step.

German Patent Application Publication No. 1020131312267

DISCLOSURE OF THE INVENTION An object of the present invention is a method for manufacturing an electrical device comprising an electrical component at least partially coated with a coating comprising a cement material, the method comprising:
-Preparing cement material;
Mixing an additive into the cement material;
Applying a coating comprising an entrained cement material to the electrical component such that the electrical component is at least partially covered by the coating;
The step of treating the cladding, whereby the additives reach the interface between the cement and the cladding and the electrical component to form a functional layer at the interface and / or Or to enlarge the interface wetted by the coating, and
Having.

  The subject of the present invention is further an electrical device comprising an electrical component at least partially coated by a coating comprising a cement material, wherein an additive is arranged at an interface between the coating and the electrical component. The additive reaches the interface between the coating material and the electrical component from inside the cement material, thereby forming a functional layer containing the additive at the interface, and / or The interface wetted by the material will be enlarged.

  Another object of the invention is the use of additives for forming a functional layer on a coating, including a cement material, of an electrical component of an electrical device, wherein the additive is treated with the coating by treating the coating. The interface between the electrical components is reached, forming a functional layer on the interface and / or enlarging the interface wetted by the coating.

  The electrical component may be, for example, a semiconductor component, a sensor element, an inductance, a capacitance, a battery cell, a battery module, or an entire circuit. However, the electrical component can mean any active / passive component or high power component within the framework of the present invention. In this case, the electric device may include a support substrate on which electric components are arranged.

  Cement can mean, in the context of the present invention, an inorganic, metal-free hydrobinder. In this case, the cement hardens in water, ie it chemically reacts with water to form a stable compound that does not decompose. In this case, at the beginning of the process or before hydration, the cement is formed as a finely ground powder, which reacts with water or added water to set and harden to form a hydrate. It is good. In this case, the hydrates may form needles and / or platelets that mesh with one another and thus provide a high strength of the cement. In contrast, phosphate cement does not harden in water. An acid-base reaction is performed to form a salt gel, which later condenses to a largely amorphous material. In the acid-base reaction, H + (hydrogen ion) is exchanged.

The cement may consist primarily of calcium aluminate and may form calcium aluminate hydrate during hydration. It is advantageous if the cement material comprises alumina cement, in particular if it consists of alumina cement. Alumina cement (abbreviated CAC) has been prepared according to DIN EN 14647 in a European manner. Alumina cement consists mainly monocalcium aluminate ^{_{(CaO * Al 2 O 3)}} .

Alumina cement has, for example, the following composition:
-Al ₂ O ₃ : 67.8% by weight or more-CaO: 31.0% by weight or less-SiO ₂ : 0.8% by weight or less-Fe ₂ O ₃ : 0.4% by weight or less Good to do.

  Additives can mean, within the framework of the present invention, admixtures or layer formers. The additive may optionally or additionally have properties that promote wetting. Prior to the step of mixing the additive into the cement material, the additive may be formed into a powder. However, the additive may include a liquid component. Thus, the additive may be present, for example, as a solution or dispersion or suspension containing water. Ideally, the additives are mixed or dissolved in the water mixture. Additives may be incorporated into the dry cement material or cement powder mixture, ie, optionally before the added water is added. However, the additives may also be incorporated into the wet cementitious material or the cement powder mixture, ie after the optional addition of water.

Coating material can mean any kind of sealing means (package) within the framework of the present invention. The dressing may be formed as a cement composite material. That is, in other words, the coating material may include a cement matrix including a filler and an additive. The coating, before and / or after the processing step, has the following composition:
-Binder Alumina cement: 8% by weight or more and 47% by weight or less (for example, SECAR71)
-Reactant water: 10 to 28% by weight-Additive: 1 to 25% by weight-Filler: 25 to 82% by weight.

The filler is
-Al ₂ O ₃ : Fine d50 about 1 μm to coarse d50 about 150 to 200 μm
-Α-type Si ₃ N ₄ : Fine about 1 μm to coarse about 100 μm
-Hex. BN: about 15 μm to coarse about 250 μm
-SiC: Fine about 10 to 50 μm to coarse about 600 μm
-AlN: about 1 μm to coarse about 100 μm
Should be selected from the group consisting of:

  The processing step can further stimulate the additive. A processing step may include a number of sub-steps. The processing steps may include a hydration step and / or a setting step and / or a drying step and / or a curing step. The processing steps may include a waiting step, for example, to wait or advance a "voluntary" process. The treating step allows the additive to be "driven" from within the cement material to the interface between the cladding and the electrical component. However, the processing step may allow the additive to continue without doing anything from the interior of the cement material until it reaches the interface between the coating and the electrical component. That is, in other words, in the processing step, it is possible to wait until the additive reaches the interface between the cladding and the electrical component, for example due to gravity. The treating step may further stimulate the additive such that a functional layer is formed at the interface and / or the interface wetted by the coating material is enlarged. In this case, the interface preferably also includes the contact surface between the coating material and, if appropriate, the carrier substrate on which the electrical components are arranged.

  The coating according to the invention, advantageously by adding appropriate additives to the cementitious material during or during the treatment of the coating, i.e. additionally simultaneously in the same manufacturing step, simultaneously with the coating and the electrical component It is possible to form a functional layer at the interface between and and / or to enlarge the interface wetted by the coating. In other words, in other words, for example, during the setting or drying of the coating, a boundary layer is created at the interface, which deposits or deposits on the electrical components and hardens there, thereby already having an electrical effect during this stage. Provides protective means for the component and possibly another component. Alternatively or additionally, for example, during the setting or drying of the coating, the additives deposit on the interface and, based on their properties, enlarge the interface wetted by the coating. Thus, on the one hand, the additional processing step of coating the electrical component before applying the cement material to the electrical component is completely omitted. On the other hand, the (protective) function of the functional layer is not provided only after it is completed, but is already provided during the processing of the coating.

  It is furthermore advantageous if the functional layer is formed as an electrical and / or chemical insulating layer and / or as an adhesion-mediating layer. Therefore, the functional layer may have an electrically and / or chemically insulating property and / or a property of mediating adhesion. Due to the electrically insulating functional layer or the electrically insulating layer formed at the interface, during the treatment step of the coating material, ie during the hydration and / or setting and / or drying and / or curing processes However, it is possible to prevent an electric short circuit caused by the coating material that is still wet. Due to the chemically insulating functional layer or the chemical insulating layer formed at the interface, during the treatment step of the coating, i.e. during the hydration and / or setting and / or drying and / or curing processes In it, (perishable) metals or components can be protected from strong basic cementitious materials. Furthermore, such functional layers provide a means of additionally protecting the electrical components from the ingress of foreign matter into the coating, either after completion of the electrical device or during operation. Alternatively or additionally, the functional layer may also have the property of mediating or improving the adhesion, so that the electrical components and, if appropriate, the coating on the support substrate Optimum adhesion and thus improved sealing properties can also be guaranteed.

In the coating material processing step, each of the following processing, namely,
-Applying vibration, rocking movement and / or centrifugal movement to the covering material;
-Heat treatment of the coating material,
-A process of exposing the coating material to a predetermined gas atmosphere;
A process of applying a predetermined pressure to the coating material,
It is further advantageous if the coating comprises at least one of the treatments of radiating electromagnetic radiation of a predetermined wavelength and intensity, for example UV radiation, infrared radiation, visible radiation.

  By applying vibrations, rocking movements and / or centrifugal movements to the coating, the additives can be very easily mixed and separated in order to reach the interface.

  The heat treatment may include a tempering step in a tempering furnace. The heat treatment is preferably performed in a temperature range of 40 ° C. or more and 95 ° C. or less.

  The gas atmosphere may be formed as air or air, for example, having an increased air humidity of up to 100%. The gas atmosphere may include catalyst molecules or promoter molecules.

  By this means, the parameters for activating the function of the additive can be easily adapted, so that the additive reliably and efficiently reaches the interface between the coating and the electrical component. A functional layer can be formed on this interface, or the interface wetted by the coating can be enlarged.

  Further, it is advantageous if the step of treating the coating material causes the additive to settle or float at the interface between the coating material and the electrical component. In this case, the additives are concentrated at the interface between the coating and the electrical component in order to enlarge the interface that forms the functional layer and / or is wetted and / or the coating and the electrical component The reaction may be at the interface between the component and the component. Therefore, it is preferable that the additive is formed so as to react in a specific condition frame (temperature, UV irradiation, pH value). Particularly suitable are substances or particles that settle or settle well in the cement slurry, for example by gravity, towards the interface between the cladding and the electrical component, where they are concentrated. In this case, the interface must be located below the coating in order for the additive to be able to settle based on the density difference. By rotating the arrangement by 180 °, i.e. by arranging the cladding so that the interface is above the cladding, it floats within the cement slurry and quickly forms one layer. Substances or particles may be used. It is also conceivable that the additive contains two reactants that are subcritical and densely dissolved in the cement material at the time of application of the coating to the electrical component and are concentrated during processing. By this means, the additives can easily reach the interface, where they can form a functional layer and / or enlarge the interface to be wetted.

  Furthermore, it is advantageous if the following additional steps are performed. That is, placing a reactive layer at the interface between the coating and the electrical component, thereby allowing the additive to react with the reactive layer at the interface to form a functional layer. . That is, in other words, the reaction layer is applied to the electrical component before the coating is applied to the electrical component. The reaction layer may be formed, for example, as a monomolecular polymer layer. The reaction layer may contain hexamethyldisilazane (HMDS). Now that a reaction layer is located at the interface between the cladding and the electrical component, the additive can react with the reaction surface at the interface to form a functional layer, thereby forming a layer. Is optimized, and the insulating properties and adhesion properties can be further improved.

  It is also advantageous if the additives are selected from the group consisting of monomers, polymers, especially silicones, and inorganic substances, especially oxides, nitrides, silanes, ceramics. In this case, each of the selected substances must be formed so as to stably maintain the required temperature during processing or malleability and, in some cases, during operation. The additive may comprise, in particular, vinyl alcohol or a mixture consisting of vinyl alcohol, or may consist of vinyl alcohol. Each of said substances or groups of substances has very good electrical and chemical insulation properties, and thus can be used to connect electrical components and perishable metals and other components to short-circuiting and strong basic cements with corrosive action. Particularly well-suited for protection from materials.

  Furthermore, it is advantageous if the functional layer and the additives are designed to decompose or dissolve after the processing step. This may be done, for example, by heat generated during operation, for example, above 250 ° C. That is, in other words, the functional layer is a "critical step" in order to prevent electrical short circuits in the wet cement material and to provide a means of chemical protection from the strongly basic cement material having a corrosive effect. That is, it dissolves after being provided only for the drying and curing processes. This has the advantage that very thin functional layers are sufficient, without having to provide a long-term insulating action. Since the dried cement has good insulation properties, the functional layer only needs to insulate a very small current until the cement material dries.

  It is also advantageous if the additive is further arranged inside the cement material. In this case, only a small amount of additive may be present in the cement material. Due to the "excess" additive in the cement material, some residual amount remains in the cement material after the layer is formed, so that the initial amount of the additive is reduced to a functional layer which is preferably formed in a closed manner. Is guaranteed to be sufficient to form

Furthermore, it is advantageous if the additive is a wetting aid . In this case, the wetting aid or adhesion mediator or primer may suitably be a silane adhesion mediator. By this measure, the adhesion of the cement can be greatly improved by increasing the wetted interface.

  The present invention will be described in more detail with reference to the accompanying drawings illustrated below.

FIG. 2 illustrates an electrical device according to one embodiment of the present invention.

  FIG. 1 shows an electrical device according to the invention, generally designated by the reference numeral 10.

  The electrical device 10 has an electrical component 12. The electrical component 12 is formed as a semiconductor component 12. The electrical components 12 are arranged on a support substrate 14. A copper layer 16 is arranged between the electric component 12 and the support substrate 14. In this case, the copper layer 16 has a plurality of functions, i.e., a function of improving thermal connection and heat dissipation, a function of providing an electrical contact connection to the electrical component 12, and, in some cases, a coating material at the time of application. It has a function as a flow stop.

  The electric component 12 is connected to the side of the support substrate 14 opposite to the electric component 12 via the bonding wire 18, so that the electric component 12 is electrically connected to the electric component 12 from the outside. It becomes possible. In this case, the support substrate 14 may be formed, for example, as a plate into which a conductor path for contact connection of the electrical component 12 or an electrical contact can be further incorporated. The conductor tracks may be arranged on one surface of the support substrate 14. The support substrate 14 is preferably formed so as to form a chip.

  The electric device 10 further has a covering material 20 including a cement material 22. The coating material 20 or the cement material 22 is formed as a glob-top. The coating material 20 or the cement material 22 is disposed on the support substrate 14. In this case, the cement material 22 covers the electrical component 12 on the side not covered by the support substrate 14. Therefore, the electric component 12 is entirely covered with the support substrate 14 and the covering material 20. The cement material 22 also covers a part of the support substrate 14, via which the cement material 22 is firmly connected to the support substrate 14.

The electrical device 10 has an interface 24 between the covering 20 or cement 22 and the electrical component. In this case, the boundary surface 24 includes the contact surface between the coating material 20 and the support substrate 14. On the boundary surface 24, a functional layer 26 is arranged. In the present invention, the functional layer 26 includes an additive 28. In this case, the additives 28 are applied from the interior of the cement material 22 to or at the interface 24 between the coating material 20 and the electrical component 12 by or during the treatment of the coating material 20 , especially during the setting of the cement material 22. To reach. This may be done, for example, by settling and / or floating of the additive 28 on the interface 24 between the coating 20 and the electrical component 12. In this case, the functional layer 26 is formed in the present invention by the deposition and curing of the additive 28 and, in some cases, the chemical reaction at the interface 24. In this case, the functional layer 26 is preferably formed to be electrically and chemically insulative and to mediate the adhesion, so that during the curing process, the electrical insulation of the still wet coating 20 is achieved. Providing a means of preventing short circuits and protecting the components from the basic cementitious material 22, and further improving the adhesion of the coating 20 on the electrical components 12 and possibly the support substrate 14. Can be.

However, it is also conceivable that the additive 28 does not form a functional layer on the interface 24, but rather enlarges the interface 24 that is wetted by the coating 20, thereby again providing the electrical component 12 and In some cases, the adhesion of the coating material 20 on the support substrate 14 can be improved. The additive 28 is then soluble in the basic gel phase of the dressing 20 .

  When manufacturing the electric device 10, first, the cement material 22 is prepared, for example, in a powder form. Next, an additive 28, which may also be in powder form, is mixed into the cement material 22. The liquid component, for example water, is then mixed, optionally with a solvent melflux. The wet coating 20, including the cement 22, additive 28 and water, is then evacuated and applied to the electrical component 12 and molded, for example, by injection or casting into a mold. The coating 20 is then treated, for example at 60 ° C. and 90% relative air humidity, in particular heat-treated or malleable, so that the cement 22 is gelled, crystallized, needled and hardened. In this case, the air humidity prevents moisture loss (water-cement ratio) and the heat causes the formation of the desired structure. During or during processing, i.e., from gel formation to hardening, in the present invention, the additive 28 is coated with the coating 20 and the electrical components from within the applied coating 20, for example by settling or floating. A functional layer 26 is formed at the interface 24 by reaching and reacting and hardening at the interface 24 between them. Alternatively or additionally, additive 28 may also enlarge interface 24 that is wetted by coating 20. Finally, the protective layer 26 is arbitrarily applied to the coating material 20 and then released, and the product is discharged, for example, at 300 ° C.

Claims (12)

A method for manufacturing an electrical device (10) comprising an electrical component (12) at least partially covered by a coating (20) comprising a cement material, comprising:
Providing the cement material (22);
-Mixing an additive (28) with the cement material (22);
Applying the coating material (20) including the cement material (22) mixed with the additive (28) to the electric component (12);
A step of treating said coating material (20), whereby said additive (28) converts said cement material (22) from said coating material (20) to said electrical component (12); To reach the interface (24) between them, to form a functional layer (26) at the interface (24) and / or to enlarge the interface (24) wetted by the coating (20). The steps
A method comprising:   The method of claim 1, wherein the cement material (22) comprises alumina cement.   The method according to claim 1 or 2, wherein the functional layer (26) is formed as an insulating layer (26) and / or an adhesion mediating layer (26). In the step of processing the covering material (20), each of the following processes is performed:
-Applying vibration, rocking movement and / or centrifugal movement to said covering material (20);
A treatment of heat treating the coating material (20);
-A process of exposing the coating material (20) to a predetermined gas atmosphere;
A process of applying a predetermined pressure to the coating material (20);
Method according to any of the preceding claims, wherein at least one of the treatments of irradiating the coating (20) with electromagnetic radiation is included.   Treating the coating (20) causes the additive (28) to settle or float at the interface (24) between the coating (20) and the electrical component (12); The method according to claim 1.   The additive (28) forms a layer of the functional layer (26) and / or expands the interface (24) to be wetted by the coating (20) and the electrical component (12). The method of claim 5, wherein the interface (24) is concentrated at the interface (24) and / or reacts at the interface (24) between the cladding (20) and the electrical component (12).   In an additional step, a reaction layer is arranged at the interface (24) between the cladding (20) and the electrical component (12) so that the additive (28) The method according to claim 6, wherein the method enables the formation of the functional layer (26) by reacting with the reaction layer.   The method according to any of the preceding claims, wherein the additive (28) is selected from the group consisting of monomers, polymers, and inorganic substances.   The method of claim 8, wherein the polymer is silicone and the inorganic material comprises a material selected from the group consisting of oxides, nitrides, silanes, and ceramics.   The method according to any of the preceding claims, wherein the additive (28) is a wetting aid.   The method according to any of the preceding claims, wherein the functional layer (26) and / or the additive (28) are configured to degrade after the step of treating the coating (20). The described method. The electrical components of the electrical device produced by the method according to any one of claims 1 to 11 (10) (12), the functional layer in the dressing (20) comprising a cement material (22) (26 ), Wherein the additive (28) is treated with the coating (20) and the electrical component (12) by treating the coating (20). ) To form the functional layer (26) on the interface (24) and / or to wet the interface (24) with the coating (20). Use of the additive (28) to expand.

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