JP6639672B2 - Electric device with coating - Google Patents

Description

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

BACKGROUND ART Improving the reliability and efficiency of power electronics modules and rugged sensor systems and reducing costs are 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 for coating semiconductor components is known from DE 10201312267 A1. In this case, the coating material contains an additive having a high thermal conductivity.

German Patent Application No. 102013112267

DISCLOSURE OF THE INVENTION An object of the present invention is an electrical device comprising an electrical component at least partially covered by a coating comprising a cement material, wherein the coating further comprises thermal buffer particles, wherein the thermal buffer particles comprise cement. It is arranged in the material and is formed so that the phase transition proceeds while absorbing at least a part of the amount of heat released from the electric component.

The subject of the present invention is furthermore a method of manufacturing an electrical device comprising an electrical component at least partially covered by a covering comprising a cement material,
-Preparing a cement material;
-Mixing the thermal buffer particles formed such that the phase transition proceeds while absorbing at least a part of the amount of heat released from the electric component, into the cement material;
Applying a coating comprising a cement material mixed with thermal buffer particles to the electrical component such that the coating at least partially covers the electrical component;
Heat treating the coating;
Having.

  Another object of the present invention is the use of a material comprising cement material and thermal buffer particles as a coating for electrical components of an electrical device, wherein the thermal buffer particles are disposed within the cement material. In addition, it is formed so that the phase transition proceeds while absorbing at least a part of the amount of heat released from the electric component.

  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 have a support substrate on which electric components are arranged.

  Cement can mean, within the framework of the 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 method 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. The 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 wt% or more -CaO: 31.0 wt% -SiO _2: 0.8 wt% or less _-Fe 2 _O 3: and those having a 0.4 wt% or less Good to do.

  Thermal buffer particles may mean, in the context of the present invention, a particulate additive. Prior to the step of mixing the heat buffer particles into the cement material, the heat buffer particles may be formed in a powder form. However, the heat buffer particles may include a liquid component. Thus, the thermal buffer particles may be present, for example, as a solution or dispersion or suspension containing water. The thermal buffer particles may be incorporated into the dry cement material or cement powder mixture, ie, optionally before the added water is added. However, the thermal buffer particles may also be incorporated into the wet cementitious material or cement powder mixture, ie after the optional addition of water. The thermal buffer particles may have a particle diameter D50 in the range of 0.1 μm to 0.4 mm.

  In this case, the thermal buffer particles are formed such that the phase transition proceeds while absorbing a specific amount of heat. A phase transition may mean, within the framework of the present invention, a change in the state of aggregation, during which the temperature of the thermal buffer particles changes little or only slightly. In this case, the thermal buffer particles are formed so as to transition from a solid state to a liquid aggregate state when absorbing heat released from the electric component. As the material melts, i.e., transitions from the solid to the liquid phase, heat is consumed or absorbed, and this heat is potentially stored and stored as long as the liquid state exists. It is known that typical heat is released again upon condensation, ie during the transition from the liquid to the solid phase.

Coating material can mean any kind of sealing means (package) within the framework of the present invention. The covering may be formed as a cement composite material. That is, in other words, the dressing may include a cement matrix including a filler and thermal buffer particles. The coating material has the following composition:
-Binder Alumina cement: 8% to 47% by weight (for example, SECAR71)
-Reactant Water: 10% to 28% by weight-Thermal buffer particles: 4% to 30% 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: Fine about 1 μm to coarse about 100 μm
Preferably, it is selected from the group consisting of:

  The heat treatment step may comprise, within the framework of the present invention, a hydration step and / or a setting step and / or a drying step and / or a curing step. 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.

  Therefore, in the present invention, the thermal properties of the coating material are required based on the addition of the thermal buffer particles formed so that the phase transition proceeds while absorbing at least a part of the amount of heat released from the electric component. And the heat absorption of the coating material can be significantly improved. In other words, instead of trying to increase the thermal conductivity of the coating to release heat from the electrical components to the surrounding environment as quickly as possible, rather than to improve the heat absorption by the phase transition High thermal buffering and thus thermal overload capability is achieved. In this case, thermal buffering is performed by absorbing heat as a transition energy, for example, heat of fusion. In this case, the invention provides that during or during the phase transition, the temperature of the thermal buffer particles is kept substantially constant despite the heat absorption, and thus the thermal buffer particles temporarily absorb very high pulse loss power. In this case, the coating material or the electric component is not thermally loaded at that time.

  That is, the thermal conductivity of the coating may be set relatively low to favor the thermal capacity depending on the load during curing or operation, thereby providing a thermal conductivity between the thermal conductivity and the thermal capacity for the particular application. Can be achieved, and thus the operating conditions can be adjusted or optimized. Therefore, it is possible to provide an electric device that is particularly robust even when the power loss peak during operation is high and that protects electric components from overheating.

  Even more advantageous is when the thermal buffer particles are reversible in phase transition and are formed such that the phase transition proceeds while releasing at least a portion of the heat absorbed by the electrical component. . In this case, for example, the solid thermal buffer particles first melt while absorbing the heat, then release the heat at a low speed and condense again. Due to this measure, the heat absorption process and the heat release process can be sequentially and repeatedly carried out, so that long-term overheating protection of the electrical components can be guaranteed.

  It is further advantageous if the thermal buffer particles comprise or consist of a substance having a phase transition temperature in the range from 150 ° C. to 350 ° C., in particular about 300 ° C. By means of this measure, it is possible to further improve the heat absorption of the cladding and to very efficiently absorb and re-emit the heat from the electrical components up to an operating temperature of 350 ° C. become able to.

  It is also advantageous if the thermal buffer particles comprise or consist of a material selected from the group consisting of phase change materials, metals, metal alloys, especially In-Bi-Sn, plastics and glass. Each of the above substances has very good phase transition properties. Each of the above materials further has a phase transition temperature of about 300 ° C.

  Furthermore, the amount of the thermal buffer particles is advantageously in the range from 4% to 30% by weight, based on the total weight of the coating. Based on this measure, the heat absorption of the coating material can be further improved.

  It is also advantageous if the thermal buffer particles are arranged in a cement material. Thereby, the heat buffer particles are covered with the cement material. In this case, the thermal buffer particles are preferably uniformly dispersed in the cement material. By means of this measure, the heat released from the electrical component can be very well supplied to the thermal buffer particles via the cement material or can be absorbed by the thermal buffer particles.

  Furthermore, it is advantageous to provide an electrically insulating layer arranged between the covering and the electrical component. In this case, the electrical insulation layer preferably comprises or consists of alumina cement. The electrically insulating layer preferably does not contain thermal buffer particles, ie has no thermal buffer particles. This measure electrically insulates the electrical component from the coating containing the conductive thermal buffer particles when the thermal buffer particles are conductive, thereby ensuring that short circuits do not occur. .

  A further advantage is to provide a shielding layer which is arranged on one surface of the cement material and which is formed in such a way as to prevent the escape of the thermal buffer particles in the gas phase. In particular, the gas phase generated during operation of the electrical device, ie when the thermal buffer particles undergo a phase transition, may leak out of the coating. In order to prevent this, the covering material can be sealed with a shielding layer to prevent evaporation or leakage of the gas phase of the thermal buffer particles from the covering material. Undesirable leakage of the gas phase of the thermal buffer particles can change the stoichiometry of the alloy and thus the properties of the coating, condensing the vapors in the coating and additionally adding to the environment.

  It is also advantageous if the shielding layer comprises or consists of a material selected from the group consisting of monomers, polymers, especially silicones, and inorganic materials, especially oxides, nitrides, ceramics. . These substances are particularly well suited because they have very good gas or vapor shielding properties.

  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. 4 illustrates an electrical device according to another 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 electrical components 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 support substrate 14 on the side 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 track or a contact for contact connection of the electrical component 12 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 further covers a part of the support substrate 14, via which the cement material 22 is firmly connected to the support substrate 14.

  The coating material 20 or the cement material 22 includes a large number of heat buffer particles 24. These thermal buffer particles 24 are dispersed and arranged inside the cement material 22. Therefore, the thermal buffer particles 24 are covered with the cement material 22. In the present invention, the thermal buffer particles 24 include a particulate substance formed so that a phase transition proceeds while absorbing at least a part of the heat quantity 26 released from the electric component 12. Therefore, the coating material 20 according to the present invention has higher heat absorption based on the thermal buffer particles 24 than the coating material 20 having only the cement material 22, for example. Therefore, the heat particles 24 store the amount of heat 26 released from the electric component 12, and at that time, the phase of the heat particles 24 changes, and for example, the heat particles 24 melt by starting from a solid state, so that the heat amount is reduced by the heat buffer particles 24. Thereby, absorption can be performed particularly efficiently. In this case, the heat buffer particles 24 may release the absorbed heat quantity 26 to the environment around the electric device 10 at a low speed after the phase transition. During the phase transition, the temperature of the thermal buffer particles 24 remains substantially constant despite heat absorption, or rises only very slightly, so that a very high pulse loss power is temporarily provided by the thermal buffer particles 24. Although absorbed, the coating 20 or the electrical component 12 is not thermally loaded. Thus, in the present invention, it is possible to achieve a very high thermal overload capability, and thereby ensure reliable operation and protection of the electrical component 12 especially against overheating during power loss peaks. is there.

  The electric device 10 further has an electric insulating layer 28. The electrical insulation layer 28 is arranged between the covering 20 and the electrical component 12. The electrical insulation layer 28 is formed as a glob top. The electrical insulation layer 28 covers the electrical component 12 and thus forms an electrical insulating means for the electrical component 12. Thereby, for example, it is possible to prevent an electrical short circuit when the thermal buffer particles 24 are formed conductive.

  The electric device 10 further has a shielding layer 30. The shielding layer 30 is disposed on one surface 32 of the covering material 20 or the cement material 22. The shielding layer 30 is formed closed, thereby forming a kind of gas shield or vapor shield for the covering material 20. Thereby, for example, the gas phase of the thermal buffer particles 24 generated during the phase transition can be prevented from leaking from the coating material 20.

  FIG. 2 shows another electrical device 10 'according to the present invention. The electric device 10 'has the same configuration as the device 10 shown in FIG. However, the electric insulating layer 28 'of the electric device 10' is formed as a thin film. The electrical insulation layer 28 ′ extends over the entire interface between the covering 20 and the electrical component 12 or the support substrate 14.

  When manufacturing the electric devices 10, 10 'according to the present invention, first, the cement material 22 is prepared, for example, in a powder form. Next, the thermal buffer particles 24, which may also be in powder form, are mixed into the cement material 22, for example. The liquid component, for example water, is then mixed, optionally with a solvent melt flux. The cement material 22, the thermal buffer particles 24, and the wet coating 20, including water, are 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 heat treated or malleable, for example, at 60 ° C. and 90% relative air humidity, whereby the gelation, crystallization, needling and hardening of the cement 22 is performed. In this case, the air humidity prevents moisture loss (water / cement ratio) and the heat causes the formation of the desired structure. Finally, the heat-absorbing particles 24 are optionally applied to the coating material 20 and then released and released, for example, at 300 ° C.

  Additionally, at the start of production, additionally, a moist cement material free of heat buffer particles may be prepared according to the steps described above. In this case, the cement material can be applied as an electrically insulating layer 28 to the electrical component 12 and possibly the support substrate 14 before the application of the coating material 20 containing the thermal buffer particles 24. However, the electrically insulating layer 28 may be disposed between the electrical component 12 and the cladding 20 in any manner known to those skilled in the art without departing from the scope of the present invention.

  Additionally and additionally, the shielding layer 30 may be applied to the surface 32 of the dressing 20 or cementitious material 22 in any manner known to those skilled in the art, for example, by injecting or pouring the shielding layer 30 into the coating 20, or by immersion water The coating material 20 may be applied by immersing the coating material 20 in the coating material.

Claims (16)

An electrical device comprising an electrical component (12) at least partially coated with a coating (20) comprising a cement material (22),
The coating (20) includes thermal buffer particles (24), the thermal buffer particles (24) being disposed within the cement material (22), and further comprising a thermal buffer particle (24) from the electrical component (12). It is formed such that the phase transition proceeds while absorbing at least a part of the released heat (26) ,
The thermal buffer particles (24) include a substance having a phase transition temperature in a range from 150 ° C to 350 ° C,
An electrical device, characterized in that:   The electrical device (10) of claim 1, wherein the cement material (22) comprises alumina cement.   The phase transition of the thermal buffer particles (24) is reversible, and the thermal buffer particles undergo the phase transition while releasing at least a part of the heat quantity (26) absorbed by the electric component (12). The electrical device (10) according to claim 1 or 2, wherein the electrical device (10) is formed as follows.   The thermal buffer particles (24) are configured to transition from a solid to a liquid agglomerated state upon absorption of the amount of heat (26) released from the electrical component (12). An electrical device (10) according to any one of the preceding claims.   The electrical device (10) according to any of the preceding claims, wherein the thermal buffer particles (24) comprise a substance having a phase transition temperature of 300C.   The electrical device (10) according to any of the preceding claims, wherein the thermal buffer particles (24) comprise a material selected from the group consisting of phase change materials, metal alloys, plastics and glass. The electrical device (10) according to claim 6 , wherein the metal alloy is In-Bi-Sn. Wherein the amount of the total weight of the coating material (20), wherein the thermal buffer particles (24) is in the range of 4 wt% to 30 wt% or less, according to any one of claims 1 to 7 The electrical device (10). Wherein during the coating material (20) and said electrical component (12) is electrically insulating layer (28) is arranged, the electrical device according to any one of claims 1 to 8 (10) . The electrical device (10) according to claim 9 , wherein the electrical insulation layer (28) comprises alumina cement. A shielding layer (30) is disposed on one surface (32) of the cement material (22), and is formed so as to prevent leakage of the gas phase of the thermal buffer particles (24). It has electrical device according to any one of claims 1 to 10 (10). The electrical device (10) of claim 11 , wherein the shielding layer (30) comprises a material selected from the group consisting of a monomer, a polymer, and an inorganic material. The electrical device (10) according to claim 12 , wherein the polymer is silicone and the inorganic material comprises a material selected from the group consisting of oxides, nitrides, and ceramics. The electrical components (12), the semiconductor component (12), the sensor element, an inductance, a capacitance, the battery cell, the battery module, or a circuit, an electrical device according to any one of claims 1 to 13 (10). According to any one of claims 1 to 14, for manufacturing an electrical device (10) comprise an electrical component (12) at least partially coated with a coating material containing cement material (22) (20) A method for
Providing the cement material (22);
Mixing the thermal buffer particles (24) formed so that the phase transition proceeds while absorbing at least a part of the heat quantity (26) released from the electric component (12) into the cement material (22). Steps to
Applying the coating material (20) including the cement material (22) mixed with the thermal buffer particles (24) to the electric component (12);
-Heat treating said coating material (20);
A method comprising: Thermal buffer particles arranged in the cement material (22) and further formed to absorb at least a part of the heat quantity (26) released from the electric component (12) and to cause the phase transition to proceed. An electrical device (10) according to any one of claims 1 to 14 , or an electrical device (10) made by a method according to claim 15 , of a material comprising (24) and a cement material (22). 10) Use as a covering material (20) for an electric component (12).

Images